大气CO_2浓度和温度升高对稻麦轮作系统土壤剖面甲烷分布的影响

Effects of elevated CO_2 concentration and temperature on methane distribution characteristics within soil profile in rice-wheat annual rotation system

在田间开放式空气条件下模拟未来50年后气候变化的情况,包括大气温度升高(T)和CO2浓度升高(FACE)以及二者同时升高(FACE+T)对稻麦轮作生态系统稻田土壤剖面温室气体甲烷(CH4)分布的影响。通过田间小区试验,运用土壤剖面气体原位采集系统周年观测,研究CH4在水稻-小麦轮作周期淹水或排水状态下4个不同土壤层次(0~7cm,7~15cm,15~30cm,30~50cm)的行为特征。研究表明:各处理的不同土壤剖面CH4的动态变化趋势相同;水稻生长季CH4浓度随着土层深度的增加而减少,各土壤剖面CH4平均浓度显著高于小麦生长期;小麦生长季CH4浓度则随着土层深度的增加而增加,而且降水显著增加了该季表层CH4浓度。与对照(CK)相比,气候变化的3个处理(FACE、T、FACE+T)均显著增加了土壤剖面各层次的CH4浓度(P【0.05),其中T处理7cm处CH4的平均浓度最高。

To determine the impacts of climate change on the distribution of greenhouse gas methane(CH4)within soil profile in the native rice-wheat annual rotation ecosystem,the climate change situations after future 50 years including ambient conditions(CK),elevated CO2concentration(FACE),elevated temperature(T),and combined elevated CO2 concentration and temperature(FACE+T)were simulated in the field of open air conditions.A multilevel sampling probe was designed to allow sampling the atmosphere composition of soil profiles at 0-7cm,7-15 cm,15-30 cm,and 30-50 cm.The results show that CH4 concentration decreases gradually from 0to 50 cm during the rice season,while increases gradually with the depth during the wheat season.Production of CH4 is strongly influenced by the increasing CO2 and rising temperature,while the T treatment produces the highest CH4 concentration.Heavy rainfall events result in a higher CH4 concentration in the shallow soil layers as compared to the deep layers during the wheat season.The results indicate that the three climate change treatments of FACE,T,FACE+T can significantly increase CH4 production in a rice-wheat annual rotation field(P <0.05).Moreover,the T treatment significantly affects the distribution of soil CH4 with the highest CH4 concentration at 7cm soil depth.