An investigation on the Effects of Exclosure on Quantitative and Qualitative changes of Rangeland Vegetation Cover

We investigated the effect of 19 years of grazing exclosure on production, vegetation cover and species composition in a region located in the southern part of Zanjan Township. The Headquarters of Natural Resources Office of Zanjan has exclosed the mentioned area since 1985. Four transects within the exclosure and another 4 transects, each with 30 m length in the vicinity of the exclosure had been established. The sampling method was a Randomized Systematic one comprised of 16 plots, each of 1 m2 in area. Annual growths of vegetation cover were clipped and weighed for the production to be calculated. In comparison to non-exclosure area the decreasing palatable plant composition increased (280%) while increasing and invading plants decreased. The production within the exclosed area was twice that in non-exclosure area.