Effects of Warming and Grazing on Soil Physicochemical Properties and Enzyme Activities in Salinized Grassland in Hexi Corridor

［Objective］ To explore the effects of grazing on soil enzyme activities in salinized grasslands during the freezing period under the background of global warming. ［Methods］ Taking salinized grasslands in the Hexi Corridor as the research objects, four treatments were set up, including control (CK), grazing (FCK), warming (W), and warming + grazing (FW), in order to explore the variation law and spatial distribution characteristics of soil enzyme activities under different treatments. ［Results］ Compared with CK, the FCK treatment significantly increased soil water content and total nitrogen content, and decreased soil organic carbon content. The W treatment reduced soil water content and increased soil organic carbon content and total nitrogen content by 97.61% and 16.89%, respectively. The FW treatment significantly increased soil water content, organic carbon content and total nitrogen content, while total phosphorus content of the FW treatment was significantly (40.81%) lower than that of CK. The FCK treatment significantly increased the activities of β-glucosidase, amylase, urease and phosphatase; the W treatment significantly increased the activities of amylase, urease and nitrite reductase, while the FW treatment increased the activities of β-glucosidase, amylase, urease and nitrate reductase. Compared with other treatments, the stoichiometric ratios of soil enzymes in W and FW treatments were significantly increased. Through vector analysis, it was found that the study area was significantly limited by nitrogen. ［Conclusion］ Warming and grazing treatments directly or indirectly affect soil enzyme activities through soil physicochemical properties, of which SOC is one of the key factors affecting soil enzyme activities in salinized grasslands in Hexi Corridor.