中文摘要：

对黄土高原水平方向的4种主要草地类型（森林草原、典型草原、高寒草甸草原、荒漠草原）,分析其土壤有机碳含量、有机碳密度及其碳储量,以期揭示黄土高原中部不同草地类型土壤有机碳分布特征,初步估算黄土高原中部天然草地土壤有机碳储量。结果表明：各草地类型土壤有机碳含量和土壤碳密度均随深度增加而减少,但类型不同其减少程度不同。高寒草甸草原的土壤有机碳含量减少幅度最大,荒漠草原减幅最小;4种类型草地的土壤有机碳密度排序为：高寒草甸草原〉典型草原〉森林草原〉荒漠草原,对于整个土层而言,草地类型间的土壤有机碳密度变异程度不同,典型草原变异系数最大,高寒草甸草原最小;在水平方向上,黄土高原中部有机碳密度分布很不均匀。黄土高原中部天然草地总面积2.02×107hm2,其1 m深度土壤碳储量为1.06 Pg C。

英文摘要：

Soil organic carbon（SOC）,organic carbon density and organic carbon storage in four different natural grassland types（forest steppe,typical grassland,alpine meadow steppe and desert steppe） in the Loess Plateau were analyzed.Results indicate that the content of soil organic carbon decreases with soil depth and a diversity in different grassland types.The variation of soil organic carbon content with soil depth in alpine meadow grassland has the biggest amplitude,while the variation has the smallest one in desert grassland.Organic carbon density of four different grassland types are ranked as Alpine meadow grassland typical steppe forest steppe desert steppe.In the whole soil layer of 0～100 cm,the coefficients of variation of soil organic carbon density are different in four grassland types.The coefficient of variation of typical grassland is the largest while the Alpine meadow grassland is the minimum.In the horizontal direction,organic carbon density is unevenly distributed in the natural grassland of central Loess Plateau.The total area of natural grassland in the region is 2.02 × 107 hm2,and the soil carbon storage is 1.06 Pg C in 1 m depth.