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 speciesdiversity. Many researchers regard higher species diversity as the stability of ecologicalsystems. The aim of this study is to investigate the stability and relationships betweentopographical factors with diversity indices in Ghorkhud mountainous rangeland innorthern 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, thepresence of species and cover percent were estimated. For data analysis and meanscomparison of species diversity between the study sites, One-way ANOVA and Duncantests were used. The species diversity was investigated using numerical indices andstability of the habitat was determined using parametric indices. The results showed thatspecies diversity was decreased due to the increased altitude. Diversity indices wereincreased by the increased slope percent. Also, eastern slopes had the most diversity ascompared to the other driving directions since the communities with high and lowdiversities generally follow the Log-Normal and Geometric models, respectively.According to our results, the areas with light slopes, middle altitudes and north and westdirections followed the Log Normal distribution which had the most stable levels. It wasconcluded that the area with Log-Normal model represents a relatively stable communitieswith medium to high species richness.