The relationship between ecological species groups and non-parametric indicators of biodiversity and environmental factors in Arasbaran (Case study: Ilgenechai & Kaleybarchai Watershed)

The aim of this study was identification of ecosystem units in Arasbaran forests and determination of effective environmental factors and biodiversity indices on their distribution. For this purpose, 130 circular plots with an area of ​​314 m2 were examined in a random - systematic design with 300 × 300 m dimensions. Tree and shrub species in the original sample plots were measured. Species, canopy cover and vegetation cover were considered as basic measurement criteria. Herbaceous species were studied in micro sample plots, each 3.14 m2. Six ecological groups were classified using two-way analysis of indicator species (TWINSPAN) and comparative analysis (RA) methods. Analysis of groups was performed by applying analysis of variance and discriminant analysis based on topographic and biodiversity index. The discriminative analysis showed that altitude and gradient-direction as two topography variable, and the Margalef richness index, evenness indices of Smith - Wilson, Sheldon and Simpson, and heterogeneity (diversity) indices of Simpson, Hill (N1) and Shannon-Wiener were the five important indices which were significant (α = 0.01) which confirmed the accuracy of the classification at 83.8%. Therefore, it was concluded that topographical characteristics had more influence on the formation of ecosystem units than plant biodiversity indices. We also concluded that the ecological classification system can present a suitable prediction of environmental characteristics.