Javad Motamedi; Esmaeil Sheidai Karkaj
Abstract
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. ...
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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<0.01) insites. Highest diversity is observed in the light grazing intensity site and lowest diversity is in heavygrazing intensity site. Species rank-abundance curves point out that low-abundance species are seenlower in light grazing site and its curve have gentler slope than moderate and high grazing intensitysites thus its diversity is higher. There is lowest species number in high grazing intensity site andevenness is lowest too due to its high number of rare and dominant species. Log-normal model wasfitted to light site implying on sustainable community and high grazing intensity site is fitted withgeometric model which point out on distractive communities with low diversity. Overall resultsshowed that implementing light grazing can protect species diversity and heavy intensity declinesspecies diversity that this shows the need considering of management on implementing light grazingintensity in the rangeland.
