中文摘要：

土壤有机质的理化特性是黄土高原地区水土保持及生态修复的重要物质基础，充分了解黄土高原区不同土壤类型的有机碳密度与储量，对生态建设具有重要的实际意义。利用第二次全国土壤普查数据，对黄土高原不同土壤类型0～20 cm表层土体有机碳密度及储量进行估算，并分析两者的空间特征。结果表明：黄土高原区土壤有机碳密度加权平均值为2.00 kg·m^-2，棕壤碳密度值最高，为15.56 kg·m^-2，风沙土最低，仅为0.24 kg· m^-2，空间上呈中间低四周高的分布格局。黄土高原地区总碳储量为1 239.85 Tg（1 Tg=10^12g），灰褐土及黄绵土碳储量较高，两者占总体的46.86%，灰漠土、冻漠土、碱土较低，总量仅占0.17%，空间上呈由西北向东南递增的分布规律。黄绵土、风沙土在黄土高原区分布较广，但两者碳密度较低。因此，在今后的生态修复措施中，提高两者有机碳含量十分关键。

英文摘要：

Soil organic carbon is an essential material foundation for controlling soil erosion and conserving eco- logical environment on the Loess Plateau. Adequate acquaintance of soil organic carbon density （SOCD） and soil organic carbon storage （SOCS） are of practically significance for large-scale ecological construction. In this paper, SOCD and SOCS in topsoil （0 -20 cm） of different soils on the Loess Plateau were estimated based on the data of soil depth, soil organic matter content and bulk density, from the Second National Soil Survey. The results showed that the weighted mean of SOCD was 2.00 kg ·m^-2, that of brunisolic soil was the highest （ 15.56 kg·m^-2 ）, and that of aeolian soil was the lowest （0.24 kg ·m^-2）. In spatial distribution pattern, SOCD was low in the cen- tral area of the plateau but high in the marginal zone. The total SOCS on the Loess Plateau was 1 239.85 Tg, SOCS in grey cinnamonic soil and loessal soil were high and occupied 46.86% of the total, and that in grey desert soil, frozen desert soil and alkali soil were low and accounted for 0.17% only. SOCS in all soils increased gradually from the northwest to the southeast. Loessal soil and aeolian soil were extensively distributed on the Loess Plateau, but their SOCD were low. Therefore, it is very important to increase the organic carbon content in loessal soil and aeoli- an soil in ecological reconstruction on the Loess Plateau in the future.