ecologia mediterranea - Université d'Avignon et des Pays de Vaucluse
ecologia mediterranea - Université d'Avignon et des Pays de Vaucluse
ecologia mediterranea - Université d'Avignon et des Pays de Vaucluse
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<strong>ecologia</strong> <strong>mediterranea</strong><br />
SOMMAIRE – CONTENTS<br />
TOMÁS PAVLÍCEK, VLADIMIR CHIKATUNOV & EVIATAR NEVO<br />
Arthropods in the mounds of mole rats,Spalax ehrenbergi superspecies,<br />
in Israel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5<br />
FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL NAGGAR<br />
Tome 31 fascicule 1, 2005<br />
ISSN 0153-8756<br />
AND KHADIJA A. BAAYO<br />
Veg<strong>et</strong>ation structure and environmental gradients in the Sallum area, Egypt . . . 15<br />
Tome 31 fascicule 1, 2005<br />
M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
Phenological patterns of ground spi<strong>de</strong>rs (Araneae, Gnaphosidae)<br />
on Cr<strong>et</strong>e, Greece . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33<br />
L.M.M. BIDAK<br />
On the seed ecology of two life forms of Spergularia (Caryophyllaceae) . . . . . . . 55<br />
SÉBASTIEN AUBRY & FRÉDÉRIC MAGNIN<br />
Factors structuring land snail communities in South-Eastern France: a comparison of<br />
two estimation m<strong>et</strong>hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65<br />
CYRILLE B. K. RATHGEBER, ANTOINE NICAULT & JOËL GUIOT<br />
Évolution <strong>de</strong> la croissance radiale du pin d’Alep (Pinus halepensis Mill.)<br />
en Provence calcaire (sud-est <strong>de</strong> la France) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75<br />
GÉRARD DE BÉLAIR<br />
Dynamique <strong>de</strong> la végétation <strong>de</strong> mares temporaires en Afrique du Nord (Numidie<br />
orientale, NE Algérie) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83<br />
Faits <strong>de</strong> conservation en Méditerranée . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101<br />
Analyses d’ouvrages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107<br />
Résumés <strong>de</strong> thèse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111<br />
Revue in<strong>de</strong>xée dans Pascal-CNRS <strong>et</strong> Biosis<br />
<strong>ecologia</strong> <strong>mediterranea</strong><br />
Tome 31<br />
Fascicule 1, 2005<br />
ISSN 0153-8756<br />
Revue internationale<br />
d’écologie méditerranéenne<br />
International Journal<br />
of Mediterranean Ecology
<strong>ecologia</strong><br />
<strong>mediterranea</strong><br />
Revue internationale<br />
d’écologie méditerranéenne<br />
International Journal<br />
of Mediterranean Ecology<br />
Tome 31 • Fascicule 1 • 2005
Rédacteur en chef • Managing editor Secrétariat • Secr<strong>et</strong>ariat<br />
FRÉDÉRIC MÉDAIL<br />
MICHELLE DOUGNY<br />
Rédacteurs • Editors<br />
LAURENCE AFFRE<br />
THIERRY DUTOIT<br />
JÉRÔME ORGEAS<br />
PHILIP ROCHE<br />
THIERRY TATONI<br />
ERIC VIDAL<br />
Fondateur • Foun<strong>de</strong>r<br />
PROFESSEUR PIERRE QUÉZEL<br />
Comité <strong>de</strong> lecture • Advisory board<br />
ARONSON J., CEFE-CNRS, Montpellier<br />
BARBERO M., IMEP, Université Aix-Marseille III<br />
BEAULIEU J.-L. DE, IMEP, Université Aix-Marseille III<br />
BROCK M., University of New England, Armidale, Australie<br />
CHEYLAN M., EPHE, Montpellier<br />
DEBUSSCHE M., CEFE-CNRS, Montpellier<br />
FADY B., INRA, Avignon<br />
GRILLAS P., Station biologique Tour du Valat, Arles<br />
GUIOT J., CEREGE-CNRS, Aix-en-Provence<br />
HOBBS R. J., CSIRO, Midland, Australie<br />
KREITER S., ENSA-M-INRA, Montpellier<br />
LE FLOC’H E., CEFE-CNRS, Montpellier<br />
MARGARIS N. S., University of the Aegean, Mytilène, Grèce<br />
OVALLE C., CSI-Quilamapu, INIA, Chili<br />
PEDROTTI F., Universita <strong>de</strong>gli Studi, Camerino, Italie<br />
PLEGUEZUELOS J. M., Université <strong>de</strong> Grena<strong>de</strong>, Espagne<br />
PONEL P., IMEP, CNRS, Marseille<br />
PRODON R., EPHE, Montpellier<br />
RIDCHARSON D. M., University Cape Town, Afrique du Sud<br />
SANS F. X., Université <strong>de</strong> Barcelone, Espagne<br />
SHMIDA A., Hebrew University of Jérusalem, Israël<br />
TROUMBIS A., University of the Aegean Mytilene, Grèce<br />
URBINATI C., Agripolis, Legnaro, Italie<br />
Ecologia <strong>mediterranea</strong><br />
Ecologia Mediterranea<br />
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ISSN 0153-8756
<strong>ecologia</strong><br />
<strong>mediterranea</strong><br />
Revue internationale<br />
d’écologie méditerranéenne<br />
International Journal<br />
of Mediterranean Ecology<br />
Tome 31 • Fascicule 1 • 2005
Arthropods in the mounds of mole rats,<br />
Spalax ehrenbergi superspecies, in Israel<br />
Arthropo<strong><strong>de</strong>s</strong> dans les monticules <strong>de</strong> rats-taupes<br />
<strong>de</strong> la super-espèce Spalax ehrenbergi en Israël<br />
Tomás Pavlícek*, Vladimir Chikatunov** & Eviatar Nevo*<br />
* Institute of Evolution, University of Haifa, Mt. Carmel, Haifa 31905, Israel<br />
** Department of Zoology, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel<br />
Address for correspon<strong>de</strong>nce: Dr. Tomás Pavlícek, Institute of Evolution, University of Haifa,<br />
Mt. Carmel, Haifa 31905, Israel. Tel. ++972-4-8240460, e-mail: patricia@research.haifa.ac.il.<br />
5<br />
Abstract<br />
A complex of invertebrates (mites, Collembola, earthworms,<br />
snails, Diplopoda, Myriapoda, Chilopoda, Isopoda and insects)<br />
was uncovered in large breeding mounds ma<strong>de</strong> by the blind subterranean<br />
mole rat (belonging to the species Spalax carmeli Nevo<br />
& Ivanitskaya & Beiles, 2000 of the Spalax ehrenbergi (Nehring,<br />
1898) superspecies) in the Haifa region, situated in the Northern<br />
Coastal Plain of Israel. The <strong><strong>de</strong>s</strong>cribed properties of this complex<br />
were based on the 56 be<strong>et</strong>le species found there, mostly collected<br />
from the outer compact wall of the breeding mounds by forceps<br />
and exhausters. Most of the recor<strong>de</strong>d be<strong>et</strong>le species were xerophiles<br />
or mesophiles and carnivores or d<strong>et</strong>ritivores. Only few species were<br />
phytophages, coprophages or necrophages. Since the invertebrate<br />
complex <strong>de</strong>rives from the unique breeding mounds architecture, the<br />
mole rats can be consi<strong>de</strong>red as ecological architects of this microscale<br />
ecosystem.<br />
Key-words<br />
Spalax, breeding mounds, invertebrates, be<strong>et</strong>les, Israel<br />
Résumé<br />
Un complexe d’invertébrés (mites, collemboles, vers <strong>de</strong> terre, escargots,<br />
diplopo<strong><strong>de</strong>s</strong>, myriapo<strong><strong>de</strong>s</strong>, chilopo<strong><strong>de</strong>s</strong>, isopo<strong><strong>de</strong>s</strong> <strong>et</strong> insectes) a été<br />
mis au jour dans <strong>de</strong> grands monticules <strong>de</strong> reproduction construits<br />
par le rat-taupe souterrain aveugle (appartenant à l’espèce Spalax<br />
carmeli <strong>de</strong> la super-espèce Spalax ehrenbergi) dans la région <strong>de</strong><br />
Haïfa, située dans la plaine côtière septentrionale d’Israël. Les<br />
caractéristiques <strong>de</strong> ce complexe ont été décrites à partir <strong><strong>de</strong>s</strong> 56 espèces<br />
<strong>de</strong> coléoptères trouvées à c<strong>et</strong> endroit, pour la plupart dans la<br />
paroi extérieure compacte <strong><strong>de</strong>s</strong> monticules d’élevage. La majorité <strong><strong>de</strong>s</strong><br />
coléoptères recensés sont xérophiles ou mésophiles <strong>et</strong> carnivores ou<br />
détritivores. Seules quelques espèces sont phytophages, coprophages<br />
ou nécrophages. Étant donné que le complexe d’invertébrés est le<br />
produit <strong>de</strong> l’architecture unique en son genre <strong><strong>de</strong>s</strong> monticules <strong>de</strong><br />
reproduction, les rats-taupes peuvent être considérés comme <strong><strong>de</strong>s</strong><br />
architectes écologiques <strong>de</strong> ce micro-écosystème.<br />
Mots-clé<br />
Spalax, monticules <strong>de</strong> reproduction, invertébrés, coléoptères, Israël<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 5-13
◆ T. PAVLICEK, V. CHIKATUNOV & E. NEVO<br />
6<br />
INTRODUCTION<br />
Large soil structures such as breeding mounds of mole<br />
rats (fig. 1; Nevo, 1961, 1991, 1999) might be used as a<br />
shelter and as a breeding and living place by a number<br />
of invertebrates. To obtain preliminary knowledge about<br />
invertebrates living in the breeding mounds of mole rats,<br />
we studied such mounds near of the area known as Check<br />
Post in Haifa, Israel. These huge breeding mounds, built<br />
by Spalax carmeli Nevo & Ivanitskaya & Beiles, 2000<br />
(S. ehrenbergi Nehring, 1898 superspecies) might be<br />
the most elaborate in Israel, probably due to the poor<br />
soil drainage at the locality (Nevo, 1961). The mole rat<br />
superspecies, Spalax ehrenbergi, distributed in the Middle<br />
East (Nevo, 1991, 1999; Nevo <strong>et</strong> al., 2000), is a blind,<br />
solitary, subterranean mammal. Both, females and males,<br />
build relatively small nutritional mounds. However, both<br />
gen<strong>de</strong>rs build also during the winter breeding season<br />
(October to March/April), particularly in poorly-drained<br />
soil, much bigger mounds that are either dome-shaped<br />
(females) or cone-shaped (males) (Nevo, 1961). During<br />
the breeding season, females use the big winter mounds<br />
for breeding and males for resting. After this period,<br />
during summer time, males and females r<strong>et</strong>urn to <strong>de</strong>eper<br />
runways. The burrowing activity is then limited because<br />
of the soil dryness.<br />
Female breeding mounds, the subject of our study,<br />
constitute a system composed of a central breeding nest,<br />
storage chambers containing bulbs and rhizomes, and<br />
sanitary chambers (toil<strong>et</strong>s), all connected by spiraling<br />
tunnels and roofed by a solid dome (fig. 1). Female<br />
breeding mounds are connected with the peripheral<br />
region by feeding tunnels (Nevo, 1961). In floo<strong>de</strong>d<br />
areas with poorly drained dark alluvial clayey soils, the<br />
breeding mounds might be exceptionally large. They have<br />
well-plastered tunnels and are more solidly constructed<br />
than breeding mounds built in areas with good drainage<br />
(Nevo, 1961).<br />
Figure 1. Breeding mound of the blind mole rat, Spalax ehrenbergi.<br />
Cross section in a natural breeding mound (note the nest in the centre and the storage chambers in the periphery)<br />
(from Nevo, 1999, with permision of the author).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ARTHROPODS IN THE MOUNDS OF MOLE RATS, SPALAX EHRENBERGI SUPERSPECIES, IN ISRAEL ◆<br />
MATERIALS AND METHODS<br />
The study of the invertebrate complex in the breeding<br />
mounds of mole rat, Spalax carmeli (2n = 58) was<br />
conducted in an uncultivated field near of Check-Post,<br />
Haifa, Israel. Zoogeographically, the studied area is part<br />
of the Northern Coastal Plain (see zoogeographical areas<br />
in Israel in Fishelson, 1985).<br />
The studied field consists of black alluvial soil (Atlas<br />
of Israel, 1970), has poor drainage, and the water table<br />
is 0-50 cm below the surface (Nevo, 1961). The field<br />
is regularly floo<strong>de</strong>d in January/February and surface<br />
waters may stay there for many days. To avoid damage<br />
to the breeding mounds by flooding, females build large<br />
breeding mounds averaging 175 cm in length, 140 cm in<br />
width and 40 cm in height (Nevo, 1961). These mounds<br />
are always projecting above the water level in or<strong>de</strong>r to<br />
avoid the suffocation of mother and pups. Bulbs of numerous<br />
geophytes (Muscari comosum L., Gladiolus italicus<br />
Mill. and Narcissus taz<strong>et</strong>ta L.) growing in the field form<br />
the basic food of the mole rats living there. Note that<br />
the field chosen near Check-Post does not represent a<br />
solitary habitat with uniquely large breeding mounds in<br />
Israel. Nevo (1961) <strong><strong>de</strong>s</strong>cribed similarly large and even<br />
larger breeding mounds in the other floo<strong>de</strong>d areas in<br />
Israel as well.<br />
We collected invertebrates once per spring, in<br />
Februrary-March, from 1997 till 2000. In each collection<br />
session, 5 female breeding mounds were checked, and<br />
one quarter of the volume of every studied mound was<br />
searched for invertebrates, which were collected individually<br />
by means of forceps and exhausters. The be<strong>et</strong>les<br />
were i<strong>de</strong>ntified by comparison with a reference collection<br />
kept in the Department of Zoology at the Tel Aviv<br />
University. The collected specimens of invertebrates, with<br />
the exception of be<strong>et</strong>les, are <strong>de</strong>posited in the Institute of<br />
Evolution at the University of Haifa, whereas the be<strong>et</strong>les<br />
are <strong>de</strong>posited in the insect collection at the Department<br />
of Zoology at the Tel Aviv University.<br />
We collected the following groups of invertebrates in<br />
the breeding mounds of female mole rats: earthworms,<br />
land-snails, Myriapoda (Scolopendra cingulata Latreille,<br />
1789), Diplopoda (T<strong>et</strong>rarthrosoma syriacum Humbert &<br />
Saussure, 1869), Isopoda, Chilopoda, insects (H<strong>et</strong>eroptera,<br />
ants, solitary bees and be<strong>et</strong>les) and spi<strong>de</strong>rs. Additionally,<br />
mites and Collembola were observed. Since we are<br />
primarily familiar with be<strong>et</strong>les, most of our conclusions<br />
will be based on the analysis of this group, which was the<br />
richest in species numbers and the most abundant group<br />
in the breeding mounds.<br />
Be<strong>et</strong>le diversity<br />
Altog<strong>et</strong>her, we collected 422 specimens (7.5 ± 13.4<br />
specimens per be<strong>et</strong>le species) representing 56 be<strong>et</strong>le species,<br />
45 be<strong>et</strong>le genera and 9 be<strong>et</strong>le families (appendix 1).<br />
Surprisingly, 18 of these species (32 %) had not been<br />
recor<strong>de</strong>d earlier in the Northern Coastal Plain (appendix<br />
1) and two of them represented new records for Israel<br />
(Brachinus peregrinus Apfelbeck, 1904 and Harpalus basanicus<br />
Sahlberg, 1913). To our knowledge, the last record of<br />
the rare Pterostichus pertusus Schaum, 1858 in Israel was<br />
that of Bo<strong>de</strong>nheimer (1937). Ground and darkling be<strong>et</strong>les<br />
(families Carabidae and Tenebrionidae) represented the<br />
largest be<strong>et</strong>le groups in the mounds (41 species, 73% of<br />
all species assemblage, fig. 2). Those 41 species represent<br />
about 31 % of the ground and darkling be<strong>et</strong>le species<br />
known from the Northern Coastal Plain (Chikatunov,<br />
unpublished). The rest of the be<strong>et</strong>le species belonged to<br />
the following be<strong>et</strong>le families: Staphylinidae (n = 5; 8.9 %),<br />
7<br />
RESULTS<br />
Figure 2. Proportions of species from different be<strong>et</strong>le families in the breeding<br />
mounds of the mole rat Spalax carmeli, Check Post, Haifa, Israel.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 5-13
◆ T. PAVLICEK, V. CHIKATUNOV & E. NEVO<br />
8<br />
Curculionidae (n = 3; 5.4 %), Scarabaeidae (n = 3;<br />
5.4 %), Coccinellidae (n = 1; 1.8 %), Chrysomelidae<br />
(n = 1; 1.8 %), Elateridae (n = 1; 1.8 %) and Silphidae<br />
(n = 1; 1.8 %) (fig. 2).<br />
The outer and inner solid dome layers<br />
Be<strong>et</strong>les and other invertebrates were collected from<br />
the solid dome except for Aphodius spp., which were<br />
collected in the sanitary chambers. According to our<br />
observation, there might be at least two different ecological<br />
niches in the wall of the solid dome: the outer and<br />
inner wall layers. The outer wall layer of the solid dome<br />
is exposed directly to the surrounding environment and<br />
to direct solar radiation. Therefore, it might be microclimatically<br />
more fluctuating and generally drier and<br />
warmer than the inner wall layer. We observed that most<br />
of the collected specimens belonging to the be<strong>et</strong>le genera<br />
Belopus, Cabirutus, Cossyphus, Eutagenia, Gonocephalum<br />
and Coccinella were found on and in the outer wall. The<br />
inner wall layer of the solid dome bor<strong>de</strong>rs the outer layer<br />
on one si<strong>de</strong> and tunnels, the chambers and the breeding<br />
nest on the second si<strong>de</strong>. It has no direct contact with the<br />
surrounding environment and therefore might be microclimatically<br />
more stable and w<strong>et</strong>ter. Most of the specimens<br />
representing the remaining genera (N = 38, 84 %<br />
of all genera) not collected in the outer layer (appendix 1)<br />
were found in the inner layer. The only exception were<br />
Aphodius spp. collected in sanitary chambers. Apart from<br />
adults in the solid dome wall, we also found larvae and<br />
pupae of Carabus hemprichi Dejean, 1826 and noni<strong>de</strong>ntified<br />
be<strong>et</strong>le larvae. This indicates that some species<br />
<strong>de</strong>velop compl<strong>et</strong>ely insi<strong>de</strong> the breeding mounds.<br />
Trophic n<strong>et</strong>work<br />
As regards trophic relationships, we recor<strong>de</strong>d phytophage<br />
(15 species, 26.8 %), carnivore (23 species,<br />
41.1 %), coprophage (3 species, 5.4%), necrophage<br />
(1 species, 1.8 %) and d<strong>et</strong>ritivore (14 species, 25 %)<br />
be<strong>et</strong>les in the breeding mounds (fig. 3, appendix 1). In<br />
seven phytophage species (12.5 % of all be<strong>et</strong>le species)<br />
both adults and larvae were phytophages and in eight<br />
species (14.3 % of all be<strong>et</strong>le species) adults were phytophages<br />
and their larvae carnivores. Phytophages were<br />
represented by 54 specimens (12.8 % of the total be<strong>et</strong>le<br />
abundance). The most frequent phytophage species was<br />
the leaf be<strong>et</strong>le Gonioctena fornicata Br ggemann, 1873.<br />
Carnivore species involved 234 specimens (55.5 %<br />
of the total be<strong>et</strong>le abundance). Sixteen carnivore species<br />
Figure 3. Proportions of be<strong>et</strong>le species in different trophic zones in breeding<br />
mounds of Spalax carmeli, Check Post, Haifa, Israel.<br />
were mesophiles (69.6 % of carnivore species) and all<br />
carnivore and mesophile species were members of the<br />
families Carabidae and Staphylinidae (appendix 1).<br />
The <strong>de</strong>velopment of coprophage be<strong>et</strong>le species is connected<br />
with dung, and, in<strong>de</strong>ed, they were found in the<br />
sanitary chambers of the breeding mounds, in contrast<br />
to all other invertebrates collected from the solid dome.<br />
Rather surprisingly, coprophages were found in very low<br />
numbers, and every coprophage species was represented<br />
by one specimen only. One necrophage species was represented<br />
by four specimens (1 % of all be<strong>et</strong>le specimens).<br />
The d<strong>et</strong>ritophage species involved 127 specimens<br />
(30.1 % of the total be<strong>et</strong>le abundance). All tenebrionid<br />
be<strong>et</strong>les were d<strong>et</strong>ritophages and xerophiles, which might<br />
explain why many of these be<strong>et</strong>les were represented in the<br />
outer layer of the soil dome.<br />
As regards humidity preference, 19 species (34 % of<br />
all be<strong>et</strong>le species) were xerophiles (fig. 4) represented<br />
by 173 specimens (41 % of the total be<strong>et</strong>le abundance).<br />
Twenty-four species (43% of all be<strong>et</strong>le species) were<br />
mesophiles (fig. 4) and involved 174 specimens (41 %<br />
of the total be<strong>et</strong>le abundance). Only four species (7 %<br />
of the be<strong>et</strong>le assemblage) were hydrophiles (fig. 4) involving<br />
58 specimens (14 % of the total be<strong>et</strong>le abundance).<br />
Water requirements were not known for nine species<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ARTHROPODS IN THE MOUNDS OF MOLE RATS, SPALAX EHRENBERGI SUPERSPECIES, IN ISRAEL ◆<br />
Figure 4. Proportions of xerophile, hydrophile and mesophile be<strong>et</strong>le species<br />
in breeding mounds of the mole rat, Spalax carmeli, Check Post, Israel.<br />
(16 %) represented by 17 specimens (4 % of the total<br />
be<strong>et</strong>le abundance). Both mesophile and xerophile species<br />
accounted for 77 % of the species richness and for 82 %<br />
of the be<strong>et</strong>le abundance.<br />
DISCUSSION<br />
The breeding mound,<br />
a unique microhabitat and ecosystem<br />
The mole rat breeding mound represents a unique<br />
microhabitat and ecosystem for invertebrates appearing<br />
in high <strong>de</strong>nsity. No other study of invertebrates, apart<br />
of ectoparasites (Costa & Nevo, 1969) has previously<br />
been un<strong>de</strong>rtaken in the breeding mounds of mole rat, S.<br />
ehrenbergi. Even the number of recor<strong>de</strong>d species could<br />
be probably higher if other collection techniques were<br />
employed and sampling covered a larger area. Similarly,<br />
up to now, little attention had been paid to the study of<br />
the invertebrate fauna of mounds and nests of other<br />
mole-rat species (A. Scharff recently investigated insect<br />
associated with burrows of mole rat species belonging to<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 5-13<br />
the genus Cryptomys, pers. com.), again apart of parasites<br />
(for example Gupta & Trivedi, 1985; Sayin <strong>et</strong> al., 1977;<br />
Scharff <strong>et</strong> al., 1996, 1997). It does appear, however,<br />
that breeding mounds and galleries (Cox, 1972, 1984,<br />
1990; Cox & Gakahu, 1984; Cox & Hunt, 1990; Cox &<br />
Scheffer, 1991; Nevo, 1999) provi<strong>de</strong> a suitable structures<br />
for the evolution of rich un<strong>de</strong>rground micro-ecosystems<br />
generated by subterranean mammals. The studied breeding<br />
mounds were colonized by invertebrates with specific<br />
(presumably microclimatic) requirements, as might<br />
be <strong>de</strong>duced from the fact that most collected species were<br />
xerophiles or mesophiles and carnivores or d<strong>et</strong>ritivores.<br />
Remarkably, 18 of the species found in the breeding<br />
mounds constitute new records for the Northern Coastal<br />
Plain and two out of them even new records for Israel<br />
(appendix 1).<br />
Be<strong>et</strong>les and other invertebrates were collected only<br />
in the solid dome, with the exception of Aphodius sp.<br />
and A. granarius Linnaeus, 1767, which were collected<br />
solely in the sanitary chambers. Interestingly enough,<br />
Aphodius sp. represents a new species to science (David<br />
Král, pers. comm.) and might be exclusively associated<br />
with excrements of mole rats. The two other reported<br />
coprophages, A. granarius and Copris hispanus Linnaeus,<br />
1758, are also frequent in the dung of land mammals.<br />
Interestingly, phytophages were not found insi<strong>de</strong> the storage<br />
chambers which contained large amounts of stored<br />
and kept bulbs and rhizomes. Nevertheless, we did not<br />
collect very small invertebrates such as nemato<strong><strong>de</strong>s</strong> and<br />
mites. Theirs and the other small invertebrates presence<br />
in the breeding mounds of the mole rats is corroborated<br />
by the fact that 5 species of fleas and 53 species of<br />
gamasid mites had been collected previously from mole<br />
rat breeding nests in Israel (Costa & Nevo, 1969) and<br />
additional new flea species in mole rat breeding nests<br />
in Turkey (Aktas, 1989). Besi<strong><strong>de</strong>s</strong> the above mentioned<br />
fleas and gamasid mites, it might be expected that endoparasites<br />
at specific life stages are present in the sanitary<br />
room. Spalax ehrenbergi superspecies seems to host series<br />
of different endoparasites such as: helminthes and larval<br />
nemato<strong><strong>de</strong>s</strong> (Wertheim & Nevo, 1971; Fair <strong>et</strong> al., 1990),<br />
coccidia (Golemansky & Darwish, 1992, Couch <strong>et</strong> al.,<br />
1993) and Eimerian protoctists (Sayin, 1980).<br />
The solid dome<br />
The most important part of the breeding mounds for<br />
invertebrates appears to be the solid dome where most of<br />
the species and specimens concentrate. The solid dome<br />
constitues many interstices, where invertebrates might<br />
9
◆ T. PAVLICEK, V. CHIKATUNOV & E. NEVO<br />
10<br />
move and <strong>de</strong>velop. Till now, a few vertebrates had been<br />
observed in mounds, such as the warm snake (Typhlops<br />
vermicularis Merrem, 1820: Nevo, Ivanitskaya, Pavlíček<br />
& Chikatunov, pers. observ.), the mouse Mus macedonicus<br />
P<strong>et</strong>rov & Ružic, 1983, and the lesser white-toothed shrew,<br />
Crocidura suaveolens Pallas, 1811 (Nevo, pers. observ.).<br />
According to our observation, at least two different ecological<br />
niches (layers) or species gradients colonized by<br />
different species can be distinguished in the solid dome,<br />
namely the outer and inner wall layer, colonized by different<br />
species. Nevertheless, further research will be<br />
nee<strong>de</strong>d to confirm our observation and to gather precise<br />
quantitative and qualitative data. The observed distribution<br />
of be<strong>et</strong>les in outer and inner si<strong>de</strong> of the solid dome<br />
might be connected with their favorite temperature ranges<br />
for activity. According to Bo<strong>de</strong>nheimer (1934), the temperature<br />
range for high activity of the darkling be<strong>et</strong>les<br />
(prevailing on the solid dome surface) is 30.1 0 C-41.3 0 C,<br />
whereas in the ground be<strong>et</strong>les (prevailing insi<strong>de</strong> of the<br />
solid dome) it is only 31 0 C-35 0 C. The specific microclimate<br />
of breeding mounds might be the reason why<br />
xerophiles and mesophiles constituted almost 86 % of the<br />
be<strong>et</strong>le species assemblage. The interesting species from<br />
this group is Phaleria acuminata that is usually present on<br />
sea-shores (Canzoneri, 1968). In the Check-post area, it<br />
might be present since the distance from the sea shore is<br />
less than 1 km, or this species is also able to colonize some<br />
habitats more inland. The second option supports the<br />
fact that P. acuminata was collected also from the Upper<br />
Galilee (Chikatunov, unpublished) in a distance of tens<br />
kilom<strong>et</strong>ers from the coastal plain. Our observations suggest<br />
that the mole rat breeding mounds support mainly<br />
the activity of xerophile and mesophile be<strong>et</strong>les which are<br />
carnivores or d<strong>et</strong>ritivores. The carnivore trophic zone<br />
was richer in species number and abundance than the<br />
d<strong>et</strong>ritivore one. Carnivores might feed on d<strong>et</strong>ritivore<br />
species, on themselves, on species of other trophic zones<br />
and on many small invertebrates. However, the presence<br />
of some (e.g., Coccinella septempunctata Linnaeus,<br />
1758 of which adults and larvae are predators) might be<br />
acci<strong>de</strong>ntal or they are hiding in mounds during cold and<br />
rainy period. D<strong>et</strong>ritivore species are perhaps prosperous<br />
in the mounds due to the large amount of organic remains<br />
in the soil. A similar case was <strong><strong>de</strong>s</strong>cribed from the nests<br />
of the harvester ant, Messor bouvieri Bondroit, 1918, in<br />
South Europe. Insi<strong>de</strong> the nests, darkling be<strong>et</strong>les and other<br />
invertebrates were up to 660 time more concentrated than<br />
outsi<strong>de</strong>, probably due to the high concentration of organic<br />
remains gathered tog<strong>et</strong>her by ants (Sanchezpinero &<br />
Gomez, 1995). In the Check Post area, a relatively rich<br />
trophic layer was that of phytophages. We found more<br />
different phytophage species than d<strong>et</strong>ritivore ones, but<br />
they were much less abundant than the latter. In part,<br />
they might <strong>de</strong>velop in the solid dome. However, the<br />
presence of some phytophagous species (e.g., Kalcapion<br />
semivittatum Gyllenhal, 1839, Gonioctena fornicata)<br />
might be acci<strong>de</strong>ntal or they are temporally hiding there.<br />
Otherwise, the presence of K. semivittatum might be<br />
difficult to explain because it lives and <strong>de</strong>velops in galls on<br />
Mercurialis annua L. Nevertheless, the foodweb structure<br />
in the mole rat breeding mound seems to start with the<br />
phytophage and d<strong>et</strong>ritivore tropic zones followed by the<br />
carnivore trophic zone.<br />
CONCLUSIONS<br />
Mole rats are extraordinary ecological architects and<br />
subterranean ro<strong>de</strong>nt farmers. In heavy, badly drained<br />
alluvial soils they construct unique complex structures<br />
to increase their Darwinian fitness by escaping floods and<br />
avoiding mortality of the mother and offspring. These<br />
unique breeding mounds are the cradles of a remarkable<br />
concentration of primarily invertebrate fauna with predominating<br />
be<strong>et</strong>les – a phenomenon not studied earlier<br />
in the Spalax ehrenbergi superspecies. The be<strong>et</strong>les display<br />
a trophic n<strong>et</strong>work of phytophages, d<strong>et</strong>ritivores and carnivores.<br />
The warm nest in the breeding mound and the<br />
organic d<strong>et</strong>ritus harbour small arthropods (such as mites)<br />
providing food for the bigger d<strong>et</strong>ritivore and carnivore<br />
be<strong>et</strong>les and other arthropods (e.g., myriapods). Thus, the<br />
mole rat breeding mounds represent a construction which<br />
supports this unique microscale ecosystem.<br />
ACKNOWLEDGEMENTS<br />
We thank the Chair of Evolutionary Biology and the<br />
Ancell-Teicher Research Foundation for Gen<strong>et</strong>ics and<br />
Molecular Evolution for financial support. We are grateful<br />
also to Ms. Robin Permut (Institute of Evolution) for<br />
English corrections and to Ms. Patricia Card<strong>et</strong> (Haifa) for<br />
the translation of the Title and Abstract into French.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ARTHROPODS IN THE MOUNDS OF MOLE RATS, SPALAX EHRENBERGI SUPERSPECIES, IN ISRAEL ◆<br />
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from Turkey. Med. V<strong>et</strong>. Entomol., 3 : 23-27.<br />
ATLAS OF ISRAEL, 1970. Jerusalem: Ministry of Labour and<br />
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BODENHEIMER F.S., 1937. Prodromus Faunae Palestinae. Essai sur<br />
<strong><strong>de</strong>s</strong> éléments zoogéographiques <strong>et</strong> historiques du sud-ouest<br />
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CANZONERI S., 1968. Materiali per una monographia <strong>de</strong>lle<br />
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COSTA M. & NEVO E., 1969. Nidicolous arthropods associated<br />
with different chromosomal types of Spalax ehrenbergi<br />
Nehring. Zool. J. Linn. Soc., 48: 199-215.<br />
COUCH L., DUSZYNSKI D.W. & NEVO E., 1993. Coccidia (Apicomplexa),<br />
gen<strong>et</strong>ic diversity, and environmental unpredictability<br />
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181-189.<br />
COX C.B., 1972. A new digging dicynodont from the Upper<br />
Permian of Tanzania. In: Josey K.A. & Kemp T.S. (eds.),<br />
Studies in Vertebrate Evolution. Winchester Press, New York:<br />
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COX G.W., 1984. The distribution and origin of mima mound<br />
grasslands in San Diego, California. Ecology, 65: 1397-1405.<br />
COX G.W., 1990. Soil mining by pock<strong>et</strong> gopher along topographic<br />
gradients in a mima moundfield. Ecology, 71: 837-843.<br />
COX G.W. & GAKAHU C.G., 1984. The formation of mima<br />
mounds in the Kenya highlands. A test of the Dalquest-<br />
Scheffer hypothesis. J. Mammal., 65: 149-152.<br />
COX G.W. & HUNT J., 1990. Form of mima mounds in relation<br />
to occupancy by pock<strong>et</strong> gophers. J. Mammal., 71: 90-94.<br />
COX G.W. & SCHEFFER V.B., 1991. Pock<strong>et</strong> gophers and mima<br />
terrain in North America. Nat. Areas J., 11: 193-198.<br />
FAIR J.M., SCHMIDT G.D. & WERTHEIM G., 1990. New species of<br />
Andrya and Paranoplocephala (Cestoi<strong>de</strong>a: Anoplocephalidae)<br />
from voles and mole rats in Israel and Syria. J. Parasitol., 76:<br />
641-644.<br />
FISHELSON L., 1985. Fauna Palaestina. Orthoptera: Acridoi<strong>de</strong>a.<br />
The Israel Aca<strong>de</strong>my of Sciences and Humanities, Jerusalem,<br />
229 p.<br />
GUPTA S.P. & TRIVEDI K.K., 1985. Nemato<strong>de</strong> parasites of<br />
vertebrates. A new nemato<strong>de</strong>, Gongylonema fotedari sp.<br />
nov. (family: Spiruridae Oerley, 1985) from Indian mole<br />
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Helminthol., 37: 100-108.<br />
GOLEMANSKY V.G. & DARWISH A.I., 1992. The coccidian<br />
parasites (Apicomplexa: Coccidia) of the herbivorous mole<br />
rat - Spalax (Microspalax) ehrenbergi Nehring (Ro<strong>de</strong>ntia:<br />
Spalacidae) from Syria. Acta Protozool., 31: 173-176.<br />
NEVO E., 1961. Observations on Israeli populations of the mole<br />
rat, Spalax ehrenbergi Nehring 1898. Mammalia, 25: 127-<br />
144.<br />
NEVO E., 1991. Evolutionary theory and processes of active<br />
speciation and adaptive radiation in subterranean mole rats,<br />
Spalax ehrenbergi in Israel. Evol. Biol., 25: 1-125.<br />
NEVO E., 1999. Mosaic evolution of subterranean mammals: regression,<br />
progression and global convergence. Oxford University<br />
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NEVO E., IVANITSKAYA E. & BEILES A., 2000. Adaptive radiation<br />
of blind subterranean mole rats: naming and revising the four<br />
sibling species of the Spalax ehrenbergi superspecies in Israel:<br />
Spalax galili (2n=52), S. golani (2n=54), S. carmeli (2n=58)<br />
and S. judaei (2n=60). Backhuys Publishers, Lei<strong>de</strong>n, 198 p.<br />
SANCHEZPINERO F. & GOMEZ J.M., 1995. Use of ant-nest <strong>de</strong>bris<br />
by darkling be<strong>et</strong>les and other arthropod species in an arid<br />
system in South Europe. J. Arid Environ., 31: 91-104.<br />
SAYIN F., 1980. Eimeriidae of the herbivorous mole rat, Spalax<br />
ehrenbergi Nehring. J. Protozool., 27: 364-367.<br />
SAYIN F., DINCER S. & MERIC I., 1977. Coccidia, Protozoa<br />
Eimeridae of the herbivorous mole-rat, Spalax leucodon.<br />
J. Protozool., 24: 210-212.<br />
SCHARFF A., BURDA H., TENORA F., KAWALIKA M. & BARUS V.,<br />
1997. Parasites in social subterranean Zambian mole-rats<br />
(Cryptomys spp., Bathyergidae, Ro<strong>de</strong>ntia). J. Zool., 241:<br />
571-577.<br />
SCHARFF A., TENORA F., KAWALIKA M., BARUS V. & BURDA<br />
H., 1996. Helminths from Zambian mole-rats (Cryptomys,<br />
Bathyergidae, Ro<strong>de</strong>ntia). Helminthol., 33: 105-110.<br />
WERTHEIM G. & NEVO E., 1971. Helminths of birds and mammals<br />
from Israel: III. Helminths from chromosomal forms of<br />
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11<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 5-13
◆ T. PAVLICEK, V. CHIKATUNOV & E. NEVO<br />
APPENDIX 1<br />
List of be<strong>et</strong>les species recor<strong>de</strong>d from the breeding mounds of Spalax carmeli,<br />
in the Check Post area, near Haifa, Israel<br />
(N = number of collected specimens, * new record for Israel, ** new record for the Northern Coastal Plain,<br />
M – mesophile(s), X – xerophile(s), H –hydrophile(s).<br />
12<br />
SPECIES N TROPHIC ZONE CLIMATIC CORRELATE<br />
Family Carabidae<br />
Amara aenea Degeer, 1774 1 Carnivores M<br />
Anchomenus dorsalis Pontoppidan, 1763 7 Carnivores M<br />
Acinopus laevigatus Ménétries, 1823 5 Adults phytophagous, larvae carnivorous X<br />
Bembidion quadrifossulatum<br />
coelesyria N<strong>et</strong>olitzky, 1921**<br />
2 Carnivores H<br />
Bembidion lampros Herbst, 1784 1 Carnivores H<br />
Brachinus berytensis Reiche, 1855 25 Carnivores M<br />
Brachinus exhalans hebraicus Reiche, 1855 1 Carnivores M<br />
Brachinus peregrinus Apfelbeck, 1904* 12 Carnivores M<br />
Carabus hemprichi Dejean, 1826** 8 Carnivores M<br />
Carterus rufipes Chaudoir, 1843** 5 Phytophages X<br />
Chlaenius aeneocephalus Dejean, 1826 54 Carnivores H<br />
Dyschirius beludscha ganglbaueri Znojko, 1927 1 Carnivores H<br />
Ditomus calydonius Rossi, 1790 1 Phytophages X<br />
Harpalus basanicus Sahlberg, 1913** 3 Adults phytophagous, larvae carnivorous M<br />
Harpalus smyrnensis Hei<strong>de</strong>n, 1888** 14 Adults phytophagous, larvae carnivorous M<br />
Microlestes seladon Holdhaus, 1912** 1 Carnivores M<br />
Notiophilus danieli Reitter, 1897** 2 Carnivores M<br />
Ophonus battus Reitter, 1900 1 Adults phytophagous, larvae carnivorous M<br />
Ophonus cribrellus Reiche, 1855 1 Adults phytophagous, larvae carnivorous M<br />
Ophonus oblongus Schaum, 1858** 5 Adults phytophagous, larvae carnivorous M<br />
Orthomus berytensis Reiche <strong>et</strong> Saulcy, 1857 5 Adults phytophagous, larvae carnivorous M<br />
Parophonus fallax Peyron, 1858** 5 Adults phytophagous, larvae carnivorous M<br />
Pterostichus pertusus Schaum, 1858** 1 Carnivores M<br />
Scarites planus Bonelli, 1813 15 Carnivores X<br />
Scarites saxicola Bonelli, 1813** 20 Carnivores X<br />
Siagona europaea Dejean, 1816 2 Carnivores M<br />
Siagona longula Reiche <strong>et</strong> Saulcy, 1855 69 Carnivores M<br />
Family Chrysomelidae<br />
Gonioctena fornicata Br ggemann, 1873** 4 Phytophages ?<br />
Family Coccinellidae<br />
Coccinella septempunctata Linnaeus, 1758 5 Carnivores ?<br />
Family Curculionidae<br />
Brachycerus junix Lichtenstein 1796 1 Phytophages ?<br />
Hypera sp. 1 Phytophages ?<br />
Kalcapion semivittatum Gyllenhal, 1839 2 Phytophages ?<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ARTHROPODS IN THE MOUNDS OF MOLE RATS, SPALAX EHRENBERGI SUPERSPECIES, IN ISRAEL ◆<br />
Family Elateridae<br />
Cardiophorus discicollis Herbst, 1806** 1 Adults phytophagous, larvae rhizophagous ?<br />
Family Scarabaeidae<br />
Aphodius granarius Linnaeus, 1767 1 Coprophages ?<br />
Aphodius sp. 1 Coprophages ?<br />
Copris hispanus Linnaeus, 1758 1 Coprophages ?<br />
Family Silphidae<br />
Ablattaria arenaria Kraatz, 1876 4 Necrophages M<br />
Family Staphylinidae<br />
Leptolinus nothus Erichson, 1839** 1 Carnivores M<br />
Xantholinus graecus Kraatz, 1858 1 Carnivores M<br />
Platyprosopus hierichonticus Reiche <strong>et</strong> Saulcy, 1856 3 Carnivores M<br />
Philonthus corruscus Gravenhorst, 1802** 1 Carnivores M<br />
Pseudocypus excisus G. Müller, 1925** 1 Carnivores M<br />
Family Tenebrionidae<br />
A<strong>de</strong>lostoma sulcatum cordatum Solier, 1837 1 D<strong>et</strong>ritophages X<br />
Belopus syriacus Zoufal, 1893 11 D<strong>et</strong>ritophages X<br />
Cabirutus castaneus Reitter, 1904 3 D<strong>et</strong>ritophages X<br />
Clitobius variolatus Allard, 1884 9 D<strong>et</strong>ritophages X<br />
Cossyphus rugulosus Peyron, 1854 48 D<strong>et</strong>ritophages X<br />
Crypticus gibbulus Quensel, 1806 2 D<strong>et</strong>ritophages X<br />
Dichillus nitidulus Reitter, 1886 1 D<strong>et</strong>ritophages X<br />
Eutagenia cribricollis Reitter, 1886 1 D<strong>et</strong>ritophages X<br />
Gonocephalum costatum rugulosum Küster, 1849 28 D<strong>et</strong>ritophages X<br />
Gonocephalum rusticum Olivier, 1811 4 D<strong>et</strong>ritophages X<br />
Mesomorphus longulus Reiche <strong>et</strong> Saulcy, 1857** 12 D<strong>et</strong>ritophages X<br />
Phaleria acuminata Küster, 1852 1 D<strong>et</strong>ritophages X<br />
Stenosis comata Reiche <strong>et</strong> Saulcy, 1857** 3 D<strong>et</strong>ritophages X<br />
Stenosis sulcata Miller, 1861 3 D<strong>et</strong>ritophages X<br />
13<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 5-13
Veg<strong>et</strong>ation structure and environmental gradients<br />
in the Sallum area, Egypt<br />
Structure <strong>de</strong> la végétation <strong>et</strong> gradients environnementaux<br />
dans la région <strong>de</strong> Sallum, Égypte<br />
Fawzy M. Salama 1 , Monier M. Abd El-Ghani 2-* , Salah M. El Naggar 1 and Khadija A. Baayo 1<br />
1. Botany Department, Faculty of Science, Assiut University, Assiut 71516, Egypt<br />
2-*. Corresponding Author; The Herbarium, Faculty of Science, Cairo University, Giza 12613, Egypt; email: elghani@yahoo.com<br />
Abstract<br />
We examined veg<strong>et</strong>ation composition and its relation to environmental<br />
variables in the Sallum area along the <strong>mediterranea</strong>n coastal land<br />
of Egypt. The study area lies b<strong>et</strong>ween 25º 09’-25º 35’E and 31º 32’-<br />
31º 15’ N (about 1700km 2 ), and extends for about 49 km b<strong>et</strong>ween<br />
Buqbuq and Sallum on the egyptian-libyan frontier. It is inclu<strong>de</strong>d in<br />
the semi-<strong><strong>de</strong>s</strong>ert veg<strong>et</strong>ation zone with an attenuated <strong><strong>de</strong>s</strong>ert climate. An<br />
analysis of veg<strong>et</strong>ation along environmental gradients that prevail in<br />
the study area using the relative importance values of 55 perennials<br />
in 53 stands, followed by multivariate data analysis was presented.<br />
Altog<strong>et</strong>her, 111 species (75 perennials and 36 annuals) belonging<br />
to 92 genera and 34 families of the flowering plants were recor<strong>de</strong>d.<br />
Asteraceae, Fabaceae, Chenopodiaceae, Poaceae, Brassicaceae,<br />
Caryophyllaceae, Liliaceae and Zygophyllaceae were the largest<br />
families, and constitute more than 64 % of the total recor<strong>de</strong>d species.<br />
Therophytes and chamaephytes were the most frequent, <strong>de</strong>noting a<br />
typical <strong><strong>de</strong>s</strong>ert life-form spectrum. Phytochorological analysis revealed<br />
that 45.2 % of the studied species were uniregional, of which 23 %<br />
being native to the saharo-arabian chorotype. It also showed the<br />
<strong>de</strong>crease in the numbers of the Mediterranean species and increase<br />
of the saharo-arabian species along N-S direction form the see-shore<br />
inwards till the Diffa Plateau. Classification of the veg<strong>et</strong>ation was<br />
analysed using TWINSPAN technique resulted in the recognition<br />
of five veg<strong>et</strong>ation groups, each of <strong>de</strong>finite floristic composition and<br />
environmental characteristics, and could be linked to a specific<br />
habitat. Haloxylon salicornicum occupied the foot of the Diffa<br />
Plateau, Haloxylon salicornicum-Thymelaea hirsuta characterised<br />
the sand plains, Thymelaea hirsuta-Anabasis articulata inhabited<br />
the non-saline <strong>de</strong>pressions, Haloxylon salicornicum-Atriplex portulacoi<strong><strong>de</strong>s</strong><br />
characterised the saline <strong>de</strong>pressions and Salsola t<strong>et</strong>randra-Limoniastrum<br />
monop<strong>et</strong>alum on the coastal salt marshes.<br />
Ordination techniques as DCA and CCA were used to examine the<br />
relationship b<strong>et</strong>ween the veg<strong>et</strong>ation and the studied environmental<br />
param<strong>et</strong>ers: electric conductivity (EC), pH, calcium carbonate, moisture<br />
content, organic matter, silt, clay, K + , Mg ++ and altitu<strong>de</strong>. CCA<br />
axis 1 showed significant correlation with clay, moisture content, pH,<br />
EC, K + , and altitu<strong>de</strong>, while CCA axis 2 was clearly related to pH,<br />
Mg ++ and altitu<strong>de</strong>. Species richness was correlated with Mg ++ , while<br />
Shannon in<strong>de</strong>x was correlated with Na + and Mg ++ .<br />
Key-words<br />
Multivariate analysis, plant distribution, coastal veg<strong>et</strong>ation, diversity,<br />
plant communities, arid ecosystems<br />
Résumé<br />
Nous avons examiné la composition <strong>de</strong> la végétation <strong>et</strong> la relation avec<br />
les différentes variables environnementales dans la région <strong>de</strong> Sallu, le<br />
long du littoral méditerranéen <strong>de</strong> l’Égypte. La zone d’étu<strong>de</strong> se situe<br />
entre 25º 09’ - 25º 35’ E <strong>et</strong> 31º 32’ - 31º 15’ N (ca. 1 700 km 2 ),<br />
<strong>et</strong> s’étend sur environ 49 km entre Buqbuq <strong>et</strong> Sallum, à la frontière<br />
entre l’Égype <strong>et</strong> la Libye. C<strong>et</strong>te région s’intègre dans la zone semidésertique<br />
<strong>de</strong> végétation, avec un climat désertique atténué. L’analyse<br />
<strong>de</strong> végétation a été réalisée en fonction <strong><strong>de</strong>s</strong> gradients environnementaux<br />
locaux, en utilisant les valeurs relatives d’abondance <strong>de</strong> 55 espèces<br />
vivaces présentes dans 53 plac<strong>et</strong>tes ; ces données ont été traitées par<br />
analyses statistiques multivariées. Au total, 111 espèces – 75 vivaces<br />
<strong>et</strong> 36 annuelles – appartenant à 92 genres <strong>et</strong> 34 familles ont été<br />
inventoriées. Les Asteraceae, Fabaceae, Chenopodiaceae, Poaceae,<br />
Brassicaceae, Caryophyllaceae, Liliaceae <strong>et</strong> Zygophyllaceae sont les<br />
familles les plus représentées ; elles regroupent plus <strong>de</strong> 64 % <strong>de</strong> toutes<br />
les espèces enregistrées. Les thérophytes <strong>et</strong> les chamaephytes sont les<br />
types biologiques les plus fréquents, ce qui représente un cas classique<br />
pour la végétation désertique. L’analyse phytochorologique indique<br />
que 45,2 % <strong><strong>de</strong>s</strong> espèces étudiées ont une répartition uni-régionale,<br />
avec 23 % <strong>de</strong> végétaux indigènes au chorotype saharo-arabe. Il<br />
existe une diminution du nombre d’espèces méditerranéennes <strong>et</strong> une<br />
augmentation <strong><strong>de</strong>s</strong> espèces saharo-arabes selon un gradient nord-sud,<br />
<strong>de</strong>puis le bord <strong>de</strong> mer jusqu’à l’intérieur <strong><strong>de</strong>s</strong> terres (plateau <strong>de</strong> Diffa).<br />
Le classement <strong>de</strong> la végétation basé sur la métho<strong>de</strong> TWINSPAN a<br />
permis d’i<strong>de</strong>ntifier 5 groupes <strong>de</strong> végétation, chacun déterminé par<br />
une composition floristique <strong>et</strong> <strong><strong>de</strong>s</strong> caractéristiques environnementales<br />
bien déterminées, liées à un habitat particulier.<br />
Mots-clés<br />
Analyses multivariées, distribution <strong><strong>de</strong>s</strong> végétaux, végétation côtière,<br />
diversité, communautés végétales, écosystèmes ari<strong><strong>de</strong>s</strong><br />
15<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 15-32
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
16<br />
INTRODUCTION<br />
The Mediterranean coastal land of Egypt extends for<br />
about 970 km b<strong>et</strong>ween Sallum on the egyptian-libyan<br />
bor<strong>de</strong>r eastward to Rafah on the egyptian-palestinian bor<strong>de</strong>r,<br />
with an average width ranging b<strong>et</strong>ween 15-20 km in<br />
a N-S direction. It lies within the Mediterranean/Sahara<br />
regional transition zone, where the veg<strong>et</strong>ation comprises<br />
floristic elements for both of the <strong>mediterranea</strong>n and<br />
saharo-arabian regions (White, 1993). Floristically, it<br />
remains one of the less known territories of the country.<br />
El Hadidi (2000) distinguished b<strong>et</strong>ween a Mareotis sector<br />
which extends b<strong>et</strong>ween Sallum eastwards to Alexandria,<br />
where cyrenaican elements are prominent and a sinaitic<br />
sector extending from Port Said eastwards to Rafah,<br />
where East Mediterranean taxa prevail. Ecologically, it<br />
represents the narrow less arid belt of Egypt that can be<br />
divi<strong>de</strong>d into three sections: western, middle and eastern<br />
(Zahran <strong>et</strong> al., 1990). The western section extends from<br />
Sallum eastwards to Abu Qir, near Alexandria, for about<br />
550 km (fig. 1).<br />
Physiographically, the western section of the <strong>mediterranea</strong>n<br />
coastal land can be distinguished into two main<br />
provinces: an eastern province b<strong>et</strong>ween Alexandria and<br />
Ras El-Hikma, and a western province b<strong>et</strong>ween Ras<br />
El-Hikma and Sallum (Selim, 1969). One of the salient<br />
features of the latter province is the dissection of its landscape<br />
into an extensive system of shallow wadies (gullies,<br />
sensu El Hadidi, 2000). They draining from the southern<br />
limestone plateau which lies parallel to the west <strong>mediterranea</strong>n<br />
coast and reaches a maximum elevation of about<br />
200 m above sea level at Sallum. The phytosociology and<br />
veg<strong>et</strong>ation analyses of these wadies were the subject of El<br />
Hadidi & Ayyad (1975), El Hadidi <strong>et</strong> al. (1986), El-Kady<br />
& Sa<strong>de</strong>k (1992), Kamal & El-Kady (1993) and El Garf<br />
(2003).<br />
Several earlier extensive studies (1950-1996) <strong>de</strong>picted<br />
the veg<strong>et</strong>ation, flora, phytogeography and biodiversity<br />
of the western section of the <strong>mediterranea</strong>n coastal<br />
land, amongst others; Tadros & Atta (1958), Tadros &<br />
El-Sharkawi (1960), Ayyad (1973), Ayyad & El-Kady<br />
(1982), Shaltout (1985), El-Kady <strong>et</strong> al. (1995), Ayyad<br />
Fig. 1. Location map of the study area<br />
showing the distribution of the studied<br />
stands along the six transects (T 1 -T 6 ).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
& Fakhry (1996). At least 10 habitat types were recognised<br />
in this section, which belong to five veg<strong>et</strong>ation<br />
types. These inclu<strong>de</strong> the <strong><strong>de</strong>s</strong>ert veg<strong>et</strong>ation, the littoral salt<br />
marshes, the coastal sand dunes, the farmland veg<strong>et</strong>ation,<br />
and the aquatic veg<strong>et</strong>ation (see Zahran & Willis, 1992<br />
and El Hadidi, 2000 for d<strong>et</strong>ailed information). Y<strong>et</strong>, not<br />
all parts of that section have been studied in the same<br />
intense way. Less attention has been paid to the distant<br />
western part of the <strong>mediterranea</strong>n coast from Sidi Barrani<br />
to Sallum on the egyptian-libyan frontier (fig. 1), that will<br />
be here referred to as the Sallum area. It represents the<br />
distant part of the western <strong>mediterranea</strong>n coastal land of<br />
Egypt, where the human activities through cultivation,<br />
grazing and urbanisation were much less pronounced<br />
than in the other parts of the region. Therefore, the environmental<br />
correlates of species distribution in that part<br />
will be highlighted in this study.<br />
Key questions in the present study were: (1) What are<br />
the major environmental gradients associated with the<br />
observed patterns of plant communities? (2) Is the distribution<br />
of plant communities a<strong>de</strong>quately explained by<br />
the environmental factors consi<strong>de</strong>red or are other factors<br />
more important in d<strong>et</strong>ermining species distribution? and<br />
(3) Which of the studied environmental factors affecting<br />
the diversity of plant communities inhabiting the study<br />
area? These objectives were addressed by applying classification<br />
and ordination techniques to data of species<br />
composition and environment from the study area.<br />
STUDY AREA<br />
The area selected for the present study lies b<strong>et</strong>ween<br />
25º 09’-25º 35’ E and 31º 32’-31º 15’ N, extends for about<br />
49 km from Buqbuq to Sallum on the egyptian-libyan<br />
frontier with a total area of about 1 700 km 2 (fig. 1). It is<br />
inclu<strong>de</strong>d in the semi-<strong><strong>de</strong>s</strong>ert veg<strong>et</strong>ation zone that proposed<br />
by Bornkamm & Kehl (1990). The coastal plain is very<br />
narrow or, som<strong>et</strong>imes, lacking at Sallum. As reported by<br />
Selim (1969), the entire northern region of the egyptian<br />
western <strong><strong>de</strong>s</strong>ert is covered by sedimentary formations<br />
that range in age from lower Miocene to Holocene. The<br />
holocene formations comprise lagoon and loamy <strong>de</strong>posits,<br />
sand dune accumulations, wadi fillings and limestone<br />
crusts. Ol<strong>de</strong>r formations (Pleistocene-Miocene) are of<br />
limestone or dolomite (dolostone).<br />
Wickens (1992) proposed that Egypt falls within<br />
the subtropical <strong><strong>de</strong>s</strong>ert and <strong>mediterranea</strong>n zonobiomes.<br />
According to the classification of climatic zones of Egypt<br />
that suggested Ayyad & Ghabbour (1986) and recently<br />
modified by El Hadidi (2000), the study area lies within<br />
the northern arid province that runs parallel to the semiarid<br />
belt. Comparing climatic characteristics of four<br />
m<strong>et</strong>eorological stations along the western sector of the<br />
<strong>mediterranea</strong>n coast (fig. 1): Sallum station, the nearest<br />
to the study area, with other three are shown in table 1.<br />
Notably, the wi<strong>de</strong> variation in annual precipitation along<br />
the E-W direction along the coast (from Alexandria in the<br />
east to Sallum in the west) was remarkable.<br />
METHODS<br />
Veg<strong>et</strong>ation analysis<br />
During 2002-2003, a quantitative survey of the<br />
veg<strong>et</strong>ation of the study area was carried out. Six transects<br />
(T 1 -T 6 ) from the coast till the fringes of the Diffa Plateau,<br />
were used to sample the veg<strong>et</strong>ation and environmental<br />
attributes of the study area (fig. 1). Because of the variable<br />
