长江流域典型区域土壤碳库变化及其影响因素

土壤碳库是全球碳库的重要组成部分，其微小幅度的碳源汇变化就可以较显著的影响大气碳库。本文选择长江流域多目标区域地球化学调查覆盖区，利用多目标区域地球化学调查数据和第二次全国土壤普查数据计算了土壤碳密度及储量，对比了20年来土壤碳库变化趋势，并分析土壤碳源汇的影响因素。结果表明：从20世纪80年代到2000年，研究区大部分区域土壤有机碳密度明显增加，尤其成都平原西部的龙门山地区、雅安南侧地区和贵阳周边地区，其增加量约为312.38 TgC。导致研究区土壤碳库增加的主要因素是，林地草地等植被恢复性生长、农业耕作水平提高，土地利用变化对研究区土壤碳库变化的影响较小，土壤侵蚀因素对研究区的水田基本没有影响，但对旱地影响比较明显，而气候变化对该区域土壤碳库没有明显影响。

Changes of soil carbon pool in typical areas of Changjiang drainage basin and its influencing factors

Soil carbon pool is an important part of global surficial carbon pool, which will influence global climate change as a carbon source or sink for greenhouse gases. Taking areas covered by the multi purpose regional geochemical survey (MPRGS) in the Changjiang drainage basin as an example, the soil carbon density and soil carbon storage and their changes have been calculated by combining MPRGS data and the second national soil survey data. And also, the factors that caused the carbon sinks and sources were analyzed. The results show that the soil organic carbon density (SOCD) significantly increased at most regions of the study area from the 1980s to 2000s, especially in the Longmen Mountain region of western Chengdu, southern region of Yaan and the surrounding region of Guiyang. The amount of soil carbon increase is about 312.38 TgC. Recovery of vegetation in woodland and grassland, and improved land management in paddy fields and dry farmland are the major factors that increased soil carbon storage in the respective land use area. The land use change has relatively little impact to soil carbon stock changes in the study area. Soil erosion had almost no effect on paddy field, but it had obviously restrained the increase of SOCD in the dry farmlands. And also, the climate change had no obvious influence on soil carbon stock in this region.