中文摘要：

本文旨在估算陕西省土壤有机碳密度和储量及分析其空间差异特征，为准确评价陕西省土地质量以及环境质量提供参考。利用陕西省第二次土壤普查数据，采用土壤类型法计算了陕西省各土壤类型不同土层深度的土壤有机碳密度和储量，建立了以土属为单元的土壤有机碳空间数据库，分析其空间差异特征，并对影响土壤有机碳的自然和人为因素进行分析。结果表明：0．20em、0～100cm和全剖面土层中土壤有机碳平均密度分别为3．886kg／m^2，8．955kg／m^2，10．548kg／m^2，0～20em、0～100cm和全剖面土层中土壤有机碳的储量分别为7．7444亿t，17．845亿t，21．0204亿t。土壤有机碳密度在空间上呈现由北向南逐渐增加的趋势，而土壤有机碳储量高值区主要分布在榆林的东南部、延安地区、铜川、咸阳、宝鸡的北部以及秦巴山区等地，碳储量较低的区域主要有榆林的府谷县、神木县、定边县等地，以及关中的大部分地区。土壤有机碳密度随气温和降水的增加而逐渐增加，不同土地利用类型中，土壤有机碳密度大小排序为：林地〉草地〉耕地，土地利用类型变化是影响土壤有机碳最主要的人为因素。

英文摘要：

Terrestrial ecosystem carbon cycle is considered to be an important issue in the study of global change. Soil organic carbon is a huge carbon library, tiny change of which is likely to cause significant change of atmospheric CO2, thus influencing global climate. Therefore, research on soil organic carbon reserves and its spatial distribution characteristics not only has significant guiding meanings to circulation of materials in all circles and global change, but also has important realistic meanings to agricultural economy and land sustainable development. This article aims to estimate the density and reserves of soil organic carbon in Shaanxi Province, providing reference for accurate evaluation of the land quality and environment quality. With the second soil census data of Shaanxi Province and the soil type method. We have calculated the soil organic carbon density and reserves of different soil types in different soil depth and established soil organic carbon spatial database with soil genus as a unit so as to analyze the spatial distribution of soil organic carbon in Shaanxi Province as well as the natural and human influence factors. The results show that the average density of soil organic carbon in soil layers of 0-20cm, 0-100cm and full soil profile are respectively 3.886kg/m2, 8.955 kg/m2 and 10.548 kg/m2, and the soil organic carbon reserves of them are 774.4 million t, 1784.5 million t and 2102 million t respectively. The spatial distribution of soil organic carbon density presents a trend of increase gradually from the north to the south. Areas with high soil organic carbon reserves are mainly distributed in the southeast of Yulin, Yan＇ an, Xianyang, the north of Baoji and Qinba mountain while areas with low reserves are mainly distributed in the northeast of Yulin, such as Fugu county, Shenmu county, Dingbian county and most parts of Guanzhong region. Soil organic carbon density increases gradually with the growing annual precipitation and temperature. For different land use types, forest land ha