Vegetation Analysis of Sutan-Chay Basin in Arasbaran

Problem statement: Plants associations differ in relation to environmental gradients. Therefore, it is necessary to study the interaction between ecological factors and vegetation. Approach: In this study vegetation and flora of Sutan-Chay Basin in Arasbaran was investigated using Braun Blanquet method as physiognomic floristic. Sampling of soil and vegetation was carried out by selecting areas with homogenous plant compositions. The surface area of releves was determined using Nested Plot method to obtain the Minimal area. Classification of releves was conducted based on the presence and cover percentage of species using cluster analysis and Jaccard index similarity. CCA was used to determine the relationship between the groups and ecological factors and the most important factors in separating the groups and distribution of the species. The classification of releves based on Jaccard’s similarity coefficient and cluster analysis showed 6 different groups. Results: Dendrogram of cluster analysis based on these methods showed six associations: Astragaleto aureus-Thymetum kotschyanus, Poeto bulbosa-Festucetum ovina, Carpinetum betulus ،Quercetum macranthera, Paliuretum spina-christii, Juniperetum foetidissima. Canonical Correspondence Analysis (CCA) was used to determine the most important environmental factors on plant groups. This method of multivariate showed that pH, TNV%, soil texture, clay percentage, altitude and aspects had higher effect on separation of plant groups, which had correlation with axes 1 and 2 of ordination. Conclusion: Among the environmental factors the altitude has most important effect on plants distribution. With understanding of relationship between ecological factors and plant associations in a given area, it is possible to apply the obtained results in management and revival of forestland and rangeland.