Vegetation Composition Related to Environmental Factors Along the International Highway-West Alexandria, Egypt

Abstract

Roadside vegetation is exposed to a variety of biotic and abiotic stresses that can affect the abundance and distribution of natural vegetation. The present study aimed to characterize the ecological features of the vegetation along the international coastal road from El-Ajami to Ras El-Hekma, West Alexandria, Egypt. The total number of the recorded plant species surveyed in the present study was 84 species (44 annuals, two bieannial and 38 perennials) belonging to 74 genera and related to 25 families. Asteraceae, Poaceae, Fabaceae and Chenopodiaceae were the largest families (53.57% of the total species, collectively). Therophytes is the most abundant life forms. The Mediterranean chorotype (58.32%) was the most represented. On the basis of the presence values, the classification of the 84 plant species recorded in 60 stands by cluster analysis yielded four vegetation groups. Group A (47 species) was dominated by Carthamus tenuis, group B (39 species) was dominated by Lactuca serriola, group C (52 species) was dominated by Bromus diandrus and group D (71 species) was dominated by Suaeda pruinosa. Calcium carbonate, organic carbon, electrical conductivity, bicarbonate, Cl-, Na + and Ca ++ showed clear significant differences between groups. The application of Canonical Correspondence Analysis (CCA) showed that, the percentages of porosity, CaCO 3 , Cl-, SO 4-, HCO 3 and cations (Na + , K + , Ca ++ and Mg ++) are the most effective soil variables. The current study revealed that the coastal sector in Egypt suffers from unplanned development, salt water intrusion and salinization of the soil, so the development of the highway needs a balance between conservation and development.