Vol. 35 – 2009 - Ecologia Mediterranea - Université d'Avignon et des ...

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