Document Type : Research Paper
Authors
Abstract
Studies on vegetation changes in rangelands, under grazing and exclosure conditions are important in planning range management programs. This research was aimed to investigate the changes in vegetation inside and outside three exclosures of Maraveh tapeh during 1997-2005. The canopy cover was measured each year, in several permanent plots, inside and outside the exclosure. To study the effects of precipitation on the changes of cover, the correlation between canopy cover of species and vegetative forms inside the exclosure and the precipitation of months and different vegetative stages were calculated. Results showed that total canopy cover in 2005 was significantly higher than that of 1997, both inside and outside the exclosure, mainly due to the increased cover of annuals. On the contrary, the cover of perennials decreased inside and outside the exclosure. Reduction in the cover of perennials was mainly related to grasses. In the last year of study, compared to the first year, total cover of class II species reduced drastically contrary to the cover of class III species. Although changes in canopy cover were influenced by precipitation, correlation coefficients were just significant for total canopy cover and vegetation cover of perennials. However, exclosure cannot be used as a method of range improvement in these rangelands. For rehabilitation of these areas, direct human intervention is necessary.
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