International Journal of Ecology and Environmental Sciences 27:
1-11, 2001
© International Scientific Publications, New Delhi
Analysis of Aquatic Vegetation in Islands of the Nile Valley (Egypt)
Monier M. Abd El-Ghani and Ahmad G. Fahmy
ABSTRACT
The vegetation on two sedimentary islands in the middle part of the river Nile (Egypt),
vary in age and size was described. Differences in species composition of macrophytes are
visualised by means of multivariate analysis. Based on cover values of 28 species from 44
sample plots, the TWINSPAN classification revealed 6 vegetation types (A-F), indicating 9
dominant communities. Their dominant species are Myriophyllum spicatum (submerged
hydrophyte), Eichhornia crassipes (free-floating hydrophyte), Vossia
cuspidata, Echinochloa stagnina, Persicaria salicifolia, Senecio aegyptius, Glinus
lotoides, Cyperus maculatus and Cyperus articulatus (emer-gents). On a
moisture gradient basis, the first DCA axis segregated these communities into two main
groups; wetlands and drylands. It also reflects a life form gradient, separating
vegetation types dominated by emergent species from free-floating and submerged. Canonical
correspondence analysis (CCA) indicated that soil moisture content, fine sediments,
electrical conductivity, Ca++, Mg++, K+ and Cl-
were the major edaphic factors correlated with species distribution on the studied
islands. The vegetation types dominated by Myriophyllum spicatum and Cyperus
articulatus were the least diversified among the other types. The species diversity
is discussed in the view of habitat heterogeneity and disturbance. A checklist of
macrophytes in the islands is appended.