Abstract: In order to study the effects of grazing and fencing on soil nutrients and enzyme activities of different vegetation communities， Agropyron mongolicum， Glycyrrhiza uralensis， Leymus secalinus were selected as study objects. It was shown that under grazing disturbance， soil organic carbon （SOC） content significantly decreased in Glycyrrhiza uralensis land. Soil total phosphorus （TP） content in the 3 tested vegetation communities significantly increased under grazing treatment. Soil total nitrogen （TN） in Glycyrrhiza uralensis and Leymus secalinus land was also significantly increased. After grazing， soil alkaline phosphatase activity in Leymus secalinus land was significantly enhanced. Soil urease activity was significantly reduced in Agropyron mongolicum land， yet was significantly enhanced in Glycyrrhiza uralensis land under grazing. Under grazing treatment， soil catalase activity in Agropyron mongolicum and Glycyrrhiza uralensis land was significantly reduced. Overall， soil enzyme activities were correlated with soil nutrients. In conclusion， different vegetation community showed varied response to grazing and fencing treatment. Thus， different grazing intensities should be arranged for different vegetation community， in order to achieve vegetation restoration and soil fertility maintenance.

Key words: desert steppe, grazing, fencing, soil nutrient, soil enzyme