ECOLOGICAL FACTORS AFFECTING PARTS OF VEGETATION IN NORTH IRAN (ELIKA AND DUNA WATERSHEDS) BY EMPLOYING ECO-PHYTOSOCIOLOGICAL METHOD

To determine ecological factors that affect vegetation of north Iran, the eco-phytosociological method with emphasis on physiognomic-floristic-ecologic criteria have been employed and the existing endogenous milieus were identified. In next stage, the placements of releves in any endogenous milieus were determined at random. The minimal area in each releve was determined on area-species method. The concerned floristic-ecologic data of each releve was entered in the forms related to releves, by concerning Braun-Blanquet’s Composition Coefficients A-D and S. The data analysis was performed by using Anaphyto Software in F.C.A. and A.H.C. Method. After placing the ecological factors on the multiplex coordinate axes obtained from F.C.A. and comparing the axes together, the results were analyzed and interpreted and the ecological factors that affect the vegetation of the region were determined as the principal, determinant and differential ecological factors. These results showed that the factors of soil moisture, soil pH, OM%, OC%, slope degree and altitude from sea level of the region were the principal ecological factors. The factors of moisture, texture, pH, EC, OM%, OC%, percentage of the lime of soil as well as the altitude and exposition showed to be the determinant ecological factors. The factors of moisture, pH, EC, OM%, OC%, percentage of the lime of soil and exposition were effective as the differential ecological factors