干湿交替频率对不同土壤CO_2和N_2O释放的影响  

Impacts of drying-wetting cycles on CO_2 and N_2O emissions from soils in different ecosystems

作　　者：欧阳扬[1,2] 李叙勇[1] 

机构地区：[1]中国科学院生态环境研究中心城市与区域国家重点实验室,北京100085 [2]中国科学院研究生院,北京100049

出　　处：《生态学报》2013年第4期1251-1259,共9页Acta Ecologica Sinica

基　　金：国家自然科学基金(41071323;40971271);国家重点基础研究发展规划项目计划课题(2009CB421104)

摘　　要：干旱、半干旱和地中海气候区,乃至一些湿润地区,由干湿交替引起的土壤碳、氮的短暂脉冲式释放很大程度上决定着长时间尺度温室气体释放的总量,是土壤碳、氮温室气体释放的关键过程。选择我国降雨梯度下的森林、农田、草地和荒漠生态系统,采集土样进行实验室统一控制条件下的多重干湿交替循环,对比探讨不同生态系统土壤干湿交替频率对CO2和N2O释放的影响模式。结果表明:(1)干湿交替能够显著的激发土壤中CO2和N2O的释放,森林、农田、草地和荒漠土壤CO2和N2O释放速率对干湿交替的响应模式基本一致,其响应强度与土壤本底中碳和氮的含量有关;(2)在一定培养时间内,随着干湿交替频率的增加,土壤再湿润阶段CO2释放速率降低,但是,气体释放的总量较之于恒湿对照组有所增加。(3)不同土壤N2O的释放总量对干湿交替频率的响应模式表现出很大的差异,其中农田和荒漠土壤响应模式类似。In the context of climate change impacts on the rainfall patterns,understanding the effects of soil drying-rewetting cycles on green-house gas emission has become increasingly important in many ecosystems.Soil carbon and nitrogen releases caused by drying and rewetting cycles largely determine the total amount of greenhouse gases emission for a long time in an ecosystem.Such kind of influence is particularly important in arid,semi-arid and Mediterranean regions.The soil drying-rewetting cycle is a natural phenomenon that the soil experiences drying,then wetting,and then drying and rewetting again and again.When a dry soil is being rewetted,the amount of soil microbial biomass and its activity can be sharply increasing in a short time period,and then a large amount of gaseous carbon（C） and nitrogen（N） erupts from the soil.The sudden release of gaseous C and N is caused by the stimulation of the soil microbes.Such a phenomenon is called ＂Birch effect＂.The drying-rewetting cycles play an important role in the feedbacks of terrestrial ecosystems.In this study,soil samples were taken from four field sites of forest,agriculture,grassland and desert ecosystems along the precipitation gradient in China.These four sites are Beijing Forest Ecosystem Study,Ansai Agricultural Ecosystem Study,Inner Mongolia Grassland Study and Fukang Desert Ecosystem Study sites of the Chinese Ecosystem Research Network（CERN）.Based on the laboratory experiment with 0,2,5,7 and 14 drying-rewetting cycles in the controlling temperature,we examed the patterns of drying-rewetting impacts on soil CO2 and N2O emission.Our results showed that：（1） Drying and rewetting cycles significantly stimulated the CO2 and N2O releases from soil.For example,in comparison with the control experiment with constant soil moisture in the grassland soil,the average respiration rate of 14-cycle,7-cycle,5-cycle and 2-cycle treatments increased 43%、103%、116% and 192%,respectively.We also found that response patterns in CO2 and N2O release rates

关 键 词：干湿交替频率 温室气体 土壤CO2释放 土壤N2O释放 

分 类 号：S153[农业科学—土壤学]