Evaluation biodiversity in relation to physiographical factors in mountain forest in Iran

摘要

Species diversity is an important characteristic of bio -communities. Organisms diversity, diversity measurement and hypothesis test in relation to diversity causes are issues which the ecologist are interested in for long period. In this research, diversity of plant species in forest region, numbers of 60 sample plots in 256.00 square meters have been considered in random - systematic inventory was considered. In each sample plot, four micro-plots in 2.25 square meters in order to study on herbal cover, were executed that totally 240 micro-plots were considered. At each plot six diversity indices (Simpson's reciprocal (N_2), Shannon's (H~1), Hill's (N1), Pielou's (J')), Alatalo's (F), Molinari's (G)) in relation to physiographical factors (slope, geographical aspect and altitude from the sea level) were studied. The results showed that species diversity was the greatest at north aspect and slopes less than 30% has the most amounts. Factor of altitude from the sea level did not have meaningful relation with species diversity. Through study on correlation of the numbers of species in sample plots with indices and also process and role of indices in different processors of analysis, Simpson's reciprocal index was suggested as suitable index in this type of studies.