interrelations between plants and environmental variables

distribution and abundance of plants has been correlated with a variety of complex environmental gradients. environmental factors affect plants growth and need to be understood by ecosystem managers. this study was carried out to examine the relationships between site factors and different vascular and non-vascular plants in north of iran. for this purpose, vegetation and soil sampling was performed along 8 transects each with a length of 300 m in key areas of the rangeland. also, topographic properties including elevation, slope and aspect were recorded in sampling points, too. using twinspan, classification of the vegetation was performed. after grouping of the species, multivariate technique of principal component analysis (pca) was used to analyze the relationships between vegetation and site factors. the results of classification revealed that species are classified to 6 ecological groups. the interesting result was that vascular and non-vascular plants were positioned in approximately separated groups. also, each group according to the contained species showed different correlation with site factors. properties of nutrient status, ec, texture and slope aspect were the most important factors that correlated strongly with the distribution of ecological groups in the study area, but the strength and weakness of the correlation was different based on the species of each group.