Study of Plant Species Diversity and Certain Effective Factors in Helali Protected Area, Khorassan Razavi Province, NE Iran

Helali Protected Area with ca. 63495 ha. is located in west of Gonabad and southeast of Bajestan, Khorassan Razavi province, NE Iran. Biodiversity has an important role in environment protection. In order to study the plant biodiversity of Helali protected area,three sites including plain, foothill and mountainous areas and three sites with different grazing management were selected and the stratified random samples (236 plots of 1 m2) established to record the abundance and cover of each plant species. The results of biodiversity and its effective factors showed that mountainous site contains maximum value of richness (D_Mg=9/76) and minimum value of evenness (E ́=0/18). There were not significant differences in diversity of different aspects. Moderate grazing site illustrates maximum diversity and positive effect of controlled grazing on biodiversity (D_Mg=8/31,H ́=4/82 and E ́=0/36). Comparing the two years 2011 and 2012 in mountain site denotes affirmative effect of precipitation on biodiversity. Among the Rank- Abundance models, abundance data of the whole area, mountain and foothill sites fit to the lognormal model. On the other hand, plain site is fitted to logarithmic model that might be considered as an alarm for the site.