Effect of Environmental Traits and Grazing Intensities on Plant Community Distribution (Case Study: Saral Rangelands, Iran)

Understanding ecological processes is a prerequisite for the management of rangelands; therefore, recognition of the relationship between environmental factors and vegetation is very important. The present research aims to investigate environmental and management factors affecting rangeland vegetation distribution in Saral rangelands of Kurdistan province, Iran, in 2017. Sampling was done in eight vegetation types along four 300 m transects. Fifteen 1m2 plots established along each transect in 20 m distances. Ten soil samples along transects were taken according to the plants root depth in the average depth 0-50 cm in 10 profiles within each vegetation type. Various environmental factors such as topographic factors (slope, aspect, and elevation), soil physical properties (depths, soil texture, gravel, and saturation moisture) and various chemical factors such as acidity, electrical conductivity, lime, gypsum, nitrogen, phosphor, and potassium were measured and grazing intensity considered and measured as managerial factor. The collected data were subjected to Principal Component Analysis (PCA) and the important factors affecting plant community distribution were determined. According to the results, first and second components account for 39.29% and 26.28% of community distribution, respectively. The results showed that among various environmental and grazing factors affecting plant distribution, soil texture, soil depth, grazing intensity, elevation, potassium and gravel had the most significant effects on present plant community distribution in studied rangeland. Silt, gravel and grazing intensity play important roles in the spatial distribution of vegetation communities, respectively.