Effect of different levels of environmental protection on plant species diversity

Considering the importance of biodiversity conservation and protection assessment activities، the present filed study was conducted with aim to compare vegetation diversity of two areas with different levels of protection including Ghorkhod protected area with seasonal grazing and Golestan National Park without grazing، during spring and summer of 2011. Four replications were selected in each area and a modified Whittaker plot with four spatial sampling scales was fitted. Results showed that mean species richness had significant differences between two studied areas. In addition، mean species richness trend between different sampling scales at two study areas were significantly different. Moreover، plant canopy cover also showed significant differences between the two studied areas which it was higher in Golestan National Park. However، comparing the evenness and diversity indices of Shannon، Simpson، Smith-Wilson and Camargo were not different in two studied areas. For a more detailed review، as well as understanding of the distribution of species، SHE analysis method was used at species and family levels. Based on the results of distribution pattern in both areas، the study was followed by a lognormal model. The proportion of the component of the species richness was greater than component of the evenness. Distribution pattern of plant families followed by log series and lognormal models، also the proportion of the components of the species richness and evenness on the diversity in families were almost similar. In general it can be said that the more protection level of Golestan National park were lead to greater protection of species diversity.