氮添加对杨树人工林土壤活性有机碳季节变化的影响

为研究大气氮沉降对森林生态系统碳循环的影响, 从2012年5月起,选择典型的苏北杨树(Populus deltoides cv. ‘I-35’)人工林为实验地, 采用随机区组设计不同氮添加处理, 进行野外氮添加定位试验,分析氮添加对不同林龄杨树人工林土壤活性有机碳的影响。结果表明:氮添加提高了土壤微生物生物量碳、可溶性有机碳的含量; 土壤微生物生物量碳和可溶性有机碳含量有显著的季节变化,总体表现为夏秋季较高,冬春季较低。相关分析表明,微生物生物量碳含量与土壤温度呈极显著正相关(p<0.01),可溶性有机碳含量与土壤温度相关性不显著(p>0.05)。研究表明,苏北杨树人工林土壤活性有机碳含量的季节变化主要受到土壤温度影响,同时其对氮添加呈正响应。

Effects of nitrogen addition on the seasonal variations of soil labile organic carbon in different age poplar plantations

In order to understand the effects of atmospheric nitrogen deposition on the carbon cycle of forest ecosystem, a field experiment of nitrogen addition at Dongtai forest farm in Jiangsu province was conducted in May 2012. The results showed that the nitrogen addition increased the contents of soil microbial biomass carbon(MBC)and dissolved organic carbon(DOC).The soil MBC and DOC exhibited obvious seasonal patterns. Overall,the contents of soil MBC and DOC were higher in summer and autumn,but lower in winter and spring. The MBC had a significantly positive correlation with soil temperature(p<0.01).The DOC did not correlated with soil temperature(p>0.05).The results implicated that the seasonal variations of soil labile organic in poplar plantations were affected by soil temperature. In addition,the soil liable organic carbon respond positively to nitrogen addition.