放牧与围栏对荒漠草原土壤养分及酶活性的影响

以宁夏毛乌素沙地荒漠草原蒙古冰草（Agropyron mongolicum）、甘草（Glycyrrhiza uralensis）、赖草（Leymus secalinus）群落为研究对象，探讨放牧与围栏对不同植被群落土壤养分和酶活性的影响。结果表明，在放牧干扰下，甘草群落土壤有机碳（soil organic carbon，SOC）显著降低；3种植被群落土壤总磷（total phosphorus，TP）均显著升高；甘草与赖草群落土壤总氮（total nitrogen，TN）含量亦显著上升。从土壤酶活性变化来看，放牧条件下，赖草群落土壤碱性磷酸酶活性显著上升；蒙古冰草群落土壤脲酶活性显著下降，而甘草群落土壤脲酶活性显著上升；蒙古冰草与甘草群落土壤过氧化氢酶活性均显著下降。整体来看，不同植被群落土壤4种酶活性与土壤养分间均表现出一定的相关性。放牧与围栏对荒漠草原不同植被类型群落土壤养分的影响表现出差异性，应根据群落特性，有针对性地制定合理的放牧制度，以利于植被恢复及保持土壤肥力。

Effects of grazing and fencing on nutrients and enzyme activities in desert steppe soil

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.