Abstract:In order to understand the C cycle characteristics in dominant tree communities in soils developed form different lithologies in Karst area, the δ13C value and soil organic matter renewal of various tree species communities were measured for six woody species (cypress, Cupressus funebris; mansur shrub, Coriaria nepalensis; camphor, Cinnamomum bodinieri; birch, Betula luminifera; alder, Alnus cremastogyne and dyetree, Platycarya longipes) planted in three different lithologic soil types (dolomite, dolomite sandstone, limestone) in the karst area of Guizhou Province. Results showed that:(1) Changes of δ13C values in plant species in different lithologies, the δ13C value of cypress funebris on limestone had very significant difference with other lithologies (P<0.001), Alnus cremastogyne had significant difference in limestone and dolomite (P=0.024). There were significant or extremely significant differences among three tree species (Cinnamomum bodinieri, Cupressus funebris, Coriaria nepalensis), or with other tree species (P<0.05 or P=0.001). The δ13C values of each organ in tree species were leaf < branch < root. (2) Changes of δ13C values in plant-litter-soil system:on the three lithologies, the change law of community of each tree species was basically the same, that is, plant leaves (fresh litter) < litter decomposition layer < branch < root < upper soil < lower soil. There was a significant difference in δ13C values between soil layer and plant and litter (P<0.001). Compared with litter layer, the increased degree of community of Cinnamomum bodinieri and Cupressus funebris on dolomitic sandstone was larger, 11.68‰ and 11.10‰ respectively, while the increased degree of Coriaria nepalensis on dolomite and Alnus cremastogyne on limestone was smaller, by 1.07‰ and 2.73‰, respectively. (3) Renewal rate of soil organic matter:the highest was the community of Coriaria nepalensis on dolomite, 43.84%, followed by the community of Alnus cremastogyne on limestone, 34.17%, and the lowest was the community of Platycarya longipes on limestone, 1.15%. Organic carbon turnover showed that the slope K of regression equation of dolomite plant community was 3.15, followed by plant communities on limestone was 0.85. The organic carbon contents were not correlated with δ13C values in dolomitic sandstone. The results of the study would be of great significance to reveal the characteristics of C cycle, migration and nutrient transfer in different plant communities in lithologies of karst area.