suitable species diversity abundance model in three grazing intensities in dizaj batchi rangelands of west azerbaijan

species diversity is one of the important characteristics shows rangeland ecosystems changes, which isalready under effects of management practices. thus, this research was conducted to study speciesdiversity variation and assess suitable distributive abundance model in three rangeland sites in westazerbaijan. these sites were almost similar in environmental properties and differ in view point ofgrazing intensity (light, moderate and heavy intensities). after selecting sampling areas in each of thesites, species cover were recorded in 60, one square meter quadrates with 10 meter far from each otherwhich established along 100 meter transects in sites and then richness, evenness and diversity(heterogeneity) indices were calculated. thus, rank-abundance curves were plotted and fourdistribution models such as log-normal, geometric, log-series and brocken stick were fitted to each ofthese sites and then best model was selected in 0.05 level of confidence. means comparison testshowed that richness, evenness and heterogeneity indices have significant differences (p