17<br />
Station<br />
Min.<br />
Temperature (°C)<br />
Max<br />
Relative humidity (%)<br />
Rainfall (mm)<br />
Sallum 14.0 24.3 65.5 89.8<br />
Sidi Barrani 15.5 23.3 69.7 149.8<br />
Mersa Matruh 14.3 24.3 66.0 144.0<br />
Alexandria 14.9 24.9 65.0 192.1<br />
Table 1. Long-term annual averages (courtesy of the Egyptian M<strong>et</strong>eorological Authority) of some climatic factors of Sallum station<br />
in the study area, and other three stations along the <strong>mediterranea</strong>n coast of Egypt.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 15-32
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
18<br />
width b<strong>et</strong>ween the coastal plain and the Diffa Plateau,<br />
the transects ranged from approximately 2 to 20 km in<br />
length. These transects inclu<strong>de</strong>d plant communities of the<br />
major habitats prevailing in the physiographic provinces<br />
of the region. Stratified random sampling m<strong>et</strong>hod was<br />
employed (Greig-Smith, 1983; Ludwig & Reynold,<br />
1988) within each transect. A total of 53 stands (30 x<br />
20 m each) were sampled, positioned using GPS mo<strong>de</strong>l<br />
Trimble SCOUT M , and distributed along the studied<br />
transects. In each stand, the plant cover (m/100m) was<br />
d<strong>et</strong>ermined using the line-intercept m<strong>et</strong>hod (Canfield,<br />
1941). For this purpose, five parallel lines (20 m each)<br />
were laid across the stand and the intercept lengths (cm)<br />
of each perennial were summed. Density (individuals/<br />
100 m 2 ) and frequency (occurrences/100 sample plots)<br />
were estimated using a number of randomly located<br />
sample plots without overlap. The relative importance<br />
value (IV) for each species in each stand was obtained<br />
by the sum of its relative <strong>de</strong>nsity, frequency and cover<br />
with a maximum value out of 300. Voucher specimens<br />
of each species were collected and i<strong>de</strong>ntified by us in<br />
the Herbaria of Cairo (CAI) and Assiut Universities<br />
where they are <strong>de</strong>posited. Taxonomic nomenclature was<br />
according to Täckholm (1974), Cope & Hosni (1991),<br />
and Boulos (1995, 1999, 2000 & 2002).<br />
Soil analysis<br />
For each sampled stand, three soil samples were collected<br />
from profiles of 0-15, 15-25 and 25-50 cm <strong>de</strong>pth.<br />
These samples (300 g each) are then pooled tog<strong>et</strong>her to<br />
form one composite sample, air-dried, thoroughly mixed,<br />
and passes through a 2 mm-sieve to g<strong>et</strong> rid of gravel and<br />
boul<strong>de</strong>rs. The portion finer than 2 mm was kept for physical<br />
and chemical analysis according to Jackson (1967)<br />
and Allen & Stainer (1974). Soil texture was d<strong>et</strong>ermined<br />
by the Bouyoucos hydrom<strong>et</strong>er m<strong>et</strong>hod, and the results<br />
used to calculate the percentages of sand, silt and clay.<br />
Electric conductivity and pH were evaluated in 1:5 soilwater<br />
extract using electric conductivity m<strong>et</strong>er and a glass<br />
electro<strong>de</strong> pH-m<strong>et</strong>er, respectively. Total carbonate content<br />
was d<strong>et</strong>ermined using the volum<strong>et</strong>ric calcim<strong>et</strong>er (Allison<br />
& Moodie, 1965), and the Walkely-Black w<strong>et</strong> combustion<br />
m<strong>et</strong>hod (Tan, 1996) using K 2 Cr 2 O 7 and H 2 SO 4 to<br />
estimate the <strong>de</strong>composed fraction of soil organic matter.<br />
D<strong>et</strong>ermination of Na + and K + was carried out by a<br />
Drlang M 7D flame photom<strong>et</strong>er. Mg ++ was estimated<br />
using a buck scientific mo<strong>de</strong>l 210 VGP atomic absorption<br />
spectrophotom<strong>et</strong>er.<br />
Data analysis<br />
In or<strong>de</strong>r to obtain an effective analysis of the veg<strong>et</strong>ation<br />
and related environmental factors, both classification<br />
and ordination techniques were employed. Two-<br />
Way INdicator SPecies ANalysis (TWINSPAN) using<br />
the <strong>de</strong>fault s<strong>et</strong>tings of the computer program PC-ORD<br />
for windows version 4.14 (McCune & Mefford, 1999)<br />
classified a data matrix of 53 stands and 55 perennial<br />
species using their relative importance values (IV). Only<br />
species present in at least two stands were inclu<strong>de</strong>d in the<br />
analysis. TWINSPAN is a divisive hierarchical classification<br />
m<strong>et</strong>hod that doubles the number of groups at each<br />
division (positive and negative groups are formed at each<br />
dichotomy). The procedures simultaneously classify both<br />
samples and species directly, constructing an or<strong>de</strong>red twoway<br />
table to exhibit the relationship b<strong>et</strong>ween them clearly<br />
as possible (Hill, 1979; Økland, 1990).<br />
The computer program CANOCO 3.12 (ter Braak,<br />
1987-1992) was used for all ordinations. Rare species<br />
were downweighted to reduce distortion of the analysis.<br />
Preliminary analyses were ma<strong>de</strong> using D<strong>et</strong>ren<strong>de</strong>d<br />
Correspon<strong>de</strong>nce Analysis (DCA; Hill & Gauch, 1980)<br />
to check the magnitu<strong>de</strong> of change in species composition<br />
along the first ordination axis (i.e., gradient length in standard<br />
<strong>de</strong>viation (SD)- units). In the present study, DCA<br />
estimated the gradient length to be larger than 6 SD-units<br />
for all subs<strong>et</strong> analyses, thus Canonical Correspon<strong>de</strong>nce<br />
Analysis (CCA) was the appropriate ordination m<strong>et</strong>hod<br />
to perform direct gradient analysis (ter Braak & Prentice,<br />
1988). CCA was used to d<strong>et</strong>ermine the relationships<br />
b<strong>et</strong>ween veg<strong>et</strong>ation data and environmental variables<br />
(Jean & Bouchard, 1993). Ter Braak (1986) suggests<br />
using DCA and CCA tog<strong>et</strong>her to see how much of the<br />
variation in species data is accounted for by the environmental<br />
data. Due to high inflation factor of total soluble<br />
salts (TSS), sand, and Na + , they were exclu<strong>de</strong>d from<br />
the CCA analysis. Thus, 10 soil param<strong>et</strong>ers were inclu<strong>de</strong>d:<br />
electric conductivity (EC), pH, calcium carbonate<br />
(CaCO 3 ), moisture content (MC), organic matter (OM),<br />
silt, clay, K + , Mg ++ and altitu<strong>de</strong> (Alt) as a mesologic param<strong>et</strong>er.<br />
All the <strong>de</strong>fault s<strong>et</strong>tings were used for CCA, and<br />
a Monte Carlo permutation test (99 permutations) was<br />
used to test for significance of the eigenvalues of the first<br />
canonical axis. Intra-s<strong>et</strong> correlations from the CCA’s<br />
were used to assess the importance of the environmental<br />
variables. The variables in the CCA biplots were represented<br />
by arrows pointing in the direction of maximum<br />
variation, with their length proportional to the rate of<br />
change (ter Braak, 1986). Each arrow d<strong>et</strong>ermines an axis<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
on which the species points can be projected. When plot<br />
points were projected perpendicularly to the (prolonged)<br />
arrows, their or<strong>de</strong>r represents approximately the ranking<br />
of weighed averages with respect to the values of the<br />
factors involved.<br />
One-way analysis of variance (ANOVA) was applied<br />
to assess the significance of variations in soil variables<br />
and diversity indices in relation to the veg<strong>et</strong>ation groups<br />
i<strong>de</strong>ntified after TWINSPAN application. Pearson’s product-moment<br />
correlation coefficient was also used to<br />
estimate the intercorrelation b<strong>et</strong>ween the studied soil<br />
factors. All the statistical analyses were carried out using<br />
SPSS version 10.0 for Windows.<br />
Species diversity<br />
Species diversity within each separated TWINSPAN<br />
veg<strong>et</strong>ation group was assessed using two different indices<br />
expressing species richness and diversity. Species richness<br />
(alpha-diversity) is calculated as the average number of<br />
species per stand and the species diversity was estimated<br />
as the Shannon-Wiener in<strong>de</strong>x: H’ = Σ i=1 p i log 2 p i , where<br />
S is the total number of species and p i is the relative<br />
importance value (IV) of ith species (Whittaker, 1972;<br />
Pielou, 1975).<br />
RESULTS<br />
Taxonomic patterns<br />
A total of 111 species (36 annuals and 75 perennials)<br />
belonging to 92 genera and 34 families of the<br />
vascular plants were recor<strong>de</strong>d (appendix 2). The largest<br />
families were Asteraceae and Fabaceae (16 for each),<br />
Chenopodiaceae (10), Poaceae (9), Brassicaceae (7),<br />
Caryophyllaceae (5), Liliaceae and Zygophyllaceae (4 for<br />
each). The largest genera inclu<strong>de</strong> Astragalus (7), Lotus and<br />
Erodium (3 for each), Launaea, Atriplex, Silene, Medicago,<br />
Limonium, Asparagus and Aspho<strong>de</strong>lus (2 for each). The<br />
most common perennials recor<strong>de</strong>d were Haloxylon salicornicum,<br />
Thymelaea hirsuta, Aspho<strong>de</strong>lus ramosus, Anabasis<br />
articulata, Atriplex portulacoi<strong><strong>de</strong>s</strong>, Limoniastrum monop<strong>et</strong>alum<br />
and Salsola t<strong>et</strong>randra. Each of these species attains a<br />
maximum importance value (IV) of more than 140 (out<br />
of 300 for all species in a stand), and a mean of more<br />
than 60 (table 2). Common but less important perennials<br />
were R<strong>et</strong>ama ra<strong>et</strong>am, Deverra tortuosa, Lycium europaeum,<br />
Arthrocnemum macrostachyum, Halocnemum strobilaceum,<br />
Periploca angustifolia and Zygophyllum album. Common<br />
annuals inclu<strong>de</strong> Trigonella stellata, Senecio glaucus, Cotula<br />
cinerea, Eremobium aegyptiacum, Arnebia <strong>de</strong>cumbens,<br />
Calendula arvensis, Aizoon hispanicum, Schismus barbatus,<br />
Erodium laciniatum and Bassia muricata.<br />
The life-form spectrum of the Sallum area showed<br />
that the proportion of therophytes (32.4 %) is higher<br />
than that of other life forms, while the proportions of<br />
chamaephytes (25.2 %), hemicryptophytes (22.5 %) and<br />
cryptophytes (13.5 %) were noteworthy (Salama <strong>et</strong> al.,<br />
2003). The majority of the recor<strong>de</strong>d species belong to the<br />
<strong>mediterranea</strong>n and saharo-arabian chorotypes.<br />
Classification of veg<strong>et</strong>ation<br />
The application of TWINSPAN on the relative<br />
importance values (IV) of the 55 perennial species<br />
recor<strong>de</strong>d in 53 sampled stands helped to distinguish<br />
five veg<strong>et</strong>ation groups (table 2, fig. 2). These groups<br />
were named after their leading dominant species (those<br />
have the highest relative IV) as follows: (A) Haloxylon<br />
salicornicum, (B) Haloxylon salicornicum-Thymelaea<br />
hirsuta, (C) Thymelaea hirsuta-Anabasis articulata, (D)<br />
Haloxylon salicornicum-Atriplex portulacoi<strong><strong>de</strong>s</strong>, and (E)<br />
Salsola t<strong>et</strong>randra-Limoniastrum monop<strong>et</strong>alum. Each of these<br />
groups could easily be linked to a habitat type: foot of the<br />
Diffa Plateau, sand plains, non-saline <strong>de</strong>pressions, saline<br />
<strong>de</strong>pressions and the coastal salt marshes, respectively.<br />
Table 3 summarises the mean values and the standard<br />
<strong>de</strong>viations of the measured soil variables, and the diversity<br />
indices in the five groups <strong>de</strong>rived from TWINSPAN.<br />
The first TWINSPAN dichotomy differentiated the 53<br />
stands into two main groups according to pH, EC, Na + ,<br />
K + and Mg ++ (p=0.0001). Group E (12 stands) dominated<br />
by Salsola t<strong>et</strong>randra-Limoniastrum monop<strong>et</strong>alum,<br />
inhabited the coastal saline <strong>de</strong>pressions was separated<br />
on the right si<strong>de</strong> of the <strong>de</strong>ndrogram (fig. 2), while the<br />
left si<strong>de</strong> is still h<strong>et</strong>erogeneous. At the second hierarchical<br />
level, the inland dry group of stands (41) was split into<br />
two subgroups related to pH, EC, organic matter, Na +<br />
and altitu<strong>de</strong> (p=0.0001). Here, another distinct group (A;<br />
9 stands) dominated by Haloxylon salicornicum found on<br />
the gravel plains at the foot of Diffa Plateau was also separated.<br />
Description of each group will be given below.<br />
Group A. Haloxylon salicornicum group<br />
The 9 stands of this group were sampled from the<br />
foot of the Diffa Plateau (fig. 1). On the highly elevated<br />
and gravely calcareous soil with mo<strong>de</strong>rate moisture<br />
content and the least amounts of organic matter and<br />
19<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 15-32
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
Fig. 2. TWINSPAN <strong>de</strong>ndrogram<br />
of the 53 studied stands<br />
of the study area based on their<br />
importance values.<br />
A-E are the five separated<br />
veg<strong>et</strong>ation groups.<br />
For abbreviation of indicator<br />
species, see appendix.<br />
20<br />
salinity (table 3), sand she<strong>et</strong>s of Haloxylon salicornicum<br />
were found. It was differentiated by the growth of shrubs<br />
of R<strong>et</strong>ama ra<strong>et</strong>am, Lycium europaeum and Fars<strong>et</strong>ia aegyptia,<br />
and occupied parts of the drainage channels of the<br />
southern str<strong>et</strong>ches of T 3, T 4 and T 5 where surface <strong>de</strong>posits<br />
were <strong>de</strong>eper. This group had the largest share (23) of<br />
annuals. Shortly after rainfall, the soil surface supporting<br />
the sites of this group was covered with a <strong>de</strong>nse veg<strong>et</strong>ation<br />
of annual species, especially Schismus barbatus, Anthemis<br />
microsperma, Reichardia tingitana, Brassica tournefortii,<br />
Medicago laciniata, Cutandia memphitica, Erodium pulverulentum,<br />
Malva parviflora and Astragalus hamosus.<br />
Group B. Haloxylon salicornicum-<br />
Thymelaea hirsuta group<br />
The landscape of this group was characterized by a<br />
combination of Haloxylon salicornicum and Thymelaea<br />
hirsuta found on the sand plains with <strong>de</strong>ep loose soil<br />
and the lowest levels of moisture content. It represents<br />
a transitional zone b<strong>et</strong>ween the non-saline and saline<br />
<strong>de</strong>pression veg<strong>et</strong>ation groups. This group was differentiated<br />
by a number of woody species such as Periploca<br />
angustifolia, Deverra tortuosa, Globularia arabica and Zilla<br />
spinosa. The herb layer was relatively sparse, and characterized<br />
by Hor<strong>de</strong>um leporinum, Aspho<strong>de</strong>lus tenuifolius,<br />
Bupleurum lancifolium and Astragalus pereginus. The most<br />
common xerophytic species in the egyptian <strong><strong>de</strong>s</strong>ert, Sinai,<br />
and the neighboring arid environments were inclu<strong>de</strong>d in<br />
this group (Zohary, 1973; Batanouny, 1979; Salama &<br />
Fayed, 1990; Abd El-Ghani & Amer, 2003).<br />
Group C. Thymelaea hirsuta-<br />
Anabasis articulata group<br />
This veg<strong>et</strong>ation group dominated the non-saline<br />
<strong>de</strong>pressions with soils of the highest pH values and the<br />
lowest levels of carbonate content (table 3). Other physical<br />
soil properties were comparable to those of group B.<br />
While Gymnocarpos <strong>de</strong>candrum, Aspho<strong>de</strong>lus ramosus and<br />
Astragalus siberii dominated the shrub layer, the herb<br />
layer showed the lowest share of annuals (viz., Centaurea<br />
glomerata, Louts angustissimus, Aspho<strong>de</strong>lus tenuifolius and<br />
Hor<strong>de</strong>um leporinum).<br />
Group D. Haloxylon salicornicum-<br />
Atriplex portulacoi<strong><strong>de</strong>s</strong> group<br />
This was the largest group of stands (13), and the<br />
most diversified among the other veg<strong>et</strong>ation groups<br />
(table 2). It inhabited the saline <strong>de</strong>pressions on fertile<br />
soils that are rich in their fine sediment contents (silt and<br />
clay). Relatively high soil salinity favoured the growth of<br />
some salt-tolerant species as Atriplex portulacoi<strong><strong>de</strong>s</strong>, Salsola<br />
t<strong>et</strong>randra and Nitraria r<strong>et</strong>usa. The shrub layer was cha-<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
TWINSPAN GROUP<br />
A B C D E<br />
Group size 9 8 11 13 12<br />
Total number of species 14 17 16 27 19<br />
Total number of annuals 23 7 4 9 9<br />
Haloxylon salicornicum 155 78 36 94 6<br />
R<strong>et</strong>ama ra<strong>et</strong>am 49 - - - -<br />
Astragalus sieberi 4 - 8 1 1<br />
Carthamus glaucus 5 2 - 10<br />
Hyoscyamus muticus 8 2 1 - -<br />
Lycium europaeum 17 - 1 4<br />
Fars<strong>et</strong>ia aegyptiaca 9 - 1 - -<br />
Periploca angustifolia 7 16 - - -<br />
Citrullus colocynthis 7 - - - -<br />
Euphorbia r<strong>et</strong>usa 10 - - - -<br />
Marrubium alysson 6 - - - -<br />
Thymelaea hirsuta 5 75 100 25 7<br />
Deverra tortuosa - 50 2 26 7<br />
Lygeum spartaum - 1 - - 15<br />
Globularia arabica - 10 - - -<br />
Zilla spinosa subsp. biparmata - 15 - - -<br />
Anabasis articulata 5 15 82 26 -<br />
Aspho<strong>de</strong>lus ramosus - 24 46 - -<br />
Carduncellus mareoticus - - 1 3 -<br />
Echinops spinosus - - 2 1 -<br />
Gymnocarpos <strong>de</strong>candrus - - 7 - -<br />
Atriplex portulacoi<strong><strong>de</strong>s</strong> - - 3 64 31<br />
Helianthemum lippii - - - 4 -<br />
Nitraria r<strong>et</strong>usa - - - 3 -<br />
Noaea mucronata - - - 2 -<br />
Verbascum l<strong>et</strong>ourneuxii - - - 2 -<br />
Salsola t<strong>et</strong>randra - 1 3 26 66<br />
Limoniastrum monop<strong>et</strong>alum - - - - 65<br />
Halocnemum strobilaceum - - - 1 69<br />
Suaeda maritima - 1 1 1 13<br />
Arthrocnemum macrostachyum - - - 1 15<br />
Sporobolus spicatus - - - 1 9<br />
Zygophyllum album - - - 2 14<br />
Frankenia hirsuta - - - - 8<br />
Limonium pruinosum - - - - 8<br />
Table 2. Species composition<br />
of the 53 stands in the six transects,<br />
arranged in or<strong>de</strong>r of occurrence<br />
in the five TWINSPAN groups (A-E).<br />
The mean importance value<br />
(out of 300) roun<strong>de</strong>d to the nearest<br />
integer is given in each group.<br />
Entries in bold are indicator<br />
species in each group.<br />
See text for explanation.<br />
21<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 15-32
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
22<br />
Range Mean ± SD<br />
TWINSPAN veg<strong>et</strong>ation groups<br />
A B C D E<br />
F-ratio<br />
Sand 99.9 – 99.9 99.9 ± 0.08 99.7 ± 0.02 99.9 ± 0.04 99.8 ± 0.07 99.8 ± 0.07 99.9 ± 0.1 2.1<br />
Silt 0.01 – 0.4 0.07 ± 0.07 0.01 ± 0.02 0.07 ± 0.03 0.08 ± 0.06 0.1 ± 0.06 0.06 ± 0.09 2.5<br />
Clay 0.01 - 0.1 0.02 ± 0.02 0.01 ± 0.03 0.02 ± 0.01 0.01 ± 0.01 0.02 ± 0.01 0.04 ± 0.03 3.8*<br />
MC (%) 0.5 – 28.4 3.4 ± 4.6 3.16 ± 3.4 2.12 ± 0.09 2.2 ± 1.70 2.5 ± 1.6 6.7 ± 8.3 2.2<br />
OM 0.01 - 0.6 0.2 ± 0.01 0.08 ± 0.09 0.19 ± 0.13 0.2 ± 0.14 0.3 ± 0.14 0.2 ± 0.2 3.9*<br />
Total carbonates 1.8 – 12.5 5.8 ± 2.4 6.9 ± 2.2 5.7 ± 2.30 4.5 ± 1.90 6.0 ± 2.1 5.90 ± 3.1 1.3<br />
pH 8.2 – 10.0 9.1 ± 0.03 9.2 ± 0.4 9.2 ± 0.15 9.4 ± 0.20 9.3 ± 0.2 8.70 ± 0.1 7.0*<br />
EC (mS cm -1 ) 0.3 – 4.4 1.1 ± 1.80 0.36 ± 0.03 0.45 ± 0.10 0.41 ± 0.06 0.6 ± 0.2 3.30 ± 3.0 8.9*<br />
Alt (m) -40 – 100 25.6 ± 27.3 62.0 ± 28.2 31.0 ± 21.8 21 ± 15.3 23.1 ± 21.4 2.0 ± 12.7 12.1*<br />
Na + 0.02 – 3.8 0.4 ± 0.08 0.04 ± 0.01 0.11 ± 0.08 0.08 ± 0.05 0.2 ±0.15 1.5 ± 1.1 15.7*<br />
K + (m eq/l) 0.02 - 0.03 0.06 ± 0.05 0.03 ± .007 0.04 ± 0.02 0.04 ± 0.01 0.06 ± 0.02 0.12 ± 0.07 8.4*<br />
Mg ++ 0.003 -0.03 0.01 ± 0.006 0.005 ± 0.009 0.008 ± 0.003 0.008 ± 0.003 0.009 ± 0.004 0.02 ± 0.008 7.3*<br />
Species diversity 0.4 – 3.3 1.83 ± 0.07 1.5 ± 0.06 1.70 ± 0.07 1.6 ± 0.6 2.2 ± 0.5 1.9 ± 0.3 2.4<br />
Species richness 2.0 – 13.0 6.0 ± 2.6 1.9 ± 1.6 6.0 ± 2.4 5.2 ± 1.8 7.1 ± 2.9 6.5 ± 3.4 1.4<br />
Table 3. Mean values and standard <strong>de</strong>viations (±) of the environmental variables and altitu<strong>de</strong> in the stands representing the veg<strong>et</strong>ation groups obtained<br />
by TWINSPAN. MC= Moisture content, OM= Organic matter, EC= Electric conductivity and Alt= Altitu<strong>de</strong>. *= Differences significant at p< 0.05.<br />
racterised by the growth of Carthamus glaucus, Anabasis<br />
articulata, Carduncellus mareoticus and Deverra tortuosa.<br />
Other species showed certain <strong>de</strong>gree of fi<strong>de</strong>lity since<br />
they did not pen<strong>et</strong>rate to other veg<strong>et</strong>ation groups; such<br />
as Helianthemum lippii, Noaea mucronata and Verbascum<br />
l<strong>et</strong>ourneuxii. Few annual species (Bassia muricata,<br />
Astragalus hamosus, Centaurea glomerata and Aspho<strong>de</strong>lus<br />
tenuifolius) were recor<strong>de</strong>d.<br />
Group E. Salsola t<strong>et</strong>randra-<br />
Limoniastrum monop<strong>et</strong>alum<br />
On muddy fertile saline soil with high Na + , K + and<br />
Mg ++ , the coastal salt marshes with veg<strong>et</strong>ation characterized<br />
by the complex Halocnemum strobilaceum, Salsola<br />
t<strong>et</strong>randra and Limoniastrum monop<strong>et</strong>alum were found,<br />
indicating the saline nature of this group (12 stands).<br />
Notably, several halophytic species were recor<strong>de</strong>d such<br />
as Suaeda maritima, Arthrocnemum macrostachyum,<br />
Zygophyllum album, Frankenia hirsuta and Limonium<br />
pruinosum. The herb layer was mo<strong><strong>de</strong>s</strong>tly represented, and<br />
inclu<strong>de</strong>d amongst others Brassica tournefortii, Centaurea<br />
glomerata, Astragalus hispidulus and Hor<strong>de</strong>um leporinum.<br />
Environmental characteristics of the five veg<strong>et</strong>ation<br />
groups were summarised in table 3. Of the measured<br />
param<strong>et</strong>ers, clay, organic matter, pH, electric conductivity,<br />
altitu<strong>de</strong>, Na + , K + and Mg ++ showed highly significant<br />
differences b<strong>et</strong>ween groups. It can be noted that clay,<br />
moisture content, electric conductivity, K + and Mg ++<br />
displayed relatively high values on coastal salt marshes<br />
(group E), organic matter on the saline <strong>de</strong>pressions<br />
(group D), and total carbonates and altitu<strong>de</strong> on the foot<br />
of Diffa Plateau (group A). A remarkable <strong>de</strong>crease in salinity<br />
gradient from the coastal salt marshes (group E) to<br />
the foot of Diffa Plateau (group A) was also noticeable.<br />
Ordination of stands<br />
Figure 3 showed the ordination results of the DCA<br />
analysis of the floristic data s<strong>et</strong>. The 53 stands were<br />
plotted along axes 1 and 2, and tend to cluster into five<br />
groups that resulted from TWINSPAN analysis <strong><strong>de</strong>s</strong>cribed<br />
above. The stands were spread out 6.4 S.D units along<br />
the first axis (eigenvalue= 0.81), expressing the high floristic<br />
variations among veg<strong>et</strong>ation groups, and indicating<br />
a compl<strong>et</strong>e turnover in species composition took place<br />
(Hill, 1973). This diagram displayed graphically that<br />
group B was transitional in its composition b<strong>et</strong>ween the<br />
other groups. Stands of group E were separated towards<br />
and the positive end of DCA axis 1, while those of groups<br />
A and C were separated out along the other end. DCA<br />
axis 2 with an eigenvalue of 0.53 and a gradient length of<br />
3.86 S.D is less important. The species-environment correlation<br />
(table 4) was also high: 0.83 and 0.55 for DCA<br />
axis 1 and 2 showing that the species data were related<br />
to the measured environmental variables. From table 4,<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
Fig. 3. DCA ordination diagram<br />
for the 53 stands on the first<br />
two axes, with the TWINSPAN<br />
groups superimposed.<br />
23<br />
significant correlations of soil variables with the first three<br />
DCA axes revealed greater correlations along axis 1 than<br />
the higher or<strong>de</strong>r axis. DCA axis 1 showed significant correlations<br />
with altitu<strong>de</strong>, EC, K + , moisture content and clay.<br />
We interpr<strong>et</strong>ed DCA axis 1 as an altitu<strong>de</strong>-soil salinity<br />
gradient. As axis 2 was significantly correlated with total<br />
carbonates and altitu<strong>de</strong>, DCA axis 2 was interpr<strong>et</strong>ed as<br />
an altitu<strong>de</strong>-carbonate gradient.<br />
Environment-veg<strong>et</strong>ation-diversity<br />
relationships<br />
The successive <strong>de</strong>crease of the eigenvalues of the first<br />
three CCA axes (table 4), suggesting a well-structured<br />
data s<strong>et</strong>. These eigenvalues were somewhat lower than<br />
for the DCA axes, indicating that important explanatory<br />
stand variables were not measured and inclu<strong>de</strong>d in the<br />
analysis or some of the variations was not explained<br />
by environmental variables (Franklin & Merlin, 1992;<br />
McDonald <strong>et</strong> al., 1996). However, the species-environment<br />
correlations were higher for the first three canonical<br />
axes, explaining 67.3 % of the cumulative variance. These<br />
results suggested a strong association b<strong>et</strong>ween veg<strong>et</strong>ation<br />
and the measured soil param<strong>et</strong>ers presented in the biplot<br />
(Jongman <strong>et</strong> al., 1987). From the intra-s<strong>et</strong> correlation of<br />
the soil factors with the first three axes of CCA shown in<br />
table 4, it can be noted that CCA axis 1 was correlated<br />
to clay, moisture content, pH, EC, K + , and altitu<strong>de</strong>. This<br />
fact becomes more clearly in the biplot (fig. 4). A test for<br />
significance with an unrestricted Monte Carlo permutation<br />
test (99 permutations) found the F-ratio for the<br />
eigenvalue of axis 1 and the trace statistics to be significant<br />
(p
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
DCA AXIS<br />
CCA AXIS<br />
1 2 3 1 2 3<br />
Eigenvalues 0.81 0.55 0.32 0.65 0.38 0.33<br />
Species-environment correlations 0.83 0.55 0.70 0.93 0.85 0.78<br />
Silt -0.24 -0.15 0.09 0.3 -0.001 0.02<br />
Clay -0.59 * -0.03 0.01 0.74 * 0.04 0.03<br />
MC -0.60 * 0.01 -0.21 0.71 * -0.1 -0.27<br />
OM -0.32 -0.1 0.04 0.37 -0.08 0.18<br />
Total Carbonates -0.11 0.39 * -0.21 -0.2 0.10 -0.32<br />
pH 0.51 -0.22 0.32 -0.57 * -0.22 * 0.41 *<br />
EC -0.71 * 0.04 -0.05 0.86 * -0.15 -0.09<br />
K + -0.67 * 0.12 -0.1 0.80 * 0.12 -0.13<br />
Mg ++ -0.51 * 0.02 -0.42 0.41 0.65 * -0.18<br />
Altitu<strong>de</strong> 0.56 * 0.32 * -0.05 -0.50 * -0.38 * -0.34 *<br />
24<br />
Table 4. Comparison of the results of ordination for the first three axes of DCA and CCA. Intra-s<strong>et</strong> correlations of the environmental variables and altitu<strong>de</strong>,<br />
tog<strong>et</strong>her with eigenvalues and species-environment correlation coefficients. *= Significant at p
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
the relative positions of species and sites along the most<br />
important ecological gradients. Both ordination techniques<br />
clearly indicated that fine soil sediments, moisture<br />
content, pH, electric conductivity, altitu<strong>de</strong>, relative concentrations<br />
of K + and Mg ++ were the most important<br />
param<strong>et</strong>ers for the distribution of the veg<strong>et</strong>ation pattern<br />
in the present study. The role of these factors in<br />
<strong>de</strong>limiting plant communities in the western <strong><strong>de</strong>s</strong>ert has<br />
been stressed by many authors (Ayyad, 1976; Kamal &<br />
El-Kady, 1993). The percentage of surface sediments of<br />
different size classes d<strong>et</strong>ermines the spatial distribution of<br />
soil moisture (Yair & Danin, 1980), as shown for other<br />
<strong><strong>de</strong>s</strong>ert ecosystems in Egypt by Sharaf El Din & Shaltout<br />
(1985), Abd El-Ghani (1998, 2000a) and in Saudi Arabia<br />
by El-Demerdash <strong>et</strong> al. (1994).<br />
The distribution of species in saline and marshy<br />
habitat relates to salinity in many arid regions has been<br />
discussed by several authors (Kassas, 1957; Ungar, 1968<br />
and Maryam <strong>et</strong> al., 1995). Ungar (1974) indicated that<br />
the distribution of halophytes in the United States is<br />
mainly <strong>de</strong>pen<strong>de</strong>nt on the salinity gradient, while local<br />
climate, topography, soil moisture and biotic factors are<br />
less important. Ragonese & Covas (1947) <strong><strong>de</strong>s</strong>cribed the<br />
interrelation of the salinity gradient and veg<strong>et</strong>ation in the<br />
northern Argentinian saltmarshes. Abu-Ziada (1980) and<br />
Abd El-Ghani (2000b) also noted strong relationships<br />
b<strong>et</strong>ween the veg<strong>et</strong>ation pattern and the soil moisture-salinity<br />
gradients in the oases of the western <strong><strong>de</strong>s</strong>ert of Egypt.<br />
When studying the saltmarsh communities of the western<br />
<strong>mediterranea</strong>n coastal <strong><strong>de</strong>s</strong>ert, Ayyad & El-Ghareeb<br />
(1982) pointed out that salinity, the concentration of different<br />
ions and the periodical variation in the water table<br />
d<strong>et</strong>ermine the distribution of species and the differences<br />
b<strong>et</strong>ween communities. They also conclu<strong>de</strong> that the saltmarsh<br />
veg<strong>et</strong>ation in this part of the country represents a<br />
transition from the western communities in North Africa<br />
and those characteristics of the eastern <strong>mediterranea</strong>n<br />
region. In their account of the northern and eastern<br />
<strong>mediterranea</strong>n coastal saltmarshes, Zahran <strong>et</strong> al. (1996)<br />
<strong>de</strong>monstrated the distribution of some halophytic species<br />
as best correlated along a gradient of a dozen of soil variables,<br />
the most important were salinity, moisture content,<br />
soil texture, organic matter and calcium carbonate. In the<br />
present study, the gradient in soil salinity and its variation<br />
from one habitat to another was the primary d<strong>et</strong>erminant<br />
of the plant community composition.<br />
The plant life in the study area was restricted to<br />
microenvironments (as in wadies, runnels and <strong>de</strong>pressions)<br />
where runoff water collects and provi<strong><strong>de</strong>s</strong> sufficient<br />
moisture for plant growth. This was <strong><strong>de</strong>s</strong>cribed by Monod<br />
(1954) as “végétation contractée”, runoff <strong><strong>de</strong>s</strong>ert (sensu<br />
Zohary, 1962), and restricted <strong><strong>de</strong>s</strong>ert (sensu Walter, 1963).<br />
25<br />
Fig. 4. CCA biplot of axes 1<br />
and 2 showing the distribution<br />
of the 53 stands with their<br />
TWINSAPN groups<br />
and soil variables.<br />
For abbreviations, see table 2.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 15-32
◆ FAWZY M. SALAMA, MONIER M. ABD EL-GHANI, SALAH M. EL-NAGGAR, KHADIJA A. BAAYO<br />
Diversity indices<br />
26<br />
Table 5. Spearman rank correlations (r) b<strong>et</strong>ween the diversity indices<br />
and the studied environmental variables and altitu<strong>de</strong> in the study area.<br />
*= Significant at p
VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
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29<br />
APPENDIX<br />
Species<br />
Anabasis articulata (Forssk.) Moq.<br />
Arthrocnemum macrostachyum (Moric.) K. Koch<br />
Atriplex portulacoi<strong><strong>de</strong>s</strong> L.<br />
Deverra tortuosa (Desf.) DC.<br />
Halocnemum strobilaceum (Pall. ) M. Bieb.<br />
Helianthemum lippii (L.) Dum. Cours.<br />
Lycium europaeum L.<br />
R<strong>et</strong>ama ra<strong>et</strong>am (Forssk.) Webb & Berthel.<br />
Salsola t<strong>et</strong>randra Forssk.<br />
Thymelaea hirsuta (L.) Endl.<br />
Zygophyllum album L.<br />
Abbreviations<br />
Aa<br />
Am<br />
Ap<br />
Dt<br />
Hs<br />
Hl<br />
Ll<br />
Rr<br />
St<br />
Th<br />
Za<br />
Appendix 1. Names and abbreviations of the indicator<br />
species displayed in figure 2. First l<strong>et</strong>ter for the genus<br />
and the second for the species.<br />
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30<br />
Family Species Life form Chorotype<br />
Amaryllidaceae Pancratium maritimum L. Cr MED<br />
Apiaceae<br />
Bupleurum lancifolium Hornem. Th MED+IT<br />
Deverra tortuosa (Desf.) DC. Ch SA<br />
Asclepiadaceae Periploca angustifolia Labill. NPh SA+SZ<br />
Anthemis microsperma Boiss. & Kotschy Th MED<br />
Artemisia judaica L. Ch SA<br />
Atractylis carduus (Frossk.) C. Chr. H MED+SA<br />
Carduncellus mareoticus (Delile) Hanelt Th SA<br />
Carthamus glaucus M. Bieb. Th MED<br />
Centaurea glomerata Vahl Th SA<br />
Chilia<strong>de</strong>nus candicans (Delile) Brullo H MED+IT<br />
Asteraceae<br />
Echinops sipnosus L. H IT<br />
Hyoseris radiata L. subsp. graeca Halácsy Cr MED<br />
Hyoseris scabra L. Cr MED<br />
Koelpinia linearis Pall. Th SA+IT<br />
Launaea nudicaulis (L.) Hook. F. H SA+SZ+IT<br />
Launaea fragilis (Asso) Pau H SA<br />
Phagnalon barbeyanum Asch. & Schweinf. Ch SA<br />
Reichardia tingitana (L.) Roth Th SA+IT<br />
Scorzonera undulata Vahl Cr MED+IT<br />
Arnebia <strong>de</strong>cumbens (Vent) Coss. & Kralik Th SA+IT<br />
Boraginaceae<br />
Echiochilon fruticosum Desf. Ch SA<br />
Heliotropium lasiocarpum Fisch. & C.A. Mey. Ch MED+IT+ES<br />
Brassica tournefortii Gouan Th MED+SA<br />
Carrichtera annua (L.) DC. Th SA<br />
Enarthrocarpus lyratus (Forssk.) DC. Th MED<br />
Brassicaceae<br />
Erucaria microcarpa Boiss. Ch MED+IT<br />
Fars<strong>et</strong>ia aegyptia Turra Ch SA+SZ<br />
Sisymbrium irio L. Th MED+SA+IT<br />
Zilla spinosa (L.) Prantl. subsp. biparmata (O.E.Schulz) Maire & Weiller Ch SA<br />
Gymnocarpos <strong>de</strong>candrus Forssk. Ch MED+SA<br />
Herniaria hemistemon J. Gay H SA<br />
Caryophyllaceae<br />
Paronychia arabica (L.) DC. Th SA<br />
Silene succulenta Forssk. H MED<br />
Silene vivianii Steud. Th SA<br />
Anabasis articulata (Forssk.) Moq. Ch SA+IT<br />
Arthrocnemum macrostachyum (Moric.) K. Koch Ch MED+SA<br />
Atriplex halimus L. NPh MED+IT<br />
Atriplex portulacoi<strong><strong>de</strong>s</strong> L. Ch COSM<br />
Chenopodiaceae<br />
Bassia muricata (L.) Asch. Th SA+IT<br />
Halocnemum strobilaceum (Pall.) M. Bieb. Ch MED+SA+IT<br />
Haloxylon salicorincum (Moq.) Bunge ex Boiss. Ch SZ<br />
Noaea mucronata (Forssk.) Asch. & Schweinf. Ch MED+IT<br />
Salsola kali L. Th PAL<br />
Suaeda pruinosa Lange Ch MED<br />
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VEGETATION STRUCTURE AND ENVIRONMENTAL GRADIENTS IN THE SALLUM AREA, EGYPT ◆<br />
Cistaceae Helianthemum lippii (L.) Dum. Cours. Ch SA+SZ<br />
Convolvulaceae Convolvulus arvensis L. H COSM<br />
Cucurbitaceae Citrullus colocynthis (L.) Schrad. H SA<br />
Euphorbiaceae<br />
Euphorbia <strong>de</strong>ndroi<strong><strong>de</strong>s</strong> L. Ch MED<br />
Euphorbia r<strong>et</strong>usa Forssk. H SA<br />
Argyrolobium uniflorum (Decne.) Jaub. & Spach. Ch MED+SA+SZ<br />
Astragalus caprinus L. H SA<br />
Astragalus hamosus L. Th MED+IT<br />
Astragalus hispidulus DC. Th SA<br />
Astragalus peregrinus Vahl Th SA<br />
Astragalus schimperi Boiss. Th SA<br />
Astragalus sieberi DC. Ch SA<br />
Astragalus spinosus (Forssk.) Muschl. Ch SA+IT<br />
Fabaceae<br />
Lotus angustissimus L. Th MED+ES<br />
Lotus cr<strong>et</strong>icus L. H MED<br />
Lotus polyphllos E.D. Clarke H MED<br />
Medicago coronata (L.) Bartal. Th MED+IT<br />
Medicago laciniata (L.) Mill. Th SA<br />
Ononis vaginalis Vahl Ch SA+IT<br />
R<strong>et</strong>ama ra<strong>et</strong>am (Forssk.)Webb & Berthel. NPh MED+SA+IT<br />
Trigonella stellata Forssk. Th SA+IT<br />
Frankeniaceae Frankenia hirsuta L. H MED+IT+ES<br />
Erodium crassifolium L’Hér. Cr SA<br />
Geraniaceae<br />
Erodium laciniatum (Cav.) Willd. Th MED<br />
Erodium pulverulentum (Cav.) Wiild. Th SA<br />
Globulariaceae Globularia arabica Jaub. & Spach. Ch MED+SA<br />
Juncaceae<br />
Juncus acutus L. Cr COSM<br />
Juncus rigidus Desf. Cr MED+IT+ES<br />
Ajuga iva (L.) Schreb. H MED<br />
Lamiaceae<br />
Marrubium alysson L. Th MED+SA<br />
Salvia lanigera Poir. H MED+SA<br />
Asparagus aphyllus L. Cr MED<br />
Liliaceae<br />
Asparagus stipularis Forssk. Cr MED+SA<br />
Aspho<strong>de</strong>lus ramosus L. Cr MED<br />
Aspho<strong>de</strong>lus tenuifolius Cav. Th MED+SA+SZ<br />
Iridaceae Gynandriris sisyrinchium (L.) Parl. Cr MED<br />
Malvaceae Malva parviflora L. Th MED<br />
Neuradaceae Neurada procumbens L. Th SA<br />
Plantaginaceae Plantago albicans L. H MED+SA<br />
Limoniastrum monop<strong>et</strong>alum (L.) Boiss. Ch MED<br />
Plumbaginaceae<br />
Limonium narbonense Mill. H MED<br />
Limonium pruinosum (L.) Chaz. H SA<br />
31<br />
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32<br />
Aeluropus lagopoi<strong><strong>de</strong>s</strong> (L.) Trin. ex Thwaites Cr MED+IT<br />
Ammophila arenaria (L.) Link Cr MED<br />
Cynodon dactylon (L.) Pers. Cr COSM<br />
Cutandia memphitica (Sperng.) K. Richt. Th MED+SA+IT<br />
Poaceae<br />
Hor<strong>de</strong>um murinum L. subsp. leporinum (Link) Arcang. Th MED+IT<br />
Lygeum spartum Loefl. ex L. Cr MED<br />
Schismus barbatus (L.) Thell. Th SA+IT<br />
Sporobolus spicatus (Vahl) Kunth Cr MED+SA+SZ<br />
Stipa parviflora Desf. H MED+IT<br />
Resedaceae Reseda alba L. Th MED+IT<br />
Rubiaceae<br />
Galium tricornutum Dandy Th MED+IT+ES<br />
Crucianella maritima L. H MED<br />
Rutaceae Haplophyllum tuberculatum (Forssk.) Juss. H SA<br />
Santalaceae Thesium humile Vahl P MED<br />
Scrophulariaceae<br />
Kickxia aegyptiaca (L.) Nábelek Ch SA<br />
Verbascum l<strong>et</strong>ourneuxii Asch. & Schweinf. H MED<br />
Solanaceae<br />
Hyoscyamus muticus L. H SA+IT+SZ<br />
Lycium europaeum L. NPh MED+SA<br />
Tamaricaceae Reaumuria hirtella Janb. & Spach. Ch MED+IT<br />
Thymelaeaceae Thymelaea hirsuta (L.) Endl. NPh MED+SA<br />
Fagonia microphlla Pomel Ch SA+IT<br />
Zygophyllaceae<br />
Nitraria r<strong>et</strong>usa (Forssk.) Asch. NPh SA+SZ<br />
Peganum harmala L. H MED+SA+IT<br />
Zygophyllum album L.f. Ch MED+SA<br />
Appendix 2. Distribution of plant species recor<strong>de</strong>d in the Sallum area, tog<strong>et</strong>her with their life forms and chorotypes.<br />
Chorotype abbreviations: MED= Mediterranean, SA= Saharo-Arabian, IT = Irano-Turanian, SZ= Sudano-Zambezian,<br />
ES= Euro-Siberian, COSM= Cosmopolitan and PAL= Palaeotopical. Life-form Abbreviations: Th= Therophytes, Ch= Chamaephytes,<br />
H= Hemicryptophytes, Cr= Cryptophytes, P= Parasites and NPh= Nano-Phanerophytes.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Phenological patterns of ground spi<strong>de</strong>rs (Araneae, Gnaphosidae)<br />
on Cr<strong>et</strong>e, Greece<br />
Phénologie <strong><strong>de</strong>s</strong> araignées édaphiques (Araneae, Gnaphosidae)<br />
en Crète, Grèce<br />
M. Chatzaki 1-2 , G. Markakis 3 & M. Mylonas 1-2<br />
1. Natural History Museum of Cr<strong>et</strong>e, University of Cr<strong>et</strong>e, Irakleio, Greece<br />
2. Department of Biology, University of Cr<strong>et</strong>e, Irakleio, Greece<br />
3. Technological Education Institute of Cr<strong>et</strong>e, Irakleio, Greece<br />
Correspon<strong>de</strong>nce: M. Chatzaki, Natural History Museum of Cr<strong>et</strong>e, University of Cr<strong>et</strong>e, PO Box 2208, 71409 Irakleio, Cr<strong>et</strong>e, Greece.<br />
E-mail: mchatzak@nhmc.uoc.gr<br />
33<br />
Summary<br />
The phenology of one of the dominant families of ground spi<strong>de</strong>rs<br />
of Greece and along the whole Mediterranean, the Gnaphosidae,<br />
is presented. Phenological patterns of the 11 most common and<br />
abundant species of this family are compared in relation to each<br />
other and b<strong>et</strong>ween 17 sites situated on the island of Cr<strong>et</strong>e, Greece. A<br />
major difference b<strong>et</strong>ween lowland and high elevation sites is recor<strong>de</strong>d<br />
for some species. This difference is attributed to a restriction of<br />
activity and/or a shifting of one to two months towards the summer<br />
and early autumn. Based on the similarities which exist among<br />
species a mo<strong>de</strong>l that <strong><strong>de</strong>s</strong>cribes phenological patterns of ground spi<strong>de</strong>rs<br />
in Mediterranean ecosystems is proposed. Most species present<br />
single peaks of activity during the dry period, from mid spring to<br />
mid autumn, which lead to a spectrum of high activity within this<br />
period. Most Gnaphosidae species on Cr<strong>et</strong>e are consi<strong>de</strong>red to be<br />
high comp<strong>et</strong>itors, which can very efficiently take advantage of the<br />
favourable period for this area. Based on their phenology, it is conjectured<br />
that they either have annual biological cycles or that they<br />
may produce two generations per year, although, in other latitu<strong><strong>de</strong>s</strong>,<br />
the same species may have biennial cycles. The flexibility of species,<br />
as far as their presence in both time and space is concerned, reveals<br />
the combined effect of their own physiological tolerance and the<br />
environmental h<strong>et</strong>erogeneity in their niche <strong>de</strong>finition.<br />
Key-words<br />
Ground spi<strong>de</strong>rs, Gnaphosidae, Cr<strong>et</strong>e, Greece, Mediterranean,<br />
phenology<br />
Résumé<br />
La phénologie <strong><strong>de</strong>s</strong> araignées Gnaphosidae, une <strong><strong>de</strong>s</strong> familles<br />
dominantes en Crète <strong>et</strong> dans toute la Méditerranée est analysée.<br />
La phénologie <strong><strong>de</strong>s</strong> onze espèces les plus communes est comparée <strong>et</strong><br />
leur stabilité entre les 17 sites <strong>de</strong> rêcolte est testée. La plupart <strong><strong>de</strong>s</strong><br />
espèces présentent un seul somm<strong>et</strong> d’activité pendant la pério<strong>de</strong><br />
sèche d’avril à octobre, formant un spectre <strong>de</strong> gran<strong>de</strong> activité tout<br />
au long <strong>de</strong> c<strong>et</strong>te pério<strong>de</strong>. Une différence entre les régions <strong>de</strong> plaine<br />
<strong>et</strong> <strong>de</strong> montagne est notée pour quelques espèces. C<strong>et</strong>te différence est<br />
attribuée à une diminution <strong>de</strong> l’activité <strong>et</strong>/ou un décalage d’un ou<br />
<strong>de</strong>ux mois vers l’été <strong>et</strong> le début <strong>de</strong> l’automne. Basé sur les similarités<br />
qui existent entre les espèces, un modèle définissant les combinaisons<br />
phénologiques <strong><strong>de</strong>s</strong> araignées du sol dans les écosystèmes méditerranéens<br />
est proposé. La plupart <strong><strong>de</strong>s</strong> Gnaphosidae <strong>de</strong> Crète sont considérées<br />
comme <strong>de</strong> grands compétiteurs qui peuvent tirer avantage <strong>de</strong><br />
c<strong>et</strong>te pério<strong>de</strong> favorable. Elles présentent soit <strong><strong>de</strong>s</strong> cycles annuels, soit<br />
<strong>de</strong>ux générations par an, alors que sous d’autres latitu<strong><strong>de</strong>s</strong>, les mêmes<br />
espèces ont un cycle biannuel. La fléxibilité <strong><strong>de</strong>s</strong> espèces révèle l’eff<strong>et</strong><br />
combiné <strong>de</strong> leur propre tolérance physiologique <strong>et</strong> <strong>de</strong> l’hétérogénéité<br />
environnementale <strong>de</strong> leur niche écologique.<br />
Mots-clés<br />
Araignées du sol, Gnaphosidae, Crète, Grèce, Méditerranée,<br />
phénologie<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
34<br />
INTRODUCTION<br />
Seasonality in climate is reflected in the activity of<br />
organisms. Varying activity of animals b<strong>et</strong>ween seasons<br />
is interrelated (in the sense of mutual causality) with<br />
the coexistence of groups sharing the same or similar<br />
food resources in the same environment (Tr<strong>et</strong>zel, 1954;<br />
Kuenzler, 1958; Williams, 1962; Breymeyer, 1966;<br />
Dondale <strong>et</strong> al., 1972; Milner, 1988; Pianka, 1994; Majadas<br />
& Urones, 2002). In Mediterranean climates seasonality<br />
is very clear. Organisms are confronted with two periods<br />
of stress (Mitrakos, 1980): one in the winter, due to<br />
low temperatures, and one in the summer, due to high<br />
drought. The two other seasons – autumn and spring –<br />
are the transitional phases b<strong>et</strong>ween the above seasons.<br />
Spi<strong>de</strong>rs are very tolerant to both kinds of climatic<br />
stress, i.e. high/low temperatures and aridity, and that is<br />
why they constitute the main group of ground predators<br />
throughout the year in most types of Mediterranean<br />
habitats (Paraschi, 1988; Ra<strong>de</strong>a, 1993). Although<br />
maximum species richness and activity in all studies<br />
of seasonal variation of most terrestrial organisms<br />
correspond to the warmest period of the year from<br />
mid-spring to mid-autumn (Majadas & Urones, 2002),<br />
irrespective of latitu<strong>de</strong>, elevation or habitat type (Bigot &<br />
Bodot, 1972; Hagvar <strong>et</strong> al., 1978; Paraschi, 1988; Lamotte<br />
& Blandin, 1989; Ra<strong>de</strong>a, 1993; Deltshev & Blagoev, 1994;<br />
Assi, 1998; Chatzaki, 1998; Chatzaki <strong>et</strong> al., 1998), the<br />
winter activity of spi<strong>de</strong>rs is also very important and it is<br />
mostly restricted to the families Linyphiidae, Dys<strong>de</strong>ridae,<br />
Clubionidae and Lycosidae (Schaefer, 1977; Ra<strong>de</strong>a,<br />
1993; Chatzaki <strong>et</strong> al., 1998).<br />
Organisms are able to withstand low temperatures of<br />
the winter in several ways:<br />
a) by using physiological adaptations, such as<br />
reduction of m<strong>et</strong>abolic rate to a negligible amount,<br />
or cryptobiosis (Barra <strong>et</strong> al., 1989), and lowering of<br />
the supercooling point, by accumulating antifreezing<br />
compounds (Block, 1996; Sømme, 1996),<br />
b) by using behavioral adaptations, such as winter<br />
diapause, restriction of activity, vertical migrations<br />
and search for winter r<strong>et</strong>reats (Stamou, 1998),<br />
c) by synchronizing their biological cycle with the<br />
seasons and overwintering in the egg phase, which<br />
is the most tolerant <strong>de</strong>velopmental stage (Schaefer,<br />
1977; Aitchison, 1984).<br />
Spi<strong>de</strong>rs which are active during the dry period<br />
increase their hunting activity at night 1 , r<strong>et</strong>reating to<br />
shady places (un<strong>de</strong>r stones, rocks or litter) during<br />
the day, or use vertical migrations to more favourable<br />
microenvironments (Duffey, 1968; Di Castri & Vitali, Di<br />
Castri, 1981; Cloudsley-Thompson, 1982; Lamotte &<br />
Blandin, 1989), in or<strong>de</strong>r to withstand the limiting factors<br />
of this period. Cryptobiosis and aestivation are also<br />
types of physiological adaptations to the summer stress,<br />
but these probably concern organisms which are more<br />
vulnerable to aridity than spi<strong>de</strong>rs (Stamou, 1998).<br />
Seasonality in the activity of spi<strong>de</strong>rs (Cloudsley-<br />
Thompson, 1978), as well as of most invertebrates<br />
(Pearson & White, 1964; Iatrou & Stamou, 1989;<br />
Lamotte & Blandin, 1989; Stamou, 1998), is mainly<br />
influenced by photoperiod and temperature, in relation<br />
to the physiological tolerance of individual species to<br />
temperature and humidity. These are the main factors<br />
controlling survival (Wise, 1993). However, experimental<br />
data has shown that prey <strong>de</strong>nsities (i.e. Diptera, Isopoda,<br />
Thysanura, Acarea, Collembola and Psocoptera) are<br />
important factors, which influence the abundance of<br />
spi<strong>de</strong>rs more than abiotic factors (i.e. air temperature,<br />
humidity and precipitation) in a pine forest on the island<br />
of Skopelos, Greece (Ra<strong>de</strong>a, 1993 and references therein).<br />
The latter affect spi<strong>de</strong>r <strong>de</strong>nsities only in an indirect way.<br />
The observation that the majority of species overwinter<br />
as immatures, and not as eggs, in or<strong>de</strong>r to be able to take<br />
advantage of the available prey early in the spring, shows<br />
that, <strong><strong>de</strong>s</strong>pite the harshness of the climate during winter,<br />
the main d<strong>et</strong>ermining factor of the biological cycles of<br />
spi<strong>de</strong>rs is food availability (Schaefer, 1977). For most<br />
arachnid species, the increase in availability of food and<br />
in daylight, enhance reproduction towards the end of<br />
spring and lead to an increase in their activity at that<br />
time (Coulson <strong>et</strong> al., 1975; Paraschi, 1988; Majadas &<br />
Urones, 2002).<br />
There are several patterns in the literature which<br />
<strong><strong>de</strong>s</strong>cribe the seasonal variation of spi<strong>de</strong>rs. According to<br />
Aitchison (1984) the following categorization is used as<br />
a standard:<br />
a) eurychronus species, having adults present<br />
during the whole or most of the year. This pattern was<br />
earlier <strong>de</strong>fined as diplochronism by Tr<strong>et</strong>zel (1954) to<br />
<strong><strong>de</strong>s</strong>cribe the double peak of activity in males, observed<br />
from pitfall traps collections. It is not clear when the<br />
reproductive period(s) of this pattern occurs (Toft,<br />
1. Nocturnal activity is common in most arachnids, especially those of the arid or semi-arid ecosystems. It is related to biotic (predation<br />
avoidance) and abiotic (reduction of water loss) factors (Cloudsley-Thompson, 1978).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
1976; Milner, 1988) and in general there is more than<br />
one type of biological cycle that could explain it, i.e.<br />
half, one or two years (Toft, 1976).<br />
b) stenochronous species, having adults present<br />
at a certain time of the year that corresponds to the<br />
reproductive period. Depending on the season when<br />
this happens, the pattern may be further divi<strong>de</strong>d to<br />
spring, summer and autumn stenochronous (Schaefer,<br />
1977; Foelix, 1981). When pitfall traps are used, these<br />
patterns are represented by one peak of male activity,<br />
indicating a search for females and copulation,<br />
followed by (or almost at the same time) a peak in<br />
female activity, indicating the intense search for food<br />
(Tr<strong>et</strong>zel, 1954) and/or for finding suitable places<br />
(Duffey, 1956) just prior to egg <strong>de</strong>position. Usually,<br />
this is followed by an increase of immature stages that<br />
represent the following generation. These patterns may<br />
be attributed to annual or biennial cycles. In the latter<br />
case, mature individuals are observed for a longer<br />
period (from may to october) but each generation<br />
matures in two years, whilst reproduction takes place<br />
in a shorter period (june-july) (Toft, 1976).<br />
c) winter-active species which are mostly active and<br />
reproduce during winter months.<br />
Studies analyzing the phenology of spi<strong>de</strong>rs at species<br />
level in Mediterranean ecosystems are very scarce (Assi,<br />
1986; Majadas & Urones, 2002). Other studies have<br />
been carried out at family level (Bigot & Bodot, 1972;<br />
Christophe, 1974; Paraschi, 1988; Chatzaki <strong>et</strong> al., 1998)<br />
or refer to different bioclimatic zones (Tr<strong>et</strong>zel, 1954;<br />
Toft, 1976; Aitchison, 1984; Milner, 1988; Deltshev &<br />
Blagoev, 1994). Although not shown earlier, it is unlikely<br />
that studies based on family level, albeit indicative of the<br />
actual phenological patterns of the taxa, are sufficient to<br />
account for the seasonal variation of ground spi<strong>de</strong>rs in<br />
Mediterranean ecosystems, since this is directly linked<br />
to the species’ biological cycles and to the climate of<br />
a region. In this study the phenology of one of the<br />
dominant families of ground spi<strong>de</strong>rs, Gnaphosidae, is<br />
presented. Phenological patterns of the 11 most common<br />
and abundant species of Cr<strong>et</strong>e, Greece are compared in<br />
relation to each other and among the 17 sites of the study<br />
area. The main goal of the present study is to answer the<br />
following questions:<br />
1. What is the phenological pattern followed by each<br />
one of the dominant species of the family Gnaphosidae<br />
on Cr<strong>et</strong>e?<br />
2. How stable is this pattern along the sites of Cr<strong>et</strong>e,<br />
knowing that there is great habitat and climate<br />
h<strong>et</strong>erogeneity along this island? What are the main<br />
reasons for any possible variation?<br />
3. What is the phenological pattern of the family as<br />
a whole at each site and how informative can this<br />
pattern be?<br />
MATERIALS AND METHODS<br />
Study area<br />
Cr<strong>et</strong>e is the largest island of the south Aegean island<br />
arc and is situated at its centre (34°.50’-35°.40’N latitu<strong>de</strong>,<br />
23°.30’-26°.20’E longitu<strong>de</strong>). It is the fifth largest island<br />
in the Mediterranean, after Sicily, Sardinia, Cyprus<br />
and Corsica, with total area covering 8.261 km 2 . Cr<strong>et</strong>e<br />
presents great geomorphological variation, being a<br />
“miniature continent”, as Rackham & Moody (1996)<br />
very illustratively report. Even within such a small area,<br />
a great vari<strong>et</strong>y of habitats and climatic factors are present,<br />
