In this study,we investigated the changes in soil water stable aggregates of 0-5 cm surface and their organic carbon contents induced by different restoration vegetation types（grass,shrub and tree） at 3 sites including Suide,Wuqi,Yichuan in Shaanxi province on the Chinese Loess Plateau.Water stable aggregates with diameters of 〉 2 mm and 2-0.25 mm and their organic carbon contents（SOC） were significantly increased by all vegetation types and these increases were different among three investigated sites.Compared with farmland,restoration of Pinus tabulaeformis and Caragana in Suide site resulted in an increase of SOC in water stable aggregates of 〉2 mm and 2-0.25 mm by 99%-153% and 219%-350%,respectively.At Wuqi site,alfalfa and Hippophae respectively increased SOC in water stable aggregates of 〉2 mm and 2-0.25 mm by 28%-30% and 85%-130%,whereas Locust tree did not increase SOC in water stable aggregates of 〉2 mm but increased SOC by 210% of 2-0.25 mm diameter.At Yichuan site,Pennisetum flaccidum,Bothriochloa ischemum（L.） Keng,Sophora viciifolia and Pinus tabulaeformis respectively increased SOC in water stable aggregates of 〉2 mm and 2-0.25 mm by 405%–932% and 724%–1130%.The enhancement of SOC by restoration of vegetation on cultivated slopes is mainly the increase of SOC in soil water-stable aggregates of two diameters 〉2 mm（514%） and 2-0.25 mm（470%）,but not for other diameters.The increased values of SOC of 〉2 mm and 2 – 0.25 mm respectively contributed to 49% and 43% of total SOC increased by vegetation restoration while less than 16% SOC increase in other diameters of water-stable aggregates.These results suggest that the formation of water-stable aggregates of 〉 0.25 mm diameter through stabilization of soil structure by vegetation may play an important role in soil carbon sequestration in the eroding landscapes of the Chinese Loess Plateau.%本研究选择陕北黄土高原绥德、吴旗、宜川3个地区,调查分析了不同植被恢复类型（草、灌、乔）下0—5cm表层土壤水稳性团聚体粒径分布及其有机碳含量的变化。结果表明：不同植被恢复类型均显著提高了〉2 mm和2～0.25 mm两个粒级的水稳性团聚体及其有机碳（SOC）的含量,但不同植被恢复类型的作用在3个地区有所不同。与农地相比,在绥德,油松和柠条分别使〉2 mm和2～0.25 mm粒级的水稳性团聚体中的SOC含量提高了99%～153%和219%～350%,但苜蓿没有明显作用;在吴旗,苜蓿和沙棘分别使〉2 mm和2～0.25 mm水稳性团聚体中SOC含量提高了28%～30%和85%～130%,而刺槐对〉2 mm水稳性团聚体没有作用,而使2～0.25mm粒级的水稳性团聚体SOC含量提高了210%;在宜川,白草、羊胡草、狼牙刺和油松使〉2 mm和2～0.25 mm粒级的水稳性团聚体中的SOC含量提高了405%～932%和724%～1130%。植被恢复土壤增碳主要是提高了2～0.25 mm和〉2 mm两个粒级的水稳性团聚体中SOC的含量,提高值分别为514%和470%,占土壤有机碳库增量的49%和43%,而对其它粒级水稳性团聚体中SOC含量的贡献小于16%。以上研究结果说明,植被恢复稳定土层结构、促进土壤水稳性大团聚体中SOC的形成,可能在黄土丘陵侵蚀景观土壤固碳过程中起重要作用。
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