Evaluating species abundance distribution based on Niche Apportionment Models in Different Bioclimatic Regions

Species abundance distribution models are used to detect plant communities’ structure. The ecological niche of species is related to species abundance distribution. Several niche apportionment models were introduced to reveal the abundance distribution of species in different ecosystems. Ecological niche apportionment models have been presented based on the assumption that species abundance is a ratio of resources (niche) that allocated to a species when it is introduced to a new community. This study aimed to evaluate the applications of RIOUS niche apportionment models including Dominance decay, MacArthur fraction, Power fraction, Random fraction, Random assortment, and Dominance per-emption in highland mountain, cold steppe, and semi-steppe plant communities of Charmahal va Bakhtiyari province. Vegetation data was collected in each site using 60 plots with size of 1 m2, placed along six 100m transects. Data analysis was performed in R software and “nicheApport” package according to Monte-Carlo test. The results showed that both MacArthur fraction and power fraction models were fitted appropriately to the observed frequency of species distribution in different bioclimatic regions. The results of both species abundance model and MacArthur fraction model indicated the high evenness characteristics in the study area. The results suggested that ecological niche models of species abundance provide suitable tools for determining patterns and structure of plant communities, especially in highland mountain and cold Steppe ecosystems.