青海湖湖滨不同土地类型土壤酶活性的研究

目的探讨青海湖湖滨不同土地类型中土壤酶活性的变化及其影响因素，可为退化湿地的植被恢复与生态系统管理提供理论依据。方法选取青海湖东岸尕海区的湖滨湿地、以及由其退化的草地和沙地这3种土地类型为研究对象。分别采集0 ~ 10 cm、10 ~ 20 cm和20 ~ 30 cm的土壤样本，比较不同土地类型土壤化学性质与土壤酶活性的差异，运用CANOCO5.0软件对土壤酶活性与土壤化学性质间关系进行冗余分析（RDA）。结果湿地中的土壤有机碳、全氮和水溶性有机碳氮的含量显著高于沙地，而土壤易氧化碳和铵态氮含量显著高于草地和沙地；对于水溶性有机碳、硝态氮和有效磷来说，湿地和草地显著高于沙地。草地土壤β-葡萄糖苷酶、亮氨酸氨基肽酶和甘氨酸氨基肽酶的活性较湿地分别显著下降了32.17%、30.90%和39.67%；而沙地较草地分别显著下降了79.22%、73.46%和64.84%。湿地和草地的N-乙酰氨基葡萄糖苷酶和酸性磷酸酶活性均显著高于沙地，但仅湿地的纤维二糖酶和碱性磷酸酶活性显著高于沙地。冗余分析结果表明，土壤水溶性有机碳和氮是影响土壤酶活性的主要因素，对其解释程度分别为58.8%和29.4%。水溶性有机碳可以很好解释亮氨酸氨基肽酶和酸性磷酸酶活性的变化；水溶性有机氮与碱性磷酸酶相关性显著；有机碳则与纤维二糖酶存在显著的正相关。结论湖滨湿地退化为草地和沙地后，土壤有机碳和氮以及土壤酶活性呈现下降趋势，土壤水溶性有机碳、水溶性有机氮以及有机碳显著地影响土壤酶活性的变化。 

Research on soil enzyme activities of different land types in lakeside of Qinghai Lake,northwestern China

Objective Investigating the changes of soil enzyme activities and their driving factors in different land types could be used to provide references for vegetation restoration and ecosystem management reconstruction in degraded wetlands, Qinghai Lake, northwestern China. Method Three study plots involved the lakeside wetlands, grasslands and sandy land were established, and samples at 0?10 cm, 10?20 cm and 20?30 cm soil depth were collected in the Gahai area, Qinghai Lake, respectively. The chemical properties and enzyme activities of soil were analyzed, further redundancy analysis (RDA) was performed to analyze the relationship between chemical properties and enzyme activities of soil by CANOCO 5.0 software.Result The amounts of soil organic carbon, total nitrogen and dissolved organic carbon and nitrogen in wetlands were significantly higher than that in sandy land, while the amounts of active carbon and ammonium nitrogen in wetland soil were significantly higher than that in grassland and sandy land. Dissolved organic carbon, nitrate nitrogen and available phosphorus in wetlands and grasslands were significantly higher than sandy land. Compared to the wetland, the activities of β-glucosidase, leucine aminopeptidase and glycine aminopeptidase in the soil of grassland decreased significantly by 32.17%, 30.90% and 39.67%, respectively, and those in the soil of the sandy land decreased significantly by 79.22%, 73.46% and 64.84% when comparing with the grassland, respectively. The activities of N-acetyl-glucosaminidase and acid phosphatase in wetland and grassland were significantly higher than those in the sandy land. However, the activities of cellobiohydrolase and alkaline phosphatase in wetland were significantly higher than those in sandy land. The results of redundancy analysis showed that soil dissolved organic carbon and dissolved organic nitrogen were the main factors to influence soil enzyme activity, with the explanatory degree of 58.8% and 29.4%, respectively. Dissolved organic carbon was a major factor explaining the variation of leucine aminopeptidase and acid phosphatase activities, whereas dissolved organic nitrogen was significantly correlated with alkaline phosphatase. A significant positive correlation between organic carbon content and cellobiohydrolase activity was found. Conclusion Soil organic carbon, nitrogen and soil enzyme activity declined when lakeside wetland degenerated into grassland and sandy land, and soil dissolved organic carbon, dissolved organic nitrogen and organic carbon notably influenced the change of soil enzyme activity.