ranging from the insular character of the coasts to a fully<br />
continental character in the centre, where three main<br />
mountains of high altitu<strong>de</strong> (peaks of 2 000-2 400 m)<br />
exist: Lefka Ori in the western part, Psiloreitis in the<br />
central part and Lasithiotika Ori (Dikti and Thrypti) in<br />
the eastern part. As far as landscape, climate, veg<strong>et</strong>ation<br />
and human impact are concerned, Cr<strong>et</strong>e is very<br />
asymm<strong>et</strong>rical along its main axes, north-south, west-east<br />
and along the altitudinal gradients.<br />
Climate. The climate of Cr<strong>et</strong>e is typical Mediterranean,<br />
with 5-7 months of arid, hot and dry summers, alternating<br />
with smaller periods of rainy, mild winters. Along the<br />
main axes of the island there is a remarkable gradient<br />
of temperature, precipitation, winds and humidity. The<br />
south, east and inland lowlands are warmer and drier than<br />
the rest of regions (Rackham & Moody, 1996).<br />
Mean annual temperatures are 2 °C higher in the south<br />
than in the north of Cr<strong>et</strong>e (Pennas, 1977) and they fall by<br />
6 °C per 1 000 m altitu<strong>de</strong> (Grove <strong>et</strong> al., 1991). The range<br />
of temperatures is much narrower near the coasts than<br />
in the mountains, due to the more maritime character of<br />
the former (Strid, 1995). The southeastern coast of Cr<strong>et</strong>e<br />
is the warmest and most arid area throughout Greece<br />
(relative humidity can be as low as 20 % in the summer),<br />
while the northwestern parts of Lefka Ori belong to the<br />
more humid zones (Pennas, 1977; Strid, 1995).<br />
Mean annual precipitation for Cr<strong>et</strong>e is 400-650 mm.<br />
However, there is consi<strong>de</strong>rable variation in both time<br />
and space. The rainy period extends from october to<br />
35<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
36<br />
march (mainly from <strong>de</strong>cember to february), when 85-<br />
90 % of the total rain falls (Pennas, 1977). Precipitation<br />
is higher at the western and northern parts of Cr<strong>et</strong>e, as<br />
well as at the mountains. Although there are no records<br />
about the precipitation above 900 m, Rackham & Moody<br />
(1996) estimate that at the top of Lefka Ori the annual<br />
precipitation must be as high as 2 000 mm, while at the<br />
southeastern corner of Cr<strong>et</strong>e as low as 240 mm.<br />
Veg<strong>et</strong>ation. The dominant plant formations are<br />
phrygana and maquis, which on Cr<strong>et</strong>e are often<br />
intermixed due to overgrazing and human activities.<br />
Phrygana is the most wi<strong><strong>de</strong>s</strong>pread formation on the island.<br />
Lowland and middle altitu<strong>de</strong> phrygana are composed of<br />
thorny aromatic shrubs, such as: Sarcopoterium spinosum,<br />
Coridothymus capitatus, Phlomis spp., Cistus spp., Genista<br />
acanthoclada, Calicotome villosa, Euphorbia spp., Ballota<br />
spp. and many others. At higher elevations other species<br />
(chamephytes) dominate, such as: Berberis cr<strong>et</strong>ica,<br />
Rhamnus saxatilis, Prunus prostrata, Satureja spinosa,<br />
Astragalus angustifolius, <strong>et</strong>c. The upper limits of forest<br />
growth reach altitu<strong><strong>de</strong>s</strong> from 1 600 m (southern slopes) to<br />
1 800 m (northern slopes). Pinus brutia is the dominant<br />
tree species up to 1 200 m. This is the commonest forest<br />
formation on Cr<strong>et</strong>e, being found from sea level to such<br />
elevations. Beyond the timberline, only scarce veg<strong>et</strong>ation<br />
composed of small cushion-like shrubs exists.<br />
Sampling<br />
For the purposes of the present study 17 sites were<br />
selected along Cr<strong>et</strong>e, in or<strong>de</strong>r to cover its horizontal and<br />
vertical axes and the altitudinal gradients of the three<br />
main mountain massifs, Lefka Ori, Psiloreitis and Dikti<br />
(fig. 1). The veg<strong>et</strong>ation type of most of the lowland sites<br />
is phrygana. D<strong>et</strong>ails for each site are given in table 1.<br />
At all sites material was collected using pitfall traps<br />
containing <strong>et</strong>hylene glycole as preservative. Pitfalls were<br />
s<strong>et</strong> and changed at two-month intervals 2 . Collection<br />
of material lasted for one year at each site. Although<br />
this period does not sufficiently <strong><strong>de</strong>s</strong>cribe the temporal<br />
variation of species during an entire bioclimatic cycle<br />
– which in northern Greece (Stamou, 1998) as well as<br />
in most Mediterranean regions (P<strong>et</strong>anidou, 1991) lasts<br />
four years – it is however quite commonly used in similar<br />
analyses (Ra<strong>de</strong>a, 1993; Groppali <strong>et</strong> al., 1996; Assi, 1998).<br />
Fig. 1 Map of sites<br />
in the study area.<br />
2. In sites 3-6 and 11, material was collected every month. In most cases collecting periods were modified to shorter intervals in or<strong>de</strong>r to<br />
conform to the rest of data, unless the information they provi<strong>de</strong>d was very important, so they were presented in monthly intervals.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
Sites Locality Altitu<strong>de</strong> (m) Habitat type Dates of collection and corresponding groups for analysis<br />
Site 1 Gramvousa 0 Phrygana at sea level.<br />
a: 25/4/1996-26/6/1996; b: 26/6/1996-23/8/1996; c: 23/8/1996-<br />
29/10/1996; d: 29/10/1996-30/12/1996; e: 30/12/1996-14/3/1997; f:<br />
15/3/1997-12/5/1997. (A)<br />
Site 2 Elafonisi 0<br />
Phrygana-maquis (Juniperus oxycedrus, Pistacia lentiscus,<br />
Coridothymus capitatus and Ceratonia siliqua). Highly<br />
disturbed area due to touristic activities.<br />
a: 25/4/1996-26/6/1996; b: 26/6/1996-25/8/1996; c: 25/8/1996-<br />
29/10/1996; d: 29/10/1996-30/12/1996; e: 30/12/1996-13/3/1997; f:<br />
13/3/1997-7/5/1997. (A)<br />
Site 3<br />
Lefka Ori<br />
(above Anopoli village)<br />
800<br />
Mature pine forest (Pinus brutia) with very little un<strong>de</strong>rgrowth<br />
consisting mainly of Quercus coccifera.<br />
a: 18/10/1990-23/11/1990; b: 1/3/1991-28/3/1991; c: 28/3/1991-5/<br />
5/1991; d: 5/5/1991-8/6/1991; e: 8/6/1991-6/7/1991; f: 6/7/1991-4/<br />
8/1991; g: 4/8/1991-8/9/1991; h: 8/9/1991-5/10/1991; i: 5/10/1991-<br />
6/11/1991; j: 6/11/1991-7/12/1991; k: 7/12/1991-11/1/1992; l: 11/1/<br />
1992-8/3/1992; m: 9/3/1992-5/4/1992. (E)<br />
Site 4<br />
Site 5<br />
Site 6<br />
Lefka Ori<br />
(above Anopoli village)<br />
Lefka Ori<br />
(above Anopoli village)<br />
Lefka Ori<br />
(above Anopoli village)<br />
1200<br />
1600<br />
2000<br />
Old cypress wood (Cupressus sempervirens) with scarce<br />
Quercus coccifera and Acer sempervirens. Traps of this period<br />
were consi<strong>de</strong>red active only during the first 30 days<br />
Plateau over the timberline. Scarce veg<strong>et</strong>ation consisting of<br />
cushion-like bushes, mainly Juniperus oxycedrus oxycedrus,<br />
Berberis cr<strong>et</strong>ica, Prunus prostrata, Satureja spinosa.<br />
Valley with scarce veg<strong>et</strong>ation consisting of Berberis cr<strong>et</strong>ica,<br />
Prunus prostrata, Astragalus angustifolius and Satureja spinosa.<br />
a: 18/10/1990-23/11/1990; b: 1/3/1991-28/3/1991; c: 28/3/1991-5/<br />
5/1991; d: 5/5/1991-8/6/1991; e: 8/6/1991-6/7/1991; f: 6/7/1991-4/<br />
8/1991; g: 4/8/1991-8/9/1991; h: 8/9/1991-5/10/1991; i: 5/10/1991-<br />
6/11/1991; j: 7/11/1991-4/5/1992 4 . (E)<br />
a: 29/7/1990-1/9/1990; b: 1/9/1990-17/10/1990; c: 18/10/1990-23/11/<br />
1990; d: 28/3/1991-5/5/1991; e: 5/5/1991-8/6/1991; f: 8/6/1991-6/7/<br />
1991; g: 6/7/1991-4/8/1991; h: 4/8/1991-7/9/1991; i: 7/9/1991-5/10/<br />
1991; j: 5/10/1991-6/11/1991; k: 6/11/1991-6/6/1992 4 . (E)<br />
a: 29/7/1990-1/9/1990; b: 1/9/1990-16/10/1990; c: 8/6/1991-6/7/1991;<br />
d: 6/7/1991-4/8/1991; e: 4/8/1991-7/9/1991; f: 7/9/1991-6/10/1991; g:<br />
6/10/1991-7/8/1992. (E)<br />
37<br />
Site 7 Exantis 200<br />
Dense phrygana-maquis dominated by Quercus coccifera,<br />
Sarcopoterium spinosum, Corydothymus capitatus and<br />
Calicotome villosa.<br />
a: 22/4/2000-6/7/2000; b: 6/7/2000-14/9/2000; c: 14/9/2000-7/11/<br />
2000; d: 7/11/2000-13/1/2001; e: 13/1/2001-12/3/2001; f: 12/3/2001-<br />
8/5/2001. (C)<br />
Site 8<br />
Psiloreitis<br />
(above Kouroutes village)<br />
1650 Subalpine shrubs.<br />
a: 14/4/2000-2/7/2000; b: 2/7/2000-14/9/2000; c: 14/9/2000-30/10/<br />
2000; d: 30/10/2000-24/3/2001; e: 24/3/2001-12/6/2001. (D)<br />
Site 9<br />
Psiloreitis<br />
(above Lochria village)<br />
1950 Subalpine shrubs.<br />
a: 14/4/2000-2/7/2000; b: 2/7/2000-15/9/2000; c: 15/9/2000-30/10/<br />
2000; d: 30/10/2000-24/3/2001; e: 24/3/2001-12/6/2001. (D)<br />
Site 10 Panagia Almyri 100<br />
Site 11 Youchtas 200<br />
Site 12 Keratokampos 0<br />
Phrygana (Calicotome villosa, Sarcopoterium spinosum,<br />
Phlomis sp.) and Nerium olean<strong>de</strong>r by the riversi<strong><strong>de</strong>s</strong>.<br />
Phrygana (Quercus coccifera, Genista acanthoclada,<br />
Corydothymus capitatus, Ebenus cr<strong>et</strong>icus and Salvia fruticosa).<br />
Phrygana-maquis close to the beach. Abandoned cultivations<br />
close to the village.<br />
a: 16/3/1999-20/5/1999; b: 20/5/1999-26/7/1999; c: 26/7/1999-30/9/<br />
1999; d: 30/9/1999-26/1/2000; e: 26/1/2000-2/7/2000. (B)<br />
a: 16/12/1995-15/1/1996; b: 15/1/1996-18/2/1996; c: 18/2/1996-2/4/<br />
1996; d: 2/4/1996-28/4/1996; e: 28/4/1996-6/6/1996; f: 6/6/1996-2/7/<br />
1996; g: 2/7/1996-8/8/1996; h: 8/8/1996-16/9/1996; i: 16/9/1996-10/<br />
10/1996; j: 10/10/1996-14/11/1996 k: 14/11/1996-11/12/1996. (A)<br />
a: 27/11/1998-26/1/1999; b: 26/3/1999-26/5/1999; c: 26/5/1999-28/7/<br />
1999; d: 28/7/1999-28/9/1999; e: 28/9/1999-26/1/2000. (B)<br />
Site 13 Milatos 300 Degra<strong>de</strong>d phrygana.<br />
a: 21/4/2000-12/7/2000; b: 12/7/2000-11/10/2000; c: 11/10/2000-23/<br />
1/2001; d: 23/1/2001-9/3/2001; e: 9/3/2001-6/5/2001. (C)<br />
Site 14 Dikti-Limnakaro 1450 Phrygana over the plateau.<br />
a: 11/5/2000-5/8/2000; b: 5/8/2000-2/10/2000; c: 2/10/2000-9/1/2001;<br />
d: 9/1/2001-10/5/2001. (D)<br />
Site 15 Dikti-Limnakaro 1750 Subalpine shrubs.<br />
a: 12/5/2000-5/8/2000; b: 5/8/2000-2/10/2000; c: 2/10/2000-9/1/2001;<br />
d: 9/1/2001-10/5/2001. (D)<br />
Site 16 Bramiana 0<br />
Lake reservoir divi<strong>de</strong>d into a pond and a steppe-like area<br />
resulting from <strong><strong>de</strong>s</strong>iccation.<br />
a: 30/10/1998-4/1/1999; b: 4/1/1999-3/3/1999; c: 3/3/1999-4/5/1999;<br />
d: 4/5/1999-22/7/1999; e: 22/7/1999-22/9/1999; f: 22/9/1999-1/2/<br />
2000. (B)<br />
Site 17 Chamaitoulo-Xirokampos 280 Phrygana.<br />
a: 28/5/2000-6/8/2000; b: 6/8/2000-12/10/2000; c: 12/10/2000-23/1/<br />
2001; d: 23/1/2001-16/3/2001; e: 16/3/2001-6/5/2001. (C)<br />
Table 1. Description of the study sites.<br />
Symbols in brack<strong>et</strong>s (A to E) indicate sites where sampling was performed at the same year<br />
and that belong to the same group for the statistical analyses.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
38<br />
Experimental evi<strong>de</strong>nce also suggests that in spi<strong>de</strong>rs there<br />
is an impressive stability of phenological patterns, even<br />
b<strong>et</strong>ween years of great climatic divergence (Hagvar <strong>et</strong> al.,<br />
1978; Polis, 1998). It is also reported that the activity of<br />
organisms in Mediterranean ecosystems seems to <strong>de</strong>pend<br />
much more on the seasonal variations within one year<br />
than on the variation among years (Stamou, 1998). Based<br />
on this i<strong>de</strong>a, data from one year’s sampling were used here<br />
to <strong><strong>de</strong>s</strong>cribe the phenological patterns of species.<br />
Mature specimens (males and females) of the 11 most<br />
common and abundant species of the entire study area<br />
were counted at each site. All counts were transformed to<br />
numbers of individuals per 100 trap/days (td) in or<strong>de</strong>r to<br />
equate the sampling effort at all sites. Immature specimens<br />
were not taken into account, because taxonomical<br />
i<strong>de</strong>ntification at species level was not possible. Phenology<br />
of the family at each site was measured as the sum of the<br />
numbers of mature individuals per sample.<br />
Phenological patterns are presented in rabdograms.<br />
The most characteristic phenograms from the sites in<br />
which each species occurred in a relatively high number<br />
of individuals are shown in the figures. The symbol<br />
(-) is used to simplify comparison b<strong>et</strong>ween sites, when<br />
sampling periods did not fully correspond to each<br />
other, but do not correspond to an “actual” sampling.<br />
Phenology is presented as relative counts (%) of the total<br />
activity during the sampling periods. For each species,<br />
accompanying ecological comments on its habitat<br />
preferences are ad<strong>de</strong>d.<br />
Statistical analysis<br />
Two Factor ANOVA was used to test differences in<br />
phenological patterns of each species b<strong>et</strong>ween sites of<br />
the study area. Analysis was carried out with SPSS 8<br />
(SPSS Inc., 1989-1997). Seasons and sites were taken<br />
into account as the two factors, but only the sites<br />
comparisons were used in the results. Sites were divi<strong>de</strong>d<br />
into five groups of 3-6 sites (from A to E, see table 1),<br />
in which sampling was performed in the same year. For<br />
each species, counts (f) of male and female individuals<br />
were tested both separately and in total. Logarithmic<br />
transformation [log(f+1)] was used, because of great<br />
<strong>de</strong>viation among the counts. In or<strong>de</strong>r to be sure that<br />
the observed statistical differences did not result from<br />
differences in the absolute numbers of individuals, rather<br />
than of the activity patterns of the species, the analysis<br />
was also carried out by transforming the numbers<br />
of individuals into relative counts [log(rf+1)]. This<br />
transformation was calculated by dividing the number of<br />
individuals of a species collected at each period by the<br />
total number of individuals (of the same species) found<br />
at each site.<br />
In or<strong>de</strong>r to test statistically the similarities of patterns<br />
observed among species of this study, a further Two<br />
Factor ANOVA was performed using pairs of species as<br />
the first factor and season as a second. In this case we<br />
were only interested in testing the interaction b<strong>et</strong>ween<br />
season and species groups. In those cases where this<br />
interaction was not significant, patterns of the species<br />
involved were consi<strong>de</strong>red to fall into the same group of<br />
phenological pattern. The test was performed for each<br />
site group separately. Different pairs of species were<br />
tested and those that showed the greater percentage of<br />
no interaction among groups of sites were used for the<br />
creation of a mo<strong>de</strong>l representing the activity patterns<br />
which may be followed by Gnaphosidae on Cr<strong>et</strong>e.<br />
Percentages (rf) were arcsine-transformed, according to<br />
the formula y=arcsin(√rf) (Sokal & Rolhf, 1995).<br />
RESULTS<br />
Descriptive analysis<br />
Phenological patterns of species<br />
Callilepis cr<strong>et</strong>ica (Roewer, 1928)<br />
This species is quite common on Cr<strong>et</strong>e, occurring<br />
from sea level to 1 950 m. However it becomes more<br />
abundant at the zone 1 200-1 600 m and prefers rather<br />
cool and humid environments. In most lowland sites,<br />
mature individuals are found from may to september,<br />
with peak of males in may-june (fig. 2). Numbers of<br />
female individuals were too low to show a clear pattern.<br />
In the sites at higher elevations, sites 4-5 and 8-9, the<br />
activity of C. cr<strong>et</strong>ica is shortened and is shifted towards<br />
the end of summer.<br />
Drasso<strong><strong>de</strong>s</strong> oreinos (Chatzaki, 2002)<br />
This species occurs only on the mountains of Cr<strong>et</strong>e<br />
above 1 200 m and it becomes one of the dominant<br />
species above 1 650 m. At this latter elevation it is the<br />
only representative of the genus. The peak of male activity<br />
is in august-september (fig. 3). The activity of females<br />
is exten<strong>de</strong>d for a longer period, especially at the highest<br />
elevations. A similar, but less stable pattern, is observed<br />
in another high altitu<strong>de</strong> species, Gnaphosa bithynica<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
Fig. 2. Phenology of Callilepis cr<strong>et</strong>ica<br />
on Cr<strong>et</strong>e (relative counts (%) of the total<br />
catch per site).<br />
39<br />
Fig. 3. Phenology of Drasso<strong><strong>de</strong>s</strong> oreinos<br />
on Cr<strong>et</strong>e (relative counts (%) of the total<br />
catch per site).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
40<br />
(Kulczynski, 1903), with female individuals being present<br />
throughout the favourable period (Chatzaki, 2003).<br />
Drassyllus praeficus (L. Koch, 1866)<br />
This species is common on Cr<strong>et</strong>e from sea level to<br />
1 650 m. It prefers maquis of middle altitu<strong>de</strong>, mainly in<br />
central Cr<strong>et</strong>e. Mature specimens are present from midspring<br />
until mid-summer (fig. 4). Comparing the patterns<br />
at all sites, it may be conjectured that the peak of males<br />
is in april-may and that of females is in may. According<br />
to Urones, Jerardino & Barrientos (1995), D. praeficus<br />
has two generations per year, and this is also suggested<br />
by the data presented here, where females do not seem<br />
to present a stable pattern, thus indicating longer activity<br />
during the dry season.<br />
Haplodrassus cr<strong>et</strong>icus (Roewer, 1928)<br />
This species is the most common representative of the<br />
genus Haplodrassus on Cr<strong>et</strong>e having no special habitat<br />
preferences. It has a narrow activity period early in the<br />
spring with peaks of both sexes occurring at some time<br />
b<strong>et</strong>ween january and march with the female peak a bit<br />
later than that of the males (fig. 5).<br />
Micaria coarctata (Lucas, 1846)<br />
This species is the most common representative of the<br />
genus Micaria on Cr<strong>et</strong>e, reaching altitu<strong><strong>de</strong>s</strong> of 1 750 m.<br />
However it is not very active at the sites where it occurs,<br />
therefore no phenograms are presented for it. It has a<br />
rather stable phenological pattern with short activity<br />
towards the end of spring and beginning of summer<br />
(fig. 6).<br />
Nomisia excerpta (O.P. Cambridge, 1872)<br />
This species is one of the commonest on Cr<strong>et</strong>e.<br />
Mature specimens are found from mid-spring to end of<br />
summer (fig. 6) with male peak in may-june and female<br />
peak one or two months later.<br />
Fig. 4. Phenology of Drassyllus praeficus<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
41<br />
Fig. 5. Phenology of Haplodrassus cr<strong>et</strong>icus<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
Pterotricha lentiginosa (C.L. Koch, 1837)<br />
This species is the dominant species on Cr<strong>et</strong>e as far<br />
as both frequency and abundance are concerned, being<br />
common in most habitat types and altitu<strong><strong>de</strong>s</strong> of Cr<strong>et</strong>e up<br />
to 1 950 m. P. lentiginosa is one of the few species which<br />
is active in winter time as well as in the summer (fig. 7).<br />
It is also the only species that shows two distinct peaks<br />
of male activity (diplochronism) at most lowland sites<br />
and one female peak in may-june. At higher elevations<br />
the pattern changes with restriction of activity to only the<br />
warmer period. At these sites a single peak of male activity<br />
is observed in august-september, while the peak of female<br />
activity is observed a little earlier. Its close relative, P. kochi<br />
(O.P. Cambridge, 1872), shows similar activity pattern in<br />
Lebanon (Assi, 1998).<br />
Trachyzelotes malkini (Platnick, 1984)<br />
This species is the most common of all its congeners on<br />
Cr<strong>et</strong>e, reaching altitu<strong><strong>de</strong>s</strong> of 1 450 m. Mature specimens<br />
are found from mid-spring until the end of summer with<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
42<br />
Fig. 6. Phenology of Nomisia excerpta<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
male peak usually in may-june and female peak at the<br />
same time or a bit later (fig. 8). At higher elevations (i.e.<br />
site 14) activity is shifted towards the end of summer.<br />
Zelotes caucasius (L. Koch, 1866)<br />
This species is one of the commonest on Cr<strong>et</strong>e. Similar<br />
to most of its congeners (for instance Z. labilis, Z. scrutatus,<br />
Z. tenuis) the phenological pattern of Z. caucasius presents<br />
high activity throughout the dry period, with male peak<br />
in may-june and female peak at the same period or just<br />
afterwards (fig. 9). At higher elevations the pattern does<br />
not change, but it is more restricted to the summer<br />
months.<br />
Zelotes cr<strong>et</strong>icus (Kulczyski, 1903)<br />
This is a common species of middle and higher<br />
elevations of western Cr<strong>et</strong>e, but does not occur in eastern<br />
Cr<strong>et</strong>e. Its distribution at the lowland sites shows that it<br />
is rather sensitive to high aridity (Chatzaki <strong>et</strong> al., 2003).<br />
Its phenological pattern resembles that of D. oreinos with<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
43<br />
Fig. 7. Phenology of Pteroticha lentiginosa<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
Fig. 8. Phenology of Trachyzelotes malkini<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
44<br />
Fig. 9. Phenology of Zelotes caucasius<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
male peak in august-september and female peak in June,<br />
but with more exten<strong>de</strong>d presence of females during<br />
almost the whole year (fig. 10).<br />
Zelotes subterraneus (C.L. Koch, 1833)<br />
This species is very common on Cr<strong>et</strong>e. Tog<strong>et</strong>her with<br />
P. lentiginosa, they form the main bulk of Gnaphosidae<br />
present during winter time. The male peak is observed<br />
in september-october at the lowland sites and in augustseptember<br />
at the higher elevations (fig. 11), and female<br />
peak at the same time or a bit later. It is interesting to note<br />
that Aitchison (1984) classifies this species as summer<br />
stenochronous, which, as will be commented upon in<br />
the discussion, is due to latitudinal difference of the two<br />
study areas.<br />
There are not any winter-active Gnaphosidae,<br />
consequently there are no species that appear only in<br />
winter months. Instead, the few Gnaphosidae that are<br />
present during this period belong to the most cold-tolerant<br />
species that present their maximum activity within the dry<br />
season. These are: P. lentiginosa, Z. subterraneus, H. cr<strong>et</strong>icus<br />
and also Anagraphis pallens, Z. cf. ilotarum, Z. scrutatus,<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
Fig. 10. Phenology of Zelotes cr<strong>et</strong>icus<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
45<br />
Fig. 11. Phenology of Zelotes subterraneus<br />
on Cr<strong>et</strong>e (relative counts (%)<br />
of the total catch per site).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
46<br />
Z. tenuis, which are not presented here, due to lower<br />
numbers of catches.<br />
Total seasonal variation of Gnaphosidae<br />
In this section, the total phenological pattern of the<br />
family at each one of the sites is presented. In all sites<br />
maximum activity of the family is observed within the<br />
dry season of the year, irrespective of their geographical<br />
position and prevailing bioclimatic conditions. The main<br />
difference b<strong>et</strong>ween sites is in the exact time and duration<br />
of the high activity period. In each case the pattern is<br />
characterized by the dominant species at the sites. Based<br />
on these differences, phenological patterns of Gnaphosidae<br />
may be divi<strong>de</strong>d into three groups:<br />
a) those that have one narrow peak during the first<br />
period i.e. end of spring – mid summer (sites 1 and<br />
10), which is characterized by the dominance of<br />
members of the genus Zelotes.<br />
b) those that have one peak which lasts longer<br />
within the favourable period than that of (a) (sites<br />
12, 13, 16). These sites are characterized by the codominance<br />
of many species. Thus, the long activity<br />
period is produced by the conjunction of the activity<br />
patterns of many species whose peaks occur at<br />
different times within the favourable period: Zelotes<br />
spp. are responsible for the spring-summer activity,<br />
while P. lentiginosa, Z. subterraneus and Z. cr<strong>et</strong>icus are<br />
mainly responsible for the activity recor<strong>de</strong>d later in the<br />
summer and early autumn 3 .<br />
c) those that present two peaks of activity (sites 2,<br />
7, 11, 17), in which P. lentiginosa and Z. subterraneus<br />
dominate, the latter adding mainly to the autumn<br />
peak.<br />
At higher elevations some sites shown one relatively<br />
long peak of activity, while others shown two peaks of<br />
activity. However the two peaks, when present, do not<br />
result from the presence of eurychronous species as<br />
in the case of lowland sites of group (c), but instead<br />
they are produced by many species: Drassylus praeficus,<br />
Callilepis cr<strong>et</strong>ica, Haplodrassus cr<strong>et</strong>icus, Zelotes caucasius in<br />
mid-spring, Nomisia excerpta, Z. tenuis, Z. cr<strong>et</strong>icus, Z. labilis<br />
in summer and Drasso<strong><strong>de</strong>s</strong> oreinos, Pterotricha lentiginosa,<br />
Z. cr<strong>et</strong>icus, Z. subterraneus at the beginning of september.<br />
Statistical analysis<br />
Differences b<strong>et</strong>ween sites, based on the seasonal<br />
variation of each species (absolute counts), are shown<br />
in table 2. For most species there are not any significant<br />
differences in the phenological pattern they present<br />
among sites of the same group. For all species, statistically<br />
significant differences are recor<strong>de</strong>d at sites of higher<br />
elevations (group E). P. lentiginosa is the only species in<br />
which differences in the activity pattern are recor<strong>de</strong>d at<br />
a group of lowland sites (group C). When relative counts<br />
are taken into consi<strong>de</strong>ration (table 3), no differences in<br />
the patterns of each species are recor<strong>de</strong>d, except for<br />
females of P. lentiginosa and Z. subterraneus b<strong>et</strong>ween<br />
sites of group E. Consequently, most of the differences<br />
recor<strong>de</strong>d in table 2 are <strong>de</strong>rived from differences in the<br />
absolute numbers of the species at the sites of the study<br />
area.<br />
Taking into consi<strong>de</strong>ration the patterns of activity<br />
presented in the previous section, species were grouped<br />
in pairs and further tested for statistically significant<br />
differences (table 4). Non-significant P-values for the<br />
interaction b<strong>et</strong>ween species and seasons indicate cases in<br />
which pairs of species follow the same pattern of activity<br />
within groups of sites. Missing values exist in cases where<br />
there was only one species at a sites group. Several trials<br />
were performed in or<strong>de</strong>r to find those pairs of species<br />
which showed the highest similarity of patterns. In group V<br />
there is a greater number of significant interaction which<br />
implies that the activity pattern of Z. subterraneus is not<br />
close to that of P. lentiginosa, hence leaving the latter<br />
species as the main representative of activity type V.<br />
DISCUSSION<br />
Mo<strong>de</strong>l of phenological patterns<br />
From mid-spring to mid-autumn, Gnaphosidae is<br />
the dominant family of Cr<strong>et</strong>an arachnofauna. In winter<br />
time the activity of most gnaphosid species is restricted<br />
and the family is outnumbered by other families, such<br />
as Linyphiidae, Dys<strong>de</strong>ridae, Clubionidae (Chatzaki <strong>et</strong> al.,<br />
1998). Within the favourable period, there is a continuum<br />
3. Other species which are less active, but are still present in early spring or early autumn and add to this pattern, are: Drassyllus praeficus,<br />
Haplodrassus cr<strong>et</strong>icus, Haplodrassus dalmatensis, Trachyzelotes malkini, T. lyonn<strong>et</strong>i (spring), Zelotes solstitialis (autumn).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
Species Group Male Female Total<br />
Drasso<strong><strong>de</strong>s</strong> oreinos<br />
D 0,316 0,007 0,018<br />
E 0,086 0,004 0,004<br />
A 0,751 0,428 0,609<br />
B 0,949 0,391 0,837<br />
Nomisia excerpta<br />
C 0,391 0,799 0,433<br />
D 0,354 0,189 0,122<br />
E 0,054 0,013 0,011<br />
A 0,169 0,135 0,085<br />
B 0,069 0,191 0,149<br />
Pterotricha lentiginosa C 0,013 0,153 0,018<br />
D 0,049 0,118 0,668<br />
E 0,485 0,119 0,036<br />
Zelotes cr<strong>et</strong>icus E 0,726 0,007 0,039<br />
A 0,655 0,326 0,435<br />
B 0,735 0,425 0,493<br />
Zelotes subterraneus<br />
C 0,819 0,166 0,486<br />
D 0,628 0,221 0,336<br />
E 0,514 0,006 0,056<br />
Table 2. P-values of two factor ANOVA<br />
test among groups of sites – absolute counts of species.<br />
Values in bold indicate the significant results,<br />
in which phenological patterns within groups<br />
of sites are not the same. Species for which<br />
no significant values were recor<strong>de</strong>d,<br />
are not shown in the table.<br />
47<br />
Species Group Male Female Total<br />
Pterotricha lentiginosa<br />
Zelotes subterraneus<br />
A 0,871 0,823 0,865<br />
B 0,358 0,744 0,901<br />
C 0,523 0,836 0,843<br />
D 0,744 0,768 0,688<br />
E 0,702 0,026 0,376<br />
A 0,183 0,750 0,800<br />
B 0,482 0,695 0,636<br />
C 0,983 0,863 0,803<br />
D 0,705 0,937 0,903<br />
E 0,784 0,007 0,108<br />
Table 3. P-values of single factor ANOVA test among<br />
groups of sites – relative counts of species. Values in bold<br />
indicate the significant results, in which phenological<br />
patterns within groups of sites are not the same. Species<br />
for which no significant values were recor<strong>de</strong>d, are not<br />
shown in the table.<br />
in the peaks of species activity, a phenomenon that has<br />
already been observed by other authors, both in the<br />
Mediterranean (Urones, Jerardino & Barrientos, 1995)<br />
and in other temperate ecosystems (En<strong>de</strong>rs, 1976;<br />
Toft, 1976; U<strong>et</strong>z, 1977). This makes the division of<br />
phenological patterns into separate groups very difficult,<br />
especially when taking into consi<strong>de</strong>ration that the existing<br />
mo<strong>de</strong>ls of categorisation have been created to <strong><strong>de</strong>s</strong>cribe<br />
phenological patterns of spi<strong>de</strong>r species in very different<br />
ecosystems and latitu<strong><strong>de</strong>s</strong>.<br />
The best way to <strong><strong>de</strong>s</strong>cribe phenological patterns of<br />
Gnaphosidae of Cr<strong>et</strong>e – and perhaps of all Mediterranean<br />
ecosystems – is by dividing the two main periods of high<br />
activity into one which inclu<strong><strong>de</strong>s</strong> patterns with peaks<br />
from mid-spring to early summer, and another which<br />
inclu<strong><strong>de</strong>s</strong> patterns with peaks at the end of summer or at<br />
the beginning of autumn. These two rough groups may be<br />
further divi<strong>de</strong>d to subgroups, based on statistical analysis.<br />
As a result, the following categories of phenological<br />
patterns are proposed (fig. 12):<br />
I) Stenochronous species, with peak activity at the end<br />
of spring and/or beginning of summer (i.e. H. cr<strong>et</strong>icus,<br />
D. praeficus and M. coarctata).<br />
II) Species with peak activity similar to (I), but with<br />
longer total period of activity towards summer months<br />
(i.e. N. excerpta and Trachyzelotes spp.)<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
Fig. 12. Suggested mo<strong>de</strong>l of possible<br />
patterns of activity followed<br />
by Gnaphosidae on Cr<strong>et</strong>e.<br />
48<br />
Species group Site group Male Female Total<br />
A 0,071 0,021 0,001<br />
Table 4. P-values of interaction<br />
test (species*season) among grouped<br />
sites. Values in bold indicate<br />
cases in which interaction within<br />
groups of sites is not significant.<br />
(*) indicates cases of sites groups in<br />
which only one species was present<br />
and consequently no interaction<br />
could be d<strong>et</strong>ected.<br />
I<br />
II<br />
III<br />
IV<br />
V<br />
H. cr<strong>et</strong>icus, D. praeficus, M. coarctata<br />
Nomisia excerpta, Trachyzelotes malkini<br />
Callilepis cr<strong>et</strong>ica, Zelotes caucasius<br />
D. oreinos, Z. cr<strong>et</strong>icus<br />
P. lentiginosa, Z. subterraneus<br />
B - 0,342 -<br />
C 0,338 0,323 0,135<br />
D 0,274 0,796 0,299<br />
E - 0,183 -<br />
A 0,599 0,001 0,068<br />
B 0,511 0,517 0,693<br />
C 0,991 0,736 0,673<br />
D 0,453 0,629 0,001<br />
E
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
III) Species active during the whole favourable period,<br />
with peak activity in mid-summer (i.e. C. cr<strong>et</strong>ica,<br />
Z. caucasius and most other zelotine species such as<br />
Z. labilis, Z. scrutattus, Z. tenuis).<br />
IV) Stenochronous species with peak activity at the<br />
end of summer and/or beginning of autumn (i.e.<br />
D. oreinos and Z. cr<strong>et</strong>icus).<br />
V) Clearly eurychronous species with mature<br />
individuals occurring throughout the year and with<br />
two peaks of male activity (i.e. P. lentiginosa and to a<br />
lesser extent Z. subterraneus, which might as well be<br />
inclu<strong>de</strong>d in type IV).<br />
Although the <strong>de</strong>finition of phenological patterns for<br />
the rest of the gnaphosid species occurring on Cr<strong>et</strong>e, due<br />
to low abundance, is not very clear, the few individuals<br />
of each species were collected during the first period of<br />
high activity. Consequently, these species possibly belong<br />
to patterns (I) and (II) (Chatzaki, 2003). Gnaphosa<br />
bithynica, Anagraphis pallens and Zelotes cf. ilotarum<br />
possibly belong to pattern (V), Zelotes solstitialis to pattern<br />
(IV) and Drasso<strong><strong>de</strong>s</strong> lutescens to pattern (II), but they all<br />
present high flexibility in their activity patterns.<br />
According to Grime (1974; 1979) organisms pursue<br />
different strategies for survival, resulting from three factors:<br />
comp<strong>et</strong>ition, environmental stress and disturbance. Based<br />
on these three factors and used in conjunction with their<br />
phenologies, Milner (1988) divi<strong>de</strong>d the spi<strong>de</strong>rs of Oxleas<br />
Wood, UK into the following groups:<br />
a) stress-tolerant species, to which eurychronous or<br />
winter active species belong.<br />
b) high comp<strong>et</strong>itors, to which stenochronous species<br />
belong, but with extension of their presence during<br />
all summer.<br />
c) pioneer species, to which extreme stenochronous<br />
species belong.<br />
Following the above categorization, most Gnaphosidae<br />
of Cr<strong>et</strong>e (groups III and IV of our mo<strong>de</strong>l) belong to<br />
the “high comp<strong>et</strong>itors” group. These species are very<br />
efficient comp<strong>et</strong>itors compared to other predators (even<br />
other spi<strong>de</strong>rs), concentrating their energy expenditure to<br />
the most advantageous period. Species of group V are<br />
stress tolerant, and they are consi<strong>de</strong>red to be catholic<br />
fee<strong>de</strong>rs, preying on animals that are present all year<br />
round, or, finally, they are unable to outcomp<strong>et</strong>e other<br />
more vigorous species during the period of optimum<br />
conditions. Species of group I may be consi<strong>de</strong>red as<br />
pioneers. Milner (1988) suggested that these species<br />
are related to highly disturbed environments, where they<br />
show a pioneer character, although they may appear as<br />
eurychronous or stenochronous elsewhere.<br />
Concerning Mediterranean ecosystems, several<br />
mo<strong>de</strong>ls have been proposed for the survival strategies of<br />
organisms. Asikidis (1989) suggested that organisms in<br />
Mediterranean ecosystems have to adapt in response to<br />
three factors: maximum habitat h<strong>et</strong>erogeneity, maximum<br />
habitat predictability and mo<strong>de</strong>rate H/T (favourable<br />
reproductive period/generation period). According to<br />
Stamou (1998), Mediterranean arthropods have to<br />
be able to respond quickly to the abrupt changes in<br />
temperature, and to keep low levels of energy expenditure<br />
when temperatures remain stable, in or<strong>de</strong>r to optimize<br />
their energy balance. The same author postulates that<br />
these features <strong>de</strong>fine two main survival strategies: a)<br />
the conformists, i.e. organisms which synchronize<br />
their <strong>de</strong>mographic patterns to seasonal changes, being<br />
more vulnerable to low temperatures and having long<br />
hibernating or aestivating periods and b) the conservatists,<br />
i.e. organisms that are stress tolerant and are active during<br />
longer periods, keeping low and stable energy equilibria.<br />
The synchronization of <strong>de</strong>mographic events to seasons<br />
of the year implies critical ranges of environmental<br />
param<strong>et</strong>ers, outsi<strong>de</strong> of which, organisms cannot respond.<br />
As a result, conformist species are related to narrower<br />
niche factors which inclu<strong>de</strong> habitat and food.<br />
On an annual scale, most Gnaphosidae follow the<br />
conformist strategy, being mostly active during the<br />
dry period, but they possess mechanisms which allow<br />
them to respond to environmental conditions with<br />
more adaptability. If a narrow food selection results<br />
in the restriction of temporal and spatial distribution<br />
(Stamou, 1998), then the opposite should also happen.<br />
Hence, the generalized feeding of these spi<strong>de</strong>rs should<br />
allow them wi<strong>de</strong>r distributions in both time and space.<br />
A small percentage of species follow the conservative<br />
strategy, which corresponds to an even wi<strong>de</strong>r spatiotemporal<br />
distribution. Such species are found in most<br />
habitats of Cr<strong>et</strong>e, at most elevations and compose the<br />
main Gnaphosidae fauna in winter time. The main<br />
representative of this group – if not the only one – is<br />
P. lentiginosa.<br />
There is a view that processes which enhance the<br />
resistance of terrestrial arthropods to cold and to<br />
<strong><strong>de</strong>s</strong>iccation are complementary (Sømme, 1995; 1996),<br />
and that in most cases <strong><strong>de</strong>s</strong>iccation resistant species may<br />
be pre-adapted to cold tolerance (Block, 1996). This<br />
could explain why many of the Gnaphosidae occurring<br />
on the high mountains of Cr<strong>et</strong>e are those which are best<br />
adapted to the high aridity of lowland habitats. These<br />
49<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
50<br />
gnaphosid species comprise the dominant group among<br />
spi<strong>de</strong>r families, as well as among arthropods of the<br />
ground (Lymberakis, 2003). They belong to the most<br />
tolerant, conservative species that can also change their<br />
phenological patterns along altitudinal gradients in or<strong>de</strong>r<br />
to adapt to mountain conditions.<br />
Studies on a different taxonomical<br />
level give different results<br />
Until recently, the phenological pattern characterizing<br />
most Mediterranean arthropods (Di Castri & Vitali-Di<br />
Castri, 1981; Lamotte & Blandin, 1989), spi<strong>de</strong>rs inclu<strong>de</strong>d<br />
(Bigot & Bodot, 1972; Christophe, 1974; Chatzaki <strong>et</strong><br />
al., 1998; Majadas & Urones, 2002) and especially<br />
Gnaphosidae (Assi, 1986; Paraschi, 1988; Chatzaki <strong>et</strong> al.,<br />
1998), was the one that presents two peaks of activity:<br />
one at the end of spring and one at the beginning of<br />
autumn. Also in many cases, the activity of spi<strong>de</strong>rs was<br />
documented as being continuously high (Hagvar <strong>et</strong> al.,<br />
1978; Di Castri & Vitali-Di Castri, 1981; Ra<strong>de</strong>a, 1993).<br />
However, as it has been clearly shown in this study,<br />
phenological patterns are species specific (David, 1995;<br />
Stamou, 1998). The eurychronous pattern mentioned in<br />
the literature is followed by a small number of dominant<br />
species in the study area, and the high activity of the<br />
or<strong>de</strong>r as a whole, results from the conjunction of peaks<br />
of activity of different species, these peaks occurring at<br />
different times within the year.<br />
In the present study this <strong>de</strong>viation of species<br />
phenological patterns is shown for some lowland sites,<br />
where many species co-dominate, as well as in mountain<br />
sites. In the latter sites, the compartmentalization of<br />
species activity is maximized so as to allow co-existence<br />
in an environment where food availability becomes<br />
restricted.<br />
Phenological patterns are also different when different<br />
m<strong>et</strong>hods of collecting are used. Apart from the fact that<br />
pitfall traps do not give an accurate estimation of the<br />
<strong>de</strong>nsities of species (U<strong>et</strong>z & Unzicker, 1976; Adis,<br />
1979), they also lead to certain types of phenological<br />
patterns, which mostly correspond to those behavioural<br />
tactics which increase their activity on the ground (for<br />
instance searching for a mate) (Toft, 1976). Differences<br />
b<strong>et</strong>ween phenological patterns recor<strong>de</strong>d by pitfall traps<br />
and other quantitative m<strong>et</strong>hods have been reported for<br />
other arthropods in Mediterranean ecosystems as well<br />
(Magioris & Tsiourlis, 1992). Paraschi (1988) used<br />
different m<strong>et</strong>hods to study spi<strong>de</strong>r communities in two<br />
maquis ecosystems in Greece. She conclu<strong>de</strong>d that the<br />
main differences observed when different m<strong>et</strong>hods are<br />
used, are the following:<br />
1. differences in the seasonal variation and peaks of<br />
activity,<br />
2. differences in the ratio of mature/immature<br />
individuals per sampling effort,<br />
3. differences in the family composition<br />
The reason why adult Gnaphosidae are not sampled by<br />
quadrate m<strong>et</strong>hod may be related to the mechanisms they<br />
use to avoid high levels of aridity, i.e. to their nocturnal<br />
activity and to their hiding in more protected r<strong>et</strong>reats<br />
during the day.<br />
Biological cycles in relation<br />
to phenological patterns<br />
Pitfall traps do not give accurate information about<br />
biological cycles of organisms. Field observations and<br />
female dissections would give clues to specify them<br />
more accurately. Although phenological patterns of<br />
species are usually stable and are <strong>de</strong>finitely related to<br />
specific <strong>de</strong>mographic events, there are often several<br />
ways to interpr<strong>et</strong> them. For instance, many species of<br />
the genus Zelotes present one peak of activity, but they<br />
remain mature for long periods, even in winter (personal<br />
observations). Based on the analysis of Toft (1976), this<br />
pattern may be interpr<strong>et</strong>ed as stenochronous (perhaps<br />
with a biennial cycle) or as eurychronous, supposing<br />
that mature individuals survive for longer periods, but<br />
are not caught in the traps, due to low activity during<br />
winter months.<br />
More than half of spi<strong>de</strong>r species in Denmark (Toft,<br />
1976), Swe<strong>de</strong>n (Almquist, 1969) and Canada (Aitchison,<br />
1984) are reported to have biennial cycles. In Central<br />
Europe most of the species are annual (Schaefer, 1977).<br />
Grimm (1985) verified this for Gnaphosidae, with<br />
copulation occurring in spring, egg laying in summer,<br />
egg hatching in summer and autumn and overwintering<br />
as immatures. These observations are in accordance<br />
with the results presented in this study. According to the<br />
same author, some species of the genus Zelotes may have<br />
two generations per year, while biennial cycles are rare<br />
in Gnaphosidae, except for species from higher latitu<strong><strong>de</strong>s</strong><br />
(for instance Scandinavia, Lohman<strong>de</strong>r, 1942). Similarly,<br />
biennial cycles are reported by Schmoller (1970) for<br />
four Gnaphosidae species in the alpine tundras of<br />
Colorado. Apparently the duration of biological cycles<br />
is <strong>de</strong>pen<strong>de</strong>nt on the mean temperatures of a region,<br />
and on the duration of the cold period (Almquist, 1969;<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
PHENOLOGICAL PATTERNS OF GROUND SPIDERS (ARANEAE) ON CRETE, GREECE ◆<br />
Schaefer, 1977; Aitchison, 1984). It is therefore expected<br />
that in Mediterranean climates, biological cycles are either<br />
annual or with two generations per year, for groups of<br />
animals which, in higher latitu<strong><strong>de</strong>s</strong>, may have biennial<br />
cycles. In Spain, Urones, Jerardino & Barrientos (1995)<br />
reported annual cycles for most Gnaphosidae. However,<br />
it is possible that D. oreinos and Z. cr<strong>et</strong>icus (as well as<br />
G. bithynica, not presented here) may have biennial cycles,<br />
as suggested by the more exten<strong>de</strong>d presence of female<br />
activity within the year, without being accompanied by<br />
increased activity of males (Toft, 1976).<br />
The change in the duration of biological cycles is a<br />
phenomenon wi<strong>de</strong>ly reported in the literature, and is<br />
related to either latitu<strong>de</strong> or altitu<strong>de</strong> (Schmoller, 1970; Toft,<br />
1976 and references therein; Schaefer, 1977; Aitchison,<br />
1984). Often this variation is consi<strong>de</strong>red as an adaptation<br />
of species which extend their range of distribution to<br />
geographical zones with a different climate (Coulson <strong>et</strong><br />
al., 1975; Reiskind, 1981), even though changes of annual<br />
cycles to biennial have been reported in the same area<br />
during “bad” years (Kajak, 1967) or vice versa during<br />
“good” years (Dondale, 1961). This flexibility of species<br />
to change their <strong>de</strong>velopmental rates at any time shows<br />
that their presence in time and space results from the<br />
combined effect of their own physiological tolerance and<br />
the environment. As a result the <strong>de</strong>finition of their niche<br />
is a highly dynamic measure and not a static one, as was<br />
also observed by Lymberakis (2003).<br />
Ground spi<strong>de</strong>rs (Hagvar, Ostbye & Melaen, 1978)<br />
and especially Gnaphosidae (Deltshev & Blagoev, 1994)<br />
are consi<strong>de</strong>red to present stable phenological patterns,<br />
even when biological rates change for reasons previously<br />
mentioned (Toft, 1976). Along the vertical axis of Cr<strong>et</strong>e<br />
there are cases in which the activity of species is restricted<br />
(i.e. M. coarctata, Z. caucasius, P. lentiginosa) or is shifted 1-2<br />
months towards summer and early autumn (i.e. C. cr<strong>et</strong>ica,<br />
H. cr<strong>et</strong>icus, N. excerpta, T. malkini). In our view, these are<br />
responses to the more extreme climatic conditions of sites<br />
at higher elevations, without necessarily implying that a<br />
change in the biological cycle of these species actually<br />
takes place. According to Lymberakis (2003), the period<br />
b<strong>et</strong>ween the end of summer and beginning of autumn is<br />
the most stable, and hence the most predictable, as far as<br />
climate is concerned, so it is selected by some organisms<br />
as being the most appropriate for reproduction.<br />
However, when the two generations per year change<br />
into one, then a change in the phenology of the species<br />
becomes evi<strong>de</strong>nt (Toft, 1976). In Cr<strong>et</strong>e, this may be the<br />
case for P. lentiginosa, having two generations per year at<br />
the lowland sites and one at sites above 800 m. It could<br />
also be that the species has two reproductive periods<br />
at the lowland sites, leading to only one generation in<br />
springtime, so that an annual cycle takes place there as<br />
well. Even in this case, <strong>de</strong>velopmental stages occur at<br />
different moments along the altitudinal gradient, each<br />
having different duration. Two cycles, one short in the<br />
summer (5 months) and one longer in winter (7 months)<br />
is also reported for its congener P. kochi (O.P. Cambridge,<br />
1872), which also presents a similar phenological pattern<br />
(Assi, 1986).<br />
ACKNOWLEDGEMENTS<br />
This work is part of the PhD thesis of the first author,<br />
which was fun<strong>de</strong>d by the Alexan<strong>de</strong>r Onassis Public<br />
Benefit Foundation and by the University of Cr<strong>et</strong>e. We<br />
are grateful to the working team of the Natural History<br />
Museum of the University of Cr<strong>et</strong>e for the collection and<br />
sorting of the material and to Dr K. Thaler for his help in<br />
the i<strong>de</strong>ntification of species. We are also grateful to John<br />
Murphy for linguistic revision of the manuscript.<br />
References<br />
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pitfall traps. Zoologische Anzeitlung 202: 177-184.<br />
AITCHISON, C.W., 1984. The phenology of winter-active spi<strong>de</strong>rs.<br />
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ALMQUIST, S., 1969. Seasonal growth of some dune-living<br />
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populations <strong>de</strong> Thomisidae <strong>et</strong> Philodromidae (Araneae). Rev.<br />
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BARRA, J.A., BELGNAOUI, S. & POINSOT-BALAGUER, N., 1989.<br />
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51<br />
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◆ M. CHATZAKI, G. MARKAKIS & M. MYLONAS<br />
52<br />
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53<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 33-53
On the seed ecology of two life forms of Spergularia<br />
(Caryophyllaceae)<br />
Écologie <strong>de</strong> la germination chez <strong>de</strong>ux types biologiques différents<br />
<strong>de</strong> Spergularia (Caryophyllaceae)<br />
L.M.M. Bidak<br />
Botany Department, Faculty of Science, Alexandria University, Egypt.<br />
E-mail<br />
Abstract<br />
Two species representing two different life forms of the genus<br />
Spergularia have been chosen for the present study: the short lived<br />
perennial S. media (L.) C. Presl with smooth, brownish and winged<br />
seeds and the annual form S. bocconii (Scheele) Graebner,<br />
with brown, tuberculate and wingless seeds. The present study aims<br />
to compare b<strong>et</strong>ween the two species regarding seed germination and<br />
the effect of salinity and to evaluate the relation b<strong>et</strong>ween seed size<br />
and wingedness and to <strong>de</strong>monstrate the adaptive value of wings.<br />
The study showed that seeds of the perennial species attained larger<br />
size, mass and seed production than those of the annual species. The<br />
study also revealed that wingedness in the perennial species may<br />
serve in dispersal by water. Susceptibility to salt stress is increased<br />
after the emergence of radicle and plumule. Growth rates were<br />
strongly affected by increasing salinity and inhibition was clearer<br />
in the annual species. Larger seed size and <strong>de</strong>layed germination of<br />
the perennial species was associated with increasing salinity.<br />
Key-words<br />
Seed germination, seed production, dispersal, salinity<br />
Résumé<br />
Deux espèces du genre Spergularia représentant <strong>de</strong>ux types biologiques<br />
différents ont été choisies dans c<strong>et</strong>te étu<strong>de</strong> : S. media (L.)<br />
C. Presl est une espèce pérenne éphémère qui possè<strong>de</strong> <strong><strong>de</strong>s</strong> graines<br />
brunâtres, lisses <strong>et</strong> ailées, <strong>et</strong> S. bocconii (Scheele) Graebner, espèce<br />
annuelle avec <strong><strong>de</strong>s</strong> graines aptères brunes <strong>et</strong> tuberculeuses. C<strong>et</strong>te<br />
étu<strong>de</strong> a pour objectifs <strong>de</strong> comparer les <strong>de</strong>ux espèces sur le plan <strong>de</strong><br />
la germination <strong><strong>de</strong>s</strong> graines <strong>et</strong> <strong>de</strong> tester l’eff<strong>et</strong> <strong>de</strong> la salinité. Elle<br />
vise également à évaluer la relation entre la taille <strong><strong>de</strong>s</strong> graines <strong>et</strong> la<br />
présence d’ailes ainsi que <strong>de</strong> démontrer la valeur adaptative <strong>de</strong> ces<br />
appendices ailés. C<strong>et</strong>te étu<strong>de</strong> montre que l’espèce pérenne possè<strong>de</strong> <strong><strong>de</strong>s</strong><br />
graines <strong>de</strong> taille, poids <strong>et</strong> production plus importants que celle <strong>de</strong><br />
