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

Abstract

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