Abstract: In order to explore the effects of reseeding on soil organic carbon and its distribution in desert steppe,the experimental plots were deep ploughed and reseeded using Agropyron mongolicum+A. desertorum(G),A. mongolicum (M) and A.desertorumS (S).The non-reseeded grasslands were used as control group (CK). The soil organic carbon and its distribution in soil profiles and different size of aggregates at 0~40 cm depth of each treatment were studied. The results showed that the contents of the total and aggregate organic carbon increased in grasslands of different reseeding treatments compared with the control grassland,especially at 30~40 cm depth. The soil organic carbon at 10~20 cm and 20~30 cm depth in grassland reseeded with A. desertorum were significantly higher than that of control grassland (P<0.05). For profile distribution,the soil organic carbon contents in all treated grasslands increased gradually with depth,and they were significantly higher at 30~40 cm depth than those at 0~10 cm depth (P<0.05). The contents of <0.053 mm aggregates organic carbon were the highest at each depth in different treated grasslands. The contribution of macroaggregates to soil organic carbon increased with depth. At 30~40cm soil layer,0.053~0.25 mm and >2 mm aggregates contributed more to total organic carbon. Overall,reseeding was conducive to soil organic carbon sequestration for degraded desert steppe. In this study,the effect of increasing soil organic carbon was obvious by reseeded with A. desertorum.

Key words: Desert steppe, Reseeding, Soil organic carbon, Profile distribution, Particle size distribution

摘要： 本研究以未补播（CK）、隔带深翻后补播蒙古冰草（Agropyron mongolicum）（M）、沙生冰草（A. desertorum）（S）及蒙古冰草+沙生冰草（G）的草地为对象，研究不同处理荒漠草原0～40 cm土壤总有机碳在土壤剖面和不同粒级团聚体中的分布。结果表明：不同补播模式草地全土有机碳及团聚体有机碳含量较对照均有所提高，10～20 cm和20～30 cm土层，沙生冰草补播草地显著高于未补播草地（P<0.05）；30～40 cm土层，各补播草地均显著高于未补播草地（P<0.05）。各处理草地土壤有机碳含量随土层的加深逐渐增加，30～40 cm土层均显著高于0～10 cm土层（P<0.05）。不同处理草地各土层团聚体有机碳含量以<0.053 mm粒级最高。随土层加深，大团聚体对土壤有机碳的贡献增大，30～40 cm土层以0.053～0.25 mm和>2 mm粒径较高。总体看，补播有利于退化荒漠草原土壤有机碳的固存，在本研究所做处理中补播沙生冰草对土壤有机碳的增加效果较为明显。

关键词: 荒漠草原, 补播, 土壤有机碳, 剖面分布, 粒径分布