退耕还林对黄土高原地区土壤有机碳影响预测

土壤碳是全球碳循环中的重要组成部分，土地利用方式的改变对土壤碳的源和汇具有很大的影响。黄土高原地区进行的大规模退耕还林必然会通过影响土壤有机碳含量对区域碳循环产生重要影响。通过野外调查采样分析，结合使用全国土壤普查及黄土高原地区其它土地资源数据资料，研究计算了黄土高原地区的土壤有机碳量，并对实施退耕还林后土壤碳储量变化进行了预测。黄土高原地区土壤有机碳含量较低，平均土壤有机碳密度为2．49kg／m^2，仅为全国平均土壤有机碳密度的23．65％，土壤有机碳总储量为1068Tg，只占全国总有机碳量的1.16％。实施退耕还林后，土壤有机碳储量将明显增加。分步优化实施退耕30年后，黄土高原土壤有机碳储量可增至1266．8Tg，有机碳储量总体可增长19．21％。土壤有机碳储量的增加，对区域气候变化及土壤和水环境都将产生影响.

Forecast of Impact of the Returning Farms to Forests on Soil Organic Carbon of Loess Plateau

Soil carbon is a significant component of global carbon cycling, the change of land use pattern has a great influence on soil carbon source or sink. Large-scale returning farms to forests on Loess Plateau will necessarily make some important effects on carbon cycling by effecting soil organic carbon content. Based on the field investigation and sampling, as well as national soil investigation data and other soil resource data of the Loess Plateau, soil organic carbon of Loess Plateau was calculated, and the change of soil organic carbon after returning farms to forests was predicted. The content of soil organic carbon of Loess Plateau is lower, the mean soil organic carbon density is 2.49kg/m^2, which is 23.65% of mean level of China, the total soil organic carbon storage is about 1068Tg, that only account for 1.16 % of Chinese total soil organic carbon . After implementing the return- ing farms to forests, ,soil organic carbon reserves will remarkably increase. Thirty years later, the total soil organic carbon storage of Loess Plateau will increase to 1266.8Tg, rising by 19.21%.