Effects of enclosure and grazing on plant diversity using parametric models (Case study: arid and semi-arid rangelands of Boz Daghi, North Khorassan province)

Plant diversity is one of the important and fundamental issues associated with community ecology. Detection of relationship between diversity and exploit methods is one of the most important challenges in natural resource. In this study that has been done in Boz Daghi arid and semi-arid rangelands in Maneh Samalghan county in North Khorassan province, the effects of enclosure on biodiversity using parametric models is considered. With selection of two enclosured and under grazing areas, the number of 100 plots with 1 square meter is randomly located. Diversity indices including Log normal, geometric, Log and Mac Author broken stick was evaluated using BIO-Dap software. The Chi-Square test was used to considering signification of estimated levels and expected density. The results shows that the frequency-grade curve of species in the enclosure region is located above of the frequency-grade curve of in grazed region and the grazed region is following of lognormal model indicates that this region has less dominant and rarely species and more species with average frequency. Furthermore, grazed region follows the both log and log-normal models that explains at first this region has been a uniform area and has been intended to log model that explains aarea under stress due to intensive grazing.