Vegetation Analysis and Soil Characteristics on Two Species of Genus <i>Achillea</i> Growing in Egyptian Desert

Abstract

The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina , group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica . Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na + , K + , Ca ++ and Mg ++ ) and PAR.