Abstract
This study investigated the effects of spatial and environmental factors and their interactions on plant species composition in salt marsh (Sabkha) ecosystem located in arid region (Saudi Arabia). The plant species and environmental variables were investigated in 38 sites located in three regions. A total of 15 environmental variables were measured in each site and the geographical coordinates were used to extract spatial variables (using PCNM). A total of 81plant species were reported from 38 sites. The three regions showed patterns of homogeneity of multivariate dispersions (i.e. beta diversity). The PCNM analysis extracted 18 PCNM vectors and only 3 vectors were retained after forward selection. The spatial variables (selected PCNM vectors) explained only 3.21% of the variation in species composition of plants (using variation partitioning technique). However, eight environmental variables were selected after forward selection (Lead, Copper, total organic matter, Potassium, Magnesium, pH, Zinc and Iron, F= 4.72, P<0.05) and explained 19.61% of the total variation in the species composition. In conclusion, the plant communities in Sabkhas were not spatially structured due to the low percentage of variation explained by the spatial variables (PCNM vectors). The environmental variables were corresponded to the high fraction of variation explained. On the other hand, Sabkhas in Saudi Arabia are considered a hot spot for diversity not only for plants but for other animals (birds, vertebrates and invertebrates). Therefore, immediate conservation plans should be implemented to reduce the adverse effect of urbanization, industrialization as well as other anthropogenic activities.
Keywords:
spatial patterns; Sabkha; PCNM; Saudi Arabia; plant communities
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