华西雨屏区苦竹林土壤酶活性对模拟氮沉降的响应

2007年11月—2009年5月，对华西雨屏区苦竹人工林进行了模拟氮沉降试验，氮沉降水平分别为：对照(0 g N·m^-2·a^-1)、低氮(5 g N·m^-2·a^-1)、中氮(15 g N·m^-2·a^-1)和高氮(30 g N·m^-2·a^-1).在氮沉降进行半年后，每月采集各样方0～20 cm土壤样品，测定其土壤酶活性，连续测定1年.结果表明：苦竹人工林样地中6种土壤酶活性的季节变化较明显，蔗糖酶、纤维素酶和酸性磷酸酶活性的高峰期出现在春季，脲酶活性高峰期出现在秋季，而过氧化物酶和多酚氧化酶活性高峰期出现在冬季；氮沉降增加了苦竹林土壤中木质素分解酶和碳、氮、磷分解相关酶（多酚氧化酶、蔗糖酶、酸性磷酸酶和脲酶）的活性，抑制了纤维素酶活性，而对过氧化物酶的影响不显著；苦竹林生态系统处于一种氮限制状态，氮沉降刺激了微生物 酶系统对土壤有机质的分解.

Soil enzyme activities in a Pleioblastus amurus plantation in Rainy Area of West China under simulated nitrogen deposition

From November 2007 to May 2009, a simulation test was conducted in a Pleioblastus amarus plantation in Rainy Area of West China to study the effects of nitrogen deposition on the activities of soil enzymes. Four treatments were installed, i.e. ,control (0 g N · m~(-2) · a~(-1) ), low nitrogen (5 g N · m~(-2) · a~(-1) ), medium nitrogen ( 15 g N · m~(-2)· a~(-1) ), and high nitrogen (30 g N ·m~(-2)· a~(-1) ). Half year after N deposition, 0-20 cm soil samples were eolleeted monthly, and the activities of peroxidase, polyphenol oxidase, cellulase, suerase, urease, and acid phosphatase were determined. All test enzyme activities had apparent seasonal variation, with the peak of eellulase, sucrase, and acid phosphatase activities in spring, of urease activity in autumn, and of peroxidase and polyphenol oxidase activities in winter. Nitrogen deposition stimulated the activities of polyphenol oxidase, sucrose, urease, and acid phosphatase, inhibited cellulase activity, but had no significant effects on peroxidase activity. The test P. amurus plantation ecosystem was N-limited, and nitrogen deposition stimulated the decomposition of soil organic matter by microbe-enzyme system.