施氮和降水格局改变对土壤CH4和CO2通量的影响  

Effects of nitrogen addition and precipitation change on soil methane and carbon dioxide fluxes

作　　者：李伟[1,2] 白娥 李善龙[1,2] 孙建飞[1,2] 彭勃[1,2] 姜萍[1] 

机构地区：[1]森林与土壤生态国家重点实验室中国科学院沈阳应用生态研究所,沈阳110164 [2]中国科学院大学资源与环境学院,北京100049

出　　处：《生态学杂志》2013年第8期1947-1958,共12页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(31100326)资助

摘　　要：氮沉降增加和降水格局改变是全球变化的两项重要内容,但是同时考虑上述两因素对温室气体CH4和CO2通量影响的原位双因子模拟研究还相当有限。本研究以长白山温带阔叶红松林土壤为研究对象,采用静态箱法研究了外施氮源(50kgN·hm-2·a-1)和增减30%降水对土壤CH4和CO2通量的影响。结果表明:施氮能抑制土壤CH4吸收,有时甚至能将土壤对CH4的吸收转为释放,但这种抑制效应只能维持5d左右,且能在一定程度上改变CH4通量和环境因子(温度、土壤pH、粘粒含量)的相关关系。降水改变未能显著影响土壤CH4通量。对CO2通量而言,施氮能降低土壤CO2排放,长白山阔叶红松林连续施氮第4年的平均抑制效应为27.4%。长期连续施氮的平均抑制效应随施氮时间延长而逐渐增大,一定年限后达到最大值。单次施氮的抑制效应随时间延长逐渐减弱,并在1个月的施氮周期末期基本消失。施氮的抑制效应和土壤充水孔隙度(WFPS)呈显著负相关关系,且升温能增强施氮对CO2释放的抑制效应并延长抑制时间。施氮、降水有可能改变土壤呼吸的温度敏感性。本研究表明,长白山森林土壤氮素尚未达到一定阈值,未来氮沉降增加将抑制CO2的释放和CH4的吸收,因此总体来看施氮抑制土壤碳排放。Increased nitrogen deposition and changed precipitation pattern are the two important factors of global change, while the in situ experiments studying how the two factors affect greenhouse gases CO2 and CH4 fluxes are still limited. Taking the temperate broadleaved Korean pine （Pinus koraiensis） forest in Changbai Mountains of Northeast China as the object, and by using static chambers, this paper studied the effects of nitrogen addition （50 kg N＆middot;hm-2＆middot;a-1） and changed precipitation regime （30% increase and decrease of precipitation） on the soil CO2 and CH4 fluxes. Nitrogen addition inhibited the soil CH4 consumption, and even, converted the CH4 consumption into CH4 release. However, this inhibition effect only lasted for approximately 5 days. Nitrogen addition also affected the relationships between the CH4 flux and environmental factors （soil temperature, pH, and clay content） to some extent. The changed precipitation regime had no significant effects on the CH4 flux. Nitrogen addition decreased the CO2 flux, with an average decrement of 27.4% after 4 years continuous nitrogen addition. It was predicted that the effects of longterm continuous nitrogen addition on the CO2 flux would be increased with time, and reached the maximum after certain years of nitrogen addition. Oppositely, the effects of single time nitrogen addition would be decreased with time, and disappeared by the end of the 1month cycle. The inhibition effect of nitrogen addition on the CO2 flux was negatively correlated with soil water filled pore space （WFPS） （P=0.022）, and enhanced and extended at higher temperature. Nitrogen addition and precipitation change could possibly alter the temperature sensitivity of soil respiration. Our results indicated that the soil nitrogen in temperate forest in Changbai Mountains had not reached a threshold, and the future nitrogen deposition increase would inhibit the CO2 release and CH4 uptake. Overall, nitrogen

关 键 词：氮添加 降水改变 全球变化 阔叶红松林 碳收支 

分 类 号：S154.1[农业科学—土壤学]