为揭示毛乌素沙地沙漠化逆转过程中土壤颗粒的固碳效应,选择陕北榆林治沙区从流沙地、半固定沙地到林龄为20~55年生的灌木和20~50年生的乔木固沙林地,采用物理分组法分析了土壤砂粒、粉粒、黏粒结合碳的演变特征和累积速率.结果表明:对比流沙地,土壤总有机碳及各颗粒碳含量在两种固沙林地均呈显著增加趋势,并以表层0~5 cm土壤碳含量增幅最高.从流沙地到55年生灌木和50年生乔木固沙林地,0~5 cm土层砂粒碳密度增速均为0.05 Mg·hm~(-2)·a~(-1),粉粒碳密度增速分别为0.05和0.08 Mg·hm~(-2)·a~(-1),而黏粒碳密度增速分别为0.02和0.03 Mg·hm~(-2)·a~(-1).0~20 cm土层,两种林地各颗粒碳密度增速平均为0~5cm土层的2.1倍.按此增速到50~55年生的固沙林地时,两种林地0~20 cm土层的砂粒碳、粉粒碳和黏粒碳密度分别比流沙地平均提高6.7、18.1、4.4倍,并且颗粒碳对总有机碳的累积贡献率平均为粉粒碳(39.7%)≈砂粒碳(34.6%)>黏粒碳(25.6%).综上,毛乌素沙地沙漠化逆转过程土壤颗粒均表现出显著的固碳效应,且以砂粒和粉粒为主要固碳组分. In order to reveal the carbon sequestration effect of soil particles in the process of desertification reversal in Mu Us desert, we selected shrubs with 20 ~ 55 years of age and 20 ~ 50 years old trees , The evolution characteristics and accumulation rate of soil sand, silt and clay-bound carbon were analyzed by physical grouping method.The results showed that the total organic carbon and the carbon content of each grain were significantly increased in the two types of sandy land , And the highest increase of soil carbon content was observed in the 0-5 cm soil layer.The growth rate of carbon density in 0-5 cm soil layer from runoff to 55-year-old shrubs and 50-year-old trees was 0.05 Mg · hm -2, · A ~ (-1), and the growth rate of carbon density of the silt is 0.05 and 0.08 Mg · hm -2 · a -1, respectively, while the growth rate of clay density is 0.02 and 0.03 Mg · hm ~ (-2) · a ~ (-1) .0 ~ 20 cm soil layer, the average growth rate of carbon density of each grain is 2.1 times of that of 0 ~ 5 cm soil layer in both forestlands, then increase to 50 ~ 55 years In the sand fixation, the carbon density, grit size and clay grit of 0 ~ 20 cm soil layer increased by 6.7, 18.1 and 4.4 times respectively, and the cumulative contribution of particulate carbon to total organic carbon (39.7%) ≈Granular Carbon (34.6%)> Clay Carbon (25.6%) .To sum up, the soil particles in the desertification reversal process in Mu Us desert showed significant carbon sequestration, Grain as the main carbon-fixing component.