Investigation of Stability and Relationships between Species Diversity Indices and Topographical Factors (Case Study: Ghorkhud Mountainous Rangeland, Northern Khorasan Province, Iran)

One of the main objectives of ecosystem management is to preserve the species diversity. Many researchers regard higher species diversity as the stability of ecological systems. The aim of this study is to investigate the stability and relationships between topographical factors with diversity indices in Ghorkhud mountainous rangeland in northern Khorasan province, Iran. For data sampling (2012), land units were specified. Floristic list was prepared and minimal area was determined based on the nested plot (Braun-Blanquet method). 120 plots of 1m2 were selected and within each plot, the presence of species and cover percent were estimated. For data analysis and means comparison of species diversity between the study sites, One-way ANOVA and Duncan tests were used. The species diversity was investigated using numerical indices and stability of the habitat was determined using parametric indices. The results showed that species diversity was decreased due to the increased altitude. Diversity indices were increased by the increased slope percent. Also, eastern slopes had the most diversity as compared to the other driving directions since the communities with high and low diversities generally follow the Log-Normal and Geometric models, respectively. According to our results, the areas with light slopes, middle altitudes and north and west directions followed the Log Normal distribution which had the most stable levels. It was concluded that the area with Log-Normal model represents a relatively stable communities with medium to high species richness.