l’espèce annuelle. L’étu<strong>de</strong> montre également que la présence d’ailes<br />
chez l’espèce pérenne peut servir à la dispersion par l’eau. La sensibilité<br />
au sel s’accroît après l’émergence <strong>de</strong> la radicule <strong>et</strong> <strong>de</strong> la plumule.<br />
Les taux <strong>de</strong> croissance sont fortement affectés par un accroissement<br />
<strong>de</strong> la salinité <strong>et</strong> une inhibition apparaît clairement pour l’espèce<br />
annuelle. Le r<strong>et</strong>ard <strong>de</strong> germination <strong><strong>de</strong>s</strong> graines <strong>de</strong> gran<strong>de</strong> taille <strong>de</strong><br />
l’espèce pérenne est associé à un accroissement <strong>de</strong> la salinité.<br />
Mots-clés<br />
Germination <strong><strong>de</strong>s</strong> graines, production <strong>de</strong> graines, dispersion,<br />
salinité<br />
55<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 55-63
◆ L.M.M. BIDAK<br />
56<br />
INTRODUCTION<br />
Well-<strong>de</strong>veloped dispersal structures are more common<br />
in perennial than in annual species (Werner, 1979).<br />
Venable and Levin (1983) argue that Werner’s conclusion<br />
supports the i<strong>de</strong>a that dispersal in space may be more<br />
important for perennials than for annuals. Unfortunately<br />
both studies lack data on seed mass. Differences in seed<br />
size are always associated with differences in germination<br />
rate and establishment and variation in seed shape may<br />
lead to dissimilar dispersal of different seed types<br />
(Telenius & Torstensson, 1991). Seeds can become more<br />
complicated by adaptation to special mo<strong><strong>de</strong>s</strong> of dispersion<br />
(hairs, wings, appendages, <strong>et</strong>c.). However, winged seeds<br />
are generally wind dispersed (i.e. anemochorous) (Rauh<br />
<strong>et</strong> al., 1975).<br />
The number of species in the study area varies from<br />
habitat to another. The total number of perennial species<br />
in the various habitats of the study area was 42. On the<br />
other hand, the number of annuals encountered was 52.<br />
About 27 % of the species are restricted to the narrow<br />
coastal strip (ca. 15 km broad) along the Mediterranean.<br />
About 19 % of the species are also present in this coastal<br />
strip, and extend their distribution to the Nile <strong>de</strong>lta and<br />
the newly reclaimed lands (El-Ghareeb & Rezk, 1989).<br />
For most of the <strong><strong>de</strong>s</strong>ert plants soil moisture and<br />
rainfall are limiting factors influencing seed germination<br />
and establishment (Freas & Kemp, 1983: Agami,<br />
1986). Harper <strong>et</strong> al. (1965) found that variation in the<br />
microtopography of the soil surface could d<strong>et</strong>ermine<br />
the success or failure of establishment of seedlings. The<br />
shape and size of seeds may interact with h<strong>et</strong>erogeneity<br />
in soil microtopography, which d<strong>et</strong>ermines the abundance<br />
and proportions of different species in the community.<br />
One topic of germination ecology that needs further<br />
investigation is the pH requirements for germination<br />
of seeds un<strong>de</strong>r high salinity. Seeds of a number of<br />
species may have the ability to increase the hydrogen ion<br />
concentration in their immediate surroundings and thus<br />
lower the pH and hence may succeed to germinate un<strong>de</strong>r<br />
high salinity conditions (Okusanya, 1978). Germination<br />
inhibitors and salts may occur in the dispersal units (or<br />
in other parts of the plants) act as “rainclocks” which<br />
insure that no germination will take place until the soil<br />
is w<strong>et</strong>ted by several rains and seeds of some species do<br />
not germinate until the salts leached out of the seed’s<br />
microhabitat (Chapin, 1991).<br />
Spergularia (Pers.) J. <strong>et</strong> C. Presl (Caryophyllaceae,<br />
subfamily Parnychioi<strong>de</strong>ae) is commonly found in saline<br />
areas and salt marshes. The genus is represented in<br />
Egypt by five species, mostly in two life-forms; annual<br />
or short-lived perennials (S. rubra, S. boconnii, S. diandra<br />
and S. marina) and perennial herbs (S. media), som<strong>et</strong>imes<br />
with a woody base (Boulos, 1995). Seeds are winged or<br />
wingless (Boulos, 1995). Many species (e.g. Spergularia<br />
rubra) have medicinal value. The medicinal action of the<br />
plant is due to the large proportion of aromatic resins.<br />
The genus Spergularia is rich in saponins, which is wi<strong>de</strong>ly<br />
used as a domestic d<strong>et</strong>ergent (Neimann, 1993).<br />
The aims of this study is to provi<strong>de</strong> informations<br />
about the seed germination of the two investigated<br />
species, a perennial (Spergularia media) and an annual<br />
(S. bocconii) and to compare the <strong>de</strong>gree of adaptation for<br />
habitat performance and the relation b<strong>et</strong>ween seed size<br />
and wings b<strong>et</strong>ween the two species.<br />
MATERIALS AND METHODS<br />
Study area<br />
The study area extends for a distance of about 20 km<br />
along the Mediterranean coast from lake Edku in the east<br />
to Ros<strong>et</strong>ta in the west and to a <strong>de</strong>pth of 2 km. The climate<br />
is arid, warm coastal <strong><strong>de</strong>s</strong>ert type (Meig, 1973), with a<br />
mean winter temperature above 10 °C and rainy during<br />
winter. The annual rainfall ranges from 91 to 175 mm.<br />
The mean relative humidity is lower in summer than in<br />
winter (65 % and 81 % respectively) and evaporation is<br />
higher in summer than in winter (7.8 and 2.8 mm/day<br />
respectively). Eight main physiographic categories were<br />
distinguished: 1- unstabilized dunes, lying close to the<br />
seashore; 2- stabilized dunes distinguished into leeward<br />
si<strong>de</strong>, the windward si<strong>de</strong>, and the summit; 3- fields<br />
abandoned owing to rise of un<strong>de</strong>rground saline water;<br />
4- salt marshes covered by sand <strong>de</strong>posits from adjacent<br />
dunes; 5- salt flats; 6- canal banks; 7- cultivated orchards;<br />
and 8- cultivated crop fields. The coastal salt marshes<br />
extending from the foot of the youngest dunes to the sea<br />
shore and the inland salt marshes bor<strong>de</strong>ring the irrigation<br />
canals are the main habitats from where the studied<br />
species have been collected.<br />
Sampling strategy<br />
Mature individuals of the two selected species<br />
(Spergularia media and S. bocconii) were collected<br />
from their natural habitats. Four stands were selected<br />
to represent the natural habitats in which the studied<br />
species are distributed. These stands differ as regards to<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ON THE SEED ECOLOGY OF TWO LIFE FORMS OF SPERGULARIA ◆<br />
their distance from the sea and the commonly associated<br />
species but do not differ much in their soil characteristics.<br />
Two stands located near the coast (400 m) and the others<br />
were 1 km away from the coast and located in the inland<br />
salt marshes. Fresh specimens were pressed, dried and<br />
kept in the herbarium of the Botany Department, Faculty<br />
of Science, Alexandria University.<br />
A bulk of seeds was collected from many individuals<br />
of both plant species. Seeds were air dried at laboratory<br />
temperature for several days, placed in poly<strong>et</strong>hylene bags<br />
and stored at about 5 °C. Five individuals from each stand<br />
were used to study the lengths of shoot, lateral branches<br />
and root. The number of capsules per branch, seeds per<br />
capsules and the number of branches per individual were<br />
used to estimate seed production per plant. Seeds were<br />
weighed to the nearest mg, and seed dimensions were<br />
measured by microscope using a standard microm<strong>et</strong>er.<br />
Three soil samples at two <strong>de</strong>pths (0-5, 5-15 cm)<br />
were collected from each site of the study area for the<br />
d<strong>et</strong>ermination of pH and soil salinity. The concentration<br />
of Na, K, and Mg was d<strong>et</strong>ermined using an atomic<br />
absorption spectrophotom<strong>et</strong>er. The mixed acid digestion<br />
m<strong>et</strong>hod was used for elements d<strong>et</strong>ermination (Allen <strong>et</strong><br />
al., 1974). One Way-ANOVA test was applied for the soil<br />
characteristics.<br />
Only few species tolerate more than 2 % NaCl solution<br />
(Chapman, 1966; Zahran, 1975). The success or failure of<br />
seed germination in saline solution is taken as an indicator<br />
of seed establishment and salt tolerance. For this purpose,<br />
seven concentrations of NaCl solution (0.1, 0.2, 0.3, 0.5,<br />
1.0, 1.5 and 2 % w/v that equivalent to 17, 34, 51, 86,<br />
172, 259 and 344 mm respectively) were prepared. P<strong>et</strong>ridishes<br />
with filter paper moistened with distilled water or<br />
NaCl solution were prepared to examine the percentage<br />
seed germination un<strong>de</strong>r the different levels of salinity.<br />
Duplicate dishes, each with 30 seeds were used for each<br />
treatment. Observations were ma<strong>de</strong> every 24 hours.<br />
Emergence of radicle and/or plumule was taken as the<br />
criterion of successful germination. To assess the effect<br />
of salinity on germination rate the lengths of radicle and<br />
plumule (mm) were recor<strong>de</strong>d daily for 8 days from the<br />
beginning of the experiment. All the data were subjected<br />
to one-way analysis of variance. All statistical analysis<br />
applied using MINITAB 13.1 release-PC computer<br />
program (Minitab, 2000)<br />
Results<br />
Description of physical, chemical characteristic of<br />
the soil and associated species of the natural localities is<br />
illustrated in table 1. The soil of the study area is loamy<br />
sand and alkaline (table 1). The habit of growth varied<br />
from prostrate to ascending. Individuals of S. media were<br />
taller than those of S. bocconii, with <strong>de</strong>eper roots. The main<br />
branches were 5-6 and were markedly longer in S. media.<br />
Leaves of S. media were linear and fleshy whereas those<br />
of S. bocconii were narrowly linear. Leaves and interno<strong><strong>de</strong>s</strong><br />
were longer in S. media than in S. bocconii (table 2a).<br />
Average seed mass varied from 6.4 to 7.2 µg and seed<br />
length from 5.2 to 8.1 µm in S. media and S. bocconii<br />
respectively. The number of seeds/capsule was markedly<br />
higher in S. media and the number of seeds/individual<br />
was 1.4-fold the corresponding number in S. bocconii<br />
(table 2b).<br />
Seeds of S. bocconii can germinate immediately<br />
after being collected, whereas those of S. media exhibit<br />
<strong>de</strong>layed germination and seem to need a dormancy<br />
period. Hundred percent germination in S. bocconii un<strong>de</strong>r<br />
salinity conditions was attained at 0.1 % (17 mm) Nacl<br />
and thereafter germination rate <strong>de</strong>clined steadily to reach<br />
approximately 27 % at 1.5 % (259 mm) Nacl within the<br />
end of the experimental period (18 days).<br />
Up to 0.3 % (51 mm) Nacl, the percentage of<br />
germination in S. media was 100 % thereafter germination<br />
rate <strong>de</strong>clined so that 4 out of the 30 seeds germinated in<br />
2 % (344 mm) Nacl at the end of experimental period.<br />
At this salinity level, germination was totally inhibited in<br />
S. bocconii (table 3). It should be noted that during the<br />
first four days 26 seeds of S. bocconii germinated whereas<br />
no seeds of S. media could germinate.<br />
The maximum radicle and plumule lengths of S. media<br />
(56 and 75 mm respectively) were attained using distilled<br />
water. With increasing salinity, the length of both radicle<br />
and plumule were significantly <strong>de</strong>creased (fig. 1a).<br />
At 1 % (172 mm) NaCl concentration the radicle’s<br />
length of germinated seeds was more affected than the<br />
plumule’s. However, at 1.5 % (259 mm) NaCl no plumule<br />
emergence was observed.<br />
Highest germination rates were obtained for seeds<br />
of Spergularia bocconii w<strong>et</strong>ted with distilled water or<br />
dilute NaCl solution (0.1 % (17 mm), 0.2 % (34 mm).<br />
Concentration over 0.2 % <strong>de</strong>layed germination rate<br />
and r<strong>et</strong>ar<strong>de</strong>d the germination percentage (table 3). No<br />
seed of S. bocconii germinated at 2 % (344 mm) NaCl<br />
solution. The maximum radicle and plumule lengths (53<br />
& 65 mm respectively) were obtained using distilled water<br />
(fig. 1b). Lengths of both radicle and plumule as well as<br />
germination efficiency of S. bocconii were significantly<br />
affected by increasing salinization. No plumule was<br />
observed at 0.5 % (86 mm) NaCl solution. The growth<br />
57<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 55-63
◆ L.M.M. BIDAK<br />
Soil Character Value ± S. E. Associated species<br />
pH 8.61± 0.17 Alhagi graecorum Boiss<br />
E.C. (mmohs cm -1 ) 2.93 ± 1.0 Phragmites australis (Cav.) Trin. ex Steud<br />
Soil Texture (%)<br />
Sand<br />
Silt<br />
Clay<br />
81.7 ± 4.4<br />
17.7 ± 2.9<br />
0.57 ± 0.46<br />
Juncus rigidus Desf.<br />
*Aeluropus lagopoi<strong><strong>de</strong>s</strong> (L.) Trin. ex Thwaites<br />
Atriplex halimus L.<br />
Suaeda pruinosa Lange<br />
Soluble ions (meq./L.)<br />
58<br />
Table 1. Physical and chemical characteristics<br />
of the soil in the study area, the common associated<br />
species in the sites of the perennial (*)<br />
and that of the annual.<br />
Ca +2<br />
3.4 ± 1.8<br />
Mg +2<br />
Na +<br />
K +<br />
Cl -<br />
HCO<br />
- 3<br />
SO<br />
-2 4<br />
CaCO 3<br />
3.29 ± 1.17<br />
5.49 ± 2.67<br />
0.42 ± 0.13<br />
15.73 ± 4.62<br />
2.1 ± 0.49<br />
11.42 ± 3.24<br />
1.35 ± 0.29<br />
*Aster squamatus (Spreng.) Hieron.<br />
*Halocnemum strobiceum (Pall.) M. Bieb<br />
Inula crithmoi<strong><strong>de</strong>s</strong> L.<br />
*Traganum nudatum Delile<br />
*Zygophyllum album L<br />
Juncus acutus L.<br />
*Silene succulenta Forssk.<br />
*Cakile maritima Scop.<br />
Organic matter (%) 0.17 ± 0.01 *Mesembryanthemum crystallinum L.<br />
Soil Type<br />
Loamy sand<br />
rate (mm/day) of both radicles and plumules of the<br />
two studied species <strong>de</strong>creased with increasing salinity.<br />
However, the growth rate of plumule excee<strong>de</strong>d that of<br />
radicle with a few exceptions (fig. 1a&b).<br />
DISCUSSION<br />
Telenius and Torstensson (1991) report that the<br />
habitat characteristics can explain the variability in seed<br />
size of the genus Spergularia. Presence or absence of<br />
wings, for example, affect seed dispersal trait and this<br />
pattern is tightly linked with seed size. In this investigation<br />
the seeds of the perennial species (S. media) attained a<br />
larger size and mass than those of the annual (S. bocconii).<br />
Differences in seed size b<strong>et</strong>ween life histories have been<br />
reported by many authors (e.g. Baker, 1972; Pitelka,<br />
1977; Silvertown, 1981).<br />
Assuming that the pattern of seed dispersal is adaptive<br />
(Thompson, 1973; Augspurger & Franson, 1987; Matlack,<br />
1987), the evolution of larger seeds is constrained by its<br />
effect on seed dispersal. Thompson and Robinwitz (1989)<br />
hypothesized that big plants can produce big seeds and<br />
automatically brings enhanced seed dispersal. Venable<br />
and Levin (1983) found a correlation of wind dispersal<br />
adaptation and the perennial habit: well-<strong>de</strong>veloped<br />
dispersal structures were more common in perennial<br />
than in annual species. Telenius and Torstensson (1991)<br />
reported that the winged strategy is associated entirely<br />
with a perennial life history and reflected the fact that the<br />
perennial species of Spergularia produce larger seeds than<br />
do the annuals (fig. 2).<br />
Many authors emphasized the relation b<strong>et</strong>ween<br />
the morphology of the diasporas and the dispersal<br />
agent (e.g. Rauh <strong>et</strong> al., 1975; Werner, 1979; Venable &<br />
Levin, 1983; El-Sheikh, 1996). Dansereau and Lens<br />
(1957) have previously proposed a simple classification<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ON THE SEED ECOLOGY OF TWO LIFE FORMS OF SPERGULARIA ◆<br />
A<br />
B<br />
59<br />
Figure 1. Growth<br />
rate (mm/day)<br />
of radicle (R) &<br />
plumule lengths (P) of<br />
S. media (fig. 1a) and<br />
S. bocconii (fig. 1b)<br />
after 2, 4, 6 and 8<br />
days from sowing at<br />
different concentration<br />
of salinity level and<br />
distilled water (C).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 55-63
◆ L.M.M. BIDAK<br />
Attribute Spergularia media Spergularia bocconii P Value<br />
Habit of growth Prostrate or ascending Ascending --<br />
Plant height (cm) 53.4 ±2 21.3 ±0.9 *4.69<br />
Table 2a. Mean (at least 5<br />
individuals) ± SE of some<br />
morphological characters<br />
of the studied species.<br />
* P
ON THE SEED ECOLOGY OF TWO LIFE FORMS OF SPERGULARIA ◆<br />
Figure 2. Seed morphology<br />
and seed coat ornamentation<br />
pattern of S. media (A, B, C)<br />
and S. bobbonii (D, E)<br />
as shown by the SEM.<br />
61<br />
the conditions experienced by seeds in natural habitats<br />
<strong>de</strong>pends on the possession of some information on the<br />
level of variability occurring b<strong>et</strong>ween populations of<br />
different species occupying similar habitats, or with<br />
similar geographical distribution.<br />
In discussing the correlation b<strong>et</strong>ween seed size and<br />
adaptive value of wings, Sterk (1996) focused on the seed<br />
size variation and dispersal characteristics in S. marina<br />
and S. media. He reported that the unwinged and winged<br />
seed types would represent respectively the r and K-<br />
strategies. Willson (1983) instead consi<strong>de</strong>red seed types<br />
as representative of different dispersal strategies. The<br />
present study may reveal that Spergularia species, which<br />
primarily inhabit “marshy” habitats, are present now in<br />
a range of habitats mainly as a result of human impact.<br />
Wingedness in the perennial species may serve in the<br />
pattern of secondary dispersal by water.<br />
Zayed and Zeid (1997) reported that there is an<br />
inverse relationship b<strong>et</strong>ween the osmotic potential of<br />
the growth medium and the growth param<strong>et</strong>ers. The<br />
present study showed that the susceptibility to salt stress<br />
is increased after the emergence of radicle and plumule,<br />
so that their lengths as well as their growth rates were<br />
strongly affected. The inhibition was notable in the annual<br />
than in the perennial species. The radicle length was more<br />
affected than the plumule length. This inhibitory effect<br />
is in agreement with the results obtained by Hajar <strong>et</strong> al.<br />
(1996) on their studies on Nigella sativa.<br />
Tolerance mechanisms require energy expenditure and<br />
may consequently be associated with large seed reserves<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 55-63
◆ L.M.M. BIDAK<br />
Days<br />
Salinity Level (%)<br />
Distilled water 0.1 (17 mm) 0.2 (34 mm) 0.3 (51 mm) 0.5 (86 mm) 1.0 (172 mm) 1.5 (259 mm) 2.0 (344 mm)<br />
Spergularia bocconii<br />
62<br />
21/6/2002 10 9 1 0 0 0 0 0<br />
23 26 15 4 1 0 0 0 0<br />
25 30 24 12 5 11 3 2 0<br />
27 30 28 23 10 13 9 5 0<br />
29 30 28 23 22 18 10 8 0<br />
30 30 30 28 22 21 10 8 0<br />
1/7/2002 30 30 28 24 21 11 8 0<br />
3 30 30 28 25 23 11 8 0<br />
5 30 30 28 25 23 11 8 0<br />
6 30 30 28 25 23 11 8 0<br />
Spergularia media<br />
21/6/2002 0 11 5 7 8 0 0 0<br />
22 0 13 19 10 10 4 0 0<br />
23 0 19 23 19 18 4 0 0<br />
25 5 22 24 24 25 9 4 0<br />
27 12 24 24 26 26 13 6 0<br />
29 20 27 26 30 26 15 7 2<br />
30 20 27 26 30 27 19 7 2<br />
1/7/2002 22 27 28 30 27 19 7 2<br />
3 25 27 30 30 27 19 8 3<br />
5 25 27 30 30 27 19 8 4<br />
6 25 27 30 30 27 19 8 4<br />
Table 3. Results of germination percentages on the seeds of the studied species un<strong>de</strong>r different levels of salinity,<br />
compared with that of distilled water. Values are means of duplicate P<strong>et</strong>ri dishes each containing 30 seeds.<br />
and slow relative growth rate (Nieman <strong>et</strong> al., 1992).<br />
Larger seed size of Spergularia media was associated<br />
with <strong>de</strong>lay of germination un<strong>de</strong>r high salinity levels; this<br />
may enable seedlings to persist for longer time at low soil<br />
moisture and/or high soil salinity which might increase the<br />
chance of survival of these seeds. However, knowledge of<br />
the phylogen<strong>et</strong>ic interrelations in the genus still requires<br />
further investigations.<br />
ACKNOWLEDGEMENTS<br />
The authors appreciates the valuable comments of Dr.<br />
S. Barakat Prof. of Plant Physiology, Faculty of Science,<br />
Alexandria University Egypt.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ON THE SEED ECOLOGY OF TWO LIFE FORMS OF SPERGULARIA ◆<br />
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63<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 55-63
Factors structuring land snail communities in South-Eastern<br />
France: a comparison of two estimation m<strong>et</strong>hods<br />
Facteurs structurant les communautés malacologiques terrestres<br />
du SE <strong>de</strong> la France : comparaison <strong>de</strong> <strong>de</strong>ux métho<strong><strong>de</strong>s</strong> d’échantillonnage<br />
Sébastien Aubry* & Frédéric Magnin<br />
Institut méditerranéen d’écologie <strong>et</strong> <strong>de</strong> paléoécologie (IMEP-UMR 6116 CNRS), bâtiment Villemin,<br />
Europole <strong>de</strong> l’Arbois, BP80, F13545 Aix-en-Provence, CEDEX 04<br />
* Corresponding author: email: sebastien.aubry@univ.u-3mrs<br />
Abstract<br />
In or<strong>de</strong>r to shed light on the influence of sampling m<strong>et</strong>hods on the<br />
accuracy with which factors structuring land snail communities<br />
are gauged, the results of two studies were compared. The two<br />
studies, un<strong>de</strong>rtaken in the same area in South-Eastern France<br />
near Marseilles, differed in m<strong>et</strong>hods and initial aims. One was<br />
un<strong>de</strong>rtaken using a stratified sampling strategy which collected only<br />
large species within a 25 m 2 square while the other was un<strong>de</strong>rtaken<br />
using a systematic sampling strategy and collecting species of all sizes<br />
within a 400 m 2 area.<br />
Results indicate that thirty samples (using either technique) are<br />
sufficient to <strong><strong>de</strong>s</strong>cribe the main factors structuring land snail<br />
assemblages. In addition, the collection of only large species<br />
provi<strong><strong>de</strong>s</strong> an a<strong>de</strong>quate indication of the main factors structuring<br />
these assemblages. It is suggested that malacological quadrats are<br />
optimised when they cover a limited area (here 25 m 2 ) and inclu<strong>de</strong><br />
the collection of several turves.<br />
The comparison of the results of both studies revealed that human<br />
activities are the main factor structuring molluscan communities<br />
at the scale of the parish. It also highlights that this scale, which<br />
takes into account topography and human activities, is relevant to<br />
un<strong>de</strong>rstanding the distribution of land snails.<br />
Key-words<br />
Community ecology, landscape, land snail, m<strong>et</strong>hodology, South-<br />
Eastern France, succession<br />
Résumé<br />
Dans le but <strong>de</strong> révéler l’influence <strong>de</strong> la métho<strong>de</strong> d’échantillonnage<br />
sur la précision avec laquelle les facteurs structurant les<br />
communautés malacologiques sont estimés, les résultats <strong>de</strong> <strong>de</strong>ux<br />
étu<strong><strong>de</strong>s</strong> sont comparés. Ces <strong>de</strong>ux étu<strong><strong>de</strong>s</strong>, entreprises dans la même<br />
région du sud-est <strong>de</strong> la France, près <strong>de</strong> Marseille, diffèrent par<br />
leurs métho<strong><strong>de</strong>s</strong> ainsi que par leurs objectifs initiaux. L’une utilise<br />
un échantillonnage stratifié <strong>et</strong> ne prend en compte que les grosses<br />
espèces récoltées à l’intérieur d’un carré <strong>de</strong> 25 m² ; l’autre est fondée<br />
sur un échantillonnage systématique <strong>et</strong> prend en compte les espèces<br />
<strong>de</strong> toutes tailles à l’intérieur d’un carré <strong>de</strong> 400 m².<br />
Les résultats indiquent que trente échantillons (quelle que soit la<br />
technique) sont suffisants pour décrire les facteurs structurant les<br />
assemblages malacologiques à l’échelle d’une commune. De plus,<br />
la récolte <strong><strong>de</strong>s</strong> seules grosses espèces fournit une indication adéquate<br />
<strong><strong>de</strong>s</strong> principaux facteurs structurant ces assemblages. Il est suggéré<br />
que les quadrats malacologiques sont optimisés quand ils couvrent<br />
une surface limitée (ici 25 m²) <strong>et</strong> incluent la collecte <strong>de</strong> plusieurs<br />
prélèvements <strong>de</strong> sol pour la recherche <strong><strong>de</strong>s</strong> p<strong>et</strong>ites espèces.<br />
La comparaison <strong><strong>de</strong>s</strong> résultats <strong><strong>de</strong>s</strong> <strong>de</strong>ux étu<strong><strong>de</strong>s</strong> révèle que les activités<br />
humaines sont le principal facteur structurant les communautés<br />
malacologiques à l’échelle <strong>de</strong> la commune. Elle souligne aussi que<br />
c<strong>et</strong>te échelle, qui prend en compte la topographie <strong>et</strong> les activités<br />
humaines, est adéquate pour comprendre la distribution <strong><strong>de</strong>s</strong><br />
mollusques terrestres au sein du paysage.<br />
Mots-clés<br />
Écologie <strong><strong>de</strong>s</strong> communautés, paysage, mollusques terrestres, méthodologie,<br />
Sud-Est <strong>de</strong> la France, succession<br />
65<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 65-74
◆ S. AUBRY & F. MAGNIN<br />
66<br />
INTRODUCTION<br />
The role of micro-habitat in the composition of land<br />
snail communities has long been recognised (Boycott,<br />
1934). In particular, the structure of the veg<strong>et</strong>ation is one<br />
of the main factors controlling the occurrence of species.<br />
The role of habitat h<strong>et</strong>erogeneity on the structure of land<br />
snail communities has been studied at several scales and<br />
has been shown to be influential from the micro-scale<br />
(Davies & Grimes, 1999) to the landscape scale (Magnin<br />
<strong>et</strong> al., 1995).<br />
In contrast with phytosociology, where a standardised<br />
m<strong>et</strong>hod exists, sampling m<strong>et</strong>hods have always been a<br />
source of <strong>de</strong>bate in malacology and different m<strong>et</strong>hods<br />
have been used <strong>de</strong>pending on the aims of the study (e.g.<br />
Cameron & Morgan-Huws, 1975; Bishop, 1977; Boag,<br />
1982; Emberton <strong>et</strong> al., 1996; Hawkins <strong>et</strong> al., 1998; Davies<br />
& Grimes, 1999; Menez, 2001; Cameron, 2002).<br />
The aim of the present work was to compare two<br />
studies in or<strong>de</strong>r to assess both the influence of sampling<br />
m<strong>et</strong>hods and strategies in general, and the factors that<br />
structure land snail communities in rural Mediterranean<br />
environments. The two studies sampled the same area of<br />
the French Mediterranean region but differed in their<br />
aims, sampling strategies and scales. One was conducted<br />
in 1989 (Magnin & Tatoni, 1995) and the second, the<br />
results of which are presented here, was conducted in<br />
1995.<br />
METHODS<br />
Study site<br />
Auriol is situated near Marseilles (coastal) in the<br />
calcareous lower Provence on the bank of the river<br />
Huveaune (fig. 1). It has a Mediterranean climate with<br />
a mean annual temperature of 14 °C, two dry months<br />
(P < 2T, where P is precipitation of a given month in<br />
mm and T is mean temperature of the month in °C) and<br />
two to three cold months (T < 7 °C) (CNRS, 1975).<br />
The parish of Auriol, <strong>de</strong>limited to the north and south<br />
by two mountain chains reaching 900 m, covers an area<br />
of 4 464 ha. Once an agricultural village (cultivated in<br />
terraces since at least the 12 th century), it is close to<br />
an enlarging urban centre, so that the landscape has<br />
un<strong>de</strong>rgone many changes since the beginning of the<br />
20 th century. In<strong>de</strong>ed, at the <strong>de</strong>mographic maximum<br />
during the 19 th century, the entire area was covered with<br />
cultivated terraces. After World War II, abandonment<br />
of the agricultural terraces has led to the replacement<br />
of agricultural lands by woodland (Grove & Rackham,<br />
2001). More recently, the expansion of human habitations<br />
and roads has been influential.<br />
Aims of each m<strong>et</strong>hod<br />
The 1989 study aimed to <strong>de</strong>fine post-agricultural<br />
successions on abandoned cultivation terraces in<br />
calcareous Provence for both plant and land snail<br />
communities (Tatoni <strong>et</strong> al., 1994; Magnin & Tatoni,<br />
1995). The 1995 study aimed to shed light on the many<br />
factors influencing land snail species diversity at several<br />
spatial scales within the parish of Auriol.<br />
Description of each m<strong>et</strong>hod<br />
In 1989, all living and <strong>de</strong>ad snails larger than five<br />
millim<strong>et</strong>res were taken during a standard period of fifteen<br />
minutes for each sampling site. This involved searching<br />
beneath fallen logs and stones, investigating crevices,<br />
un<strong>de</strong>r the bark of trees and in other places <strong>de</strong>emed<br />
suitable for snails. In total, 65 samples were collected<br />
along nine terraced hill slopes (fig. 1a). For each of the 9<br />
slopes several cultivation terraces were sampled according<br />
to their time of abandonment. Each sample was taken in<br />
an area of, approximately, 25 m 2 .<br />
In 1995, samples were taken according to a systematic<br />
sampling strategy whereby sampling sites were chosen a<br />
priori on a map. Twenty-five samples were taken from<br />
sites (20 x 20 m square) aligned on a grid (fig. 1b).<br />
Sampling was performed in two ways. First, a visual<br />
search involving the collection of all living and <strong>de</strong>ad<br />
snails was un<strong>de</strong>rtaken for 20 minutes over the entire<br />
400 m 2 area. This involved searching beneath fallen logs<br />
and stones, investigating crevices, un<strong>de</strong>r the bark of trees<br />
and in other places <strong>de</strong>emed suitable for snails. Second, in<br />
or<strong>de</strong>r to collect shells less than 5 mm diam<strong>et</strong>er, veg<strong>et</strong>ation,<br />
litter and surface soil covering an area of 25 x 25 cm and<br />
a <strong>de</strong>pth of 5 cm were collected at five points within each<br />
sampling site, bagged, and brought back to the laboratory.<br />
There, samples were dried in an oven (40-75 °C), then<br />
immersed in water. Floating material was collected in a 0.5<br />
mm mesh sieve and dried again. The sieved samples were<br />
separated into four fractions using a s<strong>et</strong> of gra<strong>de</strong>d soil<br />
sieves (10, 2, 1 and 0.5 mm). Shells were then separated<br />
from plant material, using a binocular microscope for the<br />
smallest fractions.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
STRUCTURING FACTORS OF LAND SNAIL COMMUNITIES IN SOUTH-EASTERN FRANCE ◆<br />
67<br />
Figure 1. Locations of sampling<br />
sites in the Auriol parish: a)<br />
1989; b) 1995.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 65-74
◆ S. AUBRY & F. MAGNIN<br />
68<br />
ANALYSES<br />
Inventories of species collected during each study were<br />
compared. Nomenclature follows Kerney <strong>et</strong> al. (1983)<br />
except for Xeropicta <strong>de</strong>rbentina (Krynicki, 1836), a species<br />
recently introduced in Provence that was not inclu<strong>de</strong>d by<br />
these authors. Randomised species accumulation curves<br />
(sample-based rarefaction curves) were calculated using<br />
the Estimate v6.0b1 software (Colwell, 2000) in or<strong>de</strong>r to<br />
assess the compl<strong>et</strong>eness of each inventory. Five hundred<br />
iterations were performed for each s<strong>et</strong> of data. Species/<br />
samples data matrices for each study were examined by<br />
correspon<strong>de</strong>nce analyses performed with CANOCO<br />
for Windows 4.0 (ter Braak & Smilauer, 1998). Species<br />
abundance data were logarithmically transformed (log<br />
(X +1)) in or<strong>de</strong>r to reduce the importance of the most<br />
abundant species and to normalise their distributions<br />
(Legendre & Legendre, 1984; Labaune & Magnin,<br />
2001). Also, rare species abundance was down-weighted<br />
by an algorithm available in CANOCO.<br />
RESULTS<br />
Inventory of biodiversity<br />
Thirty-two species were recovered from the 65<br />
samples collected in 1989 (table 1). Of these, four are<br />
small species (less than 5 mm) that were not specifically<br />
sought. The list of species recovered by this m<strong>et</strong>hod<br />
therefore comprises only 28 species.<br />
Fifty-eight species were recovered from the 25<br />
samples collected in 1995 (table 1). Of these, five species,<br />
all hygrophilous, were represented only as sub-fossils,<br />
witnesses of a past environment. Therefore 53 species<br />
are found living in the area. Only 22 species were found<br />
during the visual search in 1995 (table 1).<br />
Many species, with various ecologies, were found<br />
during both studies. All the species found in 1989 were<br />
also collected during the 1995 study (table 1). Three<br />
categories of species missing from the 1989 study in<br />
comparison to the 1995 one can be highlighted. In fact,<br />
in addition to the expected absence of species less than<br />
5 mm in size, open-w<strong>et</strong>land species and forest species<br />
were also missing. This absence of species from the latter<br />
categories is a result of the 1989 sampling strategy that<br />
<strong>de</strong>liberately ignored habitats such as irrigated agricultural<br />
crops and closed woodlands that were not present on<br />
abandoned terraces. Thus, <strong><strong>de</strong>s</strong>pite a much larger number<br />
of samples, some large species were not recovered from<br />
the 1989 study.<br />
Accumulation curves<br />
The m<strong>et</strong>hod used in 1989 led to collection of a<br />
large number of species bigger than 5 mm. The sample<br />
accumulation curves (fig. 2), computed using EstimateS<br />
(Colwell, 2000), show that the commonest species were<br />
all found during this study. Only a few species larger<br />
than 5 mm were still to be found since the asymptotes<br />
are reached early in the accumulation. In fact, 30 samples,<br />
rather than the 65 taken, would have probably sufficed<br />
to record the same number of species. When the four<br />
small species are inclu<strong>de</strong>d the asymptote is not reached.<br />
Obviously, some species smaller than 5 mm were<br />
missed.<br />
The species accumulation curve computed with the<br />
25 samples and 53 species of the 1995 study shows that<br />
this inventory comes close to finding all the species in the<br />
area. However, the curve does not reach a clear asymptote<br />
(fig. 2) and some rare species are still missing. The<br />
incorporation of the five sub-fossil species into the list,<br />
by inflating the number of rare species, strongly increases<br />
the slope of the curve.<br />
Figure 2. Accumulation curves computed after 500 iterations: 1989a,<br />
all species collected during the 1989 study; 1989b, as 1989a but excluding four<br />
species smaller than 5 mm; 1996a, all species collected during the 1996 study;<br />
1996b, as 1996a but excluding the five hygrophilous species.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Species CODES 1989<br />
1995<br />
Total Visual<br />
Acanthinula aculeata (Müller, 1774) AAC (1) 3 894<br />
Abida polyodon (Draparnaud, 1801) APO 11 48<br />
Bythiospeum sp. BYT (2)<br />
Cecilioi<strong><strong>de</strong>s</strong> (Cecilioi<strong><strong>de</strong>s</strong>) acicula (Müller, 1774) CAC 2 891<br />
Chondrina avenacea (Bruguière, 1792) CAV 1<br />
Ciliella ciliata (Hartmann, 1821) CCI 12<br />
Candidula gigaxii (Pfeiffer, 1850) CGI 334 264 13<br />
Cepaea (Cepaea) nemoralis (Linnaeus, 1758) CNE 4 15 9<br />
Cochlicella acuta (Müller, 1774) COA 213<br />
Cochlicella barbara (Linnaeus, 1758) COB 7<br />
Cochlostoma (Turritus) patulum (Draparnaud, 1801) CPA 1 329<br />
Carychium tri<strong>de</strong>ntatum (Risso, 1826) CTR (3)<br />
Candidula unifasciata (Poir<strong>et</strong>, 1801) CUN 57 295<br />
Cernuella (Microxeromagna) vestita (Rambur, 1868) CVE 95 9<br />
Cernuella (Cernuella) virgata (da Costa, 1778) CVI 48 1 051 32<br />
Euconulus (Euconulus) fulvus (Müller, 1774) EFU 846<br />
Ena (Ena) obscura (Müller, 1774) EOB 20 310<br />
Eobania vermiculata (Müller, 1774) EVE 90 302 156<br />
Granopupa granum (Draparnaud, 1801) GGR (6) 2 615<br />
Galba truncatulla (Müller, 1774) GTR (683)<br />
Granaria variabilis (Draparnaud, 1801) GVA 37 624<br />
Helix (Cornu) aspersa (Müller, 1774) HAS 103 114 76<br />
H. conspurcata or C. vestita HCV<br />
Hygromia cinctella (Draparnaud, 1801) HCI 6 1<br />
Hellicella (Xerotricha) conspurcata (Draparnaud, 1801) HCO 13 74<br />
Helicigona lapicida (Linnaeus, 1758) HLA 1 1<br />
Helix (Helix) melanostoma (Draparnaud, 1801) HME 34 6 6<br />
Jaminia (Jaminia) quadri<strong>de</strong>ns (Müller, 1774) JQU 32 118<br />
Lauria (Lauria) cylindracea (da Costa, 1778) LCY 339<br />
Monacha (Monacha) cantiana (Montagu, 1803) MAN 65 199 18<br />
Monacha (Monacha) cartusiana (Müller, 1774) MAR 8 246 20<br />
Oxychilus (Oxychilus) draparnaudi (Beck, 1837) ODR 64 513 8<br />
Oxychilus (Oxychilus) hydatinus (Rossmässler, 1838) OHY 20<br />
Pomatias elegans (Müller, 1774) PEL 643 1 997 883<br />
Phenacolimax (Phenacolimax) major (Férussac, 1807) PMA 182<br />
Pupilla (Pupilla) muscorum (Linnaeus, 1758) PMU 37<br />
Punctum (Punctum) pygmaeum (Draparnaud, 1801) PPY 1 434<br />
Pyramidula rupestris (Draparnaud, 1801) PRU 11<br />
Papilifera solida (Draparnaud, 1805) PSO 97 364 8<br />
Pseudotachea splendida (Draparnaud, 1801) PSP 12 129 129<br />
Sphincterochila (Albea) candidissima (Draparnaud, 1801) SCA 33 26<br />
Succinea (Succinella) oblonga (Draparnaud, 1801) SOB (1)<br />
Solatopupa similis (Bruguière, 1792) SSI 56 228 9<br />
Truncatellina callicratis (Scacchi, 1833) TCA (1) 2 246<br />
Trochoi<strong>de</strong>a (Trochoi<strong>de</strong>a) elegans (Gmelin, 1791) TEL 188 1 066 21<br />
Testacella (Testacella) halioti<strong>de</strong>a (Draparnaud, 1801) THA 2<br />
Trichia (Trichia) hispida (Linnaeus, 1758) THI 16<br />
Theba pisana (Müller, 1774) TPI 29 986 456<br />
Trochoi<strong>de</strong>a (Trochoi<strong>de</strong>a) pyramidata (Draparnaud, 1805) TPY 3<br />
Trochoi<strong>de</strong>a (Trochoi<strong>de</strong>a) trochoi<strong><strong>de</strong>s</strong> (Poir<strong>et</strong>, 1789) TTR 43 1 586 106<br />
Perforatella (Monachoi<strong><strong>de</strong>s</strong>) ventouxiana (Forcart, 1946) UVE 118 5<br />
Vallonia costata (Müller, 1774) VAC 2 806<br />
Vitrea (Crystallus) contracta (Westerlund, 1871) VCO (1) 3 807<br />
Vallonia enniensis (Gredler, 1856) VEN (75)<br />
Vallonia pulchella (Müller, 1774) VPU 438<br />
Vertigo (Vertigo) pygmaea (Draparnaud, 1801) VPY 811<br />
Cernuella (Xeromagna) cespitum (Draparnaud, 1801) XCE 94 153 115<br />
Xeropicta <strong>de</strong>rbentina (Krynicki, 1836) XDE 600 7 017 639<br />
Zonites (Zonites) algirus (Linnaeus, 1758) ZAL 102 60 46<br />
Total number of shells 3 007 41543 2 778<br />
Table 1. Names, co<strong><strong>de</strong>s</strong> and number<br />
of individuals of the 58 species collected<br />
during the two studies.<br />
Numbers for species that were exclu<strong>de</strong>d<br />
from statistical analyses are given<br />
in parentheses. Nomenclature follows<br />
Kerney <strong>et</strong> al. (1983).<br />
The distinction b<strong>et</strong>ween individuals<br />
collected during the visual search<br />
and the total is ma<strong>de</strong> for the 1995 study.<br />
69<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 65-74
◆ S. AUBRY & F. MAGNIN<br />
70<br />
Ecological results<br />
1989 study<br />
The four small species were exclu<strong>de</strong>d from the<br />
correspon<strong>de</strong>nce analysis, which was therefore applied<br />
to 28 species and 65 samples. The first two axes explain<br />
34.2 % of the total variation (λ = 2.21414) (fig. 3a).<br />
On axis 1 the species with negative values inclu<strong>de</strong><br />
Xeropicta <strong>de</strong>rbentina, Trochoi<strong>de</strong>a elegans and Theba<br />
pisana, and those with positive values inclu<strong>de</strong> Pomatias<br />
elegans, Oxychilus draparnaudi, Cepaea nemoralis and<br />
Ena obscura. The first group of species is characteristic<br />
of dry and open habitats with herbaceous veg<strong>et</strong>ation<br />
or ru<strong>de</strong>ral environments. The second group of species<br />
is characteristic of open woodlands or environments<br />
with abundant leaf-litter. On axis 2 the species with the<br />
most positive values inclu<strong>de</strong> Pomatias elegans, Oxychilus<br />
draparnaudi, Cepaea nemoralis, Monacha cantiana and<br />
Zonites algirus, and those with the most negative values<br />
inclu<strong>de</strong> Candidula unifasciata, Papillifera solida, Granaria<br />
variabilis and Jaminia quadri<strong>de</strong>ns.<br />
On the same factorial plane, samples from cultivated<br />
and herbaceous wastelands are distinguished on axis 1<br />
(negative values) from woodland samples (positive<br />
values). Axis 2 separates samples taken in garrigues and<br />
grassland with chamaephytes (negative values) from<br />
samples taken from woodland.<br />
This analysis shows succession patterns of land snail<br />
communities in relation to the succession patterns of<br />
plant communities, from cultivation to woodland. For<br />
veg<strong>et</strong>ation, two dynamic trajectories exist <strong>de</strong>pending on<br />
perturbations or <strong>de</strong>gradation of soil. Without perturbation<br />
and on thick soil, the main trajectory links cultivated areas<br />
to broad-leaved woodlands, through grassy fallow lands<br />
and closed scrublands. This trajectory corresponds to the<br />
upper part of the first factorial plane. If perturbations<br />
(such as fire) occur, another trajectory leads to garrigues<br />
through a continuous <strong>de</strong>gradation of the terraces and<br />
soils. This trajectory corresponds to the lower part of the<br />
first factorial plane. Land snail communities, un<strong>de</strong>r the<br />
influence of veg<strong>et</strong>ation structure, are strongly <strong>de</strong>pen<strong>de</strong>nt<br />
on the age of abandonment of the terrace. They follow<br />
the two trajectories taken by plant communities along<br />
secondary successions.<br />
1995 study<br />
The five hygrophilous species were exclu<strong>de</strong>d from the<br />
correspon<strong>de</strong>nce analysis, which was therefore applied to<br />
53 species and 25 samples. The first three axes explain<br />
56.6 % of the total variation (λ = 1.32682) with 33.7, 12.3<br />
and 10.6 % respectively.<br />
A strong arch effect is apparent on the first factorial<br />
plane of the correspon<strong>de</strong>nce analysis (not shown here).<br />
Axes 1 and 2 represent the same strong contrast as in the<br />
analysis of the 1989 data b<strong>et</strong>ween two very different types<br />
of malacological communities. They contrast open-land<br />
species, such as Cochlicella acuta, C. barbara, Trochoi<strong>de</strong>a<br />
elegans, Theba pisana and Trochoi<strong>de</strong>a trochoi<strong><strong>de</strong>s</strong> to species<br />
characteristic of woodland, such as Acanthinula aculeata,<br />
Euconulus fulvus and Cepaea nemoralis. This arch effect<br />
results from the presence of two samples collected in<br />
agricultural crops. Despite the removal of the five subfossil<br />
species from these agricultural crop samples, their<br />
mo<strong>de</strong>rn fauna is still very different from that of other<br />
open-land samples. In<strong>de</strong>ed, the irrigation of these crops<br />
apparently leads to a fauna characteristic of humid open<br />
lands of southeast France such as Cochlicella spp., Trichia<br />
hispida, Vallonia pulchella and Vertigo pygmaea.<br />
The second factorial plane of this analysis (axes 1<br />
and 3; fig. 3b) is similar to the first factorial plane of<br />
the 1989 study (fig. 3b). Secondary successions are the<br />
main structuring factor on this plane. Axis 3 distinguishes<br />
saxicolous species found in garrigues, such as Jaminia<br />
quadri<strong>de</strong>ns, Pseudotachea splendida, Helicigona lapicida and<br />
Chondrina avenacea, with negative values, from litterdwelling<br />
and sha<strong>de</strong>-loving species found in woodland,<br />
such as Punctum pygmaeum, Euconulus fulvus and Ciliella<br />
ciliata, with positive values. Intermediate stages of the<br />
succession are found in the centre of the plane, where<br />
open land species, such as Cernuella cespitum, Candidula<br />
gigaxii and Granopupa granum, or open woodland species,<br />
such as Pomatias elegans, are found.<br />
DISCUSSION<br />
Comparison of the two sampling m<strong>et</strong>hods<br />
In studies of terrestrial gastropods, the area nee<strong>de</strong>d for<br />
a<strong>de</strong>quate sampling and the number of samples required<br />
from each plot has long been a source of <strong>de</strong>bate (e.g.<br />
Bishop, 1977; Menez, 2001). In his review stressing<br />
the need for quantitative sampling of molluscan faunas,<br />
Bishop (1977) suggested that the size of a quadrat should<br />
be less than 1 000 m² and that 30 (25 x 25 cm) units<br />
should be sampled within a 10 x 10 m quadrat. Menez<br />
(2001) consi<strong>de</strong>red that, in or<strong>de</strong>r to recover the entire<br />
molluscan fauna within a 1 km 2 square of Mediterranean<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
STRUCTURING FACTORS OF LAND SNAIL COMMUNITIES IN SOUTH-EASTERN FRANCE ◆<br />
71<br />
Figure 3. Correspon<strong>de</strong>nce<br />
analysis applied to the species/sample data matrix, open<br />
circles are samples and closed circles are species a) of the<br />
1989 study, axes 1 & 2; b) of the 1995 study, axes 1 &<br />
3. Arrows are the two secondary succession trajectories<br />
leading to either ‘woodland’ or ‘garrigue’.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 65-74
◆ S. AUBRY & F. MAGNIN<br />
72<br />
habitat, 2.5 hours of searching and 4.2 litres of soil and<br />
litter are necessary. However, such a sampling regime was<br />
not possible within the constraints of the present project,<br />
which aimed to i<strong>de</strong>ntify variation in faunal composition<br />
over much larger areas rather than to obtain compl<strong>et</strong>e<br />
inventories. Several different m<strong>et</strong>hods can be employed<br />
<strong>de</strong>pending on the aims of the study. For instance, Cameron<br />
(1986) sampled 5 litres of litter and soil within a 30 x 30 m<br />
square, whereas for another study (Cameron & Morgan-<br />
Huws, 1975), he sampled 10 small quadrats (20 x 20 cm,<br />
further reduced to 15 x 15 cm) within 100 m². In or<strong>de</strong>r<br />
to study small-scale variation in the molluscan fauna,<br />
Davies and Grimes (1999) sampled five 25 x 25 cm<br />
squares within an un<strong>de</strong>fined area. In conclusion, the<br />
sampled area has to be large enough to find the majority<br />
of species present in a specific environment but not so<br />
large as to inclu<strong>de</strong> too much h<strong>et</strong>erogeneity, which would<br />
reduce the information provi<strong>de</strong>d.<br />
The sampling m<strong>et</strong>hods used in both studies were<br />
intensive and conservative consi<strong>de</strong>ring the small areas<br />
involved. In 1989, 15 minutes searches were employed<br />
in quadrats of approximately 25 m 2 (middle of terrace).<br />
Using this m<strong>et</strong>hod, few large species would have been<br />
missed within the quadrat. In 1995, 20 minutes searches<br />
were employed in 400 m 2 quadrats, and all snails in the<br />
litter and soil of a 0.3125 m 2 area were collected.<br />
It is impossible to know wh<strong>et</strong>her either m<strong>et</strong>hod<br />
resulted in a compl<strong>et</strong>e inventory of the species that were<br />
being searched for (i.e. large species only in 1989 or<br />
all species in 1995). However, the difference b<strong>et</strong>ween<br />
the species list generated in 1989 (25 m 2 searched for<br />
15 minutes) with that resulting from the visual search of<br />
1995 (400 m 2 searched for 20 minutes) indicates that 20<br />
minutes is not sufficient to record all the large species in<br />
a 400 m 2 area, whereas 15 minutes searching in 25 m 2<br />
resulted in missing few large species, when compared to<br />
the 1995 compl<strong>et</strong>e list of species. Therefore it seems that<br />
the enlargement of the sampling area in fact <strong>de</strong>creased<br />
sampling efficiency, and collection of litter and soil was<br />
necessary to recover the large species that were missed.<br />
The more rapid saturation of the accumulation curve<br />
of the 25 m 2 samples of the 1989 study is counterintuitive.<br />
In<strong>de</strong>ed less h<strong>et</strong>erogeneity should be inclu<strong>de</strong>d<br />
within smaller areas and therefore more of these small<br />
areas should be sampled to obtain the same number of<br />
species. Two factors can explain this effect. First, the 1995<br />
study inclu<strong>de</strong>d more diverse habitat types, which led to<br />
a slower saturation of the curves. Second, for areas of<br />
this magnitu<strong>de</strong> (b<strong>et</strong>ween 25 and 400 m 2 ), micro-habitat<br />
h<strong>et</strong>erogeneity is the most important factor in structuring<br />
land snail communities. Here, it seems that most of this<br />
h<strong>et</strong>erogeneity is inclu<strong>de</strong>d in small 25 m 2 squares and that<br />
no more large species would be found in larger areas<br />
unless a compl<strong>et</strong>ely different type of veg<strong>et</strong>ation were<br />
present. This suggests that a quadrat size of 25 m 2 , similar<br />
to that adopted by Labaune and Magnin (2001, 2002),<br />
strikes a good balance b<strong>et</strong>ween maximising the habitat<br />
h<strong>et</strong>erogeneity sampled and minimising sampling effort.<br />
Quadrats of approximately this size are thus likely to be<br />
the most appropriate for studies of terrestrial molluscs.<br />
M<strong>et</strong>hods to estimate diversity<br />
and shed light on factors structuring<br />
land snail communities<br />
The systematic sampling of the 1995 study has led<br />
to the <strong><strong>de</strong>s</strong>cription of various land snail communities<br />
occurring in different habitats, from irrigated agricultural<br />
cropland to closed woodland. The 1989 study of postcultural<br />
succession did not sample such extreme<br />
environments but all the intermediate stages of the<br />
succession were encountered. Each species maps to a<br />
similar place on the 1989 and 1995 factorial planes.<br />
Only Cepaea nemoralis maps to a different place on the<br />
two graphs. It falls among woo<strong>de</strong>d habitats in the 1989<br />
study but in garrigues in the 1995 study. In<strong>de</strong>ed, this<br />
mostly litter-dwelling species is known to occur in various<br />
environments (Kerney <strong>et</strong> al., 1983).<br />
The two m<strong>et</strong>hods revealed the importance of the<br />
structure of veg<strong>et</strong>ation as well as that of the nature of<br />
ground cover. However, collection of soil samples at<br />
regular intervals allowed the recovery of many more<br />
species and a more accurate inventory of species<br />
diversity within the parish. Both studies showed that it<br />
is not necessary to collect an extremely large number of<br />
samples to have a good image of the factors influencing<br />
species distribution at this scale. However, the exploration<br />
of rare and spatially restricted habitat such as riparian<br />
forests seems necessary if the compl<strong>et</strong>e list of species of<br />
such an area is to be known. Neither of the present studies<br />
inclu<strong>de</strong>d such habitats and the total of 58 species is an<br />
un<strong>de</strong>restimate of the total richness of the area.<br />
The sampling strategies differed b<strong>et</strong>ween the two<br />
studies not only in the size of the quadrats but also in<br />
the initial aims and protocols. In 1989, only a few slopes<br />
in the northern and western part of the area were sampled<br />
but many samples were collected, whereas in 1995, the<br />
whole parish was covered but only a few samples were<br />
collected. The 1989 study aimed to <strong><strong>de</strong>s</strong>cribe molluscan<br />
communities along secondary successions and in or<strong>de</strong>r<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
STRUCTURING FACTORS OF LAND SNAIL COMMUNITIES IN SOUTH-EASTERN FRANCE ◆<br />
to study this structuring factor, sampling controlled for<br />
the stage of succession where land snails were collected.<br />
The 1995 study aimed to explore molluscan diversity at<br />
different spatial scales within the parish. An important<br />
result is that both studies revealed the same pattern of<br />
species distribution and the same powerful structuring<br />
