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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


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.