模拟氮沉降对高寒湿地土壤理化性质和酶活性的影响

为研究氮沉降对土壤酶和土壤理化性质的影响，本研究在青海湖东岸开展野外控制试验，设计4个施氮水平0 g·m^-2，2 g·m^-2，5 g·m^-2和10 g·m^-2（分别为N0，N2，N5和N10），测定土壤养分和土壤酶活性。结果表明：氮沉降对土壤pH值和全磷含量无显著影响，硝态氮在浅层土中含量随施氮量的增加而逐渐下降，铵态氮在10 g·m^-2浅层土中含量显著高于其它处理，有机碳含量在2 g·m^-2处理下显著高于其它处理；酸性磷酸酶和脲酶随施氮量的增加活性显著升高，氮沉降抑制过氧化氢酶活性，碱性蛋白酶对氮沉降不敏感；相关分析表明，酸性磷酸酶、脲酶活性与铵态氮含量呈显著正相关关系，过氧化氢酶活性与硝态氮含量呈显著正相关关系，碱性蛋白酶活性与有机碳含量呈极显著正相关关系。本研究表明氮沉降影响高寒湿地碳、氮含量及其计量比，进而影响土壤酶活性。

Effects of Simulated Nitrogen Deposition on Soil Physicochemical Properties and Enzyme Activities in Alpine Wetland

To investigate the effects of nitrogen deposition on soil enzymes and soil physicochemical properties,a field control experiment was carried out on the east coast of Qinghai Lake. Four nitrogen application levels (N0,N2,N5 and N10,respectively) were designed to determine soil nutrients and soil enzyme activities. The results showed that nitrogen deposition had no significant effect on soil pH value and total phosphorus content,nitrate nitrogen content in shallow soil decreased with the increase of nitrogen application rate,ammonium nitrogen content in shallow soil of 10 g·m^-2 was significantly higher than that of other treatments,and organic carbon content in 2 g·m^-2 was significantly higher than that of other treatments. The activities of acid phosphatase and urease increased significantly with the increase in nitrogen application rate. Catalase activity was inhibited by nitrogen deposition,while alkaline protease was not sensitive to nitrogen deposition. Correlation analysis showed that the activities of acid phosphatase and urease were significantly positively correlated with ammonium nitrogen,catalase was significantly positively correlated with nitrate nitrogen,and alkaline protease was extremely significantly positively correlated with organic carbon. This study showed that nitrogen deposition affected the carbon and nitrogen contents and their quantitative ratio in alpine wetland,and then affected soil enzyme activities.