An investigation on environmental factors affecting the distribution of plant communities in semi-arid rangelands of Bidokht

In order to investigate the relationship between the distribution of plant communities and environmental factors in Bidokht area, a physiognomic-floristic approach was used. The appropriate area of sampling plot and sample size were determined by the minimal area method and statistical approach, respectively. In each plot, the number of plant species and their canopy cover were determined and vegetation mapping was conducted. In each of the plant communities, six soil profiles were drilled and soil samples (composite) were taken from 0 to 100 cm depth. After transferring to the laboratory, parameters of soil texture, lime, pH, electrical conductivity, organic matter, sulfate, calcium, phosphorus, potassium and nitrogen were measured. Information layers were also provided for altitude, slope and aspect of the study area. In order to determine the factors influencing vegetation distribution, PCA-ORD software was used to analyze the principal components (PCA). The results showed that there was a relationship between the factors studied and distribution of vegetation (four rangeland types). The results of principal component analysis showed that the most important environmental characteristics affecting distribution of plant communities in the region were clay, sand, organic matter, electrical conductivity, and potassium (PCA first axis).