【摘要】 基于第二次土壤普查和新疆土壤调查等 2 4 4 0个典型土壤剖面数据和 1∶4 0 0万中国植被图 ,对中国不同植被类型下的 1 0 0cm和 2 0cm厚度土壤有机碳密度和储量进行估算 ,绘制了土壤有机碳储量的地理分布图 ,并且对土壤有机碳储量与生境条件之间的关系进行统计分析。结果表明 :不同植被类型下的土壤有机碳密度存在显著差异 ,草甸和森林最高 ,灌木和农田次之 ,再其次是草原 ,最低的是荒漠 ;基于植被分类计算的我国 1 0 0cm和 2 0cm厚度土壤有机碳总储量分别为 6 9.38Gt和 2 3.81Gt。 1 0 0cm深度土壤碳储量在森林、农田、灌丛、草甸、草原、荒漠植被下分别为 1 7.39Gt、1 4 .6 9Gt、1 3.6 2Gt、1 2 .2 2Gt、7.4 6Gt、3.93Gt;土壤有机碳储量的空间分布差异明显 ,具有明显地域性 ,青藏高原东南地区、阿尔泰山和天山山地等高寒草甸、灌丛草甸区是土壤有机碳储量最高的地区 ,其次是东北地区北部的针叶林、草甸区和我国南方的亚热带阔叶林区 ,土壤有机碳储量最低的地区是西北地区和藏北高原的荒漠、草原干旱区 ;在不同生态系统中环境变量对土壤有机碳储量的影响是不同的 ,在温带草原年平均温度是土壤有机碳储量主要控制因素 ,而对于针叶林海拔是导致土壤有机碳储量变异的主导因子 ;随着研究尺度的细化 ,环境变更多还原

【Abstract】 Soil organic C plays a key role in carbon cycle and carbon storage in the natural ecosystem. The soil carbon stocks under native vegetations in China were estimated by making use of 2 440 profiles from the second national soil survey and the vegetation map (1∶4 000 000) of China, and map the distribution of soil carbon density under native vegetations. With the aid of a simplified vegetation classification system, the digitalized vegetation map units were sorted into 6 categories and 26 types of vegetation.The median carbon stocks of the soils in China are 8.23 kg m -2 in 0～100 cm soil layer, and 2.67 kg m -2 in 0～20 cm topsoil. The difference in the soil carbon density among vegetation categories is prominent. The soil carbon density in 0～100 cm under forests, scrubs, deserts, steppes, meadows and croplands is 11.59, 7.25, 3.14, 5.29, 14.90 and 8.07 kg m -2, respectively. On the basis of vegetation types, the total soil carbon stocks were calculated at 69.38 Gt in 0～100 cm and 23.81 Gt in 0～20 cm. In 0～100 cm, the soil carbon stock under forests (17.39 Gt) was the highest, accounting for 25% of the total in China despite the fact that the forest soil amounted to only 15.81% of the total territory of the country. Under croplands, it was 14.69 Gt or 21.2%, a little higher than the percentage (19.18%) of the soil in area. Though the soil under the vegetation of meadows and swamps was low (8.64%) in percentage in area, its carbon storage amounted to 12.22 Gt or 17.63%. The soil carbon stocks under steppes were 14.69 Gt or 10.76%of the total, lower than the percentage (14.86%) of the soil in area, and it was 3.93 Gt or only 5.66% under deserts, much lower than the percentage (13.17%) of the soil in area. The storage of soil carbon varies significantly from district to district in China. The highest soil carbon stocks locate in the south and east of the Qinghai-Tibet Plateau, the Altai Mountain and the Tianshan Mountains dominated with alpine evergreen,deciduous shrubs, alpine meadows, and swamps. The boreal taiga and meadows in the north of Southwest China and subtropical broadleaf forests in South China are moderate in soil carbon stock. The Tarim Basin, the Caidam Basin, the Junggar Basin and other desertification districts in Northwest China and the north of the Qinghai-Tibet Plateau where deserts and dry steppes dominate are lower in soil carbon stock. Climate shows an important influence on the distribution of soil carbon storage, which would rise with increasing precipitation and decreasing temperature.The regression analytieal results of SOC against environmental variables demonstrate that generally SOC increases with increasing precipitation but decreases with increasing temperature, and elevation plays a positive effect on SOC. Furthermore, carbon accumulation in different areas depends differently on different environmental variables, whose impact on SOC is becoming stronger when the research gets more specific. However, human activities reduce the influence of environmental variables on SOC.更多还原