西南喀斯特地区轮作旱地土壤CO_2通量  

CO_2 flux in the upland field with corn-rapeseed rotation in the karst area of southwest China

作　　者：房彬[1,2] 李心清[1] 程建中[1] 王兵[1] 程红光[1] 张立科[1,2] 杨放[1,2] 

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002 [2]中国科学院大学,北京100049

出　　处：《生态学报》2013年第17期5299-5307,共9页Acta Ecologica Sinica

基　　金：国家自然基金(40872212);中国科学院战略性科技先导专项(碳专项);贵州省农业攻关计划项目(黔科合NY字[2011]3079号)

摘　　要：中国已承诺大幅降低单位GDP碳排放,农业正面临固碳减排的重任。西南喀斯特地区环境独特,旱地面积占据优势比例,土壤碳循环认识亟待加强。以贵州省开阳县玉米-油菜轮作旱地为研究对象,采用密闭箱-气相色谱法对整个轮作期土壤CO2释放通量进行了观测研究,结果表明:(1)整个轮作期旱地均表现为CO2的释放源。其中油菜生长季土壤CO2通量为(178.8±104.8)mg CO2·m-2·h-1,玉米生长季为(403.0±178.8)mg CO2·m-2·h-1,全年平均通量为(271.1±176.4)mg CO2·m-2·h-1,高于纬度较高地区的农田以及同纬度的次生林和松林;(2)CO2通量日变化同温度呈现显著正相关关系,季节变化与温度呈现显著指数正相关关系,并受土壤湿度的影响,基于大气温度计算得出的Q10为2.02,高于同纬度松林以及低纬度的常绿阔叶林;(3)CO2通量与土壤pH存在显著线性正相关关系,显示出土壤pH是研究区旱地土壤呼吸影响因子之一。Abstract： Farmland ecosystems constitute great carbon sources in terrestrial ecosystems and have important influence on the global carbon cycle. As China has promised to reduce carbon emission significantly, China＇s agriculture is facing the challenge of carbon sequestration and reduction of carbon emission. As the environment in karst area of southwest China is unique and upland field covers a large scale, further research is badly needed to quantify diurnal and seasonal variations of soil COa flux, and to investigate the effects of temperature, soil water content and soil properties on soil CO： flux. Taking upland field with corn-rapeseed rotation in Kaiyang country of Guizhou province as our study subject, we used static enclosed chamber coupled with GC to observe the soil CO2 flux of all the rotation period. Continuous measurements of soil temperature and moisture were conducted together with several other physical and chemical properties of the soil. It was found that the upland with corn-rapeseed rotation performed as the source of CO2. The mean CO2 flux was （178.8_＋104.8） mg CO：＇m-2＂h-~ in the rapeseed growing season, （403.0_＋178.8） mg CO2＂m-2-h-1 in the maize growing season, and （271.09_＋176.37） mg CO2. m-2. h-1 for the whole rotation period. These values are in the upper part of the range of published soil-surface CO2 flux date. There were significant positive correlations between soil CO2 flux and temperature in both diurnal changes and seasonal fluctuations. The diurnal fluctuations of CO2 flux showed similar patterns and fluctuated from minimum around 12 pm to maximum at 1 pm to 3 pm. For the seasonal variations, soil CO2 flux was positively correlated with temperature in the whole crop rotation with the minimum value of 31.10 mg CO2·m-2·h-1 in February and the maximum value of 665.46 mg CO2·m-2·h-1 in August. An exponential function provided the best fit for describing the relationship between seasonal soil CO2 flux and temperature for the whole crop rotation, wit

关 键 词：土壤CO2通量 温度 湿度 喀斯特地区 

分 类 号：X142[环境科学与工程—环境科学]