Vegetation in relation to some edaphic and physiographic characteristics of site (Case study: Zagros forest ecosystem, Kabirkuh protected area, Ilam)

The aim of this study was to survey vegetation in relation to some edaphic and physiographic conditions in Arasht catchment (approximately 510 ha) of Kabirkuh protected area in Ilam province. For this purpose, 67 sample plots (20m×20m) in a systematic grid established in the study area. Some factors, including tree and shrub species type, number and canopy coverage were recorded by measuring their small/large crown diameters in each sample plot. In order to record the herbaceous species, cover percentage for each herbaceous species were recorded in four micro–plots (1.5m²) that were defined with Domin criterion. The Canonical Correspondence Analysis (CCA) and TWINSPAN methods used for the site classification and definition of ecological species groups, respectively. Results showed that there are six ecological species groups in the study area. Some soil physicochemical properties and physiographic factors play an important role in recognizing of ecological species groups. The most important factors affecting the establishment and distribution of ecological species groups were soil texture, lime, nitrogen, organic carbon, elevation and slope.