干湿交替对土壤碳库和有机碳矿化的影响  

EFFECT OF DRYING-REWETTING ALTERNATION ON SOIL CARBON POOL AND MINERALIZATION OF SOIL ORGANIC CARBON

作　　者：王苑[1] 宋新山[1] 王君[1] 严登华[2] 王宇晖[1] 周斌[1] 

机构地区：[1]东华大学环境科学与工程学院,上海201620 [2]中国水利水电科学研究院水资源研究所,北京100044

出　　处：《土壤学报》2014年第2期342-350,共9页Acta Pedologica Sinica

基　　金：国家973计划"气候变化对旱涝灾害的影响及风险评估"(2010CB951102);国家自然科学基金项目(51079028)资助

摘　　要：水分是影响土壤活性碳库和惰性碳库周转过程的主导因子,而土壤有机碳的周转速率会对气候变化造成潜在的重要影响。以农田水稻土为供试土壤,通过培育试验研究了干湿交替过程对土壤有机碳矿化的影响,并利用两库叠加模型对土壤不同碳库及其降解动力学进行初步评估。结果表明:干湿交替激发了土壤呼吸,增加了土壤微生物代谢活性。三次湿润过程对土壤呼吸的激发量分别为119.3%、159.5%和87.3%,激发效应随干湿交替频率的增加先升高后降低。多次干湿交替后,土壤累积CO2释放量低于恒湿土壤,湿润所引起的激发的矿化量不足以弥补干旱期降低的矿化量。在湿润的数小时内,土壤溶解性有机碳含量先升高后降低。干湿交替提升了土壤活性碳库的降解速率,降低了惰性碳库的降解速率,湿润后土壤活性碳库显著增加。多次干湿交替降低了土壤真菌/细菌比,使土壤微生物群落结构发生变化,细菌成为优势种群。Soil moisture is a leading factor that affects turnover of the labile and resistant soil carbon pools, while the turnover rate of soil organic carbon has a potential important impact on global climate change. An indoor paddy soil incubation experiment was carried out to explore effect of drying-rewetting alternation on mineralization of soil organic carbon and evaluate different soil carbon pools and their degradation dynamics using a two-order model. Results show that drying-rewetting alternation significantly stimulated soil respiration as well as metabolic activity of soil microbes. Three successive rounds of drying-rewetting alternation stimulated soil respiration by 119.3%, 159.5% and 87.3%, respectively, and with the alternation increasing in frequency, the effect intensified first and then waned. After rounds of alternation, the release of CO2 accumulated in the soil fell lower than that from the soil kept permanently wet because the mineralization stimulated by rewetting was far from enough to make up the drop in mineralization during the drying period. Within the hours after rewetting, soil soluble organic carbon rose and then fell in content. Drying-rewetting alternation raised degradation rate of the soil labile carbon pool and lowered that of the soil resistant carbon pool. After rewetting, the soil labile carbon pool was significantly bigger in size. Frequent drying-rewetting alternation lowered soil fungi/bacteria ratio and altered the community structure of soil microbes, pushing bacteria into dominancy.

关 键 词：干湿交替 土壤呼吸 活性碳库 惰性碳库 土壤微生物 

分 类 号：S153.6[农业科学—土壤学]