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Plant Species Diversity of Some Wadis at Red Sea Coast, Egypt

Ramadan A Shawky and Ahmed A El-Khouly

The present study aims to investigate the variation in vegetation and species diversity in two coastal wadis which drain their water from surrounding high mountains into the Red Sea. It attempted to compare the floristic diversity between these wadis to recognize the different distribution patterns of species, and to assess the role of the edaphic factors which control the distribution of the plant communities. Fourteen sample plots were selected to represent as much as possible the variation in the vegetation, and georeferenced using GPS techniques. A total of 23 perennial species belonging to 19 genera and 14 families were recorded, with Zygophyllaceae, Fabaceae, Tamaricaceae and Asteraceae represented the species-rich families. Phanerophytes and Chamaephytes constituted the main bulk of the flora, followed by hemicryptophytes. As part of the Saharo-Arabian region, the Saharo-Arabian chorotype dominated the others. Classification of the vegetation resulted in 6 vegetation groups: (A) Juncus rigidus, (B) Zygophyllum coccinium, (C) Capparis decidua, (D) Zilla spinosa, (E) Zygophyllum coccinium and (F) Nitraria retusa. Species richness was positively correlated with fine gravel, while negatively correlated with medium sand. The Shannon’s diversity and Simpson Indices showed positive correlation with CaCO₃ and negative correlation with fine sand. Vegetation-soil relationships were assessed by canonical correspondence analysis (CCA) using 18 soil factors indicated that gravel, coarse sand, fine sand, silt, clay, sodium and chlorides were the key soil variables that affect the distribution of plant communities in the coastal wadis of Red Sea region.