Effect of Environmental Factors on Rangeland Vegetation Distribution in Divan-Darre Area, Kurdistan

The aim of this study was to investigate the relationship between physical and chemical properties of soils with vegetation distribution in Divan-Darre rangeland as one of the most important rangelands in Kurdistan province. For this purpose، a random systematic 150 m × 200 m gird sampling plan was used to establish 90 sampling plots. In each plot، soil factors and percent cover of each plant species were recorded. The minimal area method was utilized to determine the sample size in the herbaceous layer in this study that it was obtained 4m2. Percent cover of each species was estimated base on the Braun-Blanquet criterion. Vegetation classification was done to determine ecological species group using Cluster method. Ward’s method used to calculate the distance amongst clusters، and Euclidean method for distance index was used. The result of clustering analysis was indicated that four ecological species groups were found. Multivariate analysis was performed to detect the relationship between the physiographic، soil factors and the ecological groups. The most important physiographic and soil factors in these communities were belonged to N، K، OC، OM، pH، SP%، soil texture (clay، sand، and silt)، EC، elevation، aspect and slope. Since each plant species has the specific ecological requirements to soil properties and physiographic factors، study of them can be used to improve vegetation restoration.