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sur le développement des zones arides et semi-arides

Titre : STUDIES ON THE ALGAL FLORA DISTRIBUTED AT WADI-SANNUR OF THE EASTERN- DESERT OF EGYPT

Auteur : HASSAN, NOHA ABD EL-WAHAB MOHAMMED.

Etablissement de soutenance : Beni-Suef University

Grade : Master of Science (MS) in Microbiology 2007

Résumé
Screening the microalgal crusts distributed in seven sites stands) in Wadi-Sannur (Eastern-desert, Egypt) was a main target in the present studies. This study was conducted along 31.5 km of Wadi-Sannur throughout two seasons, namely summer 2000 and winter 2001. The plant communities distributed at the investigated sites were recorded and some physico-chemical characters of the collected soil samples were determined. The prokaryotic microalgae were frequently encountered constituting 51.5 % of total algal populations at all soil samples of the studied sites, as Cyanobacteria were the most predominant group and represented by 52 taxa. This was followed by Bacillariophyta (28 species), whereas, 19 species were identified as Chlorophyta and two species belonging to Euglenophyta. The data revealed that the quantity and quality of algal taxa were governed by the edaphic factors and physico-chemical characters of the soil. The data further revealed that sites with dense plant covers favored by higher algal populations. The study showed that pH and moisture contents were prime factors in distribution of the algal species, so the sites with higher pH, moisture contents in addition to relatively high chloride, sodium, magnesium, calcium and lower silicon content favored the Cyanophyceae species. where soils with lower pH, silicon and high total nitrogen, sulfates and organic matter had the highest number of Chlorophyceae species. But those soils with higher pH, silicon content and lower moisture, sulfate, calcium and magnesium content were favored for Bacillariophyta species

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