生态环境学报2009，Vol.18Issue(5)：1923-1928,6.
密云水库上游地区农田土壤有机碳储量及变化模拟
Modeling soil organic carbon storage and dynamics in croplands of the upperstream watershed of Miyun Reservoir in north China
摘要
Abstract
Soil organic carbon (SOC) pools in agricultural lands constitutes an important portion of the global carbon pool and has significant impacts on food security and global climate change. North China is one of the largest food producers where the croplands have been undergoing intensive management practices during the past decades. A well process-based biogeochemical model, DNDC (I.e., DeNitrification-DeCompositon), was adopted in the study to quantify SOC storage and dynamics in croplands of the Upper-stream Watershed of Miyun Reservoir in North China. In the study, we further tested DNDC against our datasets measured at four sites with soybean, or corn planted in Yanqing County, Beijing although the model has been validated against numerous observations obtained in other parts of China. Results from our validation tests were encouraging indicating that DNDC was capable of capturing the trends of SOC dynamics in the target region. To support upscaling of the model simulations to the entire region, we built up a GIS database to hold the spatially differentiated data of climate, soil properties, cropping systems, and agricultural management practices at county scale across the domain. By linking DNDC to the GIS database, we accomplished the regional simulations for the 214 920 hm~2 of croplands in the Upperstream Watershed of Miyun Reservoir. Results from the upscaling simulations indicated that (1) the total agricultural SOC storage in the domain was 7 646×10~6 kg (0～25 cm soil layer) with an average 35 576 kg·hm~(-2), which was lower than the national average; (2) the annual increment of SOC in all the croplands in the domain was about 140×10~6 kg in 2006; and (3) the SOC increase was predicted across the target domain. The results implied that the agricultural soils in the region acted as a sink of atmospheric CO_2 under the current climate, soil and management conditions. Alternative scenarios of climate change or farming management were tested with DNDC at regional scale, and the results indicated that (1) increases in temperature would make notably negative impacts on the agricultural SOC sequestration in the studied domain, and however (2) the SOC storage could still increase if higher fractions of above-ground crop residue were incorporated to the soils, more manure was applied, adequate irrigation was applied, or the conventional tillage was converted to no-till.关键词
密云水库上游地区/农田/土壤有机碳/DNDC模型Key words
the Upperstream Watershed of Miyun Reservoir/ cropland/ soil organic carbon/ DNDC model分类
资源环境引用本文复制引用
王淑芳,王效科,欧阳志云..密云水库上游地区农田土壤有机碳储量及变化模拟[J].生态环境学报,2009,18(5):1923-1928,6.基金项目
国家重点基础研究发展计划(973计划)项目(2006CB403402) （973计划）
