干旱区生态环境知识资源中心

This study examined the major soil attributes that affect the plant species distribution in the urban ecosystem of the north-eastern part of Nile Delta, which represents transition between the irrigated farmlands and the adjoining desert and salt marshes. It has been under human manipulations for more than 30 years. Five major habitats (desert, reclaimed, cultivated, urban and wet) subdivided into 13 minor ones were recognized. Alterations of soil characters by anthropogenic activities of the natural environment for agriculture production have provided a favorable condition for the growth of weedy species. 231 species related to 152 genera and 45 families were recorded; of which 135 species annuals (58.4 %) and 96 perennials (41.5 %). Regarding chorological analysis, Saharo-Arabian attained the maximum value of 23.5 % in Sf, followed by Sudano-Zambezian 20.0 % in Wl, Cosmopolitan (16.6 %), Irano-Turanian 11.8 % in each of Hw and Ic, After the application of TWINSPAN classification technique, five vegetation types were identified, and well segregated along the DCA axis one; which reflects the soil moisture, fertility, biotic change, aridity and species diversity gradients. When soil moisture decreases, species diversity increase. It also represents the gradient of human interference, where the full man-made vegetation (wet lands and cultivated lands) occupied the left end of this gradient, where the less disturbed vegetation (reclaimed and urban land) was in the middle and no man-made vegetation (desert land) was in the right end. This gradient is associated with the increase of the relative presence of aridity.