Abstract: Two typical plant communities, Suaeda salsa and Salicornia europaea, in Qinwangchuan National Wetland Park, new district of Lanzhou city were selected as the research objects,and the composition of soil aggregates and the particle size distribution of organic carbon under the two plant communities were analyzed. The results showed that the contents of soil aggregates in the two plant communities were significantly different, and the aggregates in the soil aggregates in the 0~30 cm soil layer were mainly >2 mm and 0.5~1 mm in particle size. The organic carbon content in the soil of Suaeda salsa and Salicornia europaea showed a V-shaped distribution in the soil layer of 0~30 cm. The content of organic carbon in >2 mm and <0.25 mm particle size aggregates in the two communities was highe, but their average contribution to organic carbon was small. Although the organic carbon in the aggregates was low in the 0.5~1 mm particle sizes, but their average contribution rate was as high as 27.74%. Which indicated that the soil organic carbon was protected by >2 mm and <0.25 mm grain size aggregates in inland salt marshes. Soil organic carbon content was positively correlated with >2 mm, 1~2 mm and 0.5~1 mm aggregates （P<0.05）. In conclusion, the carbon sequestration capacity of Salicornia europaea community is stronger. Increasing the content of >2 mm particle size aggregates in soil can effectively enhance the soil's corrosion resistance. The aggregates with particle size <0.25 mm can hold more stable carbon sources, reduce soil erosion, and improve the carbon sequestration capacity of inland salt marsh wetlands.

Key words: inland salt marsh wetland, Suaeda salsa, Salicornia europaea, organic carbon, aggregate, carbon fixation