Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...
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dinacea L. with a minimum in winter meanwhile<br />
one species persisted (Glyceria plicata<br />
L.).<br />
In spite of a taxonomic richness more important<br />
in L3, it varied in the same manner as L2<br />
(Figure 3). However, new helophytes<br />
appeared such as Lycopus europaeus L., Nasturtium<br />
officinale R. BR., Phalaris arundinacea<br />
L., Phragmites australis (Cav.) Trin.<br />
ex, Polygonum persicaria L. and Veronica<br />
anagallis-aquatica L. The terrestrial species<br />
existing in spring, summer and autumn 2005,<br />
in this station, disappeared in winter and<br />
spring 2006.<br />
In L4 new hydrophytes (phanerogames)<br />
appeared such Myriophyllum spicatum L.,<br />
Potamog<strong>et</strong>on crispus L., Potamog<strong>et</strong>on pectinatus<br />
L. and Ranunculus fluitans Lam. (Figure<br />
3). However the hydrophytes were more<br />
abundant in spring and they decreased<br />
to reach a minimum in autumn 2005<br />
(1 hydrophyte, Potamog<strong>et</strong>on pectinatus L.)<br />
and winter 2006 (1 species Ranunculus fluitans<br />
Lam.). In addition, the helophytes were<br />
more numerous in spring and summer, while<br />
they disappeared totally in winter 2006.<br />
The terrestrial species were more numerous<br />
in summer 2005 and disappeared compl<strong>et</strong>ely<br />
from autumn 2005 to spring 2006.<br />
Macrophytic cover<br />
The average percentage of macrophytic cover<br />
and the composition of the communities differed<br />
at all stations (89% at L1, 40% at L2,<br />
73% at L3 and 44% at L4; Figure 4a).<br />
Hydrophyte dominated at L1 (54%) and L4<br />
(36%), helophyte were more abundant at L3<br />
(33%) and L2 was characterized by the<br />
absence of terrestrial species (Figure 4b).<br />
Seasonal changes were observed in all stations.<br />
The overall cover was greater in spring<br />
for L1 (100%) with a maximum of<br />
hydrophytes in spring 2006 (80%) (Figure 5).<br />
For L2, L3 and L4 the overall cover was<br />
greater in summer (100% for all stations) with<br />
a minimum in winter (10% at L2, 10% at L3<br />
and 1% at L4). Helophytes were more abundant<br />
in summer and autumn for L2, L3, while<br />
they presented a minimum in winter (Figure<br />
5).<br />
In L4 hydrophytes dominated at all seasons<br />
with a greater cover for all groups, especially<br />
in spring and summer and a minimal cover for<br />
all groups in winter when helophytes and terrestrial<br />
species disappeared totally (Figure 5).<br />
ecologia mediterranea <strong>–</strong> <strong>Vol</strong>. <strong>35</strong> <strong>–</strong> <strong>2009</strong><br />
Investigation on macrophyte development in Litani River (Lebanon) subjected to human disturbances<br />
Table 2 <strong>–</strong> List of the macrophytes growing at the four sites studied:<br />
A = algae, Ph = phanerogams.<br />
Species Co<strong>des</strong> of species L1 L2 L3 L4<br />
Hydrophytes<br />
A Chara sp. Char + - - -<br />
A Cladophora sp. Clad + + + +<br />
A Vaucheria sp. Vau + + + +<br />
Ph Lemna minor L. LemM + + + +<br />
Ph Myriophyllum spicatum L. MyrS - - - +<br />
Ph Potamog<strong>et</strong>on crispus L. PotC - - - +<br />
Ph Potamog<strong>et</strong>on pectinatus L. PotP - - - +<br />
Ph Ranunculus fluitans Lam. RanF + - - +<br />
Total (8) 5 3 3 7<br />
Hélophytes<br />
Ph Apium nodiflorum (L.) Lag. ApiN - + + +<br />
Ph Butomus umbellatus L. ButU - + + +<br />
Ph Cyperus eragrostis Lam. CypE - + + -<br />
Ph Cyperus longus L. CypL - + + -<br />
Ph Glyceria plicata (Fries) Fries GycP + + + +<br />
Ph Lycopus europaeus L. LycE - - + +<br />
Ph Nasturtium officinale R. Br. NasO - - + +<br />
Ph Phalaris arundinacea L. PhaA + + + +<br />
Ph Phragmites australis (Cav.) Trin.<br />
Ex Steudel PhrA + - + -<br />
Ph Polygonum persicaria L. PolP - - + +<br />
Ph Veronica anagallis-aquatica L. VeAa - - + -<br />
Total (11) 3 6 11 7<br />
Terrestrial species<br />
Ph Galium aparine L. GalA - - + -<br />
Ph Lactuca serriola L. LacS - - + -<br />
Ph Plantago major L. PlaM - - + +<br />
Ph Plantago minor L. PlaMn - - + +<br />
Ph Rumex crispus L. RumC - - + +<br />
Ph Rumex sp. Rum + - + +<br />
Ph Urtica dioica L. UrtD - - + -<br />
Ph Xanthium strumarium L. XanS - - + +<br />
Total (8) 1 0 8 5<br />
Total species (27) 9 9 22 19<br />
The Friedman’s Anova by ranks test and the<br />
Kruskal-Wallis test applied on macrophytic<br />
cover showed that the difference in seasonal<br />
variations of macrophytic cover is significant<br />
in each station (Friedman’s Anova:<br />
L1 p< 0.05; L2 p < 0.001; L3 p < 0.001;<br />
L4 p