Utilization Intensity Effect on Plant Richness and Diversity in Shourab Rangelands of Golestan Province

A physically destructive pressure on rangeland ecosystems is livestock intensive grazing that results in decrease in vegetation and species. To evaluate the effects of grazing on diversity and species richness in Shourab summer rangelands of Gorgan, three sites were chosen as reference, key and critical areas. The sampling was done systematic randomly using 40 plots 1×1m2 on three 100m transects in each unit. List of species, percent cover and species number were recorded in each plot. The species list, plant cover percentage and number of species were recorded in each plot. Evaluation of numerical diversity indices and species richness was done. Then, the data was analyzed by ANOVA and means comparison. The results showed that the numerical values for all indicators of diversity and richness in the critical region have been less to the reference region due to intense grazing. Also, the average grazing was not negative factor in reducing plant diversity.