Document Type : Research Paper
Authors
Abstract
In recent years the utilization rate of renewable resources especially the pressure of livestock grazing has increased. Uncontrolled livestock grazing has caused reduction of quantity and quality of forage, therefore, studying the effects of exclosure on vegetation changes is very important. In this research, the effects of exclosure on vegetation changes of Sahand rangelands were studied during 2001 to 2006. The vegetation changes were investigated inside and outside the exclosure area, using fixed transects. The results showed that total canopy cover and canopy cover of perennial grasses including Agropyrum trichophorum، Bromus tomentellus، Dactylis glomerata and Festuca ovina increased significantly inside the exclosure area (P<0.01). In terms of palatability, class I species increasedsignificantly (P<0.01). Cirsium haussknechtii, one of the important invasive species of the area, decreased significantly inside the exclosure area. There was no significant changes on total canopy cover of outside of the exclosure area. Canopy cover of perennial grasses and perennial forbs decreased (P<0.05) and shrubs canopy cover increased (P<0.01). Class I species decreased and class III species increased in outside of the exclosure area but it was not statistically significant. Canopy cover of Cirsium haussknechtii increased in outside of the exclosure area (P<0.05). No significant changes of soil organic matter were detected inside and outside of the exclosure area during six years.
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