Relationship between Ecological Species Groups and Environmental Factors (Case Study: Vezg Region in Southeast of Yasouj)

In applied studies, identification and study of vegetation, for management and protection of natural ecosystems, are very important. This study was carried out in Vezg forest with an area of 308 hectares located in southeast of Yasouj city. The purpose of this study was to classify ecological species groups and survey their relation to soil physic-chemical properties and physiographic attributes. For this purpose, the field data were obtained using 52 sample plots (15m×30m) in a systematic random grid. In each sample plot, the cover percentage of tree, shrub and grass species type were recorded, by using Braun-Blanquet method. The TWINSPAN method and Canonical Correspondence Analysis (CCA) were used for the definition of ecological species groups and determintion of the relationship between ecological species groups and environmental properties. Results showed that, there were four ecological species groups in the study area. The First group included: Anchusa italic-Quercus brantii, the second group: Heteranthelium piliferum-Avena clauda, the third group: Teucrium polium and the fourth group: Salvia reautreana. The first group was in an area, where there was a higher percentage of Persian oak litter. The second group was located in site a with higher grass cover than the site of other groups in the area. The third and fourth groups, were located in the higher elevation and steep points. Results of CCA showed that soil properties were not in significant relation with ecological species groups. But, the relationships of ecological species groups with other environmental factors such as litter, altitude, grass cover and slope were significant. So, we can conclude that these properties are effective in the separation and distribution of ecological groups.