VEGETATION ANALYSIS OF THE MEDITERRANEAN REGION OF NILE-DELTA

Thirty-four vegetation clusters identified in the present study, after the application of TWINSPAN and DCA multivariate techniques, were assigned into 8 vegetation types, each of definite vegetation and habitat characters. The suggested vegetation types are well segregated along the DCA axis one which reflects soil moisture, salinity (as indicated by EC values), fertility (as indicated by the organic matter and nitrogen contents) and species diversity gradients. In general, soil moisture and soil fertility increase and species diversity decreases with the following sequence of vegetation types: Echinops spinosissimus-Ononis serrata on inland sand dunes, Pancratium maritimum on coastal sand dunes, Halocnemum strobilaceum-Salsola kali in saline sand deposits, Atriplex halimus-Chenopodium murale along the terraces and slopes of drains, Arthrocnemum glaucum-Tamarix nilotica in salt marshes, Chenopodium murale along the slopes of drains, Phragmites australis along the littoral zones of drains, and Lemna gibba-Potamogeton crispus in the water zone. This sequence reflects also a gradient of human interference, starting with the vegetation of the less disturbed habitats (sand dunes and saline sand deposits) and ending with the fully man-made habitats (drain zones).