[Spatial variation of soil carbon and stable isotopes in the southern margin desert of Junggar Basin, China].

The southern margin desert of Junggar Basin in the central arid region of Asia was selec-ted as the study area. To gain insight into the distribution characteristic of stable carbon isotope and the relationship between the change of soil carbon and the distance to oasis of soil organic carbon (SOC) and soil inorganic carbon (SIC), three belt transects were set according to the distance between the desert and the oasis in edge, middle and hinterland of the desert respectively, and collected the soil profile samples with depth of 2 m. The results indicated that the SOC content reduced with the soil depth, and the variation with the distance to oasis was the edge> the middle> the hinterland. The δ13 C value of SOC varied in the range of -21.92‰ to -17.41‰, and decreased with the depth; the range in the middle and hinterland was -25.20‰ to -19.30‰, and increased then declined with the depth. Therefore, we could infer that the C3 plants played a dominant role in the central of desert, and had experienced the succession from C3 plants to C4 plants. The average content of SIC was 38.98 g·kg-1 in the edge of desert, which was about 6.01 folds as large as the content in the hinterland. This indicated that a large number of SIC with 0-2 m depth were clustered in the edge of the desert. The δ13 C value of SIC increased first then decreased with the soil depth, and enriched in the bottom layer, which was mainly affected by the original carbonate content and soil carbon dioxide.