Abstract: The objective of this study was to characterize the soil organic carbon content and its spatial distribution of 14 dominant plant communities in typical desert area and extremely dry desert area in western desert of Alagxa League of Inner Mongolia.The significance analysis results demonstrated that in the aspect of horizontal distribution,the soil organic carbon content among the varied plant communities were categorized into the followingⅠ-Ⅳ levels: the communities of Tamarix chinensis and Sympema regelii were determined as levelⅠwith average organic carbon content of 3.62 g/kg; the communities of Kalidium foliatum,Artemisia xanthochroa and Brachanthemum pulvinatum were included in level Ⅱ with average organic carbon content of 2.38 g/kg; the communities of Salsola passerine and Potaninia mongolica were classified in level Ⅲ with average organic carbon content of 1.66 g/kg; the communities of Artemisia sphaerocephala,Nitraria sphaerocarpa,Haloxylon ammodendron,Reaumuria soongorica,Nitraria tangutorum,Ephedra przewalskii and Convolvulus tragacanthoide were sorted in level Ⅳ with average organic carbon content of 1.00 g/kg.Furthermore,in the aspect of vertical distribution,there was a curve or linear correlation between soil organic carbon content and soil depth,and the soil organic carbon content were all decreased with the increase of soil depth among the observed plant communities.

Key words: Desert communities, Soil organic carbon content, Spatial distribution