施氮对亚热带樟树人工林土壤氮矿化的影响

Effect of nitrogen application on soil nitrogen mineralization of Cinnamomum camphora plantation in subtropical area

20世纪以后,全球工业、农业飞速发展,从而导致大量活性氮输入至森林生态系统,作为生物地球化学循环的重要部分,森林生态系统中土壤氮元素的转换过程及其对外源性氮输入的响应机制越来越被重视。以亚热带樟树Cinnamomum camphora人工林为研究对象,在施加氮肥(低氮5 g·m-2、中氮15 g·m-2、高氮30 g·m-2)的基础上,用树脂芯法对其不同季节土壤氮矿化特征的影响进行了研究。结果表明:经过施氮肥处理后,在1、4、7月份樟树人工林的土壤氮矿化量均表现为随施肥量的增加而递增,但10月份的高氮浓度处理樟树人工林土壤氮矿化量呈现下降趋势,但高于对照处理,说明施氮肥处理可以增加樟树林土壤氮矿化速率;施肥处理可以显著增加樟树林土壤铵态氮含量及氨化速率,但是对土壤硝态氮量和硝化速率影响不显著。

Since 20th century, with the rapid development of global industry and agriculture, a large number of reactive nitrogen has been inputting into the forest ecosystems. As an important part of biogeochemical cycles, the forest soil nitrogen conversion process and the response mechanism of to exogenous nitrogen input were concerned more widely. By taking the subtropical C. camphor plantation as the research object, the effects of applied nitrogen fertilizer （low nitrogen 5 g·m-2, middle nitrogen 15 g·m-2, high nitrogen 30 g·m-2） in the plantations in different seasons on soil nitrogen mineralization characteristics were investigated by means of resin-core technique. The results show that after nitrogen treatments （in January, April, July and October respectively）, the C. camphor plantation appeared a declining trend under high nitrogen treatment in October, but it showed a increasing trend with fertilizing concentration increased in the other three months, and the soil nitrogen mineralization of four mouths were higher than that of the control treatment group;This suggests that the nitrogen application increased the soil nitrogen mineralization rate and significantly increase ammonium nitrogen content in the forest soil, but had slight influence on soil nitrate nitrogen and the nitriifcation rate in the forest soil.