factor, that is, secondary successions. This factor applies<br />
as much to the entire community as to a section of<br />
the community (i.e. large species) and highlights the<br />
strong influence of humans on the present landscape.<br />
Furthermore, the geographical position of the samples<br />
from the two studies sheds light on the landscape<br />
organisation of the studied area. At present, agricultural<br />
crops are found at lower altitu<strong>de</strong>, close to the village<br />
centre and the river, whereas habitats at the end of the<br />
succession are found at higher altitu<strong>de</strong> and further from<br />
the village.<br />
The ‘parish’ or ‘finage’ is a critical<br />
scale for landscape ecology<br />
Landscapes are forged by human activities (Forman<br />
& Godron, 1986). In the context of a rural French<br />
landscape, the scale of the parish is the most appropriate<br />
at which to <strong><strong>de</strong>s</strong>cribe this landscape and shed light<br />
on factors structuring it. The ‘parish’ (or ‘finage’ in<br />
French) is a well-<strong>de</strong>limited territory managed by a<br />
human community or village. This territory is divi<strong>de</strong>d<br />
into zones of different land uses, creating a mosaic of<br />
different elements (habitations, agricultural crops, pasture<br />
and forest). These elements are organised according to<br />
the topography, the agricultural potential of the area and<br />
the distance from the village. Thus, habitations are usually<br />
found close to a river or to any water source and are<br />
most closely surroun<strong>de</strong>d agricultural crops, then pastures,<br />
and most distantly, forests. For a given region, the same<br />
pattern of land-use is found in all parishes, creating a<br />
mosaic of these repeated elements.<br />
This structure has existed for centuries. In the<br />
Mediterranean region, during Antiquity, three zones were<br />
<strong>de</strong>fined: ‘sylva’ (managed forest) ‘ager’ (agriculture) and<br />
‘saltus’ (scrublands and pasture). Because of the difficulty<br />
of access and the steep slopes that preclu<strong>de</strong>d agriculture,<br />
‘sylva’ correspon<strong>de</strong>d to zones at higher altitu<strong>de</strong> and<br />
distant from habitations. ‘Ager’ surroun<strong>de</strong>d habitations<br />
and ‘saltus’ was where the soil could not support crops.<br />
The mo<strong>de</strong>rn landscape of the Auriol parish is similar in<br />
structure, although this similarity does not result directly<br />
from the antique structure, as it has un<strong>de</strong>rgone several<br />
changes. Un<strong>de</strong>r the pressure of human population<br />
increase, agriculture covered the entire area in the<br />
nin<strong>et</strong>eenth century. Later, following the mechanization<br />
of agriculture and the movement of population to towns<br />
most of this land was abandoned (Grove & Rackham,<br />
2001) and left to ecological succession. Furthermore,<br />
the mo<strong>de</strong>rn landscape, although similar to that of the<br />
Antiquity in appearance, supports different functions.<br />
Today’s landscape structure at Auriol is explained in<br />
terms of secondary succession following abandonment<br />
of terraces because of the greater difficulty of accessing<br />
them. Garrigues correspond to poor stony soils and more<br />
arid environments and can be created by perturbations<br />
such as fire. In terms of secondary succession, these<br />
garrigues are usually found on <strong>de</strong>gra<strong>de</strong>d terraces with<br />
ero<strong>de</strong>d soil. However, they also result from human<br />
activities. Historically, they result from the opening of<br />
the environment by cattle and the collection of woody<br />
plants.<br />
The activities of the village, as a human community,<br />
structure the landscape. They are organised according<br />
to the interaction b<strong>et</strong>ween soil <strong>de</strong>pth, access to water<br />
sources and topography. This explains why both studies<br />
show the same pattern. By studying abandoned terraces<br />
along a few slopes, the 1989 study in fact studied the<br />
main structuring factor of the ‘finage’, while the 1995<br />
study revealed the spatial structure of this factor at the<br />
‘finage’ scale.<br />
Each zone <strong>de</strong>fined by human activities offers<br />
peculiar veg<strong>et</strong>ation structure and microhabitats to which<br />
molluscan communities are responding closely. Land snail<br />
communities are the result of historic management and<br />
are influenced by the recent evolution of the landscape,<br />
which reconstructs, to some extent, the antique spatial<br />
mo<strong>de</strong>l of land use. This recent evolution is taking two<br />
paths: reforestation following land abandonment and<br />
urbanisation. The 1995 study highlighted the importance<br />
of the former path in structuring land snail communities<br />
at the scale of the parish. However, the importance of the<br />
latter will certainly grow dramatically in the future.<br />
ACKNOWLEDGEMENTS<br />
The authors thank Errol Vela, Sébastien Della Casa<br />
and Bernard Hill for their help in the field. They also<br />
thank Dr R.H. Cowie, Dr N. Pike and an anonymous<br />
referee for their helpful comments on an earlier version<br />
of the manuscript. This work was supported by the<br />
programme of the EGPN (Écologie <strong>et</strong> gestion du<br />
73<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 65-74
◆ S. AUBRY & F. MAGNIN<br />
74<br />
patrimoine naturel) committee of the French Ministry<br />
of Environment « Dynamique <strong>de</strong> la biodiversité <strong>et</strong><br />
action <strong>de</strong> l’homme » programme: « Changement dans la<br />
structuration du paysage <strong>et</strong> dynamique <strong>de</strong> la biodiversité<br />
en région méditerranéenne – Approche à différentes<br />
échelles d’espace <strong>et</strong> <strong>de</strong> temps ».<br />
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<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Évolution <strong>de</strong> la croissance radiale du pin d’Alep (Pinus<br />
halepensis Mill.) en Provence calcaire (sud-est <strong>de</strong> la France)<br />
Evolution of Aleppo pine (Pinus halepensis Mill.)<br />
radial growth in calcareous Provence (South-Eastern France)<br />
Cyrille B. K. Rathgeber 1 , Antoine Nicault 2 & Joël Guiot 3<br />
1. Auteur pour correspondance : Centre INRA <strong>de</strong> Nancy, UMR- INRA-ENGREF 1092, Laboratoire d’étu<strong>de</strong> <strong>de</strong> la ressource forêt-Bois (LERFoB),<br />
Équipe qualité <strong><strong>de</strong>s</strong> bois, 54280 Champenoux, France. Tél. : +33 3 83 39 40 64 ; Fax : +33 3 83 39 40 69. Courrier électronique : cyrille.rathgeber@<br />
nancy.inra.fr<br />
2. Centre d’étu<strong><strong>de</strong>s</strong> nordiques (CEN), Université Laval, Sainte-Foy, Québec, G1K 7P4, Canada<br />
3. CEREGE, CNRS-UMR 6635, BP80, Europôle méditerranéen <strong>de</strong> l’Arbois, 13545 Aix-en-Provence Ce<strong>de</strong>x 4, France<br />
Résumé<br />
Les changements planétaires (changements climatiques, augmentation<br />
du taux <strong>de</strong> CO 2 atmosphérique <strong>et</strong> augmentation <strong><strong>de</strong>s</strong><br />
dépôts azotés) sont susceptibles d’avoir un eff<strong>et</strong> sur la production<br />
<strong><strong>de</strong>s</strong> écosystèmes forestiers. La <strong>de</strong>ndrochronologie offre un moyen <strong>de</strong><br />
vérifier c<strong>et</strong>te hypothèse en milieu naturel, car les données <strong>de</strong> croissance<br />
radiale peuvent être interprétées comme <strong><strong>de</strong>s</strong> indicateurs <strong>de</strong> la<br />
productivité <strong><strong>de</strong>s</strong> écosystèmes forestiers. Les données <strong>de</strong>ndrochronologiques<br />
utilisées dans c<strong>et</strong>te étu<strong>de</strong> proviennent <strong>de</strong> 21 peuplements<br />
<strong>de</strong> pin d’Alep localisés en Provence calcaire, dans le sud-est <strong>de</strong> la<br />
France. Les variables analysées sont : la <strong>de</strong>nsité minimale, la <strong>de</strong>nsité<br />
du bois initial, la largeur du bois initial, la <strong>de</strong>nsité maximale, la<br />
<strong>de</strong>nsité du bois final, la largeur du bois final, ainsi qu’un indice<br />
synthétique <strong>de</strong> croissance. Les tendances sont détectées sur la pério<strong>de</strong><br />
1950-1990. C<strong>et</strong>te étu<strong>de</strong> n’a pas permis <strong>de</strong> m<strong>et</strong>tre en évi<strong>de</strong>nce <strong>de</strong><br />
tendances générales positives <strong>et</strong> significatives concernant les variables<br />
relatives à la largeur <strong><strong>de</strong>s</strong> cernes, contrairement à ce que laissait<br />
prévoir la littérature scientifique. Ce travail a cependant permis <strong>de</strong><br />
m<strong>et</strong>tre en évi<strong>de</strong>nce une augmentation <strong>de</strong> la <strong>de</strong>nsité moyenne du bois<br />
initial <strong>et</strong> une diminution <strong>de</strong> la <strong>de</strong>nsité moyenne du bois final ainsi<br />
que <strong>de</strong> la <strong>de</strong>nsité maximale. Ces résultats montrent que la baisse <strong>de</strong><br />
<strong>de</strong>nsité du bois final observée par différents auteurs pour le nord<br />
<strong>et</strong> le centre <strong>de</strong> l’Europe semble également être vali<strong>de</strong> pour le sud <strong>de</strong><br />
l’Europe. Cela suggère l’influence d’un facteur commun à toutes ces<br />
régions qui pourrait être l’augmentation <strong><strong>de</strong>s</strong> dépôts azotés.<br />
Mots-clés<br />
Changements planétaires, <strong>de</strong>ndrochronologie, <strong>de</strong>nsité du bois,<br />
pin d’Alep, Provence<br />
Abstract<br />
Global changes: climatic change, atmospheric CO 2 rise and nitrogen<br />
<strong>de</strong>position increase, are likely to have an effect on forest production.<br />
Dendrochronology offers the possibility to verify this hypothesis in<br />
natural conditions since tree-ring data can be interpr<strong>et</strong>ed as indicators<br />
of forest ecosystem productivity. Numerous studies of radial<br />
tree growth have been carried out, mainly in temperate and cold<br />
climate regions. However, the Mediterranean region appears particularly<br />
promising for researching the causes of the observed trends.<br />
Dendrochronological data used in this study come from 21 Aleppo<br />
pine stands located in South-Eastern France. Analysed variables<br />
are: minimal <strong>de</strong>nsity, earlywood <strong>de</strong>nsity, earlywood width, maximal<br />
<strong>de</strong>nsity, latewood <strong>de</strong>nsity, latewood width, and a tree growth in<strong>de</strong>x.<br />
Raw data are used for minimal and maximal <strong>de</strong>nsity, whilst the<br />
other variables are standardised. Trends are d<strong>et</strong>ected using simple<br />
linear regressions over the period from 1950 to 1990. In contrast to<br />
the results published in the scientific literature, this study does not<br />
find out positive general significant trends regarding ring widths.<br />
However, this work shows an increase of earlywood <strong>de</strong>nsity and a<br />
<strong>de</strong>crease of latewood and maximum <strong>de</strong>nsity. These observations<br />
are coherent with some recent experimental results, suggesting that<br />
the increase of the earlywood <strong>de</strong>nsity could be a consequence of<br />
CO 2 increase, whilst the <strong>de</strong>crease of latewood <strong>de</strong>nsity could be a<br />
consequence of the increase of nitrogen <strong>de</strong>position. Moreover, these<br />
results show that the <strong>de</strong>crease of latewood <strong>de</strong>nsity, observed by several<br />
authors for North and Central Europe, seems also to be pertinent for<br />
South Europe. This suggests the influence of a common factor to all<br />
these regions which could be the increase of nitrogen <strong>de</strong>position.<br />
Key-words<br />
Global change, tree-ring, wood <strong>de</strong>nsity, Aleppo pine,<br />
French Mediterranean region<br />
75<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 75-82
◆ C.B.K. RATHGEBER, A. NICAULT & J. GUIOT<br />
76<br />
INTRODUCTION<br />
L’augmentation du taux <strong>de</strong> CO 2 atmosphérique, <strong>de</strong>puis<br />
une concentration préindustrielle <strong>de</strong> 280 µmol.mol -1<br />
jusqu’à une concentration actuelle <strong>de</strong> 370 µmol.mol -1<br />
(Keeling & Worf, 2001), est susceptible d’avoir un eff<strong>et</strong><br />
fertilisant sur les écosystèmes forestiers (Hättenschwiler<br />
<strong>et</strong> al., 1997 ; Curtis, 1998 ; Norby <strong>et</strong> al., 1999). Son<br />
action peut être directe : l’augmentation du substrat le<br />
plus limitant <strong>de</strong> la photosynthèse <strong>de</strong>vrait perm<strong>et</strong>tre une<br />
accélération <strong>de</strong> c<strong>et</strong>te <strong>de</strong>rnière ; <strong>et</strong> indirecte : limitation <strong>de</strong><br />
la photorespiration (Mousseau, 1998) <strong>et</strong> amélioration <strong>de</strong><br />
l’efficience <strong>de</strong> l’utilisation <strong>de</strong> l’eau (Scarascia-Mugnozza<br />
& Angelis, 1998). De plus, les changements climatiques,<br />
provoqués par l’augmentation <strong><strong>de</strong>s</strong> gaz à eff<strong>et</strong> <strong>de</strong> serre,<br />
ainsi que la pollution atmosphérique sont également<br />
susceptibles <strong>de</strong> modifier la productivité <strong><strong>de</strong>s</strong> écosystèmes<br />
forestiers.<br />
La largeur <strong>et</strong> la <strong>de</strong>nsité <strong><strong>de</strong>s</strong> cernes annuels <strong>de</strong> croissance<br />
peuvent être considérées comme <strong><strong>de</strong>s</strong> indicateurs <strong>de</strong><br />
la productivité <strong><strong>de</strong>s</strong> écosystèmes forestiers (Graumlich <strong>et</strong><br />
al., 1989). Ainsi, <strong>de</strong> nombreuses analyses <strong>de</strong> la tendance<br />
à long terme ont été réalisées sur <strong><strong>de</strong>s</strong> séries <strong>de</strong> largeurs<br />
<strong>de</strong> cernes provenant <strong>de</strong> peuplements <strong>de</strong> feuillus ou <strong>de</strong><br />
résineux, principalement en France, Suisse, Allemagne<br />
<strong>et</strong> Amérique du Nord (Innes, 1991 ; Graybill & Idso,<br />
1993 ; Ba<strong>de</strong>au <strong>et</strong> al., 1996 ; Spiecker <strong>et</strong> al., 1996). La<br />
détection <strong>et</strong> l’analyse <strong><strong>de</strong>s</strong> tendances à long terme en<br />
région méditerranéenne apparaissent particulièrement<br />
intéressantes dans la recherche actuelle <strong>de</strong> l’attribution<br />
<strong><strong>de</strong>s</strong> causes responsables <strong><strong>de</strong>s</strong> augmentations <strong>de</strong> croissance<br />
observées <strong>et</strong> <strong>de</strong> leurs conséquences pour l’avenir. En eff<strong>et</strong>,<br />
en région méditerranéenne les arbres sont généralement<br />
plus sensibles à l’eff<strong>et</strong> du bilan hydrique qu’à celui du<br />
bilan thermique (Cherubini <strong>et</strong> al., 2003). Les ligneux<br />
<strong>de</strong>vraient donc également être plus sensibles à l’eff<strong>et</strong><br />
<strong>de</strong> l’augmentation du taux <strong>de</strong> CO 2 (amélioration <strong>de</strong><br />
l’efficience <strong>de</strong> l’utilisation <strong>de</strong> l’eau) qu’à l’eff<strong>et</strong> <strong>de</strong> l’augmentation<br />
<strong><strong>de</strong>s</strong> températures (Feng <strong>et</strong> al., 1999 ; Knapp <strong>et</strong><br />
al., 2001). Malgré cela, peu <strong>de</strong> travaux ont été consacrés<br />
à c<strong>et</strong>te région (Scarascia-Mugnozza <strong>et</strong> al., 2000). Il est<br />
également intéressant <strong>de</strong> noter que peu d’étu<strong><strong>de</strong>s</strong> sur la<br />
tendance à long terme prennent en compte la <strong>de</strong>nsité du<br />
bois. Or, l’utilisation <strong><strong>de</strong>s</strong> différentes variables <strong>de</strong> <strong>de</strong>nsité<br />
<strong>de</strong>vrait perm<strong>et</strong>tre <strong>de</strong> mieux apprécier la répartition <strong><strong>de</strong>s</strong><br />
augmentations <strong>de</strong> productivité au cours <strong>de</strong> l’année <strong>et</strong> ainsi<br />
<strong>de</strong> mieux analyser leurs causes.<br />
C<strong>et</strong> article a donc pour objectif : (1) <strong>de</strong> détecter<br />
l’existence potentielle <strong>de</strong> tendances à long terme dans<br />
les séries <strong>de</strong> largeur <strong>et</strong> <strong>de</strong> <strong>de</strong>nsité <strong>de</strong> cernes provenant <strong>de</strong><br />
21 peuplements <strong>de</strong> pins d’Alep (Pinus halepensis Mill.)<br />
situés en Provence calcaire (sud-est <strong>de</strong> la France) ; (2)<br />
d’analyser les causes possibles <strong><strong>de</strong>s</strong> tendances mises en<br />
évi<strong>de</strong>nce ; <strong>et</strong> (3) <strong>de</strong> confronter les résultats obtenus à la<br />
fois aux résultats d’autres étu<strong><strong>de</strong>s</strong> <strong>de</strong>ndrochronologiques<br />
<strong>et</strong> aux résultats d’expériences réalisées sous conditions<br />
contrôlées en laboratoire.<br />
MATÉRIEL ET MÉTHODES<br />
Les données <strong>de</strong>ndrochronologiques utilisées dans c<strong>et</strong>te<br />
étu<strong>de</strong> proviennent <strong>de</strong> 21 peuplements <strong>de</strong> pin d’Alep localisés<br />
en Provence calcaire, dans le sud-est <strong>de</strong> la France<br />
(fig. 1). Ces données sont présentées en détail dans<br />
les thèses <strong>de</strong> Nicault (1999) <strong>et</strong> Rathgeber (2002). Les<br />
variables analysées au cours <strong>de</strong> la présente étu<strong>de</strong> sont : la<br />
<strong>de</strong>nsité minimale (ND), la <strong>de</strong>nsité du bois initial (ED), la<br />
largeur du bois initial (EW), la <strong>de</strong>nsité maximale (XD), la<br />
<strong>de</strong>nsité du bois final (LD), la largeur du bois final (LW) ;<br />
ainsi qu’un indice <strong>de</strong> croissance synthétique (TGI), défini<br />
comme suit : TGI = EW×ED + LW×LD. (1)<br />
L’intérêt <strong>de</strong> ce <strong>de</strong>rnier indice est <strong>de</strong> mieux prendre en<br />
compte la production <strong>de</strong> biomasse en combinant à la fois<br />
les variables <strong>de</strong> largeur <strong>et</strong> <strong>de</strong> <strong>de</strong>nsité (Hättenschwiler &<br />
Körner, 1996 ; Rathgeber <strong>et</strong> al., 2000).<br />
Dans c<strong>et</strong>te étu<strong>de</strong>, les variables ND <strong>et</strong> XD n’ont pas<br />
été standardisées car elle sont moins sensibles à l’eff<strong>et</strong><br />
<strong>de</strong> l’âge que les autres variables <strong>de</strong>ndrochronologiques<br />
(Schweingruber, 1990). Les variables ED, EW, LD <strong>et</strong><br />
LW sont tout d’abord standardisées par un indice <strong>de</strong><br />
productivité spécifique à chaque site ce qui perm<strong>et</strong> d’éliminer<br />
les différences <strong>de</strong> fertilité entre les peuplements<br />
(voir Rathgeber <strong>et</strong> al., 2000). L’indice utilisé est calculé en<br />
faisant la somme <strong><strong>de</strong>s</strong> 50 premières valeurs <strong>de</strong> la variable à<br />
standardiser. C<strong>et</strong>te métho<strong>de</strong> est communément employée<br />
pour standardiser les largeurs <strong>de</strong> cernes à l’ai<strong>de</strong> du rayon<br />
<strong>de</strong> l’arbre à 50 ans (Rathgeber <strong>et</strong> al., 1999). Ces variables<br />
sont ensuite standardisées à l’ai<strong>de</strong> <strong>de</strong> la loi biologique<br />
afin d’éliminer l’eff<strong>et</strong> <strong>de</strong> l’âge (Becker, 1989). Le TGI<br />
est calculé à partir <strong><strong>de</strong>s</strong> variables standardisées. Enfin,<br />
une chronologie régionale valable pour l’ensemble <strong>de</strong><br />
l’aire d’étu<strong>de</strong> est calculée pour chacune <strong><strong>de</strong>s</strong> variables<br />
<strong>de</strong>ndrochronologiques en moyennant les chronologies<br />
<strong><strong>de</strong>s</strong> 21 populations.<br />
La tendance à long terme est examinée sur la pério<strong>de</strong><br />
1950-1990, pour chaque variable <strong>et</strong> pour chaque population,<br />
à l’ai<strong>de</strong> <strong>de</strong> régressions linéaires simples en fonction<br />
du temps. C<strong>et</strong>te pério<strong>de</strong> est cependant marquée par un<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ÉVOLUTION DE LA CROISSANCE RADIALE DU PIN D’ALEP EN PROVENCE ◆<br />
Figure 1. Localisation <strong><strong>de</strong>s</strong> 21 peuplements <strong>de</strong> pin d’Alep.<br />
Les points indiquent les peuplements <strong>et</strong> le carré noir la station<br />
météorologique. Le co<strong>de</strong> <strong><strong>de</strong>s</strong> peuplements fait référence au tableau 1.<br />
Figure 1. Locations of the 21 Aleppo pine stands.<br />
Black dots mark the stands and the square represents<br />
the m<strong>et</strong>eorological station. Stands co<strong>de</strong> refers to table 1.<br />
77<br />
phénomène climatique d’une ampleur exceptionnelle :<br />
le gel <strong>de</strong> février 1956. C<strong>et</strong> événement a très fortement<br />
réduit la croissance <strong>de</strong> l’année en cours <strong>et</strong> même parfois<br />
<strong><strong>de</strong>s</strong> années suivantes (Devaux & Le Bourhis, 1978). Nous<br />
avons préféré ne pas le prendre en compte dans l’analyse<br />
<strong><strong>de</strong>s</strong> tendances <strong>et</strong> r<strong>et</strong>irer systématiquement les années susceptibles<br />
d’être affectées (1956, 1957, 1958 <strong>et</strong> 1959).<br />
Les données météorologiques utilisées dans ce travail<br />
ont été fournit par Météo France <strong>et</strong> proviennent <strong>de</strong> l’observatoire<br />
du Palais Longchamp à Marseille. À partir <strong>de</strong><br />
ces données, les tendances climatiques observées au cours<br />
du XX e siècle en Provence ont été décrites par Rathgeber<br />
(2002).<br />
Les relations cernes-climat concernant une partie <strong><strong>de</strong>s</strong><br />
variables utilisées ont été analysées par Nicault (1999) <strong>et</strong><br />
Rathgeber <strong>et</strong> al. (2000) à l’ai<strong>de</strong> <strong>de</strong> fonctions <strong>de</strong> réponse<br />
(Guiot, 1991). À partir <strong>de</strong> ces travaux, nous déterminerons<br />
si les changements climatiques observés peuvent être<br />
rendus responsables <strong><strong>de</strong>s</strong> tendances mises en évi<strong>de</strong>nce sur<br />
la croissance.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 75-82
◆ C.B.K. RATHGEBER, A. NICAULT & J. GUIOT<br />
RÉSULTATS<br />
À l’échelle régionale, on observe pour le bois initial une<br />
diminution <strong>de</strong> la <strong>de</strong>nsité minimale (fig. 2a) alors que la<br />
<strong>de</strong>nsité moyenne ne présente pas <strong>de</strong> tendance significative<br />
(tableau 1). Pour le bois final, on observe une diminution<br />
très n<strong>et</strong>te <strong>de</strong> la <strong>de</strong>nsité minimale <strong>et</strong> <strong>de</strong> la <strong>de</strong>nsité moyenne<br />
(fig. 2b). La série régionale <strong>de</strong> TGI ainsi que les largeurs<br />
<strong>de</strong> bois initial <strong>et</strong> final ne présentent pas <strong>de</strong> tendance significative<br />
lorsque l’on considère l’ensemble <strong>de</strong> la pério<strong>de</strong><br />
1950-1999. Mais c<strong>et</strong>te pério<strong>de</strong> peut être décomposée en<br />
<strong>de</strong>ux phases distinctes : (1) une pério<strong>de</strong> <strong>de</strong> relative stabilité<br />
allant <strong>de</strong> 1950 à 1976 <strong>et</strong> (2) une pério<strong>de</strong> <strong>de</strong> forte<br />
diminution allant <strong>de</strong> 1977 à 1990 (fig. 2c).<br />
Au niveau local, on observe une tendance générale à<br />
l’augmentation pour la <strong>de</strong>nsité du bois initial : 9 populations<br />
présentent <strong><strong>de</strong>s</strong> tendances significatives positives<br />
alors qu’une seule population présente une tendance<br />
significative négative (tableau 1). La <strong>de</strong>nsité minimale,<br />
en revanche, présente <strong><strong>de</strong>s</strong> tendances négatives significatives<br />
pour 7 populations sans présenter aucune tendance<br />
positive. En ce qui concerne la largeur du bois initial, 7<br />
populations montrent <strong><strong>de</strong>s</strong> tendances significatives négatives<br />
alors que 2 populations seulement montrent <strong><strong>de</strong>s</strong><br />
tendances significatives positives. Une forte tendance<br />
générale à la baisse se manifeste pour les variables <strong>de</strong><br />
<strong>de</strong>nsité du bois final. En ce qui concerne la <strong>de</strong>nsité du<br />
bois final, 12 populations présentent <strong><strong>de</strong>s</strong> tendances néga-<br />
78<br />
Peuplements<br />
ND EDS EWS XD LDS LWS TGI<br />
α S a α S a α S a α S a α S a α S a α S a<br />
AUR NS *** + 2 NS *** - 1.36 ** - 0.61 NS NS<br />
CIO NS NS NS *** - 0.96 ** - 0.88 NS NS<br />
CVI ** - 0.19 NS NS *** - 1.53 * - 0.75 * - 9.0 NS<br />
FAR *** - 0.40 *** + 1 NS *** - 1.52 *** - 1.00 * + 14.0 * + 15.0<br />
FOO NS NS NS * - 0.43 NS NS NS<br />
GAR abs abs abs NS ** - 3.00 abs abs abs ** - 0.91 NS ** - 2.0<br />
MAL NS NS * - 2.00 *** - 1.62 NS NS ** - 4.0<br />
MAN *** - 0.64 *** - 1 NS *** - 1.54 *** - 0.00 NS ** - 11.0<br />
MEE NS ** + 0.78 NS *** - 0.81 NS NS NS<br />
MOU NS NS NS *** - 1.06 NS NS NS<br />
MUR NS NS NS *** - 1.23 *** - 0.60 *** - 9.0 ** - 13.0<br />
NYO NS *** + 2 ** - 6.00 *** - 1.42 NS * - 5.0 ** - 10.0<br />
PER *** - 0.93 NS *** + 18.00 ** - 0.57 NS *** + 16.0 *** + 33.0<br />
PNM *** - 0.67 NS NS *** - 1.46 ** - 1.00 NS NS<br />
RDA *** - 0.51 NS * + 4.00 *** - 1.21 NS NS * + 9.0<br />
RIA NS *** + 2 NS *** - 1.73 *** - 1.00 NS NS<br />
ROB *** - 0.38 NS *** - 7.00 *** - 2.13 *** - 2.00 *** - 13.0 *** - 20.0<br />
ROG NS *** + 2 ** - 7.00 *** - 1.65 NS NS NS<br />
ROU NS ** + 1 *** - 16.00 ** - 0.86 NS NS ** - 22.0<br />
SIM NS *** + 1 NS *** - 1.54 ** - 0.77 NS NS<br />
SIS NS ** + 0.56 *** - 10.00 *** - 2.96 *** - 3.00 ** - 12.0 *** - 24.0<br />
Régional ** - 0.18 NS 0.67 NS 0.17 *** - 1.32 *** - 0.88 NS 2.0 NS 2.00<br />
Total NS 13 11 12 0 9 14 10<br />
Total + 0 9 2 0 0 2 3<br />
Total - 8 1 7 21 12 5 8<br />
Tableau 1. Tendances à long terme observées. Pour chaque population <strong>et</strong> chaque variable <strong>de</strong>ndrochronologique : <strong>de</strong>nsité minimale (ND), <strong>de</strong>nsité du bois initial (ED), largeur<br />
du bois initial (EW), <strong>de</strong>nsité maximale (XD), <strong>de</strong>nsité du bois final (LD), largeur du bois final (LW) <strong>et</strong> indice synthétique <strong>de</strong> croissance (TGI), la tendance est détectée sur la<br />
pério<strong>de</strong> 1950-1990 par régression linéaire simple. Les années 1956 à 1959 ne sont pas prises en compte. Le niveau <strong>de</strong> significativité α (NS pour p > 0.1, * pour p ≤ 0.1,<br />
** pour p ≤ 0.05 <strong>et</strong> *** pour p ≤ 0.01) <strong>de</strong> la tendance, ainsi que le signe s <strong>et</strong> la pente a (×10 3 ) <strong>de</strong> la droite <strong>de</strong> régression sont fournis en colonne.<br />
Table 1. Observed long term trend. For each population and each <strong>de</strong>nrochronological variable : minimal <strong>de</strong>nsity (ND), earlywood <strong>de</strong>nsity (ED), earlywood width (EW),<br />
maximal <strong>de</strong>nsity (XD), latewood <strong>de</strong>nsity (LD), latewood width (LW) and tree growth in<strong>de</strong>x (TGI), trend is d<strong>et</strong>ected on the 1950–1990 period using simple linear regression.<br />
Years from 1956 to 1959 are not taken into account. Significance level α (NS for p > 0.1, * for p ≤ 0.1, ** for p ≤ 0.05 and *** for p ≤ 0.01) of the trend, as well<br />
as the sign s and the slope a (×10 3 ) of the regression line are given in column.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ÉVOLUTION DE LA CROISSANCE RADIALE DU PIN D’ALEP EN PROVENCE ◆<br />
79<br />
Fig. 2. Tendances régionales à long terme.<br />
a. Densité minimale (ND) <strong>et</strong> <strong>de</strong>nsité du bois initial (ED).<br />
b. Densité maximale (XD) <strong>et</strong> <strong>de</strong>nsité du bois final (LD).<br />
c. Largeur du bois initial (EW), largeur du bois final (LW) <strong>et</strong> indice synthétique<br />
<strong>de</strong> croissance (TGI) en relation avec le cumul <strong><strong>de</strong>s</strong> précipitations annuelles (P).<br />
Les statistiques relatives aux régressions linéaires (en pointillés) sont données<br />
dans le tableau 1.<br />
Fig. 2. Regional long term trends.<br />
a. Minimal <strong>de</strong>nsity (ND) and earlywood <strong>de</strong>nsity (ED).<br />
b. Maximal <strong>de</strong>nsity (XD) and latewood <strong>de</strong>nsity (LD).<br />
c. Earlywood width (EW), latewood width (LW) and tree growth<br />
in<strong>de</strong>x (TGI) in relation with total annual precipitation (P).<br />
Statistics of the regression lines (dotted) are presented in table 1.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 75-82
◆ C.B.K. RATHGEBER, A. NICAULT & J. GUIOT<br />
80<br />
tives significatives. Pour la <strong>de</strong>nsité maximale toutes les<br />
populations étudiées présentent <strong><strong>de</strong>s</strong> tendances négatives<br />
significatives. Pour la largeur du bois final, 5 populations<br />
présentent <strong><strong>de</strong>s</strong> tendances significatives négatives alors<br />
que 2 populations présentent <strong><strong>de</strong>s</strong> tendances significatives<br />
positives. En ce qui concerne le TGI, 3 populations<br />
présentent <strong><strong>de</strong>s</strong> tendances positives, alors que 8 populations<br />
présentent <strong><strong>de</strong>s</strong> tendances négatives. Les tendances<br />
positives sont globalement plus prononcées (pentes plus<br />
fortes) que les tendances négatives, elles sont pourtant<br />
moins significatives car elles sont souvent masquées par<br />
<strong><strong>de</strong>s</strong> variabilités interannuelles plus fortes.<br />
DISCUSSION<br />
Quatre facteurs principaux sont susceptibles d’être<br />
responsables <strong><strong>de</strong>s</strong> tendances observées : (1) l’eff<strong>et</strong> <strong>de</strong><br />
l’âge, (2) l’eff<strong>et</strong> <strong><strong>de</strong>s</strong> changements climatiques, (3) l’eff<strong>et</strong><br />
<strong>de</strong> l’augmentation du taux <strong>de</strong> CO 2 <strong>et</strong> (4) l’eff<strong>et</strong> <strong>de</strong><br />
l’augmentation <strong><strong>de</strong>s</strong> dépôts azotés. Malgré la standardisation,<br />
l’eff<strong>et</strong> <strong>de</strong> l’âge reste le premier facteur à prendre<br />
en compte pour expliquer les tendances à long terme<br />
observées sur les variables <strong>de</strong>ndrochronologiques (Briffa<br />
<strong>et</strong> al., 1996). La métho<strong>de</strong> <strong>de</strong> standardisation utilisée dans<br />
c<strong>et</strong>te étu<strong>de</strong> donne <strong>de</strong> très bons résultats pour les largeurs<br />
(fig. 2a <strong>et</strong> 2c dans Rathgeber <strong>et</strong> al., 2000). L’ajustement<br />
<strong>de</strong> la loi biologique sous-estime en revanche légèrement<br />
la <strong>de</strong>nsité moyenne du bois initial pour les arbres <strong>de</strong> plus<br />
<strong>de</strong> 40 ans en raison <strong>de</strong> la forme <strong>de</strong> la courbe polynomiale<br />
r<strong>et</strong>enue (fig. 2b dans Rathgeber <strong>et</strong> al., 2000). C<strong>et</strong>te sousestimation<br />
est susceptible d’induire une légère tendance<br />
positive dans les données standardisées. Cependant, en ne<br />
nous intéressant qu’à la pério<strong>de</strong> récente, nous avons limité<br />
ce problème qui ne <strong>de</strong>vrait donc pas être responsable<br />
<strong>de</strong> la tendance à l’augmentation détectée pour la <strong>de</strong>nsité<br />
du bois initial. La loi biologique relative à la <strong>de</strong>nsité du<br />
bois final présente également <strong><strong>de</strong>s</strong> difficultés d’ajustement<br />
<strong><strong>de</strong>s</strong> données (fig. 2d dans Rathgeber <strong>et</strong> al., 2000). Ces<br />
difficultés se manifestent pour les classes d’âge <strong>de</strong> 50 à<br />
80 ans qui apparaissent comme hors norme <strong>et</strong> infléchissent<br />
fortement la courbe polynomiale. La loi biologique<br />
surestime donc la <strong>de</strong>nsité pour les âges compris entre<br />
50 <strong>et</strong> 80 ans, pour revenir à un ajustement <strong>de</strong> meilleure<br />
qualité ensuite. Ceci <strong>de</strong>vrait donc induire une tendance<br />
positive dans les données standardisées <strong>et</strong> peut être rendu<br />
responsable du fait que l’on observe moins <strong>de</strong> tendances<br />
significatives négatives pour la <strong>de</strong>nsité du bois final que<br />
pour la <strong>de</strong>nsité maximale.<br />
Les changements climatiques ayant eu lieu au cours<br />
<strong><strong>de</strong>s</strong> 50 <strong>de</strong>rnières années dans la région étudiée consistent<br />
en : (1) une augmentation générale <strong><strong>de</strong>s</strong> températures pour<br />
toutes les saisons, c<strong>et</strong>te augmentation étant maximale en<br />
été ; <strong>et</strong> (2) une légère augmentation <strong><strong>de</strong>s</strong> précipitations<br />
hivernales alors que les précipitations <strong><strong>de</strong>s</strong> autres saisons<br />
sont restées stables (Rathgeber, 2002). Ces observations<br />
sont en accord avec une étu<strong>de</strong> récente menée à l’échelle <strong>de</strong><br />
la France (Lebourgeois <strong>et</strong> al., 2001). Une forte tendance<br />
à la baisse est cependant observable pour le cumul <strong><strong>de</strong>s</strong><br />
précipitations annuelles entre 1977 <strong>et</strong> 1990 qui paraît être<br />
la cause <strong>de</strong> la baisse du TGI <strong>et</strong> <strong>de</strong> la largeur <strong><strong>de</strong>s</strong> bois initial<br />
<strong>et</strong> final sur c<strong>et</strong>te même pério<strong>de</strong>. L’analyse <strong><strong>de</strong>s</strong> relations<br />
cernes-climat à l’ai<strong>de</strong> <strong><strong>de</strong>s</strong> fonctions <strong>de</strong> réponses montre<br />
que la <strong>de</strong>nsité du bois initial <strong>et</strong> la <strong>de</strong>nsité minimale sont<br />
toutes <strong>de</strong>ux influencées négativement par les précipitations<br />
<strong><strong>de</strong>s</strong> mois <strong>de</strong> mars <strong>et</strong> avril <strong>et</strong> les températures du mois<br />
<strong>de</strong> février (Nicault, 1999). Les précipitations relatives aux<br />
mois <strong>de</strong> mars <strong>et</strong> avril sont stables sur les cinquante <strong>de</strong>rnières<br />
années alors que la température du mois <strong>de</strong> février<br />
a augmenté. L’influence du climat <strong>de</strong>vrait donc induire<br />
une tendance négative pour ces variables. La tendance<br />
générale à la baisse observée pour la <strong>de</strong>nsité minimale<br />
peut donc être expliquée par l’évolution du climat alors<br />
que la tendance générale à la hausse observée sur la <strong>de</strong>nsité<br />
du bois initial ne peut pas l’être. La <strong>de</strong>nsité du bois<br />
final <strong>et</strong> la <strong>de</strong>nsité maximale sont toutes <strong>de</strong>ux influencées<br />
positivement par les précipitations <strong><strong>de</strong>s</strong> mois d’avril <strong>et</strong> mai.<br />
Les précipitations printanières étant quasiment stables,<br />
le climat ne peut être tenu pour responsable <strong><strong>de</strong>s</strong> fortes<br />
tendances négatives observées pour ces variables.<br />
Deux étu<strong><strong>de</strong>s</strong> récentes analysent la réponse <strong><strong>de</strong>s</strong> variables<br />
<strong>de</strong>ndrochronologiques à une augmentation du taux<br />
<strong>de</strong> CO 2 . La première étu<strong>de</strong> (Hättenschwiler & Körner,<br />
1996) concerne <strong>de</strong> jeunes plants d’épicéa (Picea abies)<br />
soumis à un enrichissement en CO 2 <strong>et</strong>/ou en azote. Ces<br />
plants poussent dans une chambre fermée qui reproduit<br />
(du point <strong>de</strong> vue du sol, du climat, <strong>et</strong> <strong>de</strong> la compétition)<br />
les conditions <strong>de</strong> la station forestière dans laquelle ils<br />
ont été prélevés (Alpes suisses, 1 500 m d’altitu<strong>de</strong>). La<br />
secon<strong>de</strong> étu<strong>de</strong> concerne <strong>de</strong> jeunes plants <strong>de</strong> pins (Pinus<br />
taeda) soumis uniquement à un enrichissement en CO 2 <strong>et</strong><br />
poussant dans <strong><strong>de</strong>s</strong> conditions nutritionnelles non limitantes<br />
(Telewski <strong>et</strong> al., 1999). En conditions nutritionnelles<br />
non limitantes on observe toujours un eff<strong>et</strong> positif <strong>de</strong><br />
l’enrichissement en CO 2 que ce soit sur la largeur ou bien<br />
sur la <strong>de</strong>nsité du cerne (ibi<strong>de</strong>m). Or ce n’est pas le cas en<br />
conditions nutritionnelles limitantes, où l’eff<strong>et</strong> du CO 2<br />
est le plus souvent moins important que celui <strong>de</strong> la fertilisation<br />
azotée (Hättenschwiler & Körner, 1996). Pour<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ÉVOLUTION DE LA CROISSANCE RADIALE DU PIN D’ALEP EN PROVENCE ◆<br />
une augmentation simultanée <strong>de</strong> l’enrichissement en CO 2<br />
<strong>et</strong> en azote, Hättenschwiler <strong>et</strong> Körner (1996) décrivent<br />
(1) une très faible augmentation du TGI due à l’ensemble<br />
<strong><strong>de</strong>s</strong> eff<strong>et</strong>s du CO 2 <strong>et</strong> <strong>de</strong> l’azote sur les différentes<br />
variables ; (2) une très faible augmentation <strong>de</strong> la largeur<br />
totale due à une augmentation <strong>de</strong> la largeur du bois final ;<br />
(3) une augmentation <strong>de</strong> la <strong>de</strong>nsité du bois initial due<br />
à l’eff<strong>et</strong> <strong>de</strong> l’augmentation du taux <strong>de</strong> CO 2 ; <strong>et</strong> (4) une<br />
diminution <strong>de</strong> la <strong>de</strong>nsité du bois final due à l’eff<strong>et</strong> négatif<br />
<strong>de</strong> l’enrichissement en azote sur la <strong>de</strong>nsité. Les résultats<br />
obtenus par Hättenschwiler <strong>et</strong> Körner (1996) sont donc<br />
très proches <strong><strong>de</strong>s</strong> résultats obtenus par la présente étu<strong>de</strong>,<br />
si l’on adm<strong>et</strong> que <strong>de</strong> vieux arbres en conditions naturelles<br />
sont susceptibles <strong>de</strong> présenter <strong><strong>de</strong>s</strong> réponses plus faibles<br />
que <strong>de</strong> jeunes arbres en conditions expérimentales.<br />
La majeure partie <strong><strong>de</strong>s</strong> étu<strong><strong>de</strong>s</strong> <strong>de</strong>ndrochronologiques<br />
sur la tendance à long terme présente <strong><strong>de</strong>s</strong> résultats m<strong>et</strong>tant<br />
en évi<strong>de</strong>nce <strong>de</strong> fortes tendances positives qu’elles<br />
associent généralement à l’augmentation du taux <strong>de</strong> CO 2<br />
<strong>et</strong> à l’amélioration <strong><strong>de</strong>s</strong> conditions climatiques (Spiecker<br />
<strong>et</strong> al., 1996). De telles tendances n’ont pas été mises en<br />
évi<strong>de</strong>nce au cours <strong>de</strong> ce travail, alors même qu’il a été<br />
conduit en région méditerranéenne, région qui <strong>de</strong>vrait<br />
être théoriquement particulièrement sensible à l’eff<strong>et</strong><br />
<strong>de</strong> l’augmentation du taux CO 2 . La baisse <strong>de</strong> la <strong>de</strong>nsité<br />
moyenne du bois final <strong>et</strong> <strong>de</strong> la <strong>de</strong>nsité maximale est cohérente<br />
avec les résultats <strong>de</strong> la littérature à l’échelle nationale<br />
(Bergès <strong>et</strong> al., 2000) comme à l’échelle mondiale (Briffa<br />
<strong>et</strong> al., 1998a ; Briffa <strong>et</strong> al., 1998b). L’étu<strong>de</strong> précé<strong>de</strong>nte<br />
(Briffa <strong>et</strong> al., 1998b) concerne cependant essentiellement<br />
<strong><strong>de</strong>s</strong> peuplements <strong>de</strong> hautes latitu<strong><strong>de</strong>s</strong> <strong>et</strong> altitu<strong><strong>de</strong>s</strong> sensibles<br />
aux températures estivales ; alors que notre étu<strong>de</strong><br />
concerne <strong><strong>de</strong>s</strong> peuplements méditerranéens, <strong>de</strong> basses<br />
altitu<strong><strong>de</strong>s</strong>, <strong>et</strong> qui ne sont pas sensibles aux températures<br />
estivales mais aux précipitations printanières. Les raisons<br />
<strong>de</strong> c<strong>et</strong>te baisse générale <strong>de</strong> la <strong>de</strong>nsité du bois final ne<br />
sont pas encore connues. Briffa <strong>et</strong> al. (1998b) proposent<br />
comme explication un changement dans la saisonnalité<br />
<strong><strong>de</strong>s</strong> variables climatiques. Vaganov <strong>et</strong> al. (1999) montrent<br />
que le r<strong>et</strong>ar<strong>de</strong>ment actuel <strong>de</strong> la fonte <strong><strong>de</strong>s</strong> neiges a une<br />
influence certaine en ce qui concerne les arbres <strong>de</strong> la forêt<br />
boréale. Notre étu<strong>de</strong> quant à elle suggère qu’il existe une<br />
cause commune capable d’affecter <strong><strong>de</strong>s</strong> écosystèmes aussi<br />
différents que la forêt boréale <strong>et</strong> la forêt méditerranéenne<br />
<strong>et</strong> qui pourrait être l’augmentation <strong><strong>de</strong>s</strong> dépôts azotés.<br />
REMERCIEMENTS<br />
Ce travail a été financé par l’Union européenne, à travers<br />
le proj<strong>et</strong> FORMAT (contrat ENV4-CT97-0641) <strong>et</strong> à<br />
travers une bourse individuelle post-doctorale Marie Curie<br />
(contrat EVK2-CT-2002-50021). Ce travail a également<br />
été soutenu par le ministère français <strong>de</strong> la Recherche à<br />
travers une bourse individuelle <strong>de</strong> thèse. Les données<br />
météorologiques ont été fournies par Météo France.<br />
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<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Dynamique <strong>de</strong> la végétation <strong>de</strong> mares temporaires<br />
en Afrique du Nord (Numidie orientale, NE Algérie)<br />
Veg<strong>et</strong>ation dynamics in temporary ponds of North Africa<br />
(Oriental Numidia, NE Algeria)<br />
Gérard <strong>de</strong> Bélair<br />
Laboratoire <strong>de</strong> recherche sur les zones humi<strong><strong>de</strong>s</strong> (LRZH), Université Badji Mokhtar, BP533, 23000 Annaba, Algérie.<br />
Email : gerard_<strong>de</strong>_belair@yahoo.com<br />
Résumé<br />
La dynamique écologique <strong><strong>de</strong>s</strong> milieux endoréiques temporaires<br />
méditerranéens a été peu étudiée en Afrique du Nord, <strong>et</strong> jamais en<br />
Numidie (NE algérien). Dans c<strong>et</strong>te région, 26 mares temporaires<br />
ont fait l’obj<strong>et</strong> <strong>de</strong> suivis phytoécologiques <strong>et</strong> hydrologiques <strong>et</strong> la<br />
végétation a été systématiquement échantillonnée chaque mois<br />
durant l’hydropério<strong>de</strong>, au cours <strong>de</strong> trois cycles annuels (1998-<br />
2001). Les stations étudiées sont distribuées le long <strong>de</strong> <strong>de</strong>ux transects<br />
<strong>de</strong> 90 km environ. Une analyse inter-classes a été appliquée sur<br />
un tableau rassemblant 539 relevés <strong>et</strong> 136 espèces végétales.<br />
C<strong>et</strong>te analyse a pour but <strong>de</strong> séparer <strong>de</strong>ux eff<strong>et</strong>s, l’un temporel<br />
qui perm<strong>et</strong> <strong>de</strong> décrire la succession <strong><strong>de</strong>s</strong> espèces, l’autre spatial qui<br />
est relatif à la typologie stationnelle. Les résultats perm<strong>et</strong>tent <strong>de</strong><br />
distinguer n<strong>et</strong>tement <strong>de</strong>ux pério<strong><strong>de</strong>s</strong> dans l’année (été/automne <strong>et</strong><br />
hiver/printemps), définies notamment par la présence <strong>de</strong> Panicum<br />
repens d’une part <strong>et</strong> <strong>de</strong> Ranunculus baudotii d’autre part. La<br />
typologie aboutit à définir trois groupes parmi les mares, déterminés<br />
successivement par : groupe 1, Characeae <strong>et</strong> Juncus acutus ;<br />
groupe 2, Callitriche obtusangula <strong>et</strong> Iso<strong>et</strong>es velata subsp. typica ;<br />
groupe 3, C. obtusangula <strong>et</strong> Alisma plantago-aquatica.<br />
Une annexe comporte une <strong><strong>de</strong>s</strong>cription détaillée <strong><strong>de</strong>s</strong> 26 hydrosystèmes<br />
<strong>de</strong> mares temporaires <strong>et</strong> perm<strong>et</strong> d’en percevoir la richesse floristique,<br />
incluant la présence remarquable d’un élément original représentatif<br />
d’une « poche relictuelle afrotropicale ».<br />
Mots-clés<br />
Mares temporaires, analyse inter-classes, succession végétale,<br />
typologie, biogéographie, élément afrotropical.<br />
Abstract<br />
The temporary ponds have been less studied in Northern Africa<br />
than in Mediterranean Europe. Moreover, no study is <strong>de</strong>voted to<br />
the ecology of these ponds in Numidia (North-Eastern Algeria).<br />
Thus to fill this gap, we have surveyed 26 temporary ponds and<br />
we have examinated the fluctuations of plant assemblages and<br />
hydrology. These samples were performed monthly (nine months)<br />
during the hydroperiod and along three annual cycles (1998-<br />
2001). The studied ponds are distributed along two transects of<br />
90 km. We obtain a table of 539 relevés and 136 plant taxa.<br />
This table was submitted to an ACP and then to a Discrimin :<br />
B<strong>et</strong>ween analysis. This analysis allows to distinguish temporal and<br />
spatial effects : the first <strong><strong>de</strong>s</strong>cribes the succession of taxa, and the<br />
second the typology of ponds. Our results show that the temporal<br />
effect conveyied two periods (summer-autumn and winter-spring)<br />
with respectively Panicum repens and Ranunculus baudotii. The<br />
spatial effect permits to divi<strong>de</strong> the twenty-six temporary ponds into<br />
three groups: group 1, Characeae and Juncus acutus; group 2,<br />
Callitriche obtusangula and Iso<strong>et</strong>es velata subsp. typica; group 3,<br />
C. obtusangula and Alisma plantago-aquatica.<br />
An appendix inclu<strong><strong>de</strong>s</strong> a d<strong>et</strong>ailed <strong><strong>de</strong>s</strong>cription of these 26 temporary<br />
ponds, with some data related to plant richness and a focus about<br />
the most outstanding biogeographic elements present within the<br />
« afrotropical relict pock<strong>et</strong> ».<br />
Key-words<br />
Temporary ponds, discrimin: b<strong>et</strong>ween analysis, plant succession,<br />
typology, biogeography, afrotropical element.<br />
83<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
84<br />
INTRODUCTION<br />
La flore <strong>et</strong> la végétation <strong><strong>de</strong>s</strong> mares temporaires<br />
méditerranéennes ont fait l’obj<strong>et</strong> <strong>de</strong> nombreux travaux<br />
<strong>et</strong> synthèses récents (Quézel, 1998 ; Médail <strong>et</strong> al.,<br />
1998 ; Marti & Esteban, 2001 ; Rhazi <strong>et</strong> al., 2003 ;<br />
Grillas <strong>et</strong> al., 2004 ; Deil, 2005). Leur intérêt <strong>et</strong> leur<br />
originalité biogéographique <strong>et</strong> écologique ne sont plus<br />
à démontrer à l’échelle du bassin méditerranéen, mais<br />
les étu<strong><strong>de</strong>s</strong> phytodynamiques <strong>de</strong> ces milieux complexes<br />
<strong>de</strong>meurent peu nombreuses, particulièrement au sud <strong>de</strong><br />
la Méditerranée alors que ces mares subissent <strong><strong>de</strong>s</strong> impacts<br />
anthropiques majeurs (Rhazi <strong>et</strong> al., 2001).<br />
L’Algérie, <strong>et</strong> plus particulièrement la Numidie<br />
(au sens <strong><strong>de</strong>s</strong> divisions biogéographiques proposées<br />
par Quézel & Santa, 1962-1963), est riche en mares<br />
temporaires répondant aux critères Ramsar (Grillas<br />
<strong>et</strong> al., 2004). Plus d’une centaine d’entre elles ont été<br />
échantillonnées <strong>de</strong> 1995 à 2001 (Samraoui & <strong>de</strong> Bélair,<br />
1997, 1998). Un certain nombre d’étu<strong><strong>de</strong>s</strong> avait été<br />
effectué auparavant sur l’Algérie <strong>de</strong> manière sporadique,<br />
incluant <strong><strong>de</strong>s</strong> travaux non seulement sur les Spermaphytes<br />
ou les Ptéridophytes, mais également sur les algues d’eaux<br />
douces : Cyanophycées, Diatomées, Myxophycées<br />
<strong>et</strong> Chlorophycées <strong>et</strong>, notamment, les Charophycées<br />
(Lefranc, 1865 ; Gauthier-Lièvre, 1937 ; Feldmann, 1946 ;<br />
Morgan, 1982 ; Stevenson <strong>et</strong> al., 1989). Gauthier-Lièvre<br />
(1937) présente dans sa thèse un historique très détaillé<br />
<strong><strong>de</strong>s</strong> travaux réalisés en Algérie <strong>et</strong>, plus particulièrement<br />
en Numidie, sur les zones humi<strong><strong>de</strong>s</strong>. C<strong>et</strong> auteur soulignait<br />
« qu’en Algérie, les conditions optimales pour le développement<br />
d’une flore riche <strong>et</strong> variée sont réalisées sur toute l’étendue du<br />
secteur numidien, car c’est là que la pluviosité est la plus élevée<br />
<strong>et</strong> que se trouvent sur <strong>de</strong> gran<strong><strong>de</strong>s</strong> surfaces <strong><strong>de</strong>s</strong> affleurements <strong>de</strong><br />
terrains siliceux, en l’espèce <strong><strong>de</strong>s</strong> grès éocènes ».<br />
Tous ces motifs nous ont amené à choisir 26 mares<br />
temporaires <strong>de</strong> Numidie orientale, dispersées le long d’un<br />
axe <strong>de</strong> 90 km environ. Sur les cinq campagnes réalisées<br />
<strong>de</strong> 1996 à 2001, seules les trois <strong>de</strong>rnières campagnes<br />
ont été r<strong>et</strong>enues en raison <strong>de</strong> l’effort homogène<br />
d’échantillonnage exercé durant ces trois cycles (1998-<br />
2001) sur les 26 stations. L’objectif envisagé <strong>de</strong> c<strong>et</strong>te<br />
étu<strong>de</strong> était triple : (i) évaluer la biodiversité végétale <strong>de</strong><br />
ces mares, (ii) étudier la succession <strong><strong>de</strong>s</strong> espèces dans le<br />
temps (structure temporelle), <strong>et</strong> (iii) définir la typologie<br />
stationnelle (structure spatiale) <strong><strong>de</strong>s</strong> mares, dont seule une<br />
étu<strong>de</strong> partielle portant sur un seul cycle avait été déjà<br />
présentée (<strong>de</strong> Bélair, 2004). Ces <strong>de</strong>ux <strong>de</strong>rnières questions<br />
sont souvent soulevées par les écologues à partir <strong>de</strong><br />
recherches en hydrobiologie, sur la flore comme sur la<br />
faune (Degiorgi & Grandmott<strong>et</strong>, 1993 ; Born<strong>et</strong>te <strong>et</strong> al.,<br />
1994 ; Gaertner <strong>et</strong> al., 1998). C<strong>et</strong>te approche dynamique<br />
se base sur les analyses statistiques multivariées qui ont<br />
déjà fait leur preuve en milieu aquatique (Dolé<strong>de</strong>c &<br />
Chessel, 1987, 1989 ; Beffy & Dolé<strong>de</strong>c, 1991). Une<br />
double analyse, interclasses (mois <strong>et</strong> stations), <strong><strong>de</strong>s</strong><br />
données floristiques perm<strong>et</strong> <strong>de</strong> séparer l’eff<strong>et</strong> temporel<br />
<strong>de</strong> l’eff<strong>et</strong> spatial <strong>et</strong> perm<strong>et</strong> <strong>de</strong> discriminer les facteurs<br />
responsables <strong>de</strong> l’évolution <strong>de</strong> la végétation <strong>de</strong> ces mares<br />
temporaires <strong>de</strong> Numidie.<br />
MATÉRIELS ET MÉTHODES<br />
Zone d’étu<strong>de</strong><br />
La Numidie forme une unité biogéographique précise,<br />
développée en croissant autour du Djebel Edough<br />
(somm<strong>et</strong> : 1 008 m) à l’Ouest d’Annaba (fig. 1). Elle est<br />
délimitée au nord par la Méditerranée, au sud par un<br />
ensemble <strong>de</strong> collines d’altitu<strong>de</strong> moyenne (massifs <strong>de</strong> la<br />
Medjerda <strong>et</strong> <strong>de</strong> Guelma), n’excédant pas les 1 200 m<br />
(Djebel Rhorra, à la frontière tunisienne), à l’est par la<br />
frontière algéro-tunisiennne, correspondant au « rebroussement<br />
» <strong>de</strong> l’Atlas tellien vers la mer (Joleaud, 1936) <strong>et</strong><br />
à l’ouest par le massif <strong>de</strong> Filfila.<br />
À l’Est comme à l’Ouest <strong>de</strong> ce massif, se sont développés,<br />
au Quaternaire récent, <strong>de</strong>ux ensembles dunaires,<br />
pouvant atteindre 100 m <strong>et</strong> formant barrage pour les<br />
eaux d’amont. Aussi, les apports hydriques abondants<br />
<strong><strong>de</strong>s</strong> oueds, rejoignant les plaines sub-littorales numidiennes<br />
