Revue internationale d'écologie méditerranéenne International ...

SAMI YOUSSEF, ERROL VELA, ALEX BAUMEL, THIERRY TATONI
Appendix 2.3 – Cluster no 3
Species Frequence Family Biological Seeds Biological Demographic Biogeography
(%) cycle dispersal traits stratigies
Thymus vulgaris subsp. vulgaris 100 Lamiaceae Perennial Zele Ch S Steno-W-Medit.
Galium corrudifolium 94 Rubiaceae Perennial Zepi H S Steno-Medit.
Amelanchier ovalis (s.l.) 82 Rosaceae Perennial Zend P CS Medit.-Mont.
Lactuca perennis 82 Asteraceae Perennial Aleg H CS Euri-W-Medit.
Laserpitium gallicum 76 Apiaceae Perennial Alou H S NW-Medit.-Mont.
Ononis minutissima 76 Fabaceae Perennial AuM Ch S Steno-W-Medit.
Rosmarinus officinalis 76 Lamiaceae Perennial Zele p CSR Steno-Medit.
Brachypodium retusum 71 Poaceae Perennial Zepi Ch CS Steno-W-Medit.
Centranthus ruber 71 Valerianaceae Perennial Alou Ch CR Steno-Medit.
Juniperus phoenicea subsp. phoenicea 71 Pinaceae Perennial Zend P CS Euri-Medit.
Festuca marginata subsp. marginata 65 Poaceae Perennial Zepi H S Endem. W-Alpica
Helichrysum stoechas 65 Asteraceae Perennial Apro Ch S Steno-W-Medit.
Sedum sediforme 65 Crassulaceae Perennial Apro Ch S Steno-Medit.
Teucrium polium subsp. polium 65 Lamiaceae Perennial Zoochory Ch S Steno-Medit.
Sedum ochroleucon 59 Crassulaceae Perennial Hydr Ch S N-Medit.-Mont.
Sesleria caerulea 59 Poaceae Perennial Apro H CS Oroph. C-Europ.
Campanula rotundiflora subsp. macrorhiza 53 Campanulaceae Perennial Apro H S Endem. S-France
Euphorbia characias 47 Euphorbiaceae Perennial Zele p S Steno-Medit.
Catapodium rigidum subsp. rigidum 41 Poaceae Annual Baro Th SR Euri-Medit.
Coronilla juncea 41 Fabaceae Perennial AuM NP CSR Steno-W-Medit.
Reichardia picroides 41 Asteraceae Perennial Aleg H CS Steno-Medit.
Santolina chamaecyparissus 41 Asteraceae Perennial Apro Ch S N-Medit.-Mont.
Staehelina dubia 41 Asteraceae Perennial Aleg Ch S Steno-W-Medit.
Alyssum spinosum 35 Brassicaceae Perennial Baro Th S W-Medit.-Mont.
Anthyllis vulneraria (s.l.) 35 Fabaceae Annual, Perennial Alou Th, H SR Eurasiatic
Arabis collina 35 Brassicaceae Perennial Apro H S Medit.-Mont.
Asperula cynanchica (s.l.) 35 Rubiaceae Perennial Baro H S Euri-Medit.
Asterolinon linum-stellatum 35 Caryophyllaceae Annual Baro Th SR Steno-Medit.
Bupleurum baldense 35 Apiaceae Annual Apro Th SR Euri-Medit.
Helianthemum oelandicum subsp. incanum 35 Cistaceae Perennial Apro Ch SR Oroph. S-Europ.
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species, decreases as a consequence of trees
colonization, a global pattern of French
Mediterranean landscape change (Debussche
et al. 1999). However, our current knowledge
about the rate and extent of this dynamics in
Basse Provence, as well as dispersal capacities
of G. lobelii, are too scarce to evaluate if
trees colonization represents a real threat for
the persistence of G. lobelii.
In our study, the geological nature of substrate
does not seem to play an important role on the
population size variation of G. lobelii stations
as we observed the three classes of populations
size on each type of substrate (calcareous
or dolomie). However, our field investigations
revealed two geographical trends of
population size variation. First, the surface
occupied by G. lobelii populations regularly
increased with altitude (Figure 3). Above
800 m, near the summits of Sainte-Baume and
Sainte-Victoire mountains, G. lobelii becomes
one of the dominant species. In parallel, when
G. lobelii is found at lower altitude where
populations are smaller, the stations are in
northward exposures promoting the effects of
strong winds (S. Youssef, pers. obs.). Second,
the most isolated populations, found on the
north and south eastern limits, are also the
smallest (Figures 2 and 4). Postulating that
population size is an indicator of individual
fitness and observing that vegetation is different
between central and marginal stations,
we can hypothetize that geographically marginal
populations of G. lobelii, are situated
within non-optimal habitats. These populations
may suffer from non optimal conditions
of individual growth and reproduction in parallel
with genetic stochastic effects that could
reduce individual fitness (Honnay & Jacquemyn
2007). Genetic diversity analysis and
monitoring of reproduction and recruitment
phase are then necessary to check for potential
decrease of individual fitness in marginal
populations of G. lobelii. Cytogenetic studies
in relation to monitoring individual fitness
should also be conducted to investigate the
potential demographic effect of the complex
caryological nature of G. lobelii (Verlaque
1992). At least cost, a regular monitoring of
population size, particularly at the edge of its
distribution, should be a priority for conservation
of this rare species in a context of
global change.
ecologia mediterranea – Vol. 36 (1) – 2010