VARIATIONS IN COMMUNITY STRUCTURE AND PLANT SPECIES DIVERSITY WITH SOIL PROPERTIES IN A HYPER-ARID COASTAL DESERT OF EGYPT - A. Amro; F. M. Salama; M. M. Abd El-Ghani; A. M. El-Zohary; R. M. El-Shazoly3. (Journal of Animal and Plant Sciences, 2021)
Vegetation composition and soil attributes in the lower tributaries were studied from 33 georefereced stands (20 × 20m) in the deltaic part and along the main trunks of studied wadis from north to south of Eastern Desert along the Red Sea coast. The aim of the present study was to investigate the present status of the floristic composition of wadis distributed in the study area, the plant communities inhabiting different habitats and the environmental factors affecting species diversityin the study area. The studied stands were randomly chosen at locations where considerable vegetation cover and/or sensible changes in floristic composition were encountered. In each stand, presence percentage (P%), life forms and chorological affinities for each species were calculated. Soil physico-chemical analyses were carried out, and 16 parameters were used in the multivariate analyses where TWINSPAN (classification) and CCA (ordination) were applied. Significant differences between TWINSPAN vegetation groups were tested by ANOVA. Sixty-three species (40 perennials and 23 annuals) were recorded in this area, belonging to 58 genera from 28 different families. 42% of the recorded flora was belonging to five families arranged descending as: Fabaceae > Brassicaceae > Asteraceae > Chenopodiaceae > Zygophyllaceae. Therophytes and Chamaeophytes constituted 66 % of the main bulk of life form the spectrum of the recorded flora. Also, Saharo-Arabian species consisted 65% followed by the Mediterranean (̴29%). TWINSPAN yielded 5 vegetation groups; group E were located in the proximity of Wadi El-Mallaha and Wadi Beli. Groups A, C and D appeared to be closer to Wadi Dib and W. Abu Had, while stands of group (B) were in Wadi Beli. These groups were clearly separated along the first two axes of DCA. Both diversity indices showed positive significant correlations with phosphates and chlorides, and negative significant correlations with sodium, magnesium, total soluble salts and fine sand. Canonical Correspondence Analysis (CCA) revealed the importance of Na, K, Ca, PO4, gravels, coarse sand, silt and clay in species distribution patterns.
Keywords: journal article; desert vegetation; arid environments; soil variables; multivariate numerical analysis; diversity; plant communities