Vegetation Analysis and Soil Characteristics on Two Species of Genus Achillea Growing in Egyptian Desert

Abstract

The\rpresent study provides a vegetation analysis and species distribution at 50\rsites, emphasizing the environmental factors that affect species distribution.\rA total of 74 plant species belonging to 67 genera and related to 23 families\rof vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae,\rBrassicaceae, Fabaceae and Zygophyllaceae are the largest\rfamilies, and therophytes (41.89) and chamaephytes (24.32%) are the most\rfrequent, indicating a typical desert life-form spectrum. Chorological analysis\rrevealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian\rchorotypes, either pure or penetrated into other regions, comprised\r47 species. After application of the TWINSPAN and DCA programs, 4 vegetation\rgroups (A-D) were identified, groups A and B were dominated by Achillea\rsantolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica.\rGroups A and B may represent the vegetation types of the Western Mediterranean\rcoast of Egypt, while groups C and D may represent the Wadi Hagul. The\rlinear correlation of soil variables with the importance values of some\rdominant species and the application of Canonical Correspondence\rAnalysis (CCA-biplot) indicates significant associations between the\rfloristic composition of the studied area and the edaphic factors such as\relectrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations\r(Na+, K+, Ca++ and Mg++) and PAR.