<strong>de</strong> faible altitu<strong>de</strong> (1 à 5 m), atteignent difficilement<br />
la mer <strong>et</strong> forment <strong>de</strong> nombreux méandres ; c’est le cas, à<br />
l’est, <strong><strong>de</strong>s</strong> oueds El Kébir Est <strong>et</strong> Bou Namoussa, drainant<br />
tous les oueds secondaires sur près <strong>de</strong> 50 km par un<br />
seul exutoire (oued Mafragh) <strong>et</strong> Seybouse, tandis qu’à<br />
l’ouest, un seul oued, El Kébir Ouest, draine toutes les<br />
eaux d’amont. Ces plaines, où l’écoulement est difficile,<br />
sont donc facilement inondables <strong>et</strong> favorisent la formation<br />
<strong>de</strong> nombreux marais (garâas) <strong>et</strong> mares <strong>de</strong> surface variable.<br />
De plus, un ensemble <strong>de</strong> phénomènes tectoniques<br />
explique la présence d’un grand marais, d’une lagune <strong>et</strong><br />
<strong>de</strong> <strong>de</strong>ux lacs ; <strong>de</strong> plus, toutes les plaines sublittorales sont<br />
soumises à un phénomène <strong>de</strong> subsi<strong>de</strong>nce (Marre, 1992).<br />
Les dunes elles-mêmes recèlent <strong>de</strong> très nombreux hydrosystèmes<br />
plus ou moins éphémères, liées aux ondulations<br />
du massif dunaire <strong>et</strong> alimentées par la remontée hivernale<br />
<strong>de</strong> la nappe hydrique.<br />
C<strong>et</strong>te géomorphologie contrastée détermine un vaste<br />
éventail d’hydrosystèmes endoréiques, dont l’alimentation<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
Figure 1. Carte <strong>de</strong> situation <strong>de</strong> 26 mares temporaires<br />
étudiées en Numidie orientale, i<strong>de</strong>ntifiées<br />
selon leur numéro en gras.<br />
85<br />
hydrique est assurée temporairement par les pluies,<br />
les inondations ou la nappe hydrique. Ces mares<br />
temporaires peuvent être groupées en quatre types, en<br />
fonction <strong>de</strong> leur environnement géomorphologique :<br />
dunes, plaines alluvionnaires, plaines colluvionnaires <strong>et</strong><br />
collines gréseuses (tableau 1 : paramètres mésologiques<br />
<strong>et</strong> annexes). Les mares étudiées sont réparties le long <strong>de</strong><br />
<strong>de</strong>ux axes routiers, d’Ouest en Est <strong>de</strong>puis Annaba : la<br />
RN 44 au Sud <strong>et</strong> le CW 109 au Nord. Le premier axe<br />
traverse les plaines sublittorales, le second longe le massif<br />
dunaire <strong>de</strong> Boutelja (fig. 1).<br />
Échantillonnages<br />
Durant chaque hydropério<strong>de</strong> (tableau 2), la végétation<br />
<strong>de</strong> 26 mares a été systématiquement échantillonnée chaque<br />
mois lors <strong>de</strong> trois cycles, répartis entre les années 1998-<br />
1999, 1999-2000 <strong>et</strong> 2000-2001. Ont été intégrés, dans<br />
la mesure du possible, <strong><strong>de</strong>s</strong> relevés précédant la pério<strong>de</strong><br />
d’inondation ou lui succédant. Il s’avère ainsi possible<br />
<strong>de</strong> décrire la végétation résistant à l’assèchement, sinon<br />
même une flore particulière précédant l’hydropério<strong>de</strong> ou<br />
lui succédant. Deux cas ont été distingués :<br />
— Toutes les hydrophytes, hygrophytes <strong>et</strong> amphiphytes<br />
sont affectées d’un indice d’abondance-recouvrement<br />
<strong>de</strong> 1 à 10. La somme <strong>de</strong> ces indices pour une mare<br />
à une date donnée peut excé<strong>de</strong>r 10 en raison <strong>de</strong> la<br />
présence <strong>de</strong> plusieurs strates :<br />
* hydriques : hydrophytes flottantes, enracinées, submergées,<br />
hygrophytes au milieu <strong><strong>de</strong>s</strong>quelles se développent<br />
<strong><strong>de</strong>s</strong> hydrophytes, <strong>et</strong>c., occupant donc <strong><strong>de</strong>s</strong> lames<br />
d’eau différentes ;<br />
* aériennes : en raison <strong>de</strong> l’importance <strong>de</strong> l’ombre dans<br />
les paramètres écologiques, il a été tenu compte <strong>de</strong> la<br />
frondaison <strong><strong>de</strong>s</strong> arbres ou arbustes dominant partiellement<br />
ou totalement certaines mares (cf. p. 17, Frênes,<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
86<br />
Tableau 1. Paramètres mésologiques <strong>de</strong> vingt-six mares (analyses effectuées par la Tour du Valat).<br />
Table 1. Mesological param<strong>et</strong>ers of twenty-six ponds (analyses carried out by Tour du Valat).<br />
N° Mares Altitu<strong>de</strong> Surface Profon<strong>de</strong>ur Argile Limon Sable Sable pH Unité<br />
Analyses (m) (ares) (cm) (%) fin grossier morphologique<br />
1 Fei1 3 0.5 120 24.9 15.9 22.6 15.5 4.70 plaine alluvionnaire<br />
2 Fei2 3 0.5 120 43.1 14.1 9.5 4.4 4.05 plaine alluvionnaire<br />
3 Fei3 3 0.5 80 44.7 13.8 7.2 4.1 3.90 plaine alluvionnaire<br />
4 Fei4 3 0.5 120 43.1 14.1 9.5 4.4 4.05 plaine alluvionnaire<br />
5 Fren 18 7.0 75 45.3 7.5 2.3 0.2 7.90 plaine alluvionnaire<br />
6 Mess 28 4.5 80 34.3 9.0 17.3 27.0 4.80 plaine colluvionnaire<br />
7 Gau1 35 10.0 40 21.0 18.3 24.7 18.1 5.60 plaine colluvionnaire<br />
8 Gau2 35 3.5 45 21.0 18.3 24.7 18.1 5.60 plaine colluvionnaire<br />
9 Gau3 35 2.0 65 37.8 8.2 7.1 16.4 4.80 plaine colluvionnaire<br />
10 Gau4 35 2.5 70 37.8 8.2 7.1 16.4 4.80 plaine colluvionnaire<br />
11 Fedj 110 6.5 100 19.9 10.8 29.9 26.8 5.00 colline gréseuse<br />
12 Gera 15 3.5 50 22.1 4.5 5.6 56.7 6.25 dune<br />
13 Isoe 20 3.0 25 14.4 3.3 6.2 66.9 5.70 dune<br />
14 Ecol 15 3.5 42 23.5 6.6 8.3 44.7 5.35 dune<br />
15 Sud 8 5.5 70 6.0 1.2 5.2 85.8 6.05 dune<br />
16 Hrib 10 6.0 130 5.8 0.5 3.6 88.1 4.20 dune<br />
17 Tama 28 3.5 120 11.3 2.0 19.5 63.6 6.70 dune<br />
18 Carr 18 3.5 100 4.3 0.7 4.8 88.7 5.95 dune<br />
19 Mafr 2 6.5 86 6.1 0.7 5.3 87.4 8.35 dune<br />
20 Sang 3 7.0 86 6.3 0.5 7.0 84.7 8.25 dune<br />
21 Bouk 1 20.0 90 20.0 14.6 25.1 24.1 7.75 plaine alluvionnaire<br />
22 Sali 3 100.0 45 56.0 5.9 3.7 0.4 8.15 plaine alluvionnaire<br />
23 Rupp 2 15.0 70 4.3 0.5 2.2 92.5 7.45 dune<br />
24 Frin 30 2.0 25 5.1 0.5 7.3 85.9 5.60 rives lac: dune<br />
25 Bleu 8 0.5 90 5.1 1.3 5.5 86.8 5.45 dune<br />
26 Buto 9 15.0 70 61.3 1.7 1.1 2.3 5.80 plaine alluvionnaire<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
Tableau 2. Hydropério<strong><strong>de</strong>s</strong> <strong>de</strong> 26 mares temporaires durant 3 cycles.<br />
Table 2. Hydroperiods of twenty-six ponds for three cycles.<br />
1998-99<br />
Sept. Oct. Nov. Décembre Janvier Février Mars Avril Mai Juin Juill<strong>et</strong><br />
1,7,9,16, 7,14,21, 3,12,22, 15,17,19, 12,23, 5,12, 10,17, 1,7, 5.VII<br />
r: relevé.<br />
23.XI.98 26,27.XII. 25,28.I.99 23.II. 31.III. 19.IV. 22.V. 12.VI.<br />
Pluviosité (Salines) 63 61 237 64 157 103 48 44 38 9 13<br />
Pluviosité (El Kala) 54.1 90 241.2 95.2<br />
N° Mares<br />
1 Fe1 r r r r r r r sec<br />
2 Fe2 r r r r r r r sec<br />
3 Fe3 r r r r r r r sec<br />
4 Fe4 r r r r r r r sec<br />
5 Frê r r r r r r sec<br />
6 Mes r r r r r r r r<br />
7 Ga1 r r r r r r r r sec<br />
8 Ga2 r r r r r r r r sec<br />
9 Ga3 r r r r r r r r sec<br />
10 Ga4 r r r r r r r r sec<br />
11 Fedj r r r r r r r r r (faiblt en eau)<br />
12 Gér r r r r r r r r<br />
13 Iso r r r r r r r<br />
14 BeEc r r r r r r r r<br />
15 BeS r r r r r r r<br />
16 HrN r r r r r r r<br />
17 Tam r r r r r r r r<br />
18 Carr r r r r r r r r<br />
19 Maf r r r r r r r<br />
20 San r r r r r r<br />
21 Bouk r r r r r r r faiblt en eau<br />
22 Sal r r r r r r sec<br />
23 Rup r r r r r r r r r<br />
24 ElFr r r r<br />
25 MLB r r r r r r r r r<br />
26 But r r r r r r r r<br />
87<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
88<br />
Tableau 2. Hydropério<strong><strong>de</strong>s</strong> <strong>de</strong> 26 mares temporaires durant 3 cycles (suite).<br />
Table 2. Hydroperiods of twenty-six ponds for three cycles.<br />
1999-2000<br />
3,13, 10,24, 4,14,21,II. 13,20.III. 10,24.IV. 8,15,29.V. 519,VI<br />
20.XII.1999 I.2000<br />
N° Mares<br />
1 Fe1 à sec: r r r r r r<br />
2 Fe2 à sec: r r r r r r<br />
3 Fe3 à sec: r r r r r r<br />
4 Fe4 à sec: r r r r r r<br />
5 Frê r r r r r à sec<br />
6 Mes r r r r r quasi-sec:r r<br />
7 Ga1 r r r r r quasi-sec:r r<br />
8 Ga2 r r r r r quasi-sec:r r<br />
9 Ga3 r r r r r quasi-sec:r r<br />
10 Ga4 r r r r r quasi-sec:r r<br />
11 Fedj r r r r r r r<br />
12 Gér r r r r r sec:r<br />
13 Iso r r r r r sec:r<br />
14 BeEc r r r r r r<br />
15 BeS r r r r r lab: r<br />
16 HrN r r r r r réd: r<br />
17 Tam r r r r r r r<br />
18 Carr r r r r r r 3 bassins<br />
19 Maf r r r r r r r<br />
20 San r r r r r r r<br />
21 Bouk r r r r r r r<br />
22 Sal r r r r r 3°bas: r<br />
23 Rup r r r r r r r<br />
24 ElFr r r à sec:r<br />
25 MLB r r r r r r<br />
26 But r r r r r r sec<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
Tableau 2. Hydropério<strong><strong>de</strong>s</strong> <strong>de</strong> 26 mares temporaires durant 3 cycles (suite).<br />
Table 2. Hydroperiods of twenty-six ponds for three cycles.<br />
2000-2001<br />
19 105 37 108 112 75 19 40 28 0.4 0.4<br />
Pluviosité<br />
(Salines)<br />
33.8 118.5 49.9 85.2 159.2 79.5 21.9 57.8 60.9 Nt Nt<br />
Pluviosité<br />
(El Kala)<br />
26,27.X. 2000 12,24,27.XI. 22,30.XII. 22,26.I.2001 19,25.II-2.II. 23.III-6.IV. 27,29.IV. 25.V. 22,25.VI<br />
N° Mares<br />
1 Fe1 sec sec r r r r r sec:r<br />
2 Fe2 sec sec r r r r r sec:r<br />
3 Fe3 sec sec r r r r r sec:r<br />
12 Gér lab r r r<br />
13 Iso r (sec <strong>de</strong> nouveau) r r r r r à sec:r<br />
14 BeEc r r r r r r r sec/lab:r<br />
15 BeS r r r r r r<br />
16 HrN r r r r réd:r quasi-sec:r<br />
17 Tam r r r r r r r r r<br />
18 Carr r r r r r r r r<br />
19 Maf r r r r r r r r r<br />
20 San r r r r r r r r r<br />
21 Bouk r r r r r<br />
22 Sal r r r r r r r<br />
23 Rup r r r r r r r r r<br />
24 ElFr r r r<br />
25 MLB r r r r r r r r r<br />
26 But r r r r r r r<br />
89<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
90<br />
Tableau 3. Liste <strong>de</strong> 136 espèces végétales, inventoriées dans 26 mares <strong>de</strong> Numidie.<br />
Table 3. Checklist of 136 plant species, sampled in twenty-six ponds of Numidia (Northeastern Algeria).<br />
Co<strong>de</strong> Taxa analysés Taxa<br />
N°<br />
analyse<br />
Co<strong>de</strong> Taxa analysés Taxa<br />
N°<br />
analyse<br />
(Quezel & Santa, 1962-1963) (selon Valdès <strong>et</strong> al., 2002) (Quezel & Santa, 1962-1963) (selon Valdès <strong>et</strong> al., 2002)<br />
1 Agsv Agrostis semi-verticillata Polypogon viridis 69 Lyeu Lycopus europeus<br />
2 Albu Alopecurus bulbosus subsp. macrostachys 70 Lyhy Lythrum hyssopifolia<br />
3 Alpa Alisma plantago-aquatica 71 Lyju Lythrum junceum<br />
4 Altr Allium triqu<strong>et</strong>rum 72 Lynu Lythrum numulariaefolia<br />
5 Apcr Apium crassipes 73 Lysa Lythrum salicaria<br />
6 Apno Apium nodiflorum 74 Mepu Mentha pulegium<br />
7 Atlit Atriplex littoralis 75 Mero Mentha rotundifolia<br />
8 Atpa Atriplex patula A. littoralis ? 76 Myal Myriophyllum alterniflorum<br />
9 Atpo Atriplex portulacoi<strong><strong>de</strong>s</strong> Halimione portulacoi<strong><strong>de</strong>s</strong> 77 Naof Nasturtium officinale<br />
10 Bere Bellis repens 78 Oefi Oenanthe fistulosa<br />
11 Bevu B<strong>et</strong>a vulgaris subsp. maritima B<strong>et</strong>a maritima 79 Oegl Oenanthe globulosa<br />
12 Buum Butomus umbellatus 80 Oleu Olea europea<br />
13 Cadi Carex divisa 81 Orpr Ormenis praecox<br />
14 Calpe Callitriche pedunculata C. brutia 82 Padi Paspalum distichum<br />
15 Caob Callitriche obtusangula 83 Pare Panicum repens<br />
16 Capu Carex punctata 84 Phau Phragmites australis<br />
17 Catr Callitriche truncata 85 Plco Plantago coronopus<br />
18 Ce<strong>de</strong> Ceratophyllum <strong>de</strong>mersum 86 Plcr Plantago crassifolia<br />
19 Char Characeae 87 Poal Populus alba<br />
20 Chlo Chlorophyceae 88 Poan Poa annua<br />
21 Chmy Chrysanthemum myconis 89 Poatr Poa trivialis<br />
22 Cicfi Cicendia filiformis 90 Pola Polygonum lapathifolium<br />
23 Coco Cotula coronopifolia 91 Poma Polypogon maritimum subsp. subspathaceum<br />
24 Coli Corrigiola littoralis 92 Pomo Polypogon monspeliensis<br />
25 Craox Crataegus oxyacantha subsp. monogyna 93 Ponod Potamog<strong>et</strong>on nodosus<br />
26 Cyda Cynodon dactylon 94 Pope Potamog<strong>et</strong>on pectinatus<br />
27 Cyfl Cyperus flavescens Pycreus flavescens 95 Pore Potentilla reptans<br />
28 Cylo Cyperus longus subsp. eu-longus 96 Posa Polygonum salicifolium<br />
29 Cyro Cyperus rotundus subsp. eu-rotundus 97 Potatr Potamog<strong>et</strong>on trichoi<strong><strong>de</strong>s</strong><br />
30 Daal Damasonium alisma subsp. bourgei 98 Raba Ranunculus baudotii<br />
31 Disa Digitaria sanguinalis 99 Rafi Ranunculus ficaria<br />
32 Ecra Echinodorus ranunculoi<strong><strong>de</strong>s</strong> Bal<strong>de</strong>llia ranunculoi<strong><strong>de</strong>s</strong> 100 Rahe Ranunculus he<strong>de</strong>raceus<br />
33 Elal Elatine alsinastrum 101 Rama Ranunculus macrophyllus<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
34 Elbr Elatine brochonii 102 Ramu Ranunculus muricatus<br />
35 Elemu Eleocharis multicaulis 103 Raop Ranunculus ophioglossifolius<br />
36 Elhyd Elatine hydropiper 104 Rasa Ranunculus sardous<br />
37 Elpa Eleocharis palustris 105 Rasc Ranunculus sceleratus<br />
38 Eupu Euphorbia pubescens 106 Ratr Ranunculus trichophyllus<br />
39 Fran Fraxinus angustifolia 107 Ruco Rumex conglomeratus<br />
40 Frlae Frankenia laevis 108 Ruma Ruppia maritima<br />
41 Fupu Fuirena pubescens 109 Rupu Rumex pulcher<br />
42 Gapa Galium palustre 110 Ruul Rubus ulmifolius<br />
43 Glfl Glyceria fluitans 111 Saat Salix atrocinerea<br />
44 Gllot Glinus lotoi<strong><strong>de</strong>s</strong> 112 Saleu Salicornia arabica (S. fruticosa) Sarcocornia fruticosa<br />
45 Hola Holcus lanatus 113 Saso Salsola soda<br />
46 Ilve Illecebrum verticillatum 114 Sava Samolus valerandi<br />
47 Irps Iris pseudo-acorus 115 Scce Scirpus cernuus Isolepis cernua<br />
48 Ishi Iso<strong>et</strong>es histrix 116 Scho Scirpus holoschoenus Scirpoi<strong><strong>de</strong>s</strong> holoschoenus<br />
49 Isve Iso<strong>et</strong>es velata subsp. typica 117 Scin Scirpus inclinatus<br />
50 Juac Juncus acutus 118 Scla Scirpus lacustris Schoenoplectus lacustris<br />
51 Juan Juncus anceps 119 Scma Scirpus maritimus Bolboschoenus maritimus<br />
52 Juart Juncus articulatus 120 Scni Schoenus nigricans<br />
53 Jubu Juncus bufonius 121 Seja Senecio jacobaea<br />
54 Juca Juncus capitatus 122 Sicr Silene coeli-rosa<br />
55 Jucon Juncus conglomeratus 123 Soni Solanum nigrum<br />
56 Juef Juncus effusus 124 Sper Sparganium erectum subsp. polyedrum<br />
57 Juhe Juncus h<strong>et</strong>erophyllus 125 Spfl Spergula flaccida Spergula fallax<br />
58 Juin Juncus inflexus 126 Spsa Spergularia salina Spergularia marina<br />
59 Juma Juncus maritimus J. rigidus 127 Taga Tamarix gallica<br />
60 Jupy Juncus pygmaeus 128 Trfi Trifolium filiforme<br />
61 Jusu Juncus subulatus 129 Trrep Trifolium resupinatum<br />
62 Jute Juncus tenageia 130 Trres Trifolium repens<br />
63 Labi Laurentia bicolor 131 Tyan Typha angustifolia subsp. australis<br />
64 Lehex Leersia hexandra Oryza hexandra ? 132 Utex Utricularia exol<strong>et</strong>a<br />
65 Lemi Lemna minor 133 Utvu Utricularia vulgaris subsp. major<br />
66 Lino Lippia nodiflora Phyla nodiflora 134 Veaa Veronica anagallis-aquatica<br />
67 Loco Lotus corniculatus subsp. <strong>de</strong>cumbens 135 Woar Wolffia arrhiza<br />
68 Lupa Ludwigia palustris 136 Zapa Zanichellia palustris subsp. pedunculata<br />
91<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
92<br />
entièrement couvert par c<strong>et</strong>te espèce, El Feïd 1, partiellement<br />
couvert par l’olivier ou, p. 18, Fedjouj, par<br />
le peuplier <strong>et</strong> le saule, <strong>et</strong>c.).<br />
— Toutes les mésophytes ou espèces ripicoles présentes<br />
sont notées 1, en raison <strong>de</strong> leur présence constante <strong>et</strong><br />
<strong>de</strong> l’information qu’elles apportent sur la formation<br />
végétale à laquelle appartiennent les mares.<br />
Analyse inter-classes<br />
Les données sont par la suite cumulées dans un<br />
tableau unique, comprenant la somme <strong><strong>de</strong>s</strong> relevés <strong><strong>de</strong>s</strong><br />
trois campagnes (1998-2001), soient 539 relevés <strong>et</strong> 136<br />
espèces végétales. Un tel tableau a été soumis à l’analyse<br />
inter-classes qui conduit à une <strong><strong>de</strong>s</strong>cription <strong>de</strong> la structure<br />
globale sur trois cycles. La liste <strong><strong>de</strong>s</strong> espèces <strong>et</strong> leurs co<strong><strong>de</strong>s</strong><br />
sont rassemblés dans le tableau 3.<br />
Une première analyse par Analyse en composantes<br />
principales (ACP) est nécessaire pour accé<strong>de</strong>r à la<br />
suivante. Sur la base <strong>de</strong> c<strong>et</strong>te ACP, il est alors possible<br />
d’effectuer l’analyse inter-classes, dont le déroulement est<br />
décrit dans le logiciel ADE-4 (Thioulouse <strong>et</strong> al., 1996).<br />
RÉSULTATS<br />
Conséquences écologiques<br />
globales <strong><strong>de</strong>s</strong> hydropério<strong><strong>de</strong>s</strong><br />
Les résultats hydrologiques montrent clairement que<br />
les trois cycles <strong>de</strong> mise en eau/assèchement sont très<br />
différents (tableau 2) : 8 mois pour le premier cycle, à<br />
peine 7 mois pour le <strong>de</strong>uxième, <strong>et</strong> 9 mois pour le <strong>de</strong>rnier.<br />
Ceci reflète parfaitement la variabilité inter-annuelle <strong><strong>de</strong>s</strong><br />
conditions climatiques en Afrique du Nord. Lorsque<br />
l’hydropério<strong>de</strong> est courte, certaines espèces végétales<br />
ne s’expriment pas, particulièrement en fin <strong>de</strong> cycle<br />
qui est brutalement interrompu par la pério<strong>de</strong> estivale ;<br />
c’est le cas par exemple <strong><strong>de</strong>s</strong> p<strong>et</strong>ites Gentianaceae comme<br />
Exaculum pusillum ou Cicendia filiformis. Par contre,<br />
les cycles <strong><strong>de</strong>s</strong> espèces principales (cf. analyses : ACP <strong>et</strong><br />
Analyse inter-classes) comme Callitriche obtusangula,<br />
C. truncata <strong>et</strong> Ranunculus baudotii ont tendance à se<br />
chevaucher.<br />
Si la majorité <strong><strong>de</strong>s</strong> mares se rem<strong>et</strong> en eau simultanément,<br />
un certain nombre d’entre elles accusent un r<strong>et</strong>ard<br />
plus ou moins important (cas <strong><strong>de</strong>s</strong> mares El Feïd) ou<br />
elles achèvent brusquement leur cycle en raison <strong>de</strong><br />
perturbations externes tels que les labours <strong>et</strong> la mise en<br />
culture. Enfin, certaines mares peuvent se maintenir en<br />
eau au-<strong>de</strong>là <strong>de</strong> la pério<strong>de</strong> d’échantillonnage <strong>et</strong> présenter<br />
ainsi une hydropério<strong>de</strong> qui franchit la pério<strong>de</strong> estivale si<br />
la pluviosité a été bien répartie tout au long <strong>de</strong> l’année<br />
(ex. Fedjouj, Tamaris, Mafragh ou Sangliers). Aussi les<br />
statuts <strong><strong>de</strong>s</strong> mares, à l’intérieur d’une même campagne,<br />
sont-ils variables : aux <strong>de</strong>ux extrêmes, existent <strong><strong>de</strong>s</strong><br />
mares temporaires très éphémères (hydropério<strong>de</strong> <strong>de</strong> 2 à<br />
3 mois), comme El Frin, <strong>et</strong> <strong><strong>de</strong>s</strong> mares temporaires semipermanentes<br />
où l’hydropério<strong>de</strong> peut, une année sur <strong>de</strong>ux<br />
ou trois, franchir la pério<strong>de</strong> estivale. Seules les mares les<br />
plus profon<strong><strong>de</strong>s</strong> appartiennent à ce <strong>de</strong>rnier ensemble.<br />
Analyse inter-classes<br />
L’inventaire <strong><strong>de</strong>s</strong> 26 mares étudiées <strong>et</strong> la réalisation <strong>de</strong><br />
539 relevés ont permis d’i<strong>de</strong>ntifier 136 espèces végétales<br />
en Numidie, relevés qui ont été soumis à une ACP puis<br />
à une analyse inter-classes. Les quatre premiers facteurs<br />
<strong>de</strong> l’ACP (0.13, 0.09, 0.07 <strong>et</strong> 0.06) ne m<strong>et</strong>tent pas en<br />
évi<strong>de</strong>nce une structure très forte <strong><strong>de</strong>s</strong> données. L’analyse<br />
inter-classes, concernant la succession <strong><strong>de</strong>s</strong> espèces dans<br />
le temps <strong>et</strong> la typologie <strong><strong>de</strong>s</strong> mares, a été précédée <strong>de</strong> <strong>de</strong>ux<br />
tests <strong>de</strong> permutation, afin <strong>de</strong> déterminer la pertinence<br />
d’une telle analyse. Les tests sont dans les <strong>de</strong>ux cas très<br />
significatifs.<br />
Structure temporelle (fig. 2)<br />
L’analyse interclasses affiche <strong>de</strong>ux axes rassemblant<br />
la majorité <strong>de</strong> l’information (respectivement, 0.42 <strong>et</strong><br />
0.40).<br />
L’axe 1 m<strong>et</strong> en évi<strong>de</strong>nce dans la structure principale,<br />
<strong>de</strong>ux groupes (2 semestres ?) :<br />
— groupe 1 (automne-hiver surtout), marqué par la<br />
présence <strong>de</strong> Panicum repens (83), Digitaria sanguinalis<br />
(31), Iso<strong>et</strong>es histrix (48) <strong>et</strong> Lippia nodiflora (= Phyla<br />
nodiflora) (66) : mois d’octobre à décembre <strong>et</strong> mois<br />
<strong>de</strong> juin (1 à 3 <strong>et</strong> 9 dans la fig. 2) ;<br />
— groupe 2 (printemps-été), dominé par Ranunculus<br />
baudotii (98), Alisma plantago-aquatica (3), Apium<br />
crassipes (5), Myriophyllum alterniflorum (76), Poa<br />
annua (88), Ranunculus ophioglossifolius (103),<br />
R. sardous (104), Scirpus cernuus (115) <strong>et</strong> Scirpus<br />
maritimus (119) : mois <strong>de</strong> janvier à mai (4 à 7 dans<br />
la fig. 2).<br />
L’axe 2 distinguerait, dans la structure secondaire,<br />
<strong>de</strong>ux nouveaux groupes, chevauchant chacun <strong><strong>de</strong>s</strong><br />
groupes précé<strong>de</strong>nts ; il perm<strong>et</strong> la séparation :<br />
— <strong><strong>de</strong>s</strong> mois dominés par Ranunculus baudotii <strong>et</strong><br />
Callitriche obtusangula (15 : en italiques dans la fig. 2) :<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
Figure 2. Structure temporelle<br />
<strong>de</strong> la végétation <strong><strong>de</strong>s</strong> 26 mares<br />
temporaires. Carte factorielle<br />
1-2 <strong>de</strong> l’analyse interclasses<br />
: 9 mois x 136 espèces<br />
végétales x 3 cycles. A droite,<br />
graphe <strong><strong>de</strong>s</strong> valeurs propres.<br />
Chaque mois, d’octobre à<br />
juin (chiffres romains : X à<br />
XII <strong>et</strong> I à VI), est figuré au<br />
centre (chiffres arabes : 1 à 9,<br />
entourés d’un cercle). Chaque<br />
mois est au barycentre <strong><strong>de</strong>s</strong><br />
relevés (figurés à l’extrémité<br />
<strong><strong>de</strong>s</strong> flèches par un carré noir),<br />
effectués sur 26 mares durant<br />
3 cycles. La succession <strong><strong>de</strong>s</strong><br />
espèces est présentée sous<br />
forme <strong>de</strong> quadrats, à échelle<br />
réduite <strong>de</strong> la carte factorielle<br />
initiale. La distribution <strong>de</strong><br />
chaque espèce est figurée par<br />
<strong><strong>de</strong>s</strong> carrés blancs, lorsqu’elle<br />
est absente, par <strong><strong>de</strong>s</strong> cercles,<br />
lorsqu’elle est présente ; le<br />
diamètre <strong>de</strong> ces cercles est<br />
proportionnel à l’indice<br />
d’abondance. En caractères<br />
normaux, les espèces<br />
dominantes, en italiques, les<br />
espèces secondaires.<br />
93<br />
mois 2 <strong>et</strong> 3 (novembre-décembre) dans le groupe 1,<br />
mois 4 <strong>et</strong> 5 (janvier-février) dans le groupe 2 ;<br />
— <strong><strong>de</strong>s</strong> mois où se développent Apium crassipes,<br />
<strong><strong>de</strong>s</strong> Characeae (19) <strong>et</strong> Lythrum hyssopifolia (70),<br />
accompagnés <strong>de</strong> Cyperus longus (28), Bal<strong>de</strong>llia<br />
ranunculoi<strong><strong>de</strong>s</strong> (32), Galium palustre (42) <strong>et</strong> Paspalum<br />
distichum (82) : mois 1 <strong>et</strong> 9 (octobre <strong>et</strong> juin) d’une<br />
part, mois 6 à 8 (mars à mai) d’autre part.<br />
Pouvons-nous en inférer que quatre saisons avec<br />
<strong><strong>de</strong>s</strong> nuances sont mises en évi<strong>de</strong>nce dans ce <strong>de</strong>rnier<br />
découpage ? De plus, c<strong>et</strong>te discrimination apporte-t-elle<br />
un élément nouveau à la réflexion ?<br />
Structure spatiale (fig. 3)<br />
L’analyse inter-classes repose sur <strong>de</strong>ux axes qui<br />
récoltent une information n<strong>et</strong>tement plus faible que dans<br />
l’analyse précé<strong>de</strong>nte (0.22 <strong>et</strong> 0.16) ; les autres axes seront<br />
abordés, mais ils n’apportent qu’une information limitée<br />
(axes 3 <strong>et</strong> 4 : 0.10 <strong>et</strong> 0.09).<br />
L’axe 1 fait apparaître une structure principale,<br />
répartissant les mares en <strong>de</strong>ux groupes :<br />
— groupe 1 à Characeae (19) <strong>et</strong> Juncus acutus (50)<br />
qu’accompagnent Juncus maritimus (J. rigidus Valdès<br />
<strong>et</strong> al., 2002) (59), Typha angustifolia (131) <strong>et</strong> Tamarix<br />
gallica (127) : mares 3 à 6, 11 <strong>et</strong> 18 à 26.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
94<br />
— groupe 2 à Callitriche obtusangula (15), Iso<strong>et</strong>es velata<br />
(49) <strong>et</strong> Myriophyllum alterniflorum (76) principalement<br />
<strong>et</strong>, secondairement, Bal<strong>de</strong>llia ranunculoi<strong><strong>de</strong>s</strong> (32),<br />
Eleocharis palustris (37) <strong>et</strong> Glyceria fluitans (43) :<br />
mares 1, 2, 7 à 10 <strong>et</strong> 12 à 17.<br />
L’axe 2 fait ressortir une structure secondaire distinguant<br />
dans chacun <strong><strong>de</strong>s</strong> groupes un nouveau groupement, défini<br />
par Scirpus maritimus (= Schoenoplectus maritimus) (119 :<br />
en italiques dans la fig. 3) <strong>et</strong> Alisma plantago-aquatica (3 :<br />
en italiques), qu’accompagne souvent Scirpus lacustris (=<br />
Schoenoplectus lacustris) (118).<br />
C<strong>et</strong>te analyse perm<strong>et</strong> une partition <strong><strong>de</strong>s</strong> 26 mares <strong>de</strong><br />
la manière suivante :<br />
— du groupe 1, se dégage un groupe à Scirpus maritimus,<br />
S. lacustris <strong>et</strong> Typha angustifolia : mares 1, 2, 4,<br />
15, 16 <strong>et</strong> 17,<br />
— du groupe 2 se détache, <strong>de</strong> la même manière, un<br />
groupe à Scirpus maritimus : mares 3, 4, 5, 6, 21, 22,<br />
24, 25 <strong>et</strong> 26.<br />
En résumé, il existe trois groupes n<strong>et</strong>tement éloignés<br />
<strong><strong>de</strong>s</strong> axes 1 <strong>et</strong> 2, <strong>et</strong> donc clairement i<strong>de</strong>ntifiables par la<br />
dominance <strong><strong>de</strong>s</strong> espèces qu’ils contiennent :<br />
* groupe 1 à Characeae, J. maritimus <strong>et</strong> J. acutus : 11,<br />
18 à 20 <strong>et</strong> 23 ;<br />
* groupe 2 à Callitriche obtusangula, Iso<strong>et</strong>es velata <strong>et</strong><br />
Myriophyllum alterniflorum : 7 à 10 (8 masqué par 9)<br />
<strong>et</strong> 12 à 14 ;<br />
* groupe 3 à Callitriche obtusangula, Scirpus maritimus<br />
<strong>et</strong> Alisma plantago-aquatica : 1, 2 (masqué par 4), 15,<br />
d’une part, 3 à 6 avec 21 <strong>et</strong> 26 d’autre part.<br />
En outre, un groupe mal défini par ces axes <strong>et</strong><br />
rassemblé vers l’origine, comporte les mares 16, 17<br />
Figure 3. Structure spatiale<br />
<strong>de</strong> la végétation <strong><strong>de</strong>s</strong> 26 mares<br />
temporaires. Carte factorielle 1-<br />
2 <strong>de</strong> l’analyse inter-classes : 26<br />
mares x 136 espèces végétales x 3<br />
cycles. En haut, à droite, graphe<br />
<strong><strong>de</strong>s</strong> valeurs propres. Chaque<br />
station (affectée d’un chiffre <strong>de</strong><br />
1 à 26) est au barycentre <strong>de</strong><br />
l’ensemble <strong><strong>de</strong>s</strong> relevés (liés à la<br />
durée <strong>de</strong> l’hydropério<strong>de</strong>) effectués<br />
durant 3 cycles. La distribution<br />
<strong>de</strong> chaque taxon est représenté<br />
dans un quadrat à échelle<br />
réduite <strong>de</strong> la carte factorielle<br />
principale. La distribution <strong>de</strong><br />
chaque espèce est figurée par<br />
<strong><strong>de</strong>s</strong> carrés blancs, lorsqu’elle est<br />
absente, par <strong><strong>de</strong>s</strong> cercles, lorsqu’elle<br />
est présente ; le diamètre <strong>de</strong> ces<br />
cercles est proportionnel à l’indice<br />
d’abondance. La typologie <strong><strong>de</strong>s</strong><br />
mares est définie par 3 groupes<br />
végétaux, clairement i<strong>de</strong>ntifiés.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
(masqué par 25), 22, 24 <strong>et</strong> 25. Chacune <strong>de</strong> ces mares<br />
est originale :<br />
(i) soit par sa composition floristique (ainsi, les mares<br />
16 <strong>et</strong> 17 relèvent à la fois <strong><strong>de</strong>s</strong> groupes 2 <strong>et</strong> 3 ; la mare 22,<br />
marquée par une forte salinité, comporte une association<br />
végétale particulière à Salicornia arabica <strong>et</strong> Salsola soda ;<br />
la station 25 est dominée par plusieurs espèces, absentes<br />
<strong><strong>de</strong>s</strong> autres, comme Wolffia arrhiza, Ludwigia palustris <strong>et</strong><br />
Oryza hexandra) ;<br />
(ii) soit par la brièv<strong>et</strong>é <strong>de</strong> son hydropério<strong>de</strong> ; tel est le<br />
cas <strong>de</strong> la station 24.<br />
Les axes 3 <strong>et</strong> 4 ne prennent en charge que <strong><strong>de</strong>s</strong><br />
situations particulières en raison <strong>de</strong> la dominance d’une<br />
espèce. Ainsi, Wolffia arrhiza (135) est permanente <strong>et</strong><br />
abondante dans la mare du lac Bleu <strong>et</strong> Ruppia maritima<br />
(108) dans la mare Ruppia.<br />
DISCUSSION<br />
Structure temporelle :<br />
succession <strong><strong>de</strong>s</strong> espèces végétales<br />
A propos du climat en Algérie, Seltzer (1946) souligne :<br />
« Le climat est partout méditerranéen, i.e. caractérisé par une<br />
saison pluvieuse allant en moyenne <strong>de</strong> septembre à mai, <strong>et</strong><br />
par un été sec <strong>et</strong> ensoleillé ». La végétation exprimée lors<br />
<strong><strong>de</strong>s</strong> mois d’été est dans notre étu<strong>de</strong>, par définition, sousreprésentée<br />
dans notre échantillonnage. La structure<br />
bi-partite recouvre donc surtout la « saison pluvieuse » ;<br />
elle est déterminée par l’axe 1 <strong>et</strong> sépare <strong>de</strong>ux ensembles<br />
végétaux, l’un englobant les mois d’octobre à décembre <strong>et</strong><br />
<strong>de</strong> juin, définis par Panicum repens <strong>et</strong> ses associés, l’autre,<br />
les mois <strong>de</strong> janvier à mai, marqués par la présence <strong>de</strong><br />
Ranunculus baudotii <strong>et</strong> ses associés. Le premier ensemble<br />
se développe en eff<strong>et</strong> particulièrement au début <strong>de</strong><br />
l’été (juill<strong>et</strong> <strong>et</strong> août n’ont pas été échantillonnés) <strong>et</strong> se<br />
poursuit durant l’automne, où les Graminées, comme<br />
Panicum repens <strong>et</strong> Paspalum distichum à développement<br />
concomitant, entrent dans le sta<strong>de</strong> végétatif. Lors <strong>de</strong> la<br />
remise en eau <strong><strong>de</strong>s</strong> mares, un délai <strong>de</strong> germination <strong>et</strong> <strong>de</strong><br />
floraison est évi<strong>de</strong>mment nécessaire pour que R. baudotii<br />
puisse, à son tour, coloniser les mares.<br />
L’axe 2 introduit <strong><strong>de</strong>s</strong> nuances, <strong>et</strong> à R. baudotii<br />
s’adjoint la présence <strong>de</strong> Callitriche obtusangula. C<strong>et</strong>te<br />
<strong>de</strong>rnière espèce précè<strong>de</strong> la mise en place <strong>de</strong> R. baudotii<br />
<strong>et</strong> peut persister longtemps en association avec elle ; elle<br />
disparaît lorsque R. baudotii occupe progressivement les<br />
mares <strong>et</strong> entre en compétition avec C. obtusangula pour<br />
la lumière. Elle est capable <strong>de</strong> germer, se développer <strong>et</strong><br />
occuper la niche écologique, libérée <strong>de</strong> toute autre espèce,<br />
dès le début <strong>de</strong> l’hydropério<strong>de</strong> <strong><strong>de</strong>s</strong> mares. À la lecture<br />
<strong>de</strong> la fig. 3, c’est la succession habituelle <strong><strong>de</strong>s</strong> groupes<br />
écologiques, sinon <strong><strong>de</strong>s</strong> espèces, « imbriquées en écailles »<br />
(Godron, 1967) que laissent apparaître les distributions<br />
<strong>de</strong> C. obtusangula (sta<strong><strong>de</strong>s</strong> 3, 4, 5 <strong>et</strong> 6), R. baudotii (sta<strong><strong>de</strong>s</strong><br />
5, 6 <strong>et</strong> 7), Alisma plantago-aquatica (sta<strong><strong>de</strong>s</strong> 5, 6 7 <strong>et</strong> 8),<br />
Apium crassipes (sta<strong><strong>de</strong>s</strong> 6, 7, 8 <strong>et</strong> 9) <strong>et</strong> les Characeae<br />
(sta<strong><strong>de</strong>s</strong> 8, 9, 1 <strong>et</strong> 2).<br />
Il est important <strong>de</strong> noter que les sta<strong><strong>de</strong>s</strong> 1 à 4 sont<br />
con<strong>de</strong>nsés, tandis que les suivants sont plus dispersés.<br />
Les premiers sta<strong><strong>de</strong>s</strong> ne m<strong>et</strong>tent que peu en évi<strong>de</strong>nce<br />
les différences entre stations, où dominent partout les<br />
Graminées à floraison estivalo-automnale, Panicum repens<br />
<strong>et</strong> Paspalum distichum. Durant les sta<strong><strong>de</strong>s</strong> suivants, la flore<br />
se diversifie (cf. typologie) <strong>et</strong> son analyse discrimine plus<br />
clairement les étapes <strong>de</strong> la succession <strong><strong>de</strong>s</strong> espèces.<br />
Structure spatiale : typologie <strong><strong>de</strong>s</strong> stations<br />
Les trois groupes (1, 2, 3) signalés ci-<strong><strong>de</strong>s</strong>sus ont été<br />
décrits par les phytosociologues comme appartenant à<br />
trois ordres différents (Braun-Blanqu<strong>et</strong> <strong>et</strong> al., 1951).<br />
Le groupe 1 à Juncus acutus, J. maritimus <strong>et</strong> Typha<br />
angustifolia, avec les nuances qui s’imposent pour le<br />
Sud méditerranéen <strong>et</strong> particulièrement la Numidie,<br />
formerait une association appartenant aux Junc<strong>et</strong>alia<br />
maritimi Br.-Bl. 1931 (Gehu, 1993) ; les groupements<br />
<strong>de</strong> c<strong>et</strong> ordre appartiendraient aux « prés salés »,<br />
selon ces auteurs, <strong>et</strong> seraient surtout constitués <strong>de</strong><br />
Glumiflores. Ce groupement à Juncus acutus <strong>et</strong><br />
J. maritimus a fait l’obj<strong>et</strong> <strong>de</strong> nombreux travaux, mais<br />
les Characeae ne sont pas incluses dans la définition<br />
<strong>de</strong> ce syntaxon. Pourtant, Feldmann (1946) a<br />
décrit un grand nombre <strong>de</strong> Characeae en Numidie :<br />
Tolypella mucronata, huit espèces <strong>de</strong> Nitella <strong>et</strong> cinq<br />
Chara, sur 35 espèces en Afrique du Nord, dont 28<br />
pour l’Algérie. Les Characeae rencontrées dans les<br />
mares étudiées appartiennent à divers milieux, dont<br />
certains plus ou moins saumâtres. Une actualisation<br />
<strong>de</strong> ces travaux semble donc indispensable <strong>et</strong> <strong>de</strong>vrait<br />
ouvrir à une i<strong>de</strong>ntification <strong><strong>de</strong>s</strong> Characeae récoltées.<br />
L’association entre plantes pérennes (hélophytes ou<br />
succulentes), <strong><strong>de</strong>s</strong> genres Arthrocnemum, Juncus <strong>et</strong><br />
Scirpus est connue <strong>et</strong> a fait l’obj<strong>et</strong> <strong>de</strong> travaux, comme<br />
ceux <strong>de</strong> l’équipe d’Espinar <strong>et</strong> al. (2002) sur la zonation<br />
<strong><strong>de</strong>s</strong> macrophytes submergées dans les marais salants<br />
méditerranéens.<br />
95<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
96<br />
Le groupe 2, souvent dénommé “prairies à Iso<strong>et</strong>es”, a<br />
particulièrement été étudié par Chevassut & Quézel<br />
(1956), Poirion & Barbero (1965), Aubert & Loisel<br />
(1971), Barbero (1965, 1967), Rhazi <strong>et</strong> al. (2004).<br />
La présence importante <strong>de</strong> formations tourbeuses<br />
dans la région est favorable à la formation <strong>de</strong> ces<br />
prairies humi<strong><strong>de</strong>s</strong> à très humi<strong><strong>de</strong>s</strong>. Souvent situées en<br />
interface entre les dunes <strong>et</strong> les plaines sublittorales,<br />
donc à biodiversité souvent très élevée, ce type <strong>de</strong><br />
formation appartiendrait à l’ordre Iso<strong>et</strong>alia. Br.-Bl.<br />
1931 (Gehu, 1993). De manière générale, les mares<br />
<strong>de</strong> Numidie comportant Iso<strong>et</strong>es velata (probablement,<br />
subsp. typica) sont situées dans <strong><strong>de</strong>s</strong> prairies mésophiles<br />
à Iso<strong>et</strong>es histrix ; la texture est sableuse avec <strong><strong>de</strong>s</strong> sables<br />
grossiers <strong>de</strong> dunes, <strong>et</strong> <strong><strong>de</strong>s</strong> sables fins ayant pour origine<br />
les grès <strong>et</strong> argiles dits <strong>de</strong> Numidie (Joleaud, 1936).<br />
Le groupement à Iso<strong>et</strong>es <strong>et</strong> Myriophyllum alterniflorum<br />
est, sans conteste, celui qui attire le plus notre attention sur<br />
le plan <strong>de</strong> la richesse spécifique, composition floristique<br />
<strong>et</strong> valeur patrimoniale en raison <strong><strong>de</strong>s</strong> espèces présentes,<br />
souvent rares ou appartenant à l’élément afrotropical.<br />
Médail <strong>et</strong> al. (1998) pour la France méditerranéenne,<br />
Quézel (1998) <strong>et</strong> Grillas <strong>et</strong> al. (2004) pour les pays<br />
méditerranéens m<strong>et</strong>tent en exergue ce groupement <strong>et</strong> les<br />
espèces qui le composent, y compris certaines Characeae,<br />
qui lui sont associées. Ainsi, Callitriche truncata,<br />
Ceratophyllum <strong>de</strong>mersum, Elatine alsinastrum, E. brochoni,<br />
Illecebrum verticillatum, Cicendia filiformis, Exaculum<br />
pusillum (non noté dans la liste <strong><strong>de</strong>s</strong> espèces, mais présent<br />
dans les stations Gauthier) sont considérées comme rares<br />
en Algérie, <strong>et</strong> spéciales à la Numidie. Trois espèces sont<br />
d’origine afrotropicale : Scirpus inclinatus, Utricularia<br />
exol<strong>et</strong>a <strong>et</strong> Wolffia arrhiza qui peut être envahissante. Une<br />
endémique algéro-tunisienne, Bellis repens, est largement<br />
présente dans ce groupement. D’autres espèces, connues<br />
sur tout le pourtour <strong>de</strong> la Méditerranée, appartiennent<br />
également à ce groupement, comme Apium crassipes<br />
ou Ranunculus sceleratus, considérées comme rares<br />
en Algérie. R. ophioglossifolius, Bal<strong>de</strong>llia ranunculoi<strong><strong>de</strong>s</strong><br />
ou Glyceria fluitans sont, elles, communes. Les mares<br />
temporaires, occupées par ce groupement, présentent la<br />
plus gran<strong>de</strong> richesse spécifique <strong>et</strong> elles <strong>de</strong>vraient avoir<br />
un statut prioritaire <strong>de</strong> protection. Or, la plupart d’entre<br />
elles sont convoitées en raison d’une autre richesse, celle<br />
<strong>de</strong> leur sol, dont la texture recèle un taux élevé <strong>de</strong> matière<br />
organique, favorable à certaines cultures (arachi<strong>de</strong>,<br />
notamment). Ce groupement avait fait l’obj<strong>et</strong> en Algérie<br />
<strong>de</strong> plusieurs étu<strong><strong>de</strong>s</strong>, citées plus haut, mais il n’avait pas<br />
été décrit pour la Numidie.<br />
Le groupe 3 à Scirpus maritimus dépendrait <strong>de</strong> l’ordre<br />
Phragmit<strong>et</strong>alia, <strong>et</strong> plus particulièrement <strong>de</strong> l’association<br />
Scirp<strong>et</strong>um maritimi compacti Dahl <strong>et</strong> Hadac 1941<br />
(Gehu, 1993). La notation <strong><strong>de</strong>s</strong> auteurs est éclairante :<br />
« l’association colonise les vases fines au bord <strong><strong>de</strong>s</strong> étangs <strong>et</strong><br />
<strong><strong>de</strong>s</strong> fleuves <strong>de</strong> la région côtière ; elle est faiblement halophile<br />
<strong>et</strong> supporte un <strong><strong>de</strong>s</strong>sèchement temporaire ».<br />
Ce groupement à Scirpus maritimus a été largement<br />
étudié, <strong>et</strong> l’espèce principale, qui occupe <strong>de</strong> gran<strong><strong>de</strong>s</strong> surfaces<br />
autour <strong>de</strong> la Méditerranée, a fait l’obj<strong>et</strong> <strong>de</strong> plusieurs<br />
investigations récentes. Ainsi, Charpentier <strong>et</strong> al. (2000)<br />
<strong>et</strong> Charpentier (2002) ont étudié les conséquences <strong>de</strong> la<br />
croissance clonale sur la dynamique <strong>et</strong> la structure spatiale<br />
<strong><strong>de</strong>s</strong> populations <strong>de</strong> ce scirpe. Il est connu comme<br />
étant un bioindicateur <strong>de</strong> l’alcalinité du sol, mais dans la<br />
région d’étu<strong>de</strong>, l’écologie <strong>de</strong> c<strong>et</strong>te unité nuancerait c<strong>et</strong>te<br />
affirmation (cf. annexes). Ce groupement comporte<br />
souvent <strong><strong>de</strong>s</strong> Characeae, qu’il possè<strong>de</strong> en commun avec le<br />
groupe précé<strong>de</strong>nt. Trois espèces liées à ce groupe – Oryza<br />
hexandra, Fuirena pubescens <strong>et</strong> Glinus lotoi<strong><strong>de</strong>s</strong> –appartiennent<br />
à l’élément tropical. La <strong>de</strong>rnière tapisse le fond <strong><strong>de</strong>s</strong><br />
mares <strong>et</strong> <strong><strong>de</strong>s</strong> marais, sinon <strong><strong>de</strong>s</strong> lacs durant toute la pério<strong>de</strong><br />
estivale.<br />
C<strong>et</strong>te première typologie mérite toutefois quelques<br />
compléments. En eff<strong>et</strong>, si les espèces les plus caractéristiques<br />
<strong>de</strong> ces mares sont souvent i<strong>de</strong>ntiques à celles<br />
<strong>de</strong> l’Europe méditerranéenne, d’autres sont particulières<br />
à l’Afrique du Nord, notamment à la Numidie. Elles<br />
forment ainsi <strong><strong>de</strong>s</strong> associations locales, étudiées par Gehu<br />
(1993) qui fait également un état <strong><strong>de</strong>s</strong> végétaux rares, sinon<br />
rarissimes <strong>de</strong> la région. L’élément le plus original est sans<br />
conteste la présence significative d’espèces d’origine biogéographique<br />
afrotropicale (8,8 % <strong><strong>de</strong>s</strong> végétaux recensés).<br />
Ce caractère n’avait pas échappé à Lefranc (1865) <strong>et</strong> il<br />
a aussi été signalé dans l’étu<strong>de</strong> générale concernant les<br />
zones humi<strong><strong>de</strong>s</strong> <strong>de</strong> la région d’El Kala par Stevenson <strong>et</strong> al.<br />
(1989). La présence <strong>de</strong> c<strong>et</strong> élément est plus importante<br />
dans les <strong>de</strong>ux groupes à Iso<strong>et</strong>es <strong>et</strong> Scirpus maritimus, avec<br />
Fuirena pubescens, Glinus lotoi<strong><strong>de</strong>s</strong>, Leersia (= Oryza) hexandra,<br />
Scirpus inclinatus, Utricularia exol<strong>et</strong>a <strong>et</strong> Wolffia arrhiza,<br />
toutes réputées rares au niveau national. Ainsi la Numidie,<br />
où ces taxons sont souvent signalés comme exclusifs <strong>de</strong><br />
c<strong>et</strong>te région, représente le siège <strong>de</strong> c<strong>et</strong>te « poche afrotropicale<br />
». Il faudrait y ajouter <strong>de</strong>ux espèces, très envahissantes<br />
<strong>et</strong> <strong>de</strong> même origine : Panicum repens <strong>et</strong> Paspalum distichum.<br />
C<strong>et</strong>te situation biogéographique suppose <strong><strong>de</strong>s</strong> conditions<br />
écologiques particulières à la Numidie, qui sont favorables<br />
au maintien <strong>et</strong> au développement <strong>de</strong> tels végétaux<br />
exigeants en température <strong>et</strong> humidité.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
L’originalité <strong>de</strong> <strong>de</strong>ux mares (déterminée par les axes 3<br />
<strong>et</strong> 4) mérite d’être soulignée. Vincent (2004) invite à<br />
prendre en compte c<strong>et</strong>te originalité, quand il indique<br />
que l’« on n’a plus ici une opposition entre le typique (ici une<br />
typologie à trois groupements) <strong>et</strong> le singulier (les <strong>de</strong>ux mares,<br />
l’une à Ruppia maritima, l’autre à Wolffia arrhiza), mais ce<br />
<strong>de</strong>rnier est présent comme l’obstacle qui perm<strong>et</strong> <strong>et</strong> exige que<br />
l’on dépasse la première généralisation ». Ces <strong>de</strong>ux mares<br />
posent <strong><strong>de</strong>s</strong> questionnements écologiques en raison <strong>de</strong><br />
leur composition floristique bien à part. En Numidie,<br />
aucune <strong>de</strong> nos investigations ne nous a permis <strong>de</strong> trouver<br />
une autre mare dominée ainsi par Ruppia maritima qui<br />
entre en concurrence avec les autres espèces végétales<br />
particulièrement pour la lumière. Simultanément, en<br />
oxygénant le milieu, elle favorise une multitu<strong>de</strong> <strong>de</strong> niches<br />
écologiques, occupées par <strong><strong>de</strong>s</strong> Amphibiens comme la<br />
Grenouille verte, par le phytoplancton <strong>et</strong> le zooplancton.<br />
Le groupement où intervient Wolffia arrhiza est plus<br />
fréquent ; il occupe non seulement la mare du lac Bleu,<br />
mais les rives <strong>de</strong> certains lacs ou étangs en Numidie,<br />
chaque fois que le milieu s’eutrophise (Samraoui & <strong>de</strong><br />
Bélair, 1997).<br />
CONCLUSION<br />
L’échantillonnage <strong>de</strong> 26 mares temporaires réalisé<br />
durant trois cycles (1998-2001) a permis d’inventorier<br />
136 espèces végétales en Numidie. L’ACP puis l’analyse<br />
inter-classes ont permis <strong>de</strong> séparer <strong>de</strong>ux eff<strong>et</strong>s : temporel<br />
<strong>et</strong> spatial. La succession <strong><strong>de</strong>s</strong> espèces (eff<strong>et</strong> temporel) m<strong>et</strong><br />
en évi<strong>de</strong>nce la séparation <strong>de</strong> l’année en <strong>de</strong>ux groupes, l’un<br />
dominé par Panicum repens en automne-été, l’autre par<br />
Ranunculus baudotii en hiver-printemps ; une partition<br />
dans ce <strong>de</strong>rnier groupe paraît plus aléatoire en raison<br />
<strong>de</strong> la structure habituelle « en écailles » <strong><strong>de</strong>s</strong> espèces. La<br />
typologie m<strong>et</strong> très n<strong>et</strong>tement en évi<strong>de</strong>nce trois groupes,<br />
caractérisés successivement par (i) Juncus maritimus,<br />
J. acutus <strong>et</strong> <strong><strong>de</strong>s</strong> Characeae, (ii) par Scirpus maritimus <strong>et</strong><br />
ses associés <strong>et</strong> enfin (iii) par Iso<strong>et</strong>es velata <strong>et</strong> Myriophyllum<br />
alterniflorum.<br />
Comme l’on dispose d’autres paramètres environnementaux<br />
caractéristiques du milieu, une analyse supplémentaire<br />
pourra être effectuée en croisant les tableaux<br />
floristique <strong>et</strong> mésologique afin d’établir le bien-fondé <strong>de</strong><br />
c<strong>et</strong>te typologie. L’analyse <strong>de</strong> co-inertie représente probablement<br />
l’instrument répondant le mieux à ce type <strong>de</strong><br />
manipulation (Thioulouse <strong>et</strong> al., 1996).<br />
L’ensemble <strong>de</strong> ces hydrosystèmes temporaires correspond<br />
à une large amplitu<strong>de</strong> du pH allant d’une alcalinité<br />
élevée à une acidité forte. Ces mares rassemblent une<br />
flore diversifiée, dont beaucoup d’espèces sont rares à<br />
très rares en Algérie ; elles sont partiellement d’origine<br />
tropicale (8 espèces), <strong>et</strong> majoritairement inféodées à la<br />
seule Numidie. C<strong>et</strong>te originalité confère donc aux mares<br />
temporaires <strong>de</strong> Numidie un intérêt patrimonial indéniable.<br />
Face à la vulnérabilité <strong>de</strong> ces mares, ces résultats<br />
<strong>de</strong>vraient inciter à la mise en place <strong>de</strong> rapi<strong><strong>de</strong>s</strong> mesures<br />
conservatoires afin <strong>de</strong> sauver ces fragiles écosystèmes<br />
d’une disparition sans doute inéluctable liée à l’anthropisation<br />
croissante du littoral algérien.<br />
REMERCIEMENTS<br />
L’auteur tient à remercier le Laboratoire <strong>de</strong> recherche<br />
sur les zones humi<strong><strong>de</strong>s</strong> d’Annaba <strong>et</strong> la Station biologique <strong>de</strong><br />
la tour du Valat pour les ai<strong><strong>de</strong>s</strong> appréciables apportées dans<br />
le cadre <strong>de</strong> c<strong>et</strong>te étu<strong>de</strong>. Merci également au Dr Frédéric<br />
Médail (IMEP-CNRS, Univ. Aix-Marseille III) pour ses<br />
remarques <strong>et</strong> suggestions.<br />
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du Nord du Maroc, incluant <strong><strong>de</strong>s</strong> clés d’i<strong>de</strong>ntification. CSIC,<br />
Madrid. Vol. I & II, 1 007 p.<br />
VINCENT H., 2004. Parler <strong><strong>de</strong>s</strong> animaux : une rhétorique furtive.<br />
Le Courrier <strong>de</strong> l’Environnement INRA, 51 : 55-60.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
DYNAMIQUE DE LA VÉGÉTATION DE MARES TEMPORAIRES EN AFRIQUE DU NORD (NUMIDIE ORIENTALE) ◆<br />
ANNEXES<br />
Paramètres floristiques <strong>et</strong> mésologiques<br />
<strong><strong>de</strong>s</strong> 26 mares temporaires étudiées<br />
D’ouest en est, les 26 mares temporaires décrites sont situées<br />
dans <strong><strong>de</strong>s</strong> environnements différents déterminés par <strong><strong>de</strong>s</strong> paramètres<br />
mésologiques <strong>et</strong> <strong><strong>de</strong>s</strong> formations végétales diverses. Ces mares ont<br />
été classées selon quatre unités géomorphologiques, <strong>et</strong> une brève<br />
<strong><strong>de</strong>s</strong>cription mésologique <strong>et</strong> floristique est fournie.<br />
1. Plaines sublittorales alluvionnaires<br />
* Boukamira (21) est une mare littorale sablo-argileuse, à<br />
proximité <strong>de</strong> la ville d’Annaba ; son pH est alcalin : 7.75. Elle sert<br />
<strong>de</strong> dépotoir <strong>et</strong> d’exutoire pour les eaux usées, mais ce n’est pas, du<br />
moins actuellement, un obstacle à l’expression d’une biodiversité<br />
floristique élevée. Elle fait partie d’un complexe <strong>de</strong> mares du même<br />
type, naturelles ou artificielles. Elle est entourée d’une prairie à<br />
Trifolium campestre, Melilotus infestus <strong>et</strong> M. siculus, Lolium rigidum,<br />
Hor<strong>de</strong>um marinum, Crypsis alopecuroi<strong><strong>de</strong>s</strong>, Medicago intertexta,<br />
Ricinus communis <strong>et</strong> <strong>de</strong> quelques espèces rares, comme Heliotropium<br />
curassavicum, Scirpus littoralis (origine biogéographique : paléosubtropicale)<br />
ou Rumex algeriensis (endémique).<br />
* Salines (22) fait partie d’un ensemble, aujourd’hui<br />
abandonné, <strong>de</strong> bassins <strong>de</strong> décantation pour la production <strong>de</strong> sel ; elle<br />
est également en position littorale, sans contact direct avec la mer.<br />
La dominante est argileuse (56 %). Elle comporte une formation à<br />
Hor<strong>de</strong>um marinum <strong>et</strong> Lolium rigidum, accompagnés <strong>de</strong> Puccinellia<br />
distans, Melilotus infestus, Medicago intertexta <strong>et</strong> Rumex algeriensis ;<br />
c<strong>et</strong>te mare se caractérisée par un milieu alcalin (pH = 8.15) <strong>et</strong> un<br />
grand nombre d’espèces messicoles en raison <strong>de</strong> la présence tout<br />
autour <strong>de</strong> terres cultivées.<br />
* Mares d’El-Feïd (1 à 4). Elles sont situées sur les rives<br />
sud-ouest du marais <strong>de</strong> la M’krada ou plaine <strong>de</strong> la Mafragh<br />
(<strong>de</strong> Bélair & Bencheikh-Lehocine, 1987) ; elles ont été creusées<br />
pour l’abreuvement du bétail dans une prairie d’une gran<strong>de</strong><br />
richesse spécifique (ainsi, un transect effectué sur 150 m avait<br />
mis en évi<strong>de</strong>nce près <strong>de</strong> 150 taxons). Citons Glinus lotoi<strong><strong>de</strong>s</strong> qui<br />
se développe dans les mares asséchées en été, Dactylis glomerata,<br />
Gaudinia fragilis, Myosotis sicula, Hor<strong>de</strong>um bulbosum, Sonchus asper,<br />
Stachys arvensis, Medicago intertexta, Aspho<strong>de</strong>lus aestivus, Hypochoeris<br />
radicata, Festuca elatior <strong>et</strong> Phalaris arundinacea, ces <strong>de</strong>ux <strong>de</strong>rnières<br />
souvent dominantes au printemps. La dominante texturale est<br />
argilo-limoneuse, sauf pour Feïd 1 à texture équilibrée. Malgré la<br />
proximité d’un marais relativement alcalin, les pH sont aci<strong><strong>de</strong>s</strong> (<strong>de</strong> 4<br />
à 5). Deux Orchidées sont disséminées dans c<strong>et</strong>te prairie : Serapias<br />
