模拟氮沉降增加对寒温带针叶林土壤CO_2排放的初期影响  

Early nitrogen deposition effects on CO_2 efflux from a cold-temperate coniferous forest soil

作　　者：温都如娜[1] 方华军[2] 于贵瑞[2] 程淑兰[3] 周梅[1] 高文龙[4] 张裴雷[3] 徐敏杰[3] 

机构地区：[1]内蒙古农业大学生态环境学院,呼和浩特010019 [2]中国科学院地理科学与资源研究所,北京100101 [3]中国科学院研究生院,北京100049 [4]东华大学环境科学与工程学院,上海201620

出　　处：《生态学报》2012年第7期2185-2195,共11页Acta Ecologica Sinica

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

摘　　要：研究大气氮沉降增加情景下北方森林土壤CO2排放通量及其相关控制因子至关重要。在大兴安岭寒温带针叶林区建立了大气氮沉降模拟控制试验,利用静态箱-气相色谱法测定土壤CO2排放通量,同时测定土壤温度、水分、无机氮和可溶性碳含量等相关变量,分析寒温带针叶林土壤CO2排放特征及其主要驱动因子。结果表明:氮素输入没有显著改变森林土壤含水量,但降低了有机层土壤溶解性无机碳(DIC)含量,并增加有机层和矿质层土壤溶解性有机碳(DOC)含量。增氮短期内不影响土壤NH+4-N含量,但促进了土壤NO-3-N的累积。增氮倾向于增加北方森林土壤CO2排放。土壤CO2通量主要受土壤温度驱动,其次为土壤水分和DIC含量。虽然土壤温度整体上控制着土壤CO2通量的季节变化格局,但在生长旺季土壤含水量对其影响更为明显。在分析增氮对土壤CO2通量的净效应时,除了土壤温度和水分外,还要考虑土壤有效碳、氮动态的影响。It is generally thought that high latitude forests are a massive potential global carbon（C） sink.Nitrogen（N） limitation is thought to be the primary reason why these forests are a ＇missing C sink＇ as atmospheric N deposition is shown to significantly promote plant growth and increase C sequestration in forests of these regions.Boreal forests are the second largest biome on earth and are limited by N availability.Soil CO2 emission is an important process of C cycling in boreal forests and it has shown promotion,no change and inhibition responses to N addition.Therefore studies on the CO2 flux from boreal forest soils and its control factors under increased atmospheric N deposition are essential.In this study,a manipulative N addition experiment was created in a cold-temperate coniferous forest in the Daxing′anling region to investigate this.NH4NO3 fertilizer was added at four rates,each with three replicates： control（0 kg N hm-2 a-1）,low N（10 kg N hm-2 a-1,the current N deposition level）,medium N（20 kg N hm-2 a-1） and high N（40 kg N hm-2 a-1）.Each plot had an area of 200 m2（10 m × 20 m） and a 10 m isolation band set between them.During the growing season（May to September）,soil CO2 fluxes were measured by the static chamber-gas chromatography method and soil temperature,soil moisture,soil inorganic N and dissolved carbon content（DOC） were simultaneously measured to explore the main factors affecting CO2 emission.Results showed that N addition did not significantly change soil moisture content but significantly reduced soil dissolved inorganic carbon（DIC） in the organic layer and increased soil DOC in the organic and mineral soil layers.Short-term N addition did not increase soil NH＋4-N content,but significantly increased soil NO-3-N content.In control plots,soil CO2 flux ranged from 195.24 to 544.91 mg CO2 m-2 h-1,with an average of（357.33±18.72） mg CO2 m-2 h-1.Exogenous N input tended to increase CO2 emission from the coniferous forest soil by 8.3% to 18.2%.S

关 键 词：大气氮沉降 土壤CO2通量 土壤无机氮 土壤可溶性碳 寒温带针叶林 

分 类 号：S718.5[农业科学—林学]