Defining the most important effective factors on species diversity of medicinal plants in the mountainous Olang rangeland, Golestan province

The present research is done in order to investigating the relation between species diversity of medicinal plants and environmental and management factors in the Olang rural rangeland located in Golestan province. Data sampling was implemented in two managing parts consisting of low and heavy grazing areas using 100 of 1m2 plots with randomized-systematic method. In each plot, density and canopy cover of plant species were recorded. For analyzing the physical and chemical characteristics of soil, sampling was done in the center of some plots. After recognizing the medicinal plants, Shannon and Simpson indexes were used to calculate species diversity of these plants. Results showed that the most of medicinal plants, species were belonged to Compositae (21%), Fabaceae (17%) and Cruiferae (10%) families. Management factor had no significant effect on the species diversity of medicinal plants in this area, while the results from regression experiment of medicinal plants and environmental factors, indicated that bare soil, total nitrogen and gravel in the area with low grazing and also bare soil, slope and total cover in the over grazing area had the most effect on the species diversity on medicinal plants. The common environmental factor between the two management area affecting on Shannon index was litter and on the Simpson index was slope.