strictiflora <strong>et</strong> S. parviflora.<br />
* Frênes (5) est localisé dans la ripisylve à Ulmus campestris <strong>et</strong><br />
Populus alba <strong>de</strong> l’oued El Kébir-Est. La zone où s’est développée<br />
c<strong>et</strong>te mare a été plantée <strong>de</strong> Fraxinus angustifolia. Sa texture<br />
est principalement argileuse (45.3 %) ; son environnement est<br />
constitué par une formation à Aspho<strong>de</strong>lus aestivus, Urginea maritima,<br />
Hypochoeris radicata, Ranunculus bulbosus, Plantago lanceolata,<br />
Medicago littoralis <strong>et</strong> Ormenis mixta.<br />
2. Plaines sublittorales colluvionnaires<br />
* Messida (6) présente une texture sablo-argileuse (sable : 40 %<br />
<strong>et</strong> argile : 34 %) ; située en aval <strong>de</strong> collines gréseuses <strong>et</strong> à proximité<br />
<strong>de</strong> l’oued Messida, son pH est très aci<strong>de</strong> (4.80). Proche <strong>de</strong> terres<br />
cultivées, Medicago sp., Melilotus sp. <strong>et</strong> Trifolium sp. abon<strong>de</strong>nt avec<br />
quelques graminées.<br />
* Les mares Gauthier (7 à 10). Leur dominante texturale<br />
est plutôt sableuse pour les mares 7 <strong>et</strong> 8 (21 % d’argile, 18 % <strong>de</strong><br />
limon <strong>et</strong> 36 % <strong>de</strong> sable), n<strong>et</strong>tement plus argileuse (38 %) pour les<br />
mares 9 <strong>et</strong> 10. Leur pH est également aci<strong>de</strong> (<strong>de</strong> 4.80 à 5.60). Des<br />
bosqu<strong>et</strong>s <strong>de</strong> Quercus suber, Pistacia lentiscus <strong>et</strong> Myrtus communis<br />
sont dispersés dans une prairie humi<strong>de</strong>, jalonnée <strong>de</strong> mares aux<br />
dimensions variables (<strong>de</strong> quelques ares à plusieurs hectares). La<br />
formation est dominée, en <strong>de</strong>hors <strong><strong>de</strong>s</strong> vestiges d’une subéraie, par<br />
Aspho<strong>de</strong>lus aestivus, Hypochoeris radicata, Eryngium barrelieri <strong>et</strong>,<br />
au gré <strong><strong>de</strong>s</strong> saisons, par Bellis annua, Triglochin laxiflora, Leucojum<br />
autumnale, Romulea bulbocodium, Briza maxima <strong>et</strong> Radiola linoi<strong><strong>de</strong>s</strong>.<br />
* Butomes (26). Elle occupe une dépression étalée en longueur,<br />
rapi<strong>de</strong>ment inondée lors <strong><strong>de</strong>s</strong> crues <strong>de</strong> l’oued El Kébir-Est. Située<br />
au nord-est du marais du Mkrada, elle présente une végétation<br />
similaire. Sa texture est dominée par les argiles (61.3 %). Son<br />
caractère remarquable rési<strong>de</strong> dans une population d’extension<br />
variable <strong>de</strong> Butomus umbellatus ; c<strong>et</strong>te espèce, considérée en Algérie<br />
comme très rare (Quézel & Santa, 1962), a été signalée aux environs<br />
d’Alger (Maison-Carrée = El Harrach ?) <strong>et</strong> surtout en Numidie (5<br />
stations ont été repérées entre Skikda <strong>et</strong> El Kala). Scirpus littoralis est<br />
également présente avec Dipsacus sylvestris <strong>et</strong> Verbena officinalis.<br />
3. Massif dunaire<br />
* El Frin (24) appartient à un ensemble, souvent très fugace, <strong>de</strong><br />
mares mises en eau sur les rives du lac Oubeïra, favorisées par une<br />
série <strong>de</strong> micro-reliefs <strong>et</strong> <strong>de</strong> micro-dépressions. La totalité <strong>de</strong> c<strong>et</strong>te<br />
prairie humi<strong>de</strong>, plus ou moins tourbeuse à l’origine, est désormais<br />
cultivée <strong>de</strong>puis les années 1990 (arachi<strong>de</strong>, principalement) ; la<br />
végétation s’est rapi<strong>de</strong>ment banalisée, la tourbe s’étant minéralisée.<br />
Peu d’espèces ont le temps <strong>de</strong> se développer du fait <strong>de</strong> la brève<br />
hydropério<strong>de</strong> (3 mois en moyenne) <strong>et</strong> elles sont rapi<strong>de</strong>ment<br />
remplacées par un tapis d’Ormenis mixta. Signalons que les fossés<br />
proches sont favorables à certaines Orchidées, comme Serapias<br />
stenop<strong>et</strong>ala ou Ophrys bombyliflora.<br />
* La mare Ruppia (23) est adossée en pleine dune aux rochers<br />
maritimes dans une dépression. Sa texture est évi<strong>de</strong>mment dominée<br />
par les sables (95 %) avec un pH alcalin (7.45). Ceci explique la<br />
présence massive <strong>de</strong> Ruppia maritima, seule mare repérée avec ce<br />
taxon. Tamarix gallica (T. africana ?) l’entoure presque totalement en<br />
ceinture, suivie d’une ceinture externe <strong>de</strong> Phillyrea latifolia, Myrtus<br />
communis <strong>et</strong> Quercus coccifera. Le sol est légèrement tourbeux, mais<br />
fortement dégradé par le piétinement <strong>et</strong> le pâturage du bétail.<br />
99<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 83-100
◆ G. DE BÉLAIR<br />
100<br />
* Mare Lac Bleu (25). Temporairement alimentée par une<br />
source se déversant sur le lac, elle est située à mi-pente <strong>et</strong> sert à<br />
abreuver le bétail <strong>et</strong>, éventuellement à irriguer les terres, toutes<br />
cultivées, sur le pourtour. La texture est composée à près <strong>de</strong> 93 %<br />
<strong>de</strong> sable, mais l’accumulation <strong>de</strong> matière organique (une p<strong>et</strong>ite<br />
aulnaie s’est développée en aval) crée un milieu plus ou moins<br />
tourbeux riche en azote (C/N = 5.08). Ces conditions mésologiques<br />
sont à l’origine du développement <strong><strong>de</strong>s</strong> Utricularia. L’anthropisation<br />
(tendance à l’eutrophie) se traduit par le fort développement <strong>de</strong><br />
Wolffia arrhiza <strong>et</strong> <strong>de</strong> Nasturtium officinale.<br />
* Gérard (12) se situe en aval du cordon littoral septentrional,<br />
s’étalant d’est en ouest entre Annaba <strong>et</strong> le Djebel Koursi. Le sable<br />
domine (62 %), l’argile ne représentant que 22 % <strong>de</strong> la fraction<br />
texturale. Adossée à ce cordon, l’accumulation <strong>de</strong> la végétation<br />
<strong>et</strong> donc <strong>de</strong> la matière organique favorise la formation <strong>de</strong> tourbe.<br />
En situation d’interface entre dunes <strong>et</strong> plaines sublittorales, elle<br />
présente une très gran<strong>de</strong> biodiversité, où domine la magnocariçaie<br />
(Carex elata, C. acutiformis, Cladium mariscus, <strong>et</strong>c.), ainsi que Salix<br />
atrocinerea, Erica scoparia, Alliaria officinalis, Oxalis corniculata,<br />
Brassica <strong>de</strong>cumbens <strong>et</strong> les rares Anagallis crassifolia <strong>et</strong> Radiola<br />
linoi<strong><strong>de</strong>s</strong>.<br />
* Iso<strong>et</strong>es (13) <strong>et</strong> Berrihane école (14) sont en situation <strong>de</strong><br />
prairie humi<strong>de</strong> tourbeuse, à texture sableuse (76 % <strong>de</strong> sable) sur<br />
dune <strong>et</strong> à pH aci<strong>de</strong> (5.6). Le plus souvent mises en culture (arachi<strong>de</strong><br />
principalement), ces mares sont très vulnérables <strong>et</strong> d’une très gran<strong>de</strong><br />
richesse spécifique, y compris en espèces patrimoniales avec la<br />
présence <strong>de</strong> plusieurs taxons en voie <strong>de</strong> disparition. Prédominent<br />
les Iso<strong>et</strong>es, Isolepis s<strong>et</strong>acea, Imperata cylindrica <strong>et</strong> Serapias strictiflora.<br />
Les quelques haies basses qui jalonnent ces prairies rassemblent<br />
les reliques <strong>de</strong> forêts humi<strong><strong>de</strong>s</strong> sur tourbes (aulnaies), avec Erica<br />
scoparia, Pteridium aquilinum, Myrtus communis, Salix atrocinerea,<br />
Carex sp., <strong>et</strong>c.<br />
* Berrihane Sud (15) se trouve à la sortie ouest du village <strong>de</strong><br />
même nom. C’est une station à dominante sableuse (91 % <strong>de</strong> sable)<br />
<strong>et</strong> à pH aci<strong>de</strong> (6.05). Dépression largement entourée d’Eucalyptus<br />
sp., ayant servi <strong>de</strong> déversoir à un élevage <strong>de</strong> poul<strong>et</strong>s, la réserve <strong>de</strong><br />
graines <strong>et</strong> fruits <strong>de</strong>meure suffisante pour exprimer une certaine<br />
richesse spécifique certaines années. La présence <strong>de</strong> tourbe, malgré<br />
sa mise en culture saisonnière, est favorable à c<strong>et</strong>te expression. Elle<br />
subit périodiquement les inondations <strong>de</strong> l’oued El Kébir-Est, ce qui<br />
explique son caractère mixte : formations à Iso<strong>et</strong>es velata (dunes) <strong>et</strong><br />
à Scirpus maritimus (plaines sublittorales).<br />
* Hrib Nord (16) est une ancienne carrière <strong>de</strong> sable, <strong>et</strong> c<strong>et</strong>te<br />
mare est périodiquement connectée à la précé<strong>de</strong>nte, située en aval.<br />
Sa texture sableuse est du même ordre que la précé<strong>de</strong>nte (92 %)<br />
avec un pH très aci<strong>de</strong> (4.20). Souvent asséchée <strong>et</strong> cultivée, c<strong>et</strong>te<br />
mare exprime certaines années une très gran<strong>de</strong> biodiversité, y<br />
compris certaines Orchidées. Aux espèces, citées dans l’analyse,<br />
s’ajoutent quelques espèces banales, comme Euphorbia helioscopia,<br />
Linaria pinnifolia ou Senecio leucanthemifolius.<br />
* Tamaris (17) appartenait à un ensemble assez proche <strong>de</strong><br />
celui du groupement à Iso<strong>et</strong>es, témoin le nombre d’individus<br />
d’Iso<strong>et</strong>es velata présents à proximité ; c<strong>et</strong> ensemble, très marqué par<br />
la mise en culture, était naguère occupé par <strong><strong>de</strong>s</strong> bosqu<strong>et</strong>s <strong>de</strong> Quercus<br />
suber. La fraction sableuse est élevée (84 %). Comme la plupart<br />
<strong>de</strong> ces hydrosytèmes dunaires, elle est riche en matière organique,<br />
donc avec une dominante <strong>de</strong> l’azote (C/N = 5.89). La frondaison<br />
d’un individu <strong>de</strong> Quercus suber centenaire recouvre partiellement<br />
ce site. Imperata cylindrica, Arundo donax, Hypericum humifusum,<br />
Aster squamatus, Inula graveolens, Bellis annua, Alliaria officinalis <strong>et</strong><br />
Chenopodium album sont fréquents autour <strong>de</strong> c<strong>et</strong>te mare.<br />
* Carrière (18) a été utilisée pour l’extraction du sable, <strong>et</strong><br />
elle perm<strong>et</strong> l’abreuvement <strong><strong>de</strong>s</strong> troupeaux <strong>et</strong> l’irrigation <strong><strong>de</strong>s</strong> terres<br />
cultivées environnantes. Elle est parfois alimentée par une source,<br />
issue <strong>de</strong> la nappe dunaire. Sableuse à 93 %, son pH est aci<strong>de</strong> (5.95).<br />
Elle est la seule où ont été trouvés Damasonium alisma <strong>et</strong>, avec les<br />
Salines, Zanichellia palustris subsp. pedunculata (sous-espèce à<br />
confirmer, étant donné les conditions écologiques très différentes<br />
<strong><strong>de</strong>s</strong> Salines).<br />
* Mafragh (19) fait partie d’un complexe <strong>de</strong> mares, favorisé<br />
par l’altitu<strong>de</strong> faible (à peine 2 m au-<strong><strong>de</strong>s</strong>sus du niveau <strong>de</strong> la mer).<br />
Au nord-ouest du marais du Mkrada <strong>et</strong> à proximité <strong>de</strong> l’exutoire<br />
<strong>de</strong> 3 oueds (oued Mafragh), un certain nombre <strong>de</strong> diaspores sont<br />
véhiculées par les inondations hivernales avec <strong><strong>de</strong>s</strong> pénétrations<br />
maritimes possibles ce qui favorise une relative richesse spécifique.<br />
Sa texture est dominée par l’argile à 93 % avec un pH alcalin <strong>de</strong> 8.35.<br />
Entièrement entourée naguère par la cocciféraie, ce sont désormais<br />
les Joncs qui dominent dans c<strong>et</strong>te plaine basse aux nombreuses<br />
p<strong>et</strong>ites dépressions inondables. Le développement <strong><strong>de</strong>s</strong> Characeae<br />
s’avère remarquable <strong>et</strong> ces taxons peuvent occuper la totalité <strong>de</strong> la<br />
strate végétale immergée.<br />
* Sangliers (20) est une dépression située en interface entre les<br />
dunes <strong>et</strong> la plaine sublittorale. Sa texture <strong>et</strong> son pH sont presque<br />
i<strong>de</strong>ntiques à ceux <strong>de</strong> la Mafragh. Cependant, à la différence <strong>de</strong> la<br />
précé<strong>de</strong>nte, elle est largement entourée <strong>de</strong> végétation, y compris<br />
arbustive, puisqu’une cocciféraie la domine sur trois côtés. Elle<br />
a subi plusieurs incendies, probablement pour perm<strong>et</strong>tre la<br />
repousse <strong>de</strong> graminées palatables. Les Characeae s’y développent<br />
régulièrement, tapissant le fond du site.<br />
Ces <strong>de</strong>ux stations ont un statut particulier par rapport aux autres<br />
mares dunaires. Elles appartiennent à la partie basse <strong>de</strong> la plaine<br />
<strong>de</strong> la Mafragh, proche <strong>de</strong> la mer, à une altitu<strong>de</strong> très faible (entre 2<br />
<strong>et</strong> 3 m au-<strong><strong>de</strong>s</strong>sus du niveau <strong>de</strong> la mer) <strong>et</strong> elles présentent donc un<br />
pH alcalin.<br />
4. Collines gréseuses<br />
* Fedjouj (11) est une mare artificielle, utilisée dans les années<br />
1990 comme carrière <strong>de</strong> tout-venant. Localisée au creux <strong>de</strong> collines<br />
gréseuses (aval du djebel Koursi), sa texture est sablo-argileuse<br />
(57 % <strong>de</strong> sable <strong>et</strong> 20 % d’argile). Le cortège floristique environnant<br />
est celui <strong><strong>de</strong>s</strong> subéraies, accompagné d’Inula viscosa <strong>et</strong> I. graveolens.<br />
En l’espace <strong>de</strong> 10 années, c<strong>et</strong>te mare, très pauvre en espèces, s’est<br />
considérablement enrichie, y compris en espèces rares, comme<br />
Eleocharis multicaulis ou Fuirena pubescens <strong>et</strong> même en Characeae.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Faits <strong>de</strong> conservation en Méditerranée<br />
Mediterranean Conservation News<br />
Assessing favourable and unfavourable areas<br />
for Bonelli’s Eagle in Spain<br />
and its conservation implications<br />
To know and un<strong>de</strong>rstand where and why species occur is crucial<br />
to manage biodiversity, and a necessary precursor for schemes<br />
to mitigate population <strong>de</strong>cline. The <strong>de</strong>velopment of relatively<br />
simple species distribution mo<strong>de</strong>ls is particularly interesting in the<br />
case of endangered species. Bonelli’s Eagle, Hieraa<strong>et</strong>us fasciatus<br />
(Vieillot, 1822), is a wi<strong><strong>de</strong>s</strong>pread raptor whose Western Palaearctic<br />
populations are distributed mainly in the Mediterranean area.<br />
In recent <strong>de</strong>ca<strong><strong>de</strong>s</strong> this species has suffered a severe population<br />
<strong>de</strong>cline, and has been listed as an endangered European species.<br />
In Spain, which with 650-713 breeding pairs supports about 70 %<br />
of the European population, local extinction rates ranging from<br />
32.1 % to 48.6 % have been reported, and the species has recently<br />
changed its status from Vulnerable to Endangered (IUCN categories).<br />
The main reported causes of the <strong>de</strong>cline are direct persecution,<br />
and electrocution by and collision with electric power<br />
lines. At present, European (Council Directive 79/409/EEC)<br />
and Spanish (Real Decr<strong>et</strong>o 439/1990) legislation inclu<strong><strong>de</strong>s</strong> it as a<br />
priority targ<strong>et</strong> species for special conservation measures.<br />
Investigation on the factors that affect Bonelli’s eagle has been<br />
mostly based on local-scale ecological studies. However, Bonelli’s<br />
eagle populations are not only affected by local habitat characteristics,<br />
but also by environmental, and human-related processes<br />
that act on larger geographical scales. Consequently, broad-scale<br />
distribution mo<strong>de</strong>ls may help conservation programs to attain<br />
more satisfactory results, as the factors that affect the populations<br />
on a larger scale are taken into account.<br />
We predicted the potential distribution of Bonelli’s Eagle in<br />
Spain, performing a stepwise logistic regression, using 29 in<strong>de</strong>pen<strong>de</strong>nt<br />
variables related to spatial situation, topography, climate,<br />
lithology, and human activity, and the presence/absence data on<br />
the UTM 10x10-km squares as geographic units. We also classified<br />
each UTM 10x10-km square into three categories (favourable,<br />
unfavourable and of intermediate favourability) <strong>de</strong>pending<br />
on the favourability values yiel<strong>de</strong>d by the mo<strong>de</strong>l.<br />
Mean slope, temperature of July and precipitation were found<br />
to correctly predict more than 76 % of Bonelli’s Eagle presences<br />
and absences in Spain. Although the species presence is more<br />
likely as the distance to highways and to big cities increases, the<br />
human activity plays a secondary role in Bonelli’s Eagle distribution<br />
at the consi<strong>de</strong>red scale. The fragmented spatial structure of<br />
the favourable areas in our distribution mo<strong>de</strong>l suggests the exis-<br />
tence of a m<strong>et</strong>apopulation dynamics, superimposed to the sourcesink<br />
dynamics implicated in the distribution of the species.<br />
From January 1997 to June 2006 Bonelli’s Eagle has benefited<br />
from LIFE projects an amount of nearly 8 millions (http:<br />
//europa.eu.int/comm/environment/life/home.htm), co-financed<br />
by the European Union (68.7 % of the budg<strong>et</strong>) and the Spanish<br />
Government. These projects are generally focused on those areas<br />
where a huge <strong>de</strong>cline has been recor<strong>de</strong>d, in the limit of its range,<br />
whereas southern and south-eastern populations remain apparently<br />
stable. We propose to pay attention also to southern favourable<br />
areas, where the auspicious status of the species could be<br />
<strong>de</strong>ceptive, since an increase in the percentage of pairs with at least<br />
one non-adult has been d<strong>et</strong>ected. The conditions of southern and<br />
more favourable areas could also explain the <strong>de</strong>cline of northern<br />
populations if they fail in exporting enough emigrants. So, those<br />
actions <strong>de</strong>veloped in unfavourable areas, favoured through LIFE<br />
projects, should be complemented with actions in favourable<br />
areas, which might favour population persistence in unfavourable<br />
areas through dispersal processes.<br />
A. ROMÁN MUÑOZ<br />
DEPARTAMENTO DE BIOLOGÍA ANIMAL, FACULTAD DE CIENCIAS,<br />
UNIVERSIDAD DE MÁLAGA, E-29071 MÁLAGA, SPAIN.<br />
E-MAIL: roman@uma.es<br />
For more information, read:<br />
Muñoz, A. R.; Real, R.; Barbosa, A. M. & Vargas, J. M., 2005. Mo<strong>de</strong>lling<br />
the distribution of Bonelli’s Eagle in Spain: Implications for conservation<br />
planning. Diversity and Distribution, vol. 11: 477-486.<br />
What is required for pond turtles to survive?<br />
More than just a pond<br />
The European pond turtle, Emys orbicularis, is a species having<br />
strong conservation concern. It has <strong>de</strong>clined in all the European<br />
countries were it lives: actually, in many areas it is very rare. The<br />
European Union founds actions for the protection of this species<br />
and for the management of habitats. It is clear that prior to start a<br />
management plan, the causes of the <strong>de</strong>cline of a species should be<br />
addressed, to optimise the available founding and to increase the<br />
possibility of success. To date, most of actions for the protection<br />
of the “pond” turtle Emys orbicularis have focused on the conservation<br />
of w<strong>et</strong>lands. However, in the last years several studies,<br />
mainly in North America, outlined the importance of terrestrial<br />
101<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 101-105
◆ FAITS DE CONSERVATION EN MÉDITERRANÉE / MEDITERRANEAN CONSERVATION NEWS<br />
102<br />
habitat for freshwater turtles, and suggested that a more broad<br />
scale approach should be more appropriate for their protection.<br />
Therefore, we evaluated the importance of terrestrial habitat for<br />
the European pond turtle, by measuring turtle presence and<br />
abundance in a large number of w<strong>et</strong>lands in the Po River Delta,<br />
a large protected w<strong>et</strong>land system in Northern Italy.<br />
Despite some of the w<strong>et</strong>land features were important for<br />
this turtle (for example, E. orbicularis prefers permanent, large<br />
w<strong>et</strong>lands), we did not find a relationship b<strong>et</strong>ween water features<br />
and turtle distribution: we frequently observed E. orbicularis also<br />
in w<strong>et</strong>lands having very eutrophic water. Surprisingly, we found<br />
that the composition of landscape surrounding a w<strong>et</strong>land was<br />
apparently more important than the w<strong>et</strong>land features: turtles were<br />
more frequent and more abundant in w<strong>et</strong>lands surroun<strong>de</strong>d by<br />
woodlands. This result suggests that the management of habitats<br />
surrounding the w<strong>et</strong>lands is very important for this species; however,<br />
too often the management of semi aquatic species focused<br />
only in the aquatic component of their habitat.<br />
It should not be forgotten that vital activities for these animals,<br />
such as nesting, can occur far from the w<strong>et</strong>lands: for example,<br />
females has been observed laying their eggs thousand of m<strong>et</strong>ers<br />
far from their pond. Emys orbicularis is a long-lived animal. It<br />
can survive for <strong>de</strong>ca<strong><strong>de</strong>s</strong> in areas having the minimal requirements<br />
for the survival of adults. Som<strong>et</strong>imes, in the human dominated<br />
lowlands of Mediterranean Europe, it is possible to observe<br />
E. orbicularis adults in ponds compl<strong>et</strong>ely surroun<strong>de</strong>d by crops<br />
and human s<strong>et</strong>tlements. However, if the surrounding habitat is<br />
not suitable for reproduction and it does not allow among-pond<br />
movements, the fate of these isolated individuals is doomed. A<br />
large scale, landscape ecology approach is required for the protection<br />
of this endangered turtle. Unfortunately, the landscape of<br />
Mediterranean Europe, where E. orbicularis was once abundant, is<br />
now dominated by human activities: the protection of this species<br />
is therefore a challenge for conservationists and land managers.<br />
GENTILE FRANCESCO FICETOLA<br />
DIPARTIMENTO DI BIOLOGIA, UNIVERSITÀ DEGLI STUDI DI MILANO. V.<br />
CELORIA 26, 20133 MILANO ITALY.<br />
E-MAIL: francesco.fic<strong>et</strong>ola@unimi.it<br />
For more information, read:<br />
Fic<strong>et</strong>ola, G.F., Padoa-Schioppa, E., Monti, A., Massa, R., De Bernardi, F.<br />
& L. Bottoni 2004. The importance of aquatic and terrestrial habitat for<br />
the European pond turtle (Emys orbicularis): implications for conservation<br />
planning and management. Can. J. Zool. 82, 1704-1712.<br />
Butterflies and plants highlight traditional<br />
hay meadows as one of the most valuable and endangered<br />
habitats on the Spanish Mediterranean coast<br />
Situated in north-east of Catalonia, the Aiguamolls <strong>de</strong> l’Empordà<br />
Natural Park is one of the most outstanding w<strong>et</strong>land areas<br />
in the Iberian Peninsula and, in<strong>de</strong>ed, in the whole Mediterranean<br />
basin. Traditionally highly regar<strong>de</strong>d for its birdwatching potential,<br />
it was <strong>de</strong>clared a Natural Park in 1983 and then as a Ramsar Site<br />
as a W<strong>et</strong>land of International Importance. The initial impression<br />
gained of this protected area is one of a vast marshland; however,<br />
a closer examination reveals a mosaic of different habitats all<br />
Fig. 1. 3 males of the butterfly<br />
Plebejus argus, one of the most<br />
typical species inhabiting the<br />
« closes » and <strong>de</strong>clining (photo<br />
Marta Miralles).<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
FAITS DE CONSERVATION EN MÉDITERRANÉE / MEDITERRANEAN CONSERVATION NEWS ◆<br />
Fig. 2. A typical « closa » in<br />
the study area (photo Marta<br />
Miralles).<br />
103<br />
associated with a myriad of differing environmental conditions.<br />
Recently, botanists have un<strong>de</strong>rtaken systematic surveys aimed at<br />
i<strong>de</strong>ntifying which habitats are the most interesting in terms of<br />
their conservation value. Their results have revealed the exceptional<br />
importance of the so-called closes, the meadows enclosed<br />
by tree-lined drainage canals that flood in winter and are cut for<br />
hay once or twice during the year. These traditional hay meadows<br />
harbour the most diverse veg<strong>et</strong>ation and also the region’s rarest<br />
taxa. However, the closes are at risk because they are no longer<br />
profitable and are being converted into arable fields or being<br />
abandoned and inva<strong>de</strong>d by shrubs and scrub. The frequent lack<br />
of agreement in cross-taxonomic patterns of species richness and<br />
rarity at the fine geographical scale consi<strong>de</strong>red here encouraged us<br />
to assess the value of the closes through an in<strong>de</strong>pen<strong>de</strong>nt data s<strong>et</strong>.<br />
In particular, we used data from butterflies, an excellent indicator<br />
taxa whose populations have been monitored over the last 15<br />
years as part of the Catalan Butterfly Monitoring Scheme. Our<br />
analyses showed a strong link b<strong>et</strong>ween the various habitat types<br />
and the composition of butterfly assemblages and, once again,<br />
pointed to the closes as the most interesting habitat in the Natural<br />
Park: they hold more butterflies and a ten<strong>de</strong>ncy to boast rarer<br />
species. The coinci<strong>de</strong>nce in species richness and rarity patterns<br />
across two groups of taxa encompassing two different trophic<br />
levels, tog<strong>et</strong>her with the incredibe speed at which the closes are<br />
vanishing, highlight the necessity of placing these traditional<br />
hay meadows firmly at the top of the agenda of Spanish and<br />
European conservation bodies. It has been estimated that 80 % of<br />
the closes have been lost over the last 50 years and – even more<br />
incredibly – that at least 60 % have disappeared since the area<br />
became legally protected in 1983. In fact, they are paradigmatic<br />
of a common problem faced by most Mediterranean protected<br />
areas: a lack of effective financial support that is leading eventually<br />
to the loss of unprofitable traditionally man-managed habitats. We<br />
believe that the future of the closes and other grassland habitats<br />
supporting an exceptionally rich wildlife in the Mediterranean<br />
basin will ultimately <strong>de</strong>pend on the existence of agri-environmental<br />
schemes sponsored by the governments of individual<br />
countries and/or by projects <strong>de</strong>veloped at a broa<strong>de</strong>r level within<br />
the European Union.<br />
For more information, read:<br />
CONSTANTÍ STEFANESCU<br />
BUTTERFLY MONITORING SCHEME<br />
MUSEU DE GRANOLLERS CIÈNCIES NATURALS<br />
FRANCESC MACIÀ, 51, 08400 GRANOLLERS, SPAIN<br />
E-MAIL: canliro@teleline.es<br />
Stefanescu, C., Peñuelas, J. & Filella, I. 2005. Butterflies highlight the conservation<br />
value of hay meadows highly threatened by land-use changes in a<br />
protected Mediterranean area. Biol. Conserv., 126: 234-246.<br />
Prey d<strong>et</strong>ectability, more than prey <strong>de</strong>nsity,<br />
affects di<strong>et</strong> composition of Bonelli´s eagle<br />
Hieraa<strong>et</strong>us fasciatus: conservation implications<br />
Food availability in one of the most important factors influencing<br />
the quality of raptor habitats, which is d<strong>et</strong>ermined not only<br />
by prey <strong>de</strong>nsity, but also by the accessibility to prey by predators.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 101-105
◆ FAITS DE CONSERVATION EN MÉDITERRANÉE / MEDITERRANEAN CONSERVATION NEWS<br />
104<br />
In the di<strong>et</strong> of raptors the presence of prey species is influenced<br />
by several factors, such as their abundance and the ground-level<br />
veg<strong>et</strong>ation in territories.<br />
We analysed this situation for the Bonelli´s eagle (Hieraa<strong>et</strong>us<br />
fasciatus) in south-eastern Spain, a largely mountainous region with<br />
typical Mediterranean veg<strong>et</strong>ation and a healthy population of the<br />
Bonelli´s eagle. First, we performed a di<strong>et</strong>ary analysis of the whole<br />
population, which indicated that Oryctolagus cuniculus (29.1 %) and<br />
Alectoris rufa (28.8 %) were the main prey of the eagle, followed by<br />
Columba palumbus (13.3 %) and Columba livia (8.0 %). Second,<br />
we tested for the minimum number of prey items for the reliability<br />
of results, finding b<strong>et</strong>ween 15 and 30 prey items, <strong>de</strong>pending on the<br />
pair. Third, we checked for differences in prey frequency and productivity<br />
among pairs, discovering strong differences in both traits,<br />
but we failed to find any relationship b<strong>et</strong>ween the frequency of the<br />
main preys in the di<strong>et</strong> and productivity (mean productivity of the<br />
pairs, 1.4 nestling/year). Fourth, we found that only the percentage<br />
of European wild rabbit in di<strong>et</strong> was correlated with its abundance in<br />
territories (r = 0.81; P = 0.01) although, the percentage of rabbits<br />
in the di<strong>et</strong> was b<strong>et</strong>ter correlated with the amount of open land in<br />
the territories (r = 0.87; P = 0.005). Thus, the percentage of open<br />
land within the territories was the single variable, selected by a<br />
multiple-regression analysis, that explained the frequency of rabbits<br />
in the raptor’s di<strong>et</strong> (F 2,5 = 14.64, R 2 = 0.85; P < 0.008); the same<br />
was true for the stepwise forward (F 2,5 = 14.64, R 2 = 0.85; P <<br />
0.008) and backward multiple-regression analysis (F 1,6 = 16.67, R 2<br />
= 0.74; P < 0.006). These results suggest that accessibility of this<br />
prey type would be more important than absolute abundance for<br />
the Bonelli’s eagle. This would be important for the management<br />
of some Bonelli´s eagle populations, since prey accessibility (<strong>de</strong>pending<br />
on ground-level veg<strong>et</strong>ation) is d<strong>et</strong>erminant for the capture of<br />
rabbits, its main prey species in Spain. As expected for a raptor that<br />
relies on few and prominent prey species, the presence of rabbits in<br />
the di<strong>et</strong> influenced other prey frequencies. We found negative and<br />
significant relationships b<strong>et</strong>ween the presence of rabbits versus red<br />
legged partridge (r = -0.81; P = 0.01) and versus wood pigeons<br />
(r = -0.89; P = 0.003) in di<strong>et</strong>. Birds as prey appear to complement<br />
the di<strong>et</strong> when open-land scarcity in the territories implies low rabbit<br />
d<strong>et</strong>ectability and consumption.<br />
The results for southern and healthy populations (uncommon<br />
circumstance in this species), indicate the importance of alternative<br />
preys (partridges and pigeons) in some territories with low open-land<br />
surface area; for northern and more threatened populations, these<br />
results suggest the importance of a<strong>de</strong>quate habitat management.<br />
Conservation measures proposed concerning the increase of prey<br />
availability in areas with <strong>de</strong>clining populations should consi<strong>de</strong>r both<br />
the absolute prey <strong>de</strong>nsity and prey d<strong>et</strong>ectability, favouring a veg<strong>et</strong>ation<br />
structure a<strong>de</strong>quate for prey d<strong>et</strong>ection and hunting success of the<br />
eagle and avoiding extensive reforestation in those territories.<br />
Scientifically-based management solves conflict<br />
b<strong>et</strong>ween European storm p<strong>et</strong>rels and their facultative<br />
predator at minimum cost<br />
Large gulls are commnonly perceived as pest species by environmental<br />
managers owing to their facultative predatory habits<br />
on smaller bird species (e.g. Finney <strong>et</strong> al., 2003). Once predation<br />
is d<strong>et</strong>ected, conservation actions typically involve indicriminated<br />
gull culling in the absence of any proof of negative influence of<br />
predation on the growth rate of prey populations. Here we report<br />
on a successful management plan based on the results of an ad hoc<br />
research program carried out in a small western Mediterranean<br />
island (i.e. the island of Benidorm) holding both a storm p<strong>et</strong>rel<br />
and a yellow-legged gull colony of about 500 breeding pairs<br />
each.<br />
First, based on the long-term monitoring of the storm p<strong>et</strong>rel<br />
colony, the effects of predation on the population dynamics of the<br />
tubenose birds were explored through capture-recapture analysis<br />
(Oro <strong>et</strong> al., 2005). Before management actions, 122 and 124 birds<br />
were killed by gulls in 2002 and 2003 respectively. Results showed<br />
that as much as 10 % of the birds killed by gulls were breeding<br />
adults and that predation was in<strong>de</strong>ed an additive cause of mortality<br />
of adult birds. This was the case starting since the year of<br />
operation of a powerful public lighting installed along the nearby<br />
touristic coastline that ma<strong>de</strong> it easier for gulls to predate on p<strong>et</strong>rels<br />
at night. Hence, management actions had to be applied urgently,<br />
consi<strong>de</strong>ring that reductions in adult survival of long-lived birds<br />
have the largest influence on their population growth rates (e.g.<br />
Sa<strong>et</strong>her <strong>et</strong> al., 1996).<br />
DIEGO ONTIVEROS, JUAN M. PLEGUEZUELOS AND JESÚS CARO<br />
ADDRESS: DEPARTAMENTO DE BIOLOGÍA ANIMAL<br />
Y ECOLOGÍA, FACULTAD DE CIENCIAS,<br />
UNIVERSIDAD DE GRANADA, GRANADA E-18071.<br />
E-MAIL: dontive@ugr.es<br />
Fig. 1. A breeding storm p<strong>et</strong>rel.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
FAITS DE CONSERVATION EN MÉDITERRANÉE / MEDITERRANEAN CONSERVATION NEWS ◆<br />
Secondly, gulls were monitored as to individuals containing<br />
storm p<strong>et</strong>rels in their di<strong>et</strong> among the whole local population.<br />
Results showed unequivocally that only a small number of gulls<br />
were responsible of most predation, more especifically those whose<br />
nests were located close to the entrance of the two caves where<br />
most storm p<strong>et</strong>rels breed (Mínguez <strong>et</strong> al., 2005). Management<br />
actions were therefore addressed to removing only those predator<br />
pairs, leaving the bulk of gulls untouched. By means of<br />
nest traps 11 gulls were removed in 2004 and 18 in 2005. The<br />
removal of these individuals led to a surprising reduction in the<br />
number of gull pell<strong>et</strong>s found insi<strong>de</strong> storm p<strong>et</strong>rel colonies and<br />
along a transect b<strong>et</strong>ween them in 2004 and 2005 (51 and 75 %<br />
respectively), compared to the situation before gull removal (Sanz<br />
<strong>et</strong> al., in prep.). A number of years iares still necessary to quantify<br />
more precisely the <strong>de</strong>crease in predation on adult survival using<br />
capture-recapture mo<strong>de</strong>lling, but results show unquestionably the<br />
success of the control.<br />
Management actions should probably be implemented on<br />
an annual basis since the niche of gulls facultatively predating<br />
on storm-p<strong>et</strong>rels seems to be readily occupied by other gulls,<br />
provi<strong>de</strong>d that due changes in public lighting are not performed<br />
in the future. Although the implementation of these tasks is both<br />
time and resource consuming, its costs are neglegible compared<br />
to the traditional solution of performing massive gull cullings<br />
when faced with similar conflicts, not to mention social costs.<br />
This small-scale case study clearly illustrates the tremendous<br />
potential of scientifically-based wildlife management in terms<br />
of resource optimization and successful achievement of <strong><strong>de</strong>s</strong>ired<br />
conservation goals.<br />
Literature cited:<br />
Finney S.K., Harris M.P., Keller L.F., Elston D.A., Monaghan P. &<br />
Wanless S., 2003. Reducing the <strong>de</strong>nsity of breeding gulls influences the<br />
pattern of recruitment of immature Atlantic puffins Fratercula arctica<br />
to a breeding colony. Journal of Applied Ecology, 40: 545-552<br />
Mínguez, E., Sanz, A., <strong>de</strong> León, A. & Junza, M., 2005. No todas las gaviotas<br />
comen paíños. Quercus 228: 81.<br />
Oro, D., De León, A., Minguez, E., & Furness, R.W., 2005. Estimating<br />
predation on breeding European Storm-p<strong>et</strong>rels by yellow-legged gulls.<br />
Journal of Zoology 265: 421-429.<br />
Sa<strong>et</strong>her B.E., Ringsby T.H. & Roskaft E., 1996. Life history variation,<br />
population processes and priorities in species conservation: Towards<br />
a reunion of research paradigms. Oikos 77: 217-226<br />
ALEX DANI, ANA SANZ 1 , EDUARDO MÍNGUEZ 1 , LLANOS DE LEÓN 2 ,<br />
ALEJANDRO MARTÍNEZ-ABRAÍN 3 , BLANCA SARZO 4 ,<br />
ELENA VILLUENDAS 4 , JOSÉ SANTAMARÍA 4 AND DANIEL ORO 3<br />
1. UNIVERSIDAD MIGUEL HERNÁNDEZ<br />
2. UNIVERSITY OF GLASGOW<br />
3. IMEDEA (CSIC-UIB)<br />
4. CONSELLERIA DE TERRITORI I HABITAGE<br />
CORRESPONDING AUTHOR :<br />
DR. ALEJANDRO MARTÍNEZ ABRAÍN, POPULATION ECOLOGY GROUP<br />
IMEDEA (CSIC-UIB), AVDA. DE LOS PINARES 106,<br />
46012 EL SALER, VALENCIA (SPAIN)<br />
E-MAIL: a.abrain@uib.es<br />
http://www.ime<strong>de</strong>a.uib.es/natural/goi/seabirds<br />
105<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 101-105
Analyses d’ouvrages<br />
Atlas of climatic diagrams<br />
for the isoclimatic <strong>mediterranea</strong>n zones<br />
H.N. Le Houérou<br />
220 p., (2004) ISBN : 2-9523965-0-7<br />
Prix 35,5 euros + frais d’envoi. Disponible chez l’auteur,<br />
327 rue A.-L. <strong>de</strong> Jussieu, F-34090, Montpellier.<br />
hn.le-houerou@club-intern<strong>et</strong>.fr<br />
C<strong>et</strong> atlas comprend 1 560 diagrammes <strong>de</strong> 1 320 stations climatiques<br />
<strong>de</strong> 60 pays ayant totalement ou partiellement <strong><strong>de</strong>s</strong> climats<br />
méditerranéens, c’est-à-dire à pluies d’hiver <strong>et</strong> sècheresse estivale,<br />
tel le bassin méditerranéen. Ces types <strong>de</strong> climats sont répartis sur<br />
tous les continents, sauf l’Antarctique, entre les latitu<strong><strong>de</strong>s</strong> <strong>de</strong> 25 <strong>et</strong><br />
46°N <strong>et</strong> S. Ils représentent une superficie <strong>de</strong> quelque 15 millions<br />
<strong>de</strong> km 2 , c’est-à-dire un peu plus <strong>de</strong> 11 % <strong><strong>de</strong>s</strong> masses continentales<br />
<strong>de</strong> la planète. L’atlas comprend 220 pages, dont 170 sont <strong><strong>de</strong>s</strong><br />
planches <strong>de</strong> graphiques ombrothermiques <strong>et</strong> ombrodiapnéiques<br />
(ETP). Les graphiques sont groupés par ordre alphabétique <strong>de</strong><br />
pays <strong>et</strong> <strong>de</strong> station, ce qui facilite la consultation. L’atlas comprend<br />
aussi une classification bioclimatique fondée sur <strong>de</strong>ux critères<br />
principaux : un indice d’aridité (P/ETo) : le quotient <strong>de</strong> la pluviosité<br />
moyenne annuelle par l’évapotranspiration potentielle <strong>de</strong><br />
référence. Le second critère (m) est la moyenne <strong><strong>de</strong>s</strong> températures<br />
minimales journalières du mois le plus froid. C<strong>et</strong>te classification<br />
est donnée à la fois dans un graphique orthogonal <strong>et</strong> un tableau ;<br />
elle comprend 155 stations en provenance <strong>de</strong> 50 pays. Des explications<br />
sur la construction <strong><strong>de</strong>s</strong> diagrammes, leur interprétation, la<br />
liste <strong>et</strong> les superficies <strong><strong>de</strong>s</strong> zones à climat méditerranéen occupent<br />
19 pages, la bibliographie comprend 136 titres, <strong>et</strong> un in<strong>de</strong>x <strong>de</strong> 28<br />
pages complète le volume.<br />
Les diagrammes ombrothermiques montrent la marche mensuelle<br />
<strong><strong>de</strong>s</strong> précipitations, <strong>de</strong> la température <strong>et</strong> <strong>de</strong> l’évapotranspiration<br />
potentielle ; ils perm<strong>et</strong>tent ainsi d’évaluer la longueur <strong>et</strong><br />
l’intensité <strong><strong>de</strong>s</strong> saisons sèche <strong>et</strong> pluvieuse, la durée <strong>et</strong> la sévérité <strong><strong>de</strong>s</strong><br />
pério<strong><strong>de</strong>s</strong> <strong>de</strong> repos hivernal <strong><strong>de</strong>s</strong> plantes du aux basses températures.<br />
Il existe plusieurs types <strong>de</strong> diagrammes. Le modèle le plus simple<br />
est celui proposé par Bagnouls <strong>et</strong> Gaussen en 1953, popularisé<br />
par le Klimadiagramm Weltatlas <strong>de</strong> Walter <strong>et</strong> Li<strong>et</strong>h, publié en 1960,<br />
mais épuisé <strong>de</strong>puis <strong><strong>de</strong>s</strong> décennies. Ce modèle a été utilisé par <strong><strong>de</strong>s</strong><br />
milliers <strong>de</strong> chercheurs <strong>et</strong> techniciens <strong>de</strong> diverses disciplines dans<br />
diverses parties du mon<strong>de</strong> <strong>de</strong>puis 50 ans, pour la classification<br />
<strong><strong>de</strong>s</strong> climats. D’autres modèles utilisent en outre l’évapotranspiration<br />
potentielle <strong>de</strong> référence, ce qui perm<strong>et</strong> d’établir <strong><strong>de</strong>s</strong> bilans<br />
hydriques climatiques. Ces <strong>de</strong>rniers types <strong>de</strong> diagrammes sont au<br />
nombre <strong>de</strong> 350 ; ils sont originaux ou résultent <strong><strong>de</strong>s</strong> publications<br />
antérieures <strong>de</strong> l’auteur. Beaucoup ont été construits à partir <strong>de</strong><br />
la base <strong>de</strong> données CLINO, publiée par l’OMM en 1996. Des<br />
comparaisons zonales <strong>et</strong> continentales sont proposées pour <strong><strong>de</strong>s</strong><br />
zones ayant <strong><strong>de</strong>s</strong> diagrammes particulièrement semblables tels que<br />
ceux <strong>de</strong> la Californie <strong>et</strong> du Chili, <strong>de</strong> la Californie <strong>et</strong> du bassin<br />
méditerranéen ou du Great Basin, <strong>de</strong> la région irano-touranienne,<br />
<strong>de</strong> l’Asie moyenne <strong>et</strong> <strong>de</strong> la Patagonie argentine. Des comparaisons<br />
sont aussi offertes avec d’autres types <strong>de</strong> classifications, telles celles<br />
basées sur l’altitu<strong>de</strong>, en honneur dans certains pays du bassin<br />
méditerranéen. Des zones marginalement méditerranéennes,<br />
telles le sud <strong>de</strong> la Crimée <strong>et</strong> certaines zones <strong><strong>de</strong>s</strong> Balkans, sont<br />
incluses dans l’atlas. De même, certaines vallées à climat méditerranéen<br />
<strong>de</strong> l’Hindoukouch <strong>et</strong> du SW <strong>de</strong> l’Himalaya ainsi que la<br />
limite entre les climats méditerranéens <strong>et</strong> tropicaux dans le souscontinent<br />
indien. Une <strong><strong>de</strong>s</strong> originalités <strong>de</strong> c<strong>et</strong> atlas est la place faite<br />
à la région irano-touranienne qui s’étend <strong>de</strong> la rive orientale <strong>de</strong> la<br />
Méditerranée jusqu’à la frontière occi<strong>de</strong>ntale <strong>de</strong> la Chine sur le<br />
méridien 76°E, où le régime à précipitations hivernales <strong>de</strong> l’Asie<br />
moyenne cè<strong>de</strong> brusquement la place à un régime à pluies d’été<br />
(régime <strong>de</strong> mousson) qui caractérise le Xinjiang <strong>et</strong> la Mongolie.<br />
C<strong>et</strong> atlas peut être considéré comme un outil <strong>de</strong> référence<br />
utile pour les géographes, les biogéographes, les écologues, les<br />
forestiers, les pastoralistes <strong>et</strong> les agronomes, c’est-à-dire tous ceux<br />
pour qui la caractérisation bioclimatique est une nécessité.<br />
The isoclimatic <strong>mediterranea</strong>n biomes:<br />
Bioclimatology, diversity<br />
and phytogeography<br />
H.N. Le Houérou<br />
765 p., (2005) ISBN : 2-9523965-1-5<br />
Prix 65 euro + frais d’envoi. Disponible chez l’auteur,<br />
327 rue A.-L. <strong>de</strong> Jussieu, F-34090, Montpellier.<br />
hn.le-houerou@club-intern<strong>et</strong>.fr<br />
Il s’agit d’un ouvrage <strong>de</strong> 765 pages en <strong>de</strong>ux volumes. Le<br />
premier volume (365 p.) contient le texte, une liste <strong>de</strong> références<br />
<strong>de</strong> 1 600 titres <strong>et</strong> les remerciements. Le second volume (400 p.)<br />
contient les annexes, dont 103 tableaux hors-texte, 118 figures,<br />
un glossaire <strong>de</strong> 1 900 termes <strong>et</strong> un in<strong>de</strong>x <strong>de</strong> 650 entrées.<br />
C<strong>et</strong> ouvrage fait partie d’une trilogie dont les <strong>de</strong>ux autres<br />
termes sont publiés par ailleurs :<br />
— Atlas <strong><strong>de</strong>s</strong> diagrammes climatiques <strong><strong>de</strong>s</strong> stations <strong>de</strong> la zone isoclimatique<br />
méditerranéenne, 220 p., 1 560 graphiques <strong>de</strong> 60 pays.<br />
107<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 107-110
◆ ANALYSES D’OUVRAGES<br />
108<br />
— Atlas <strong>de</strong> la répartition <strong>de</strong> 250 espèces clés dans le bassin méditerranéen.<br />
150 p., 300 cartes <strong>et</strong> schémas. Disponible fin 2005 au<br />
CIHEAM-IAMZ. Saragosse.<br />
Les biomes se définissent comme les gran<strong><strong>de</strong>s</strong> zones continentales<br />
<strong>de</strong> milieux naturels : la Toundra, la Taïga, la Forêt tempérée,<br />
la Prairie, la Steppe, la Forêt tropicale, la Savane, la Forêt pluviale<br />
équatoriale <strong>et</strong> les Déserts. Ces biomes se caractérisent par un<br />
climat défini, une flore, une végétation, une faune, <strong><strong>de</strong>s</strong> sols, une<br />
géomorphologie, <strong><strong>de</strong>s</strong> cultures, un mo<strong>de</strong> d’habitat <strong>et</strong> d’exploitation<br />
<strong><strong>de</strong>s</strong> terres, <strong>et</strong>c. La zone isoclimatique méditerranéenne se<br />
définit comme l’ensemble <strong><strong>de</strong>s</strong> régions recevant <strong><strong>de</strong>s</strong> précipitations<br />
hivernales <strong>et</strong> subissant une sécheresse plus ou moins prononcée<br />
l’été. Elles possè<strong>de</strong>nt une végétation sclérophylle dans les zones<br />
semi-ari<strong><strong>de</strong>s</strong> à hyper-humi<strong><strong>de</strong>s</strong>, steppique dans les zones ari<strong><strong>de</strong>s</strong>, <strong>et</strong><br />
contractée dans les zones hyper-ari<strong><strong>de</strong>s</strong> ou désertiques. Les difficultés<br />
surgissent lorsqu’il faut déci<strong>de</strong>r <strong>de</strong> l’abondance relative <strong><strong>de</strong>s</strong><br />
précipitations hivernales <strong>et</strong> <strong>de</strong> l’absence partielle (ou totale) <strong><strong>de</strong>s</strong><br />
précipitations estivales pour qu’une zone déterminée puisse être<br />
qualifiée <strong>de</strong> méditerranéenne. Pour ce faire, l’auteur définit <strong>de</strong>ux<br />
indices objectifs <strong>de</strong> « méditerranéité » IM 1 <strong>et</strong> IM 2 . IM 1 est le<br />
rapport entre les précipitations du trimestre hivernal <strong>et</strong> celles du<br />
trimestre estival (IM 1 = PTH / PTE). IM 2 <strong>et</strong> le quotient <strong><strong>de</strong>s</strong><br />
précipitations du semestre hivernal (à jours courts) à celles du<br />
semestre estival (à jours longs) (IM 2 = PSH / PSE). On peut<br />
aussi invoquer, ce qui revient au même, le % <strong><strong>de</strong>s</strong> précipitations du<br />
trimestre hivernal dans le total annuel : par définition, les pluies<br />
du trimestre hivernal sont supérieures à 25 % du total annuel<br />
<strong>et</strong> les pluies semestrielles d’hiver à plus <strong>de</strong> 50 % <strong><strong>de</strong>s</strong> chutes<br />
annuelles. Par approximations successives <strong>et</strong> en se fondant sur la<br />
nature <strong>et</strong> la répartition <strong>de</strong> la flore, <strong>de</strong> la végétation, <strong>de</strong> la faune,<br />
<strong><strong>de</strong>s</strong> systèmes d’élevage <strong>et</strong> <strong><strong>de</strong>s</strong> cultures, l’auteur est arrivé à la<br />
conclusion suivante : pour qu’une zone puisse être qualifiée <strong>de</strong><br />
méditerranéenne il faut que IM 1 > 2,0 ; il peut atteindre l’infini<br />
lorsque le total <strong><strong>de</strong>s</strong> pluies du trimestre estival est nul, comme c’est<br />
souvent le cas <strong>de</strong> basses terres <strong>de</strong> la Méditerrannée orientale <strong>et</strong><br />
du Proche-Orient, ainsi qualifiées d’« hyper-méditerranéennes ».<br />
L’IM 2 doit dépasser 1,5. Le critère <strong>de</strong> température hivernale,<br />
utilisé par certains auteurs, n’entre pas en ligne <strong>de</strong> compte à ce<br />
niveau, mais plus en avant dans les critères <strong>de</strong> classification. Les<br />
cas litigieux sont résolus par l’examen détaillé <strong>de</strong> la végétation<br />
naturelle <strong>et</strong> <strong><strong>de</strong>s</strong> cultures, mais il reste, bien entendu, <strong><strong>de</strong>s</strong> zones<br />
<strong>de</strong> transition appelées sub-méditerranéennes (exemples : les<br />
Causses, les Alpes maritimes, les Apennins, la partie orientale <strong>de</strong><br />
la chaîne <strong><strong>de</strong>s</strong> Pyrénées). Les spécialistes peuvent ainsi constater<br />
que l’auteur s’est largement inspiré à la fois <strong><strong>de</strong>s</strong> concepts <strong>de</strong> ses<br />
maîtres Emberger <strong>et</strong> Gaussen, en les adaptant aux connaissances<br />
mo<strong>de</strong>rnes, sur l’ETP, par exemple. Ainsi définies, les régions<br />
méditerranéennes couvrent près <strong>de</strong> 15 millions <strong>de</strong> km 2 (30 fois la<br />
France) <strong>et</strong> représentent près <strong>de</strong> 12 % <strong><strong>de</strong>s</strong> terres émergées dans 60<br />
pays ou États partiellement ou totalement méditerranéens (16 %<br />
<strong>de</strong> la superficie nationale en France).<br />
Exemples : les 20 pays adjacents à la Méditerranée <strong>et</strong> le Portugal<br />
(avec les îles Insulo-Atlantiques orientales ou macaronésiennes),<br />
l’Asie moyenne (1/3 sud du Kazakhstan, Kirghizistan,<br />
Ouzbekistan, Tadjikistan, Turkménistan), le Proche-Orient<br />
(Turquie, Syrie, Israël, Palestine, Jordanie), Moyen-Orient (Irak,<br />
Iran, Afghanistan, Pakistan à l’ouest <strong>de</strong> l’Indus), les 2/3 NE <strong>de</strong> la<br />
Péninsule arabique, toute l’Afrique du Nord, la partie sud-ouest <strong>de</strong><br />
l’Afrique du Sud, le long <strong>de</strong> l’Atlantique, les îles Canaries, Madère<br />
<strong>et</strong> les Açores, la Californie, une gran<strong>de</strong> partie <strong>de</strong> l’Orégon, <strong>de</strong> l’état<br />
<strong>de</strong> Washington, <strong>de</strong> l’Idaho, du Nevada, la moitié ouest <strong>de</strong> l’Utah<br />
(tout l’ouest du Great Basin), l’extrémité sud-ouest <strong>de</strong> l’Arizona,<br />
la basse Californie du Nord (France), le coin SO <strong>de</strong> la Colombie<br />
Britannique (Vancouver), le Chili central entre les 25° <strong>et</strong> 35° <strong>de</strong><br />
latitu<strong>de</strong> sud, une gran<strong>de</strong> partie <strong>de</strong> la Patagonie argentine <strong>et</strong> les<br />
piedmonts orientaux <strong><strong>de</strong>s</strong> An<strong><strong>de</strong>s</strong> entre les 30° <strong>et</strong> 45° parallèles sud.<br />
Presque toute l’Australie du Sud, 1/4 sud-ouest <strong><strong>de</strong>s</strong> Nouvelles Galles<br />
du Sud <strong>et</strong> la moitié occi<strong>de</strong>ntale <strong>de</strong> Victoria <strong>et</strong> 1/3 SO <strong>de</strong> l’Australie<br />
<strong>de</strong> l’Ouest. On a ainsi montré la gran<strong>de</strong> similitu<strong>de</strong> bioclimatique<br />
entre la partie ouest du Great Basin, la région Aralo-Caspienne <strong>et</strong><br />
la Patagonie, confirmée, si besoin était, par <strong><strong>de</strong>s</strong> introductions <strong>de</strong><br />
plantes réussies <strong>et</strong> réciproques <strong>et</strong> par l’invasion d’espèces iranotouraniennes<br />
dans le Great Basin. Divers aspects <strong><strong>de</strong>s</strong> climats<br />
méditerranéens sont étudiés en détail montant <strong>et</strong> saisonnalité <strong><strong>de</strong>s</strong><br />
précipitations annuelles, évolution à long terme <strong><strong>de</strong>s</strong> précipitations<br />
annuelles, variabilité annuelle (inversement proportionnelle à la<br />
hauteur, mais variable dans une large proportion d’une région<br />
