寒温带针叶林土壤CH_4吸收对模拟大气氮沉降增加的初期响应  

Early responses of soil CH_4 uptake to increased atmospheric nitrogen deposition in a cold-temperate coniferous forest

作　　者：高文龙[1,2] 程淑兰[2] 方华军[1] 陈燕[3] 王永生[1] 张裴雷[2] 徐敏杰[2] 

机构地区：[1]中国科学院地理科学与资源研究所,生态系统观测与模拟重点实验室,北京100101 [2]中国科学院大学,北京100049 [3]东华大学环境科学与工程学院,上海201620

出　　处：《生态学报》2013年第23期7505-7515,共11页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(41071166;31070435;31130009;31290221);国家重点基础研究发展计划资助项目(2010CB833502;2010CB833501;2012CB417103);中国科学院地理与资源研究所"秉维"优秀青年人才基金资助项目(2011RC202);中国科学院战略性先导科技专项资助资助(XDA05050600)

摘　　要：土壤甲烷(CH4)吸收是森林生态系统碳循环的重要环节,研究大气氮(N)沉降增加情景下北方森林土壤CH4吸收通量及其驱动机制至关重要。以大兴安岭寒温带针叶林作为研究对象,构建了低剂量、多形态的增N控制实验,研究了2010年生长季(6—10月)土壤CH4吸收通量对增N的初期响应及其环境驱动机制。结果表明:整个生长季,寒温带针叶林土壤表现为大气CH4的汇,土壤CH4平均吸收通量为(51.5±4.7)μg m-2h-1,主要由0—10 cm层土壤水分驱动。除了低剂量的NO-3-N输入促进了土壤CH4氧化外,低剂量的N输入总体上没有显著改变寒温带针叶林土壤CH4净吸收通量。另外,增N没有显著改变0—10cm层土壤水分、温度和土壤pH值,但显著增加了0—10cm矿质土壤NH+4-N和NO-3-N含量。研究表明,受N限制的北方森林土壤CH4吸收对增N响应的敏感程度与土壤CH4活性氧化区域、土壤NH+4-N和NO-3-N含量的空间分布格局以及相对比例有关。在分析北方森林土壤CH4通量及其驱动因子对N沉降增加的响应时,除要考虑N沉降水平影响外,还应考虑N沉降类型(NH+4-N和NO-3-N)的相对影响。Methane （CH4 ） oxidation in boreal forest soils is an important factor in the global CH4budget. Previous studies have shown that nitrogen （N） deposition alters the magnitude and direction of CH4uptake in boreal forest soils. However, the critical rate of atmospheric N deposition that causes the shift from stimulation of soil CH4uptake to inhibition, and the mechanisms responsible for these trends, are poorly understood. Investigation into the responses of CH4 uptake flux from these soils and its driving factors relating to N input is important. In this study, a cold-temperate coniferous forest in theGreat Xing＇an Mountains was selected for conducting an N addition manipulative experiment. Two forms of N （ NH4-N and NO3-N） and three N addition rates （0, 10 and 40 kg N hm-2 a-1） were designed to assess the responses of soil CH4 fluxes to N addition. In the growing season （June to September） of 2010, soil atmospheric CH4 exchange flux was measured every ten days using closed clambers. Simultaneously, soil environmental variables including soil moisture, soil temperature in the 0--10 cm horizon, soil NH4-N and NO3--N contents in the organic and mineral horizons, and soil pH values in the mineral soil horizon were also measured to determine the main factors affecting soil CH4uptake. The results showed that the average rate of CH4 uptake in the cold-temperate coniferous forest soil was （51.5±4.70） μg m-2 h-1 , and this was mainly controlled by soil moisture content at 0--10 cm. Although N input did not significantly affect the soil CH4 uptake, low level NO3-N input did slightly stimulate soil CH4 uptake. Further analysis revealed that soil moisture and soil temperature at 0--10 cm were not affected by N input. Soil NH4-N and NO3-N contents decreased greatly with soil depth and the vertical distribution pattern was obvious. In the organic layer, soil NH^-N content increased with increasing N input, whereas soil NO3-N content was not affected by N addition. In the mineral layer, soil NH4-N con

关 键 词：CH4吸收 大气N沉降 土壤无机N 初期响应 北方森林 

分 类 号：X13[环境科学与工程—环境科学]