Assessment of the Effects of Overgrazing on the Soil Physical Characteristic and Vegetation Cover Changes in Rangelands of Hosainabad in Kurdistan Province, Iran

Soil physical properties have an important role on vegetation growththrough affecting the development of root system. The aim of this study was toinvestigate the trampling effect of livestock grazing on soil physical properties andvegetation cover changes. The experiment was conducted on three range conditionsites (Reference, Key and Critical area) with ten frequencies in HosseinabadeKudistan in 2009. Soil physical characteristics consist of humidity, bulk density,porosity and aggregate stability index. In this study remarked soil cover changes inthree mentioned regions. The results showed that soil moisture reduced fromreference to critical area. Soil bulk density was the lowest in reference area and thehighest in critical area. Reference site had the highest soil porosity while the soilporosity reduced in critical area. However, as the density of grazing increased, soilbulk density increased and soil moisture, soil porosity, aggregate stability index andvegetation cover percent decreased. Bare soil percentage was the highest in criticalregion. According to the results of this research, the grazing seems caused to majorchanges in the physical properties of the topsoil. Since the region has highecological potential, if the intensity of grazing would be in a moderate level, theregion soil will be able to compensate the negative aspects of livestock trampling.