à l’autre). Les climats méditerranéens présentent <strong>de</strong>ux critères<br />
essentiels pour la vie <strong>et</strong> la répartition <strong><strong>de</strong>s</strong> plantes <strong>et</strong> <strong><strong>de</strong>s</strong> animaux :<br />
le bilan entre l’offre <strong>et</strong> la <strong>de</strong>man<strong>de</strong> d’eau (indice d’aridité) <strong>et</strong> le<br />
stress thermique représenté par le froid hivernal (ou son absence).<br />
Le premier se mesure par le rapport entre les précipitations <strong>et</strong><br />
l’évapotranspiration potentielle (évaluée par lysimètre ou calculée<br />
au moyen <strong>de</strong> l’équation <strong>de</strong> Penman, (P/ETPp) <strong>et</strong> le second par la<br />
moyenne <strong><strong>de</strong>s</strong> températures minimales journalières du mois le plus<br />
froid (janvier dans l’hémisphère Nord, juill<strong>et</strong> dans l’hémisphère<br />
Sud). Les précipitations n’offrent aucune tendance évolutive à long<br />
terme au cours <strong><strong>de</strong>s</strong> 170 ans pour lesquels <strong><strong>de</strong>s</strong> mesures existent.<br />
Mais il existe <strong><strong>de</strong>s</strong> tendances positives <strong>et</strong> négatives à moyen terme<br />
(25-50 ans). La température planétaire à long terme a augmenté<br />
d’environ 0,5 °C en 100 ans ; elle est probablement <strong>de</strong> moins <strong>de</strong> la<br />
moitié <strong>de</strong> ce chiffre pour les latitu<strong><strong>de</strong>s</strong> méditerranéennes (25°-45° N<br />
<strong>et</strong> S), ce qui correspond à l’augmentation <strong>de</strong> température attribuée<br />
à l’urbanisation, mais elle est beaucoup plus élevée au-<strong>de</strong>là <strong><strong>de</strong>s</strong><br />
latitu<strong><strong>de</strong>s</strong> <strong>de</strong> 45° (<strong>de</strong> 1 à 1,5 °C entre 50° <strong>et</strong> 60° <strong>de</strong> latitu<strong>de</strong> N <strong>et</strong> S).<br />
De fait, aucune évolution à long terme <strong>de</strong> la température n’a encore<br />
pu être mise en évi<strong>de</strong>nce sous les latitu<strong><strong>de</strong>s</strong> méditerranéennes quel<br />
que soit le continent considéré, ce qui n’implique pas qu’elle ne le<br />
soient dans un avenir prévisible.<br />
L’indice d’aridité (P/ETPp) perm<strong>et</strong> <strong>de</strong> distinguer 7 zones<br />
méditerranéennes principales en fonction <strong>de</strong> l’aridité, selon la<br />
terminologie d’Emberger, reprise dans la carte mondiale <strong><strong>de</strong>s</strong><br />
zones ari<strong><strong>de</strong>s</strong> <strong>de</strong> l’Unesco :<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
ANALYSES D’OUVRAGES ◆<br />
— hyperhumi<strong>de</strong> (P > ETPp),<br />
— humi<strong>de</strong> (ETPp > P > 0,70 ETPp) ,<br />
— sub-humi<strong>de</strong> (0,70 ETPp > P > 0,45 ETPp),<br />
— semi-ari<strong>de</strong> (0,45 ETPp > P > 0,28 ETPp),<br />
— ari<strong>de</strong> (0,28 ETPp > P > 0,07 ETPp),<br />
— hyper-ari<strong>de</strong> (0, 07 ETPp > P > 0,03 ETPp)<br />
—<strong>et</strong> érémitique (0,03 ETPp > P),<br />
Les limites entre ces zones sont déterminées empiriquement<br />
par la répartition <strong>de</strong> la végétation naturelle, <strong><strong>de</strong>s</strong> cultures <strong>et</strong> <strong><strong>de</strong>s</strong><br />
systèmes <strong>de</strong> production agricole <strong>et</strong> d’élevage <strong>et</strong> la géomorphologie,<br />
comme le préconisait Emberger. Les déserts méditerranéens<br />
se caractérisent par le fait que les rares pluies qui y tombent surviennent<br />
toujours en hiver, contrairement aux déserts tropicaux<br />
(à pluies d’été) <strong>et</strong> tempérés (à régime pluviométrique saisonnier<br />
équilibré).<br />
L’indice <strong>de</strong> stress thermique hivernal est la moyenne <strong><strong>de</strong>s</strong><br />
températures minimales journalières du mois le plus froid (janvier<br />
dans l’hémisphère Nord, juill<strong>et</strong> dans l’hémisphère Sud). Ce<br />
paramètre est étroitement corrélé avec le nombre annuel <strong>de</strong> jours<br />
<strong>de</strong> gel, donnée plus difficile à rencontrer <strong>et</strong> souvent indisponible.<br />
Il perm<strong>et</strong> <strong>de</strong> distinguer 8 tranches <strong>de</strong> 2 °C <strong>de</strong>puis l’extrêmement<br />
chaud (m > +9 °C) jusqu’à l’extrêmement froid (m < -5 °C). Les<br />
raisons du choix <strong>de</strong> ces critères sont données en détail ; on ne peut<br />
s’y étendre ici. Disons cependant que m = -5 °C correspond à la<br />
limite supérieure <strong><strong>de</strong>s</strong> arbres dans les hautes montagnes méditerranéennes<br />
<strong>et</strong> que m > +9 °C correspond à l’absence <strong>de</strong> gel sous abri<br />
<strong>et</strong> à la dominance concomitante d’espèces végétales <strong>et</strong> <strong>de</strong> cultures<br />
d’affinité tropicale lorsque l’eau est disponible. Dans le premier<br />
cas, la température moyenne mensuelle du mois le plus froid est<br />
d’environ 0 °C, <strong>et</strong> 15° C dans le second, mais c<strong>et</strong>te relation est peu<br />
fiable. Ces tranches thermiques sont empiriquement justifiées par<br />
la présence ou l’absence <strong>de</strong> certaines espèces spontanées, <strong>de</strong> cultures<br />
<strong>et</strong> d’animaux. Nous avons ainsi une matrice orthogonale <strong>de</strong><br />
(7 x 8 ) 56 bioclimats méditerranéens principaux. Des variantes <strong>et</strong><br />
nuances peuvent être ajoutées en faisant intervenir la saisonnalité<br />
<strong><strong>de</strong>s</strong> précipitations, leur variabilité, les précipitations occultes, la<br />
moyenne <strong><strong>de</strong>s</strong> températures maximales journalières du mois le plus<br />
froid, le nombre <strong>de</strong> jours <strong>de</strong> gel, les dates moyennes du premier <strong>et</strong><br />
<strong>de</strong>rnier gel annuel, <strong>et</strong>c. Il s’agit donc d’un système <strong>de</strong> classification<br />
« ouvert » qui peut s’adapter aux nécessités locales, car on ne<br />
peut tout prévoir ! Ces différentes catégories peuvent s’i<strong>de</strong>ntifier<br />
visuellement <strong>et</strong> <strong>de</strong> manière quasi instantanée par l’examen <strong><strong>de</strong>s</strong><br />
graphiques ombro-thermiques ou ombro-diapnéiques montrant<br />
la marche mensuelle <strong><strong>de</strong>s</strong> précipitations <strong>et</strong> <strong><strong>de</strong>s</strong> températures <strong>et</strong> <strong><strong>de</strong>s</strong><br />
évapo-transpirations potentielles (c<strong>et</strong>te relation, inventée il y a 170<br />
ans par l’agronome A. <strong>de</strong> Gasparin est utilisée partout <strong>de</strong>puis<br />
les années 1950, suite à la « ré-invention » du concept par les<br />
botanistes <strong>et</strong> phytogéographes toulousains Gaussen <strong>et</strong> Bagnouls).<br />
Dans ces graphiques les précipitations moyennes mensuelles <strong>et</strong><br />
l’ETPp sont représentées sur une échelle double <strong><strong>de</strong>s</strong> températures<br />
moyennes (P = 2 t), ou encore (P = 0,35 ETPp). Ce <strong>de</strong>rnier<br />
critère a été établi par Le Houérou <strong>et</strong> Popov dans une étu<strong>de</strong> sur<br />
la bioclimatologie <strong>de</strong> l’Afrique, publiée par la FAO en 1981. Les<br />
<strong>de</strong>ux critères coïnci<strong>de</strong>nt dans 98 % <strong><strong>de</strong>s</strong> cas en zone isoclimatique<br />
méditerranéenne. À partir <strong>de</strong> ces critères on déduit que statistiquement<br />
ETPp (mm) ~ 0,19 °C à l’échelle journalière pour<br />
les zones où le vent est faible (< 5 m/s en moyenne) soit ETPp<br />
~ 70 T à l’échelle annuelle. Une température moyenne annuelle<br />
<strong>de</strong> 20 °C correspond donc, pour ces zones peu ventées, à une<br />
ETPp annuelle <strong>de</strong> 1 400 mm/ an.<br />
Dans les zones très ventées, comme le Sahara ou la Patagonie,<br />
ce rapport peut être beaucoup plus élevé (20 à 60 % supérieur,<br />
en raison <strong>de</strong> l’importance locale du terme aérodynamique <strong>de</strong><br />
l’équation <strong>de</strong> Penman dans l’évapotranspiration globale <strong>de</strong> référence<br />
(ETo). Ainsi définies, les zones méditerranéennes possè<strong>de</strong>nt<br />
une flore d’environ 75 000 espèces vasculaires (plantes à fleurs<br />
<strong>et</strong> fougères) dont 54 % sont endémiques, c’est-à-dire limitées<br />
aux territoires méditerranéens. Ce nombre d’espèces représente<br />
25 % <strong>de</strong> la flore terrestre sur 12 % du territoire <strong>de</strong> la planète.<br />
Pour fixer les idées, disons que la France possè<strong>de</strong> environ 4 500<br />
espèces, dont 3 500 sont présentes dans la zone méditerranéenne<br />
(2 800 en Corse), l’Espagne l’Italie <strong>et</strong> la Grèce possè<strong>de</strong>nt quelque<br />
5 500 espèces chacune, l’Afrique du Nord 7 200, la Turquie<br />
11 000, Flora palaestina 3 000, <strong>et</strong>c. Par ailleurs, on estime que les<br />
5 % plus érudits botanistes peuvent instantanément reconnaître<br />
<strong>et</strong> nommer <strong>de</strong> mémoire environ 5 000 espèces.<br />
Certaines régions méditerranéennes offrent une richesse<br />
considérable : la région du Cap s.l. 12 000 espèces, l’Australie <strong>de</strong><br />
l’Ouest 10 000. Ces <strong>de</strong>ux territoire présentent un taux d’endémicité<br />
<strong>de</strong> 80 %. Le bassin méditerranéen au sens large comprend<br />
25 000 dont 60 % d’endémiques <strong>et</strong> la région irano-touranienne<br />
17 000 espèces, dont 30 % d’endémiques. En richesse aréale<br />
spécifique le Cap arrive très largement en tête avec 600 espèces<br />
par 10 000 km 2 <strong>et</strong> le Fynbos (équivalent <strong><strong>de</strong>s</strong> garrigues en<br />
Afrique du Sud) avec 1 000 espèces par 10 000 km 2 (France 90).<br />
Il faut noter que les très riches flores du Cap <strong>et</strong> <strong>de</strong> l’Australie <strong>de</strong><br />
l’Ouest correspon<strong>de</strong>nt à <strong><strong>de</strong>s</strong> terres oligotrophes, très pauvres sur<br />
le plan <strong>de</strong> la nutrition minérale, avec <strong><strong>de</strong>s</strong> pH tombant parfois à<br />
3,0. Ce fait entraîne <strong><strong>de</strong>s</strong> adaptations très originales <strong><strong>de</strong>s</strong> systèmes<br />
d’assimilation minérale. Des espèces endémiques y sont parfois<br />
cantonnées à <strong><strong>de</strong>s</strong> zones <strong>de</strong> quelques km 2 .<br />
L’ouvrage étudie ainsi <strong>de</strong> façon détaillée, outre les climats,<br />
les flores, les végétations, les cultures (y compris ornementales)<br />
<strong>et</strong> la présence d’espèces exotiques naturalisées <strong>et</strong> leur importance<br />
dans les flores locales (environ 10 % du nombre d’espèces<br />
régionales, en moyenne). Les succès <strong>et</strong> les échecs <strong>de</strong> transfert<br />
transcontinentaux d’espèces d’une zone méditerranéenne à<br />
l’autre sont examinés. Ces échanges ont donné lieu à <strong><strong>de</strong>s</strong> succès<br />
spectaculaires en partie dus à l’émigration <strong>de</strong> populations humaines<br />
méditerranéennes au Nouveau Mon<strong>de</strong> <strong>et</strong> en Australie (Acacia australiens,<br />
Agropyron spp, Amandier, Artichaut, Asperge, Atriplex,<br />
Eucalyptus, Luzerne, Olivier, Vigne, <strong>et</strong>c.). On note aussi l’invasion<br />
d’espèces comme le brome <strong><strong>de</strong>s</strong> toits ou cheat grass (Bromus<br />
109<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 107-110
◆ ANALYSES D’OUVRAGES<br />
110<br />
tectorum), <strong>de</strong>venu au siècle <strong>de</strong>rnier une peste dans les parcours<br />
du NW <strong><strong>de</strong>s</strong> USA ainsi que d’autres espèces irano-touraniennes.<br />
On note aussi <strong><strong>de</strong>s</strong> échecs cuisants (Tamarugo, Jojoba, Maireana,<br />
Mulga). Ces échecs résultent en général d’un manque <strong>de</strong> prise<br />
en compte suffisant <strong><strong>de</strong>s</strong> spécificités bioclimatiques ou édaphiques<br />
<strong><strong>de</strong>s</strong> espèces concernées.<br />
La classification phytogéographique proposée prend en considération<br />
les critères climatiques, floristiques, végétationnels <strong>et</strong><br />
agronomiques. Elle élève la zone phytogéographique méditerranéenne,<br />
jusqu’ici considérée comme une simple région, au rang<br />
supérieur <strong>de</strong> royaume. Nous avons ainsi : un empire holarctique,<br />
lequel inclut les royaumes euro-sibérien <strong>et</strong> méditerranéen, entre<br />
autres. Ce <strong>de</strong>rnier comprend 7 régions : bassin méditerranéen,<br />
saharo-arabique, Asie moyenne (aralo-caspienne ou iranotouranienne),<br />
région du Cap, Californie <strong>et</strong> Great Basin, Chili-<br />
Argentine, Sud-Est <strong>et</strong> Sud-Ouest australiens. C<strong>et</strong>te classification<br />
est différente dans sa conception <strong>de</strong> celle <strong>de</strong> Takhtajan, mais reste<br />
compatible avec elle dans son résultat.<br />
Restoration Ecology: the new frontier<br />
J. Van An<strong>de</strong>l & J. Aronson (eds.)<br />
Blackwell Publishing, USA: 319 p. (2006)<br />
This book explores the interface b<strong>et</strong>ween restoration ecology<br />
and ecological restoration. It aims at introducing to interactions<br />
b<strong>et</strong>ween theory and practice. It challenges ecologist to explore the<br />
applicability of current theories and concepts, recognizing that<br />
these have not been <strong>de</strong>veloped with such applications in mind.<br />
The aca<strong>de</strong>mic foundations of restoration ecology are revisited for<br />
this purpose, to pave the way towards a review of the causes of<br />
successes and failures and to i<strong>de</strong>ntify the perspectives of ecological<br />
restoration in different ecosystem types. These are <strong>de</strong>alt with<br />
biome-by-biome and consi<strong>de</strong>red from the historical perspective<br />
of land use. The final section addresses problems of ecological<br />
restoration in a soci<strong>et</strong>al context, ecological restoration is meant<br />
to achieve sustainable, resilient and interconnected ecosystems<br />
and socioecological systems. This will result in newly emerging<br />
ecosystems.<br />
The originality of this book comparing to the previous<br />
published in restoration ecology is that a lot of chapters are<br />
case studies from Europe and not only from North-America.<br />
Nevertheless only one chapter is <strong>de</strong>voted to Mediterranean ecosystems<br />
(Restoration of Mediterranean woodlands, pp. 193-207).<br />
As a conclusion this book is a good introduction for Masters and<br />
Ph. D stu<strong>de</strong>nts, teachers, researchers and natural-resource managers<br />
to the theory and practices of ecological restoration.<br />
Cartografia geobotanica<br />
F. Pedrotti<br />
Pitagora editrice, bologna: 236 p. (2004).<br />
email : pited@pitagoragroup.it<br />
Ce livre, rédigé par Franco Pedrotti, professeur à l’Université <strong>de</strong><br />
Camerino (Italie) se propose <strong>de</strong> dresser un panorama <strong><strong>de</strong>s</strong> différentes<br />
métho<strong><strong>de</strong>s</strong> <strong>et</strong> techniques utilisables pour la cartographie <strong>de</strong> la végétation.<br />
Il repose sur le fruit d’une longue expérience <strong>de</strong> l’auteur, dans le<br />
cadre <strong>de</strong> la spatialisation <strong><strong>de</strong>s</strong> données <strong>de</strong> la flore <strong>et</strong> <strong>de</strong> la végétation, <strong>et</strong><br />
<strong>de</strong> très nombreux exemples sont donc issus <strong>de</strong> ses travaux antérieurs.<br />
Ce traité présente la cartographie <strong><strong>de</strong>s</strong> divers niveaux d’organisation <strong>de</strong><br />
la flore <strong>et</strong> <strong>de</strong> la végétation, <strong>de</strong>puis l’espèce (individus <strong>et</strong> populations)<br />
jusqu’aux unités phytogéographiques supérieures.<br />
L’ouvrage est divisé en 14 chapitres, d’inégale importance<br />
(le chapitre 3, consacré à la « cartographie synusiale » ne comporte<br />
qu’une seule page…). L’auteur débute par un chapitre introductif<br />
présentant la cartographie géobotanique, puis développe les<br />
aspects cartographiques au niveau <strong><strong>de</strong>s</strong> populations (chapitre 2) <strong>et</strong><br />
<strong>de</strong> l’ensemble <strong>de</strong> l’aire <strong>de</strong> distribution d’une espèce (chapitre 4).<br />
Les quatre chapitres suivants sont consacrés à la cartographie <strong>de</strong><br />
la végétation, <strong>et</strong> <strong>de</strong> nombreux exemples <strong>de</strong> cartes sont fournis. Le<br />
chapitre 9 est dévolu à la cartographie phytogéographique, avec<br />
quelques exemples <strong>de</strong> cartes <strong>de</strong> subdivision phytogéographique<br />
(Mon<strong>de</strong>, Espagne, Italie). Les <strong>de</strong>rniers chapitres concernent plus<br />
particulièrement les apports <strong>de</strong> la cartographie géobotanique à la<br />
gestion environnementale <strong>et</strong> à la conservation <strong><strong>de</strong>s</strong> territoires. Une<br />
bibliographie assez riche termine c<strong>et</strong> ouvrage.<br />
Au final, il s’agit d’un travail <strong><strong>de</strong>s</strong>criptif <strong>et</strong> qui abor<strong>de</strong> les<br />
thèmes classiques <strong>de</strong> la géobotanique, souvent sur une base<br />
phytosociologique, sans réellement proposer <strong>de</strong> méthodologies<br />
claires ; sur quelles bases, par exemple, les cartes <strong>de</strong> subdivisions<br />
phytogéographiques (chapitre 9) s’opèrent-elles ? Et le traitement<br />
<strong>de</strong> la cartographie <strong>de</strong> la biodiversité végétale en trois pages est<br />
bien décevant, alors que <strong>de</strong> nombreux travaux récents existent !<br />
Le plus dommageable est l’absence <strong>de</strong> prise en compte <strong><strong>de</strong>s</strong><br />
développements récents issus <strong>de</strong> la modélisation biogéographique<br />
(analyses DIVA, Parsimony Analysis of En<strong>de</strong>micity…) qui ont<br />
permis <strong><strong>de</strong>s</strong> avancées significatives dans ce domaine, sans parler<br />
<strong>de</strong> la phylogéographie qui n’est même pas évoquée… Il manque<br />
en fait clairement tout le vol<strong>et</strong> concernant la simulation <strong>de</strong> la<br />
répartition géographique <strong><strong>de</strong>s</strong> espèces <strong>et</strong> <strong>de</strong> la végétation ; c<strong>et</strong>te<br />
thématique est pourtant en plein essor (voir A. Guisan, 2003,<br />
Saussurea 33, pour une synthèse récente en français), notamment<br />
dans le cadre <strong><strong>de</strong>s</strong> étu<strong><strong>de</strong>s</strong> <strong>de</strong> la réponse biotique face aux<br />
changements globaux.<br />
THIERRY DUTOIT<br />
UMR INRA-UAPV 406<br />
Écologie <strong><strong>de</strong>s</strong> invertébrés<br />
IUT, Université d’Avignon <strong>et</strong> <strong><strong>de</strong>s</strong> <strong>Pays</strong> <strong>de</strong> <strong>Vaucluse</strong><br />
FRÉDÉRIC MÉDAIL<br />
Institut méditerranéen d’écologie <strong>et</strong> <strong>de</strong> paléoécologie<br />
(IMEP, UMR CNRS 6116),<br />
Université Paul-Cézanne-Aix-Marseille III.<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
Résumés <strong>de</strong> thèse<br />
Carey M. Suehs<br />
Facteurs écologiques <strong>et</strong> évolutifs influençant<br />
les processus d’invasion chez Carpobrotus (Aizoaceae)<br />
en région méditerranéenne<br />
Thèse <strong>de</strong> doctorat en sciences soutenue le 8 juill<strong>et</strong> 2005<br />
à l’université Paul-Cézanne / Aix-Marseille III,<br />
Institut méditerranéen d’écologie <strong>et</strong> <strong>de</strong> paléoécologie<br />
(IMEP, UMR-CNRS 6116)<br />
Jury<br />
Frédéric Médail (maître <strong>de</strong> conférences, université Paul-Cézanne, directeur<br />
<strong>de</strong> thèse), Laurence Affre (maître <strong>de</strong> conférences, université Paul-Cézanne,<br />
co-directrice <strong>de</strong> thèse), Carla M. d’Antonio (professeur, rapporteur), John<br />
Thompson (directeur <strong>de</strong> recherche, rapporteur), Serge Muller (professeur,<br />
examinateur), Jacques Maill<strong>et</strong> (professeur, examinateur).<br />
Malgré la présence <strong>de</strong> Carpobrotus edulis <strong>et</strong> C. affine acinaciformis<br />
sur les côtes méditerranéennes françaises <strong>de</strong>puis 200 ans, peu<br />
d’étu<strong><strong>de</strong>s</strong> ont abordé la dynamique d’invasion <strong>de</strong> ces plantes grasses<br />
d’origine sud-africaine. La prise en compte à la fois du rôle<br />
<strong><strong>de</strong>s</strong> caractères génétiques <strong>et</strong> reproducteurs, <strong>de</strong> la forte fréquence<br />
d’hybridation, <strong><strong>de</strong>s</strong> pollinisateurs indigènes <strong>et</strong> <strong>de</strong> la dissémination<br />
<strong><strong>de</strong>s</strong> graines par <strong><strong>de</strong>s</strong> mammifères introduits en liaison avec les phénomènes<br />
liés à l’insularité, suggère que l’invasion <strong><strong>de</strong>s</strong> Carpobrotus<br />
spp. constitue un phénomène complexe <strong>et</strong> évolutif qui a pour<br />
conséquence <strong><strong>de</strong>s</strong> changements profonds au sein <strong><strong>de</strong>s</strong> écosystèmes<br />
insulaires envahis. Ceci résulte, notamment, en une diminution du<br />
pourcentage d’abondance <strong>de</strong> divers groupes d’espèces végétales,<br />
en une transformation du sol dans le cas <strong>de</strong> C. affine acinaciformis,<br />
en une restructuration <strong><strong>de</strong>s</strong> réseaux <strong><strong>de</strong>s</strong> pollinisateurs <strong>et</strong> en une<br />
facilitation <strong><strong>de</strong>s</strong> mammifères introduits. La plus forte fréquence<br />
d’occurrence <strong>de</strong> C. edulis dans le sud-est <strong>de</strong> la France par rapport<br />
à C. affine acinaciformis est potentiellement expliquée par <strong><strong>de</strong>s</strong><br />
différences génétiques <strong>et</strong> reproductrices entre ces <strong>de</strong>ux taxons.<br />
Plusieurs indications d’hybridations fréquentes pourraient expliquer<br />
une partie <strong>de</strong> la nature envahissante <strong>de</strong> ces <strong>de</strong>ux xénophytes,<br />
leurs changements par rapport à leur aire d’origine, <strong>et</strong> leur fort<br />
potentiel évolutif avec possibilité <strong>de</strong> polyploïdisation. L’ensemble<br />
<strong>de</strong> ces résultats suggère que l’étu<strong>de</strong> <strong>de</strong> la biologie évolutive <strong><strong>de</strong>s</strong><br />
espèces envahissantes est nécessaire pour mieux comprendre les<br />
processus d’invasion <strong>et</strong> l’évolution contemporaine.<br />
Mots-clés : Carpobrotus, endozoochorie, évolution, invasion biologique,<br />
hybridation, pollinisateur, structure génétique, système<br />
<strong>de</strong> reproduction, xénophyte.<br />
Buisson Elise<br />
Ecological restoration of Mediterranean plant<br />
communities: case studies in Southern France<br />
and Coastal California (USA)<br />
Thèse <strong>de</strong> doctorat en sciences soutenue le 20 septembre 2005<br />
à l’université Paul-Cézanne / Aix-Marseille III, Institut méditerranéen<br />
d’écologie <strong>et</strong> <strong>de</strong> paléoécologie (IMEP, UMR-CNRS 6116)<br />
Jury<br />
Thierry Dutoit (professeur, université d’Avignon), Emmanuel Corck<strong>et</strong><br />
(MCF, université Bor<strong>de</strong>aux 1), directeur <strong>et</strong> co-directeur ; Karen Holl<br />
(professeur, university Santa Cruz, California, USA), Richard Michal<strong>et</strong><br />
(professeur, université Bor<strong>de</strong>aux 1), rapporteurs ; Thierry Tatoni (professeur,<br />
université Paul-Cézanne), James Aronson (directeur <strong>de</strong> recherche,<br />
CNRS-CEFE Montpellier), examinateurs ; Sean An<strong>de</strong>rson (docteur,<br />
Stanford University), Grey Hayes (docteur, Elkhorn Slough National<br />
Estuarine Research Reserve, USA), membres invités.<br />
Disturbances, events that change the structure of an entity<br />
(ecosystem, community, population) by modifying resources,<br />
substrates or physical environments, are a major factor in entity<br />
dynamics. Resilience is the ability of the entity to resist or recover<br />
from an exogenous disturbance (originating from outsi<strong>de</strong> forces<br />
while an endogenous disturbance originates within the entity<br />
and is thus a part of its “normal” functioning). Disturbances are<br />
studied because they are at the heart of theories in community<br />
ecology. They maintain spatial h<strong>et</strong>erogeneity and biodiversity<br />
dynamics but the mechanisms through which they function<br />
have y<strong>et</strong> to be more comprehensively <strong><strong>de</strong>s</strong>cribed. The concept of<br />
resilience is important because it is linked to that of stability and<br />
to (functional) biodiversity. Its study helps un<strong>de</strong>rstanding the<br />
relationships b<strong>et</strong>ween disturbance, biodiversity and ecosystem<br />
functioning.<br />
The absence or low long-term resilience of an ecosystem to an<br />
exogenous disturbance suggests that irreversibility thresholds have<br />
been crossed and that the ecosystem is dysfunctional. The second<br />
objective of this thesis is to use such an opportunity to isolate one<br />
or several functions and un<strong>de</strong>rstand b<strong>et</strong>ter the whole functioning<br />
of the ecosystem. Grassland species are introduced to <strong>de</strong>gra<strong>de</strong>d<br />
ecosystems as functions are manipulated (environmental factors<br />
such as soil fertility and stone cover and biotic factors such as<br />
grazing, comp<strong>et</strong>ition/facilitation of neighbor species). A factorial<br />
experiment allows for the isolation of each of the tested functions<br />
and for the un<strong>de</strong>rstanding of their combined effect. Both experiments<br />
were carried out in herbaceous ecosystems as they are a<br />
good study mo<strong>de</strong>l. They are wi<strong>de</strong>ly distributed and species-rich.<br />
They have been subjected to endogenous disturbances (e.g. graz-<br />
111<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 111-113
◆ RÉSUMÉS DE THÈSES<br />
112<br />
ing) un<strong>de</strong>r which they were formed and to exogenous disturbances<br />
un<strong>de</strong>r which they have recently been altered (plowing in<br />
the 19 or 20 th century). Both types of disturbances are relatively<br />
remnant. Mediterranean ecosystems are particularly interesting<br />
as they are species-rich (local hot-spot of biodiversity) and have<br />
a wi<strong>de</strong> vari<strong>et</strong>y of endogenous and exogenous disturbances. Our<br />
study sites thus inclu<strong>de</strong>d several Mediterranean grasslands in<br />
the plain of La Crau (South-Eastern France) and in California<br />
Central Coastal. Comparing similar mo<strong>de</strong>ls subjected to different<br />
conditions and histories allows a b<strong>et</strong>ter un<strong>de</strong>rstanding of some<br />
basic processes.<br />
In La Crau (South-Eastern France), melon cultivation (1965-<br />
1985) followed by cereal and alfafa cultivation greatly disturbed the<br />
steppe veg<strong>et</strong>ation. To assess the resilience of the steppe veg<strong>et</strong>ation,<br />
we studied the margins of three abandoned melon fields, all adjacent<br />
to the same remnant of steppe. Data on soil, above-ground veg<strong>et</strong>ation,<br />
seed bank, seed rain and seed dispersal by ants showed that<br />
resilience is low. This suggests that the presence of remnant patches<br />
of steppe do not play a role in propagule dissemination and that the<br />
ecosystem is dysfunctional. In or<strong>de</strong>r to b<strong>et</strong>ter un<strong>de</strong>rstand the functioning<br />
of the steppe, four ecosystem functions were manipulated<br />
in a factorial experiment: soil fertility, sheep grazing, stone percent<br />
cover and arable weed interactions. To do so, Thymus vulgaris and<br />
Brachypodium r<strong>et</strong>usum i<strong>de</strong>ntified as keystone species (perennial<br />
and dominant plant of the undisturbed steppe) were sown and<br />
transplanted on three plots on a fertility gradient: an abandoned<br />
melon field, an abandoned cereal field and a remnant patch of<br />
steppe. Results show that nutrient-rich/mycorrhizae-poor soil is<br />
not suitable for both steppe species (stress tolerant) to germinate.<br />
However, it is suitable to their establishment and growth if they<br />
are planted. Grazing strongly reduces seedling growth. Tall neighbors<br />
comp<strong>et</strong>e against both species for light. Shorter neighbors<br />
(cereal field) do not comp<strong>et</strong>e as much against Thymus. Restored<br />
stone percent cover plays a greater positive role on focal species<br />
growth where neighbors are short (cereal field). Results will be<br />
applied to ecological restoration.<br />
In coastal California, grasslands have been <strong>de</strong>gra<strong>de</strong>d by<br />
agriculture and over-grazing. There is no autogenic restoration,<br />
partly, because the reference ecosystem (coastal prairie) and seed<br />
sources are rare, and because exotic grasses and forbs are particularly<br />
invasive. Re-introduction of grazing alone does not make the<br />
ecosystem more resilient (grazing has a positive effect on native<br />
annual forbs, no effect on native sedges and grasses and a negative<br />
effect on native perennial forbs). In or<strong>de</strong>r to b<strong>et</strong>ter un<strong>de</strong>rstand<br />
the coastal grassland functioning, three ecosystem functions were<br />
manipulated in a factorial experiment: grazing, topsoil and exotic<br />
interactions. To do so, two keystone species (native Californian<br />
perennial species) were sown and transplanted on three sites: two<br />
sites for Danthonia california within seven km from the coast<br />
and two site for Nassella pulchra 25 km from the coast. Results<br />
show that heavy cattle grazing strongly reduces seedling growth,<br />
while light grazing (rabbits, ground squirrels and <strong>de</strong>er) may help<br />
it. However, within grazed plots, cattle <strong>de</strong>creases the negative<br />
effect of neighbors. Topsoil removal may not be necessary for<br />
plant establishment but may be useful in the long run. Results are<br />
discussed within the framework of ecological restoration.<br />
For both locations, disturbances and resilience have been i<strong>de</strong>ntified<br />
and <strong>de</strong>gra<strong>de</strong>d functions studied. A b<strong>et</strong>ter un<strong>de</strong>rstanding of<br />
ecosystem functioning shows, at an applied level, the functions<br />
that need to be manipulated to successfully re-introduce dominant<br />
grassland species to <strong>de</strong>gra<strong>de</strong>d ecosystems. Wh<strong>et</strong>her high biodiversity<br />
leads to b<strong>et</strong>ter ecosystem functioning is still being discussed.<br />
However, many ecosystem functions may only <strong>de</strong>pend on a few<br />
dominant species. One efficient ecological restoration strategy<br />
is to first improve habitats in or<strong>de</strong>r to restore major functions.<br />
Then, dominant species of the reference ecosystem (nurse plants)<br />
should be re-introduce in or<strong>de</strong>r to restore some other functions<br />
and facilitate the re-establishment of the whole biodiversity (e.g.<br />
plant and insects). Such a future study would be an opportunity<br />
to assess the role of positive biotic interactions (facilitation) in<br />
improving biodiversity within stressful conditions as well as the<br />
role of biodiversity on ecosystem functioning.<br />
Key-words: disturbance, resilience, plant dispersal, comp<strong>et</strong>ition,<br />
seed bank, seed rain, myrmecochory, comp<strong>et</strong>ition, facilitation,<br />
plant community, edge effect, ecological restoration, sheep grazing,<br />
dry grasslands, Mediterranean areas, California, Southern<br />
France.<br />
Ricouart Francine<br />
La gestion <strong>de</strong> l’espace <strong>et</strong> la prévention <strong><strong>de</strong>s</strong> incendies<br />
<strong>de</strong> forêt dans les Pyrénées méditerranéennes : paysage,<br />
diversité <strong><strong>de</strong>s</strong> Rhopalocères <strong>et</strong> réduction <strong>de</strong> combustible<br />
Thèse <strong>de</strong> doctorat en géographie soutenue le 19 septembre 2005<br />
à l’université <strong>de</strong> Toulouse-Le Mirail, UMR-CNRS 5602 GEODE<br />
(géographie <strong>de</strong> l’environnement), UFR sciences, espaces, sociétés,<br />
Département <strong>de</strong> géographie aménagement, Maison <strong>de</strong> la recherche,<br />
5 allées Antonio-Machado, 31058 Toulouse ce<strong>de</strong>x 01.<br />
Jury<br />
Thierry Dutoit (professeur, université d’Avignon), Jean-Pierre Lumar<strong>et</strong><br />
(professeur, université Montpellier), rapporteurs ; Jean-Charles Filleron<br />
(professeur, université Toulouse II), Jean-François Galtié (chargé <strong>de</strong><br />
recherche CNRS, Toulouse), examinateurs ; Jean-Paul Métailié (directeur<br />
<strong>de</strong> recherche CNRS, Toulouse), prési<strong>de</strong>nt ; Luc Legal (maître <strong>de</strong><br />
conférence, université Paul-Sabatier, Toulouse), directeur.<br />
Ce travail s’inscrit dans une problématique multiple qui<br />
traite <strong>de</strong> la question <strong><strong>de</strong>s</strong> incendies, <strong>de</strong> la gestion <strong>de</strong> l’espace <strong>et</strong> <strong>de</strong><br />
l’évaluation <strong><strong>de</strong>s</strong> impacts <strong><strong>de</strong>s</strong> coupures <strong>de</strong> combustible. Il vise à<br />
mieux comprendre les impacts <strong><strong>de</strong>s</strong> aménagements réalisés pour<br />
la gestion <strong><strong>de</strong>s</strong> milieux méditerranéens dans un but <strong>de</strong> DFCI<br />
(Défense <strong><strong>de</strong>s</strong> forêts contre les incendies), tant au niveau <strong>de</strong> la<br />
dynamique paysagère qu’au niveau <strong><strong>de</strong>s</strong> éventuels marqueurs <strong><strong>de</strong>s</strong><br />
modifications introduites par ces nouveaux milieux. Il vise aussi<br />
à proposer <strong><strong>de</strong>s</strong> outils aux acteurs locaux <strong>de</strong> l’aménagement pas-<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005
RÉSUMÉS DE THÈSES ◆<br />
toral <strong>et</strong> <strong>de</strong> la DFCI pour l’élaboration <strong><strong>de</strong>s</strong> aménagements futurs.<br />
C<strong>et</strong>te recherches s’appuie sur une analyse globale <strong><strong>de</strong>s</strong> milieux <strong>et</strong><br />
sur une approche fine <strong><strong>de</strong>s</strong> formations végétales <strong>et</strong> <strong>de</strong> la faune <strong>de</strong><br />
papillons. Les impacts paysagers <strong>et</strong> écologiques <strong><strong>de</strong>s</strong> réductions<br />
<strong>de</strong> combustibles sont appréciés à partir d’exemples localisés dans<br />
les Pyrénées-Orientales, représentatifs <strong><strong>de</strong>s</strong> milieux rencontrés en<br />
région forestière <strong>et</strong> sub-forestière méditerranéenne. Pour mesurer<br />
ces impacts, nous avons étudié la diversité biologique <strong>et</strong> nous<br />
avons choisi d’utiliser en particulier les Lépidoptères « diurnes »<br />
(Rhopalocères). Notre propos est ainsi essentiellement basé sur<br />
la mise en relation <strong>de</strong> ces populations avec les milieux évoqués.<br />
Pour réaliser une approche originale <strong>de</strong> classification hiérarchique<br />
selon les sites où les espèces sont relevées, ceux-ci ont été classés<br />
selon <strong>de</strong>ux critères écologiques, niveau d’ouverture du milieu<br />
<strong>et</strong> caractéristiques hygrométriques. À partir <strong>de</strong> la matrice ainsi<br />
constituée, nous obtenons une répartition théorique <strong><strong>de</strong>s</strong> espèces<br />
en six groupes fonctionnels, marqueurs théoriques <strong>de</strong> six types<br />
<strong>de</strong> milieu. C<strong>et</strong>te approche originale <strong>de</strong> classification hiérarchique<br />
appliquée aux relevés effectués indique <strong><strong>de</strong>s</strong> assemblages d’espèces,<br />
selon les zones, très proches du regroupement théorique.<br />
Par contre, la réorganisation obtenue dans les arbres par classe<br />
d’abondance ne nous perm<strong>et</strong> pas d’affirmer que nous obtenons<br />
une structure stable, car les espèces, pour une classe donnée, sont<br />
trop peu nombreuses. La cartographie <strong><strong>de</strong>s</strong> Rhopalocères perm<strong>et</strong><br />
<strong>de</strong> m<strong>et</strong>tre en relation les lieux, les dates <strong>et</strong> l’abondance <strong><strong>de</strong>s</strong> espèces<br />
inventoriées. Cela nous perm<strong>et</strong> également <strong>de</strong> visualiser rapi<strong>de</strong>ment<br />
les différences <strong>de</strong> faune entre les sites <strong>et</strong> entre les zones.<br />
Pour rechercher les facteurs qui établissent c<strong>et</strong>te répartition,<br />
nous avons réalisé une analyses discriminante par une analyse<br />
factorielle, multiple puis une classification <strong><strong>de</strong>s</strong> facteurs. La correspondance<br />
<strong><strong>de</strong>s</strong> Rhopalocères avec les plantes-hôtes relevées est<br />
réalisée par une analyse factorielle <strong><strong>de</strong>s</strong> correspondances binaires<br />
sur la matrice m<strong>et</strong>tant en relation Rhopalocères <strong>et</strong> plantes (198<br />
espèces végétales <strong>et</strong> 81 espèces <strong>de</strong> Rhopalocères en individus)<br />
suivie d’une classification hiérarchique.<br />
Nos résultats montrent que les aménagements <strong>de</strong> prévention<br />
entraînent <strong><strong>de</strong>s</strong> modifications <strong>de</strong> la faune locale. Mais, ces changements<br />
sont à m<strong>et</strong>tre en relation avec l’échelle <strong><strong>de</strong>s</strong> aménagements.<br />
La faune totale s’est enrichie d’espèces <strong>de</strong> milieux ouverts <strong>et</strong><br />
anthropisés. Les acquis <strong>de</strong> trois années <strong>de</strong> suivi ont permis <strong>de</strong><br />
vali<strong>de</strong>r l’utilisation <strong><strong>de</strong>s</strong> Lépidoptères comme marqueurs <strong><strong>de</strong>s</strong><br />
changements observés dans le cadre <strong>de</strong> la prévention <strong><strong>de</strong>s</strong> grands<br />
incendies <strong>de</strong> végétation. Les résultats apportés par ce travail<br />
sont encourageants quant à l’utilisation <strong><strong>de</strong>s</strong> Rhopalocères dans<br />
les étu<strong><strong>de</strong>s</strong> <strong><strong>de</strong>s</strong> impacts <strong><strong>de</strong>s</strong> mesures <strong>de</strong> gestion <strong>de</strong> l’espace sur la<br />
diversité biologique. Il serait maintenant important <strong>de</strong> poursuivre<br />
c<strong>et</strong>te étu<strong>de</strong> à long terme, incluant plusieurs cycles d’entr<strong>et</strong>ien<br />
(ouverture/ferm<strong>et</strong>ure) dont le brûlage dirigé, <strong>et</strong> en diversifiant les<br />
milieux suivis. Il faut que la base <strong>de</strong> données établie soit complétée<br />
par d’autres relevés suivant le même protocole. Une comparaison<br />
pourrait être faite entre les impacts <strong><strong>de</strong>s</strong> débroussaillements <strong>et</strong> ceux<br />
<strong><strong>de</strong>s</strong> incendies sur les populations <strong>de</strong> Rhopalocères.<br />
Mots-clés : déprise agro-pastorale, analyse structurale, bio-indicateurs,<br />
biodiversité, enfrichement, reboisement, politiques <strong>de</strong> gestion,<br />
analyses multi-variées, Pyrénées-Orientales, Albères, Aspres,<br />
Fenouillè<strong><strong>de</strong>s</strong>.<br />
113<br />
<strong>ecologia</strong> <strong>mediterranea</strong>, tome 31, fascicule 1, 2005, p. 111-113
ÉDISUD<br />
ÉCOLOGIE ❈ NATURE<br />
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Numéros thématiques<br />
Biologie <strong>de</strong> la conservation<br />
<strong>et</strong> <strong><strong>de</strong>s</strong> espaces naturels en Crau<br />
vol. 30 (1/2), 132 p., 2004, 31 €<br />
The sustainability of chesnut forest<br />
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vol. 26 (1/2), 179 p., 2000, 25 €<br />
Écologie <strong>et</strong> conservation <strong><strong>de</strong>s</strong> mares<br />
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Connaissance <strong>et</strong> conservation<br />
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vol. 16, 459 p., 1990, 20 €<br />
Offre spéciale sur les 4 volumes suivants :<br />
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Influence of fire on the stability<br />
of Mediterranean forest ecosystems<br />
vol. 13 (4), 196 p., 1987, 15 €<br />
Changements hydrologiques<br />
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vol. 11 (1), 236 p., 1985, 15 €<br />
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terrestres<br />
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Étu<strong><strong>de</strong>s</strong> écologiques<br />
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Découvrir le massif <strong>de</strong> Sainte-Victoire<br />
par son versant sud.<br />
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<strong>Pays</strong>ages <strong>de</strong> terrasses<br />
R. Ambroise, P. Frapa, S. Giorgis<br />
Photographies <strong>de</strong> V. Motte <strong>et</strong> R. Sauvaire<br />
Très beau livre illustré, hommage au travail <strong><strong>de</strong>s</strong> paysans<br />
qui ont transformé une nature parfois hostile<br />
en d’immenses jardins cultivés.<br />
24 x 30 cm • 192 p. • © 1989 • relié • nbr. photos N&B<br />
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FLORE<br />
La Connaissance <strong><strong>de</strong>s</strong> Succulentes<br />
<strong>et</strong> Xérophytes du Mon<strong>de</strong><br />
Francis <strong>et</strong> Martine Bugar<strong>et</strong><br />
Un ouvrage <strong>de</strong> référence fondamental<br />
par d’éminents spécialistes.<br />
Coll. “La Connaissance <strong>de</strong>…” • 17 x 24 cm • 408 p.<br />
• © 2006 • cartonné • très nombr. ill. couleur • 33 €<br />
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La Végétation <strong>de</strong> la Corse<br />
Jacques Gamisans<br />
Un ouvrage <strong>de</strong> référence fondamental par le plus<br />
éminent spécialiste actuel sur la question.<br />
16 x 24 cm • 408 p. • © 1999 - 2003 • broché • ill. N & B<br />
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La Flore endémique <strong>de</strong> la Corse<br />
Jacques Gamisans – Jean-François Marzocchi<br />
Chaque espèce, i<strong>de</strong>ntifiée par une photographie,<br />
est décrite avec ses noms latin, corse <strong>et</strong> français,<br />
l’indication <strong>de</strong> la famille, la pério<strong>de</strong> <strong>de</strong> floraison,<br />
son aire géographique, son indice <strong>de</strong> rar<strong>et</strong>é,<br />
son écologie <strong>et</strong> sa répartition en Corse.<br />
Une liste exhaustive figure en fin d’ouvrage.<br />
16 x 22,5 cm • 192 p. • © 1996-2003 • broché avec rabats<br />
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La Flore <strong><strong>de</strong>s</strong> montagnes méditerranéennes<br />
Christian Boucher<br />
De l’Andalousie à l’Anatolie <strong>et</strong> au Proche-Orient,<br />
250 plantes décrites <strong>et</strong> illustrées.<br />
16 x 22,5 cm • 208 p. • © 2000 • 256 photos couleur<br />
• 3 cartes • broché avec rabats • 24,39 €<br />
• ISBN 2-7449-0146-6<br />
Flore du Verdon<br />
Un parc en fleurs<br />
Parc naturel régional du Verdon – Georges<br />
Guen<strong>de</strong><br />
Après présentation du parc, l’auteur décline, par secteur<br />
géographique, les espèces qui peuplent c<strong>et</strong>te région.<br />
16 x 22,5 cm • 192 p. • © 2004 • broché • ill. couleur<br />
• 20 € • ISBN 2-7449-0467-8<br />
Flore du Luberon<br />
Georges Guen<strong>de</strong><br />
Nouvelle édition. Encore relativement bien préservé,<br />
le Luberon offre à sa flore une gran<strong>de</strong> diversité <strong>de</strong> climat <strong>et</strong><br />
<strong>de</strong> types d’habitat.<br />
Coll. “Luberon Images <strong>et</strong> Signes” • 16,5 x 22,5 cm<br />
• 144 p. • © 1993-2004 •broché • nombr. ill. couleur<br />
• 15 € • ISBN 2-7449-0476-7<br />
Orchidées sauvages du Luberon<br />
Roland Martin<br />
Le Luberon, en Provence, offre aux orchidées un habitat<br />
<strong>et</strong> un climat privilégiés. Découvrir ces trésors<br />
<strong>de</strong> la nature est un enchantement.<br />
Coll. “Luberon Images <strong>et</strong> Signes” • 16,5 x 22,5 cm<br />
• 224 p. • © 2005 •broché • env. 200 photographies couleur<br />
• 15 € • ISBN 2-7449-0468-6<br />
Fleurs <strong>de</strong> Vanoise<br />
Parc national <strong>de</strong> la Vanoise<br />
Un gui<strong>de</strong> qui recense 615 espèces florales du massif<br />
<strong>de</strong> la Vanoise, dont 500 illustrées par <strong><strong>de</strong>s</strong> photographies<br />
couleur.<br />
12 x 18 cm • 320 p. • © 1993 • cartonné<br />
• 19,81 € • ISBN 2-85744-653-5<br />
Splen<strong>de</strong>ur <strong>et</strong> harmonie <strong><strong>de</strong>s</strong> plantes libres<br />
Pierre Vignes<br />
Grâce à <strong>de</strong> magnifiques planches photographiques,<br />
inhabituelles <strong>et</strong> originales, démarche scientifique<br />
<strong>et</strong> sens artistique s’allient à la découverte esthétique.<br />
22 x 30 cm • 160 p. • © 2004<br />
• 28,50 € • ISBN 2-7449-0450-3
Herbier vagabond<br />
Clau<strong>de</strong> Meslay<br />
Aquarelles <strong>de</strong> M.-F. Delarozière<br />
Une initiation variée <strong>et</strong> passionnante<br />
à la promena<strong>de</strong> botanique.<br />
22,5 x 26,5 cm • 160 p. • © 2002 • cartonné<br />
• aquarelles • 29 € • ISBN 2-7449-0331-0<br />
Herbier <strong><strong>de</strong>s</strong> bords <strong>de</strong> l’eau<br />
Clau<strong>de</strong> Meslay<br />
Aquarelles <strong>de</strong> M.-F. Delarozière<br />
150 plantes <strong><strong>de</strong>s</strong> lacs, étangs, mares, ruisseaux, canaux<br />
d’irrigation <strong>et</strong> leur voisinage immédiat. Un regard sur les<br />
zones aquatiques à la flore si riche.<br />
22,5 x 26,5 cm • 176 p. • © 2004 • cartonné<br />
• aquarelles • 29 € • ISBN 2-7449-0387-6<br />
FAUNE<br />
Le Thon <strong>de</strong> Méditerranée<br />
La saga d’un poisson mythique<br />
Patrick Mouton<br />
Le thon <strong>de</strong> Méditerranée effectue chaque année <strong>de</strong><br />
gran<strong><strong>de</strong>s</strong> migrations <strong>de</strong> plusieurs milliers d’individus.<br />
Une saga passionnante illustrée d’une iconographie<br />
abondante <strong>et</strong> variée.<br />
Coll. “Mémoire <strong>de</strong> mer” • 27 x 21 cm • 144 p. © 2004<br />
• cartonné sous jaqu<strong>et</strong>te • photos couleur <strong>et</strong> N&B<br />
• 26 € • ISBN 2-7449-0408-2<br />
Vie secrète au royaume montagne<br />
Les quatre saisons <strong>de</strong> la faune alpine<br />
Brys Bonnal – Préface Allain Bougrain Dubourg<br />
Saison après saison, <strong><strong>de</strong>s</strong> images sans équivalent,<br />
mais aussi un texte alliant avec beaucoup <strong>de</strong> finesse<br />
les atmosphères poétiques <strong>et</strong> les faits scientifiques.<br />
24 x 23 cm • 144 p. • © 1997 • cartonné • photos couleur<br />
• 22,10 € • ISBN 2-85744-917-8<br />
Faune du Luberon<br />
Max Gallardo<br />
Le Luberon offre à sa faune une gran<strong>de</strong> diversité <strong>de</strong><br />
climat <strong>et</strong> <strong>de</strong> types d’habitat. C<strong>et</strong> ouvrage perm<strong>et</strong> d’en<br />
abor<strong>de</strong>r la connaissance selon ses milieux les plus typés.<br />
Coll. “Luberon Images <strong>et</strong> signes” • 16,5 x 22,5 cm • 144 p.<br />
• © 1993 • broché • 13,73 € • ISBN 2-85744-663-2<br />
Le Luberon <strong><strong>de</strong>s</strong> insectes<br />
Parc naturel régional du Luberon<br />
Un aperçu <strong><strong>de</strong>s</strong> 17 000 espèces d’insectes répertoriées dans<br />
le Luberon. Environ 150 d’entre elles, parmi les plus<br />
significatives, sont citées, dont une centaine illustrées <strong>de</strong><br />
<strong><strong>de</strong>s</strong>sins, d’aquarelles <strong>et</strong> <strong>de</strong> gouaches.<br />
Coll. “Luberon Images <strong>et</strong> Signes” • 16,5 x 22,5 cm<br />
• 120 p. • © 1998 • broché • nbr. ill. couleur<br />
• 12,96 € • ISBN 2-7449-0058-3<br />
Garrigue secrète<br />
Patrick Lorne<br />
D’innombrables instants <strong>de</strong> vie <strong><strong>de</strong>s</strong> insectes <strong>de</strong> la<br />
garrigue, rythmés selon les quatre saisons. Chaque<br />
partie est introduite par un texte dans lequel l’auteur<br />
dévoile les mœurs <strong>de</strong> c<strong>et</strong>te micro-faune <strong>et</strong> ses propres<br />
observations.<br />
26 x 23 cm • 144 p. • © 1998 • relié sous jaqu<strong>et</strong>te<br />
• tout en couleur • 22 € • ISBN 2-7449-0035-4<br />
Les Insectes, amis <strong>de</strong> nos jardins<br />
Pourquoi <strong>et</strong> comment les protéger<br />
Vincent Albouy, Jean-Paul Delfino<br />
Coll. “Que la nature est belle !” • 17 x 23 cm • 136 p.<br />
• © 1995 • broché • 13,73 € • ISBN 2-85744-776-0<br />
L’ARBRE<br />
L’Arbre familier en Provence<br />
De la vocation du platane <strong>et</strong> <strong>de</strong> quelques autres arbres<br />
Annie-Hélène Dufour<br />
Photos Martin Johansen <strong>et</strong> Annie-Hélène Dufour<br />
Au travers <strong>de</strong> c<strong>et</strong> aperçu historique, le lecteur découvrira<br />
si le platane est réellement <strong>de</strong>venu l’élément végétal<br />
dominant, <strong>et</strong> quelle place il occupe dans les pratiques <strong>et</strong><br />
les représentations <strong><strong>de</strong>s</strong> Provençaux.<br />
16 x 24 cm • 112 p. • © 2001 • broché • photos couleur<br />
<strong>et</strong> N&B • 15,50 € • ISBN 2-7449-0296-9<br />
Le Livre <strong>de</strong> l’Olivier<br />
Marie-Claire Amour<strong>et</strong>ti, Georges Com<strong>et</strong><br />
Les aspects culturels, économiques <strong>et</strong> culturaux <strong>de</strong><br />
l’olivier en Méditerranée.<br />
224 p. • © 1999 • 15 € • ISBN 2-7449-0198-9-7<br />
Liège <strong>de</strong> Méditerranée<br />
Gérard Dessain, Margar<strong>et</strong> Ton<strong>de</strong>lier<br />
Le liège, ses mythes, ses utilisations. Un livre où<br />
découvrir origines, transformations, utilisations passées<br />
ou présentes du liège.<br />
21,5 x 29 cm • 80 p. • © 1991 • cartonné<br />
• 14,94 € • ISBN 2-85744-548-2<br />
Le Tilleul<br />
Arbre d’amour, arbre <strong>de</strong> liberté<br />
Guy Bontempelli<br />
Le point sur les croyances, superstitions, culture,<br />
utilisation du bois, vertus thérapeutiques <strong>de</strong> c<strong>et</strong> arbre<br />
symbole.<br />
24 x 27,5 cm • 168 p. • © 1989 • relié • 22,87 €<br />
• ISBN 2-907836-00-5<br />
Le Noyer <strong>et</strong> la noix<br />
J.-J. <strong>de</strong> Corcelles, J.-Y. Catherin <strong>et</strong> Robert Mazin<br />
Ce livre répond à toutes les questions que l’on peut se<br />
poser sur c<strong>et</strong> arbre <strong>et</strong> sur ce fruit secr<strong>et</strong> <strong>et</strong> méconnu.<br />
160 p. • © 1995 • 14,94 € • ISBN 2-85744-791-4<br />
Châtaignes <strong>et</strong> châtaigniers<br />
en régions méditerranéennes françaises<br />
G. Briane, C. Catoire, P. Challaye, J.-J. Gianni,<br />
R. <strong>et</strong> A. Sauvezon<br />
Tous les usages propres au châtaignier <strong>et</strong> à ses fruits,<br />
comment on peut sauver, aujourd’hui, le patrimoine<br />
qu’il constitue, en vivre, l’aimer.<br />
168 p.• © 2001 • 15,10 € • ISBN 2-7449-0186-5<br />
LA FORÊT<br />
La Futaie irrégulière<br />
Théorie <strong>et</strong> pratique <strong>de</strong> la sylviculture irrégulière,<br />
continue <strong>et</strong> proche <strong>de</strong> la nature<br />
Max Bruciamacchie, Brice <strong>de</strong> Turckheim<br />
Max Bruciamacchie, enseignant-chercheur à l’Engref,<br />
Nancy, <strong>et</strong> Brice <strong>de</strong> Turckheim, praticien forestier,<br />
associent ici leurs compétences pour présenter aux<br />
praticiens sylvicoles <strong>et</strong> à tous ceux qui s’intéressent<br />
au <strong>de</strong>venir <strong>de</strong> nos forêts, ce livre <strong><strong>de</strong>s</strong>tiné à gui<strong>de</strong>r leur<br />
réflexion.<br />
17 x 24 cm • broché • N&B <strong>et</strong> couleur • 288 p.<br />
• 29,50 € • ISBN 2-85744-304-8<br />
Incendies <strong>de</strong> forêt <strong>et</strong> argent public<br />
Paul-Henry Fleur<br />
Quelles interventions ? Quelle prévention ?<br />
Quels résultats ? Une enquête objective <strong>et</strong> sérieuse.<br />
192 p. • © 2004 • 18 € • ISBN 2-7449-0484-8<br />
L’Économie <strong>de</strong> la forêt<br />
Mieux exploiter un patrimoine<br />
Henri Prévôt<br />
Une nouvelle approche qui embrasse tous les aspects<br />
<strong>de</strong> la forêt. L’auteur explique le blocage dont souffre ce<br />
secteur économique. Puis, il propose <strong>de</strong> nouveaux outils<br />
financiers <strong>et</strong> <strong>de</strong> nouvelles relations commerciales.<br />
16 x 24 cm • 176 p. • © 1993 • broché<br />
• 19,52 € • ISBN 2-85744-651-9<br />
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