Effects of environmental factors on vegetation in rangelands of Semirom (Isfahan province) using ordination analysis

Correlation between vegetation and environmental variables is the most important issue related to the structure and function of rangeland ecosystems. Environmental factors such as climate, topography, and soil can alter the dynamics of plant communities. In this study, the effects of environmental factors on vegetation of some rangeland sites in Semirom region of Isfahan province were evaluated. Sampling was carried out at 52 rangeland sites in a random-systematic way. At each location, 40 plots of one square meter were placed along four transects, and the percentage of vegetation cover in each plot was measured using ocular-estimate method. The grid layers of bioclimatic and topographic variables were prepared in ArcGIS 10.1 and values for each range site were extracted. Soil samples were collected from range sites and some physical and chemical properties of the samples were measured. Redundancy Analysis (RDA) was used to evaluate the relationships between environmental factors and the plant species cover. Cluster analysis was also used to group the studied range sites based on environmental factors. According to the results, annual mean temperature, isothermality, mean temperature of wettest quarter, soil texture, pH, organic matter, and elevation were identified as the most important ecological factors affecting plant species cover.