Ecological factors affecting the distribution of vegetation in the mountain rangelands of Avrin Khoy

Determining the ecological factors affecting the distribution of vegetation is one of the essential requirements for enhancing vegetation and, consequently, improving the rangeland status. For this purpose, in each plant type, a randomized-systematic vegetation was sampled in 60 plots of one square meter, located 10 meters apart, along six 100-meter transects. Soil samples were taken with three replications from the surface and depth horizons and their physical and chemical properties were measured. Considering the soil indexes and considering the height, direction, and percentage of vegetation slope, the vegetation types were classified in relation to environmental factors using PC-ORD software and PCA software. Regarding the multiplicity of soil variables, the variables were first reduced using factor analysis. During factor analysis (FA), 24 soil variables were identified in six genotypes; silt, gravel, lime, organic matter, nitrogen, carbon, and phosphorus, sodium, potassium and electrical conductivity, to find the relationship between vegetation distribution and environmental factors, it was noticed. The results of the analysis of the main components showed that the first and second components justify 63.48% and 17.08% of vegetation changes in relation to environmental factors, respectively. The first component was correlated with the direction of the gradient, lime percent and organic matter percentage and second component with the percentage of lime, potassium and soil phosphorus. Therefore, the most important factor in the separation of vegetation types is the direction of the gradient, lime percentage, organic matter percentage, potassium and phosphorus of soil, which is more important for slope than other factors