Analysis of relationship between distribution of plant communities and climatic and physiographic factors using Classification and Ordination methods in Rineh Rangelands

The original aim of this research was investigation on relationship between climatic and physiographical factors and plant species to determine the most effective factors of separating vegetation types in Rineh Rangeland. Random Equal-stratified sampling procedure was used for vegetation sampling. 10-20 quadrates were located in each homogenous unit randomly. Floristic list, density and canopy cover percentage were determined in each quadrate. Elevation, slop and aspect were physiographical factors. Mean minimum temperature, mean maximum temperature, mean daily temperature, mean relative humidity, month and annual precipitation and freezing days were selected for analysis. Incorrect data was reconstructed by correlation and normal ratio methods (Mahdavi 1374). In order to find effective analysis were used, both classification included CA and TWINSPANM classification and ordination techniques included PCA, DCA, and CCA. The TWINSPAN classification of the 75 samples sites have resulted ten groups. Using PCA 99.348 % of variance was accounted using the first three principal components. DCA axis 1 showed significant correlations with climatic factors and elevation, this suggest that DCA axis 1 represented climatic and elevation factors gradients. CCA analysis explained 16% of the cumulative variances. This result suggest that other factors affect vegetation such as soil and biological factors then should be studied in future researches.