喀斯特地区土壤碳储量及其影响因素的认识是评估我国陆地土壤生态系统碳汇能力不可或缺的内容。本文通过对中国西南北起秦岭北坡南至中越边境一条剖面上土壤有机碳的分析,研究了喀斯特森林0~10 cm土壤有机碳空间变化及其控制因素。研究发现西南地区土壤有机碳含量和碳密度平均为32.3 g/kg和33.1 t /hm~2。无论是在整个西南区还是其省市范围内,二者均低于非喀斯特森林土壤。通径分析表明,影响喀斯特表层土壤碳含量和密度的主要因素有土壤容重、地形海拔和有机质C/N;粘粒含量和年平均气温的影响很小,而降水量仅在地处最北部的陕西省构成了土壤碳密度的影响因素。此现象与世界许多地区特别是高纬度地区形成鲜明对比。本研究结果表明,不同区域/气候带土壤碳库的主要影响因素会存在很大差异,这对认识气候变化背景下土壤碳库的反馈作用具有重要意义。
英文摘要:
Knowledge of the soil carbon storage and its affecting factors to Karst area is indispensable for understanding the capacity of carbon sequestration by terrestrial ecosystems of China. Based on analysis of soil organic carbon in a continuous transect from the northern slope of the Qinling Mountains, the Central China, to the border of China to Vietnam, we studied spatial variation and its controlling factors of soil organic carbon to the top 10 cm of soil profile in Karst forests of the Southwestern China. We found that soil organic carbon content (SOC) and soil organic carbon density (SOCD) averaged 32.3 g/kg and 33.1 t/hm~2, respectively. These values are both lower than that of the forest soil of non-Karst forests in either the Southwestern China or its provinces. Path analysis indicates that soil bulk density, topographic elevation and C/N of soil organic matter are major factors to the variations of SOC and SOCD while clay content and annual temperature exert little impact, and annual precipitation only affects SOCD of Shaanxi Province in the most northern part of the studying region, where semi-arid climate dominates. The trivial effect of climate to the soil organic carbon inventory contrasts sharply with many parts of the world, especially at high latitudes, suggesting that major factors to soil organic carbon may differ from region to region or climate to climate. The results are important for understanding the feedback of soil organic carbon stock to the current global warming.