藏北高寒草原土壤酶活性对氮添加的响应及其影响因素

为阐明藏北高寒草原土壤酶活性对氮沉降响应规律,本研究于2013年开展模拟氮沉降试验(氮添加水平:0,2,5和10 g·m-2·yr-1),采用样方法对植物取样,双对角线法对土壤取样,分析土壤酶活性在氮添加5年后的变异特征及影响土壤酶活性的主要环境要素.结果表明:蔗糖酶、纤维素酶、多酚氧化酶和过氧化氢酶活性在氮添加后显著...

Responses of Soil Enzyme Activities to Nitrogen Addition and Its Impact Factors at the Alpine Steppe of Northern Tibet

To clarify the activities of various soil enzymes responding to the nitrogen deposition,we established a field experiment by adding ammonium nitrate to stimulate nitrogen deposition at alpine steppe in 2013. Four nitrogen fertilizer treatments (0,2,5,and 10 g·m^-2·yr^-1) were applied at 24 plots. We collected plant samples by the quadrat sampling method and soil samples by the double diaonal line in 2017. We analyzed the soil enzyme activity at four levels after 5 years of nitrogen addition. The results showed that the activity of invertase,cellulose,polyphenol oxidase and peroxidase significantly decreased due to nitrogen addition (P < 0.01). The activity of urease and neutral phosphatase was significantly increased by nitrogen addition (P < 0.01). Results from Pearson analysis and redundancy analysis showed that soil pH was not affected by nitrogen addition,which did not influence soil enzyme. Nitrogen increased the content of soil nitric nitrogen and ammoniacal nitrogen. The aboveground litter and underground biomass were also increased and root lignin content was decreased due to nitrogen addition. Soil microorganisms prefer low molecular weight organic nitrogen and carbon compounds,which would depress the carbon hydrolase and oxidase,and activate the urase. Nitrogen addition activated plants and increased the absorption of phosphorus,which would improve the activity of phosphatase. Therefore,the changes in the plant property under nitrogen addition were the most important factors for the soil enzyme at alpine steppe.