The average of absolute density for 62 perennial species in five types of habitats was recorded. The highest absolute density in coastal sand dune habitat was contributed by Launaea resedifolia while, in saline depression, inland plateau and ridge the highest account was recorded for Salsola tetragona, Launaea. Resedifolia and Scorzonera undulata.The ridge habitat contributed the highest number of species (32 species), while the lowest number was attained in the non-saline depression (20 species). Sixty-two species belonging to 24 families were recorded. The highest contribution was presented by members belonging to family Compositae followed by Gramineae and Chenopodiaceae (15, 13 and 13 %, respectively). On the community levels the plant community of inland ridge exhibited the highest abundance in terms of absolute density while plant community of the non-saline depression exhibited the lowest value.  Most perennial species exhibit their greatest phonological activity during winter and spring, and were less active or dormant during autumn. However, some species, particularly most shrubs and sub-shrubs, continue to be active throughout the whole year (e.g. Deverra tortuosa, Helianthemum lippii, and Artemisia herba - alba). The most common life-forms were of the woody species (76  %) which include 41 % non-succulent leaves and 5  % succulent leaves, while the contribution of herbs represented 25 % of which 5 % were  non-succulent leaves. The tallest plants recorded during the growing season in the whole area were those of Thymelaea hirsuta, Lycium shawii and Anabasis articulata were among shrubly species and Asphodelus ramosus of the perennial herbs and the grass Ammophila arenaria. On the other hand, the sub-shrubs Helianthemum lippii and H. kahiricum were the shortest. Some other human activities have more impact on the vegetation than the over grazing by livestock. The various activities have different impacts on the plant diversity (e.g. 11 species of the recorded species were rated as endangered species due to human impact or desertification). Positive significant correlation coefficients were found between soil depth and both abundance of ever-green shrubs with non succulent leaves and with herbs. This work was performed within the framework of ROSELT / OSS Program in EGYPT Supported by the Swiss technical cooperation (convention no.97/300/CH/04).