Abstract: Soil organic carbon is a large component of the global carbon cycle and the influence of land-use changes on SOC pools can significantly affect atmospheric CO2 concentrations. The response of soil carbon mineralization rates to changes in land-use type is the crux for understanding the influence of land-use changes on SOC. Over the last several centuries, extensive areas of the native vegetation of the Liupan Mountain forest zone has been converted to cropland or rangeland and, over the last several decades, some of these former croplands and rangelands have returned to forests. However, the impacts of these land-use changes on the SOC are unclear. In order to assess the impacts of land-use change on LSC, we compared the LSC concentrations in adjacent plots of natural secondary forest (i.e. dominated by Querces liaotungensis, Populus davidiana, or brushwood), cropland, rangeland, and 13, 18 and 25-year old larch (Larix principis-rupprechtii) plantations that were planted on former croplands and rangelands. To determine the rate of SOC mineralization, soils were collected from each of these land use types, incubated in the laboratory at 30 ℃ with a constant moisture of 60% field water capacity over 180 days and the amount of cumulative CO2-C released over 180 days was compared among the different land use types. It was found that the mean concentration (g CO2-C·kg-1 soil·180 d-1) of SOC mineralization in the 0-110 cm soil layer was 155% and 17% higher under the plantation than under cropland and rangeland, respectively, and was 65% lower under cropland and 23% lower under rangeland as compared to the natural secondary forest. The change in the concentration of cumulative CO2-C released by SOC mineralization with soil depth under the natural secondary forest and plantation was greater than under the cropland or rangeland. The difference in the cumulative CO2-C released by SOC mineralization between natural secondary forest and cropland or rangeland was greater in 0-40 cm depth than the 50-110 cm soil layer, but the difference between the plantation and cropland or rangeland was greater in 0-70 cm than 70-110 cm soil layer. The fraction of cumulative CO2-C mineralized as a percent of total SOC in the 0-110 cm soil layer was 12% lower under cropland than under the natural secondary forest, 29% higher under plantation than cropland, 18% and 9% higher under rangeland than natural secondary forest and plantation, respectively. There were no significant differences in the change of the fraction of cumulative CO2-C released by SOC mineralization with soil depth among the different land uses. The difference between the fraction of cumulative CO2-C released by SOC mineralization from the natural secondary forest and cropland or rangeland was greatest in the 0-40 cm soil layer, whereas this difference between plantation and cropland or rangeland was greatest in the 0-50 cm soil layer. In general, the concentration of cumulative CO2-C released by SOC mineralization was greater than the fraction among different land uses as well with changes with soil depth. These differences were attributed to differences in the inputs of SOC, stabilization, and quality of soil organic matter among different land uses. Overall, our results suggest that the rate of SOC mineralization will decline with conversion from natural forests to cropland or rangeland and will increase following afforestion of former croplands or rangelands. In addition, the distribution of cumulative CO2-C released by SOC mineralization in different soil layers will also change with the magnitude of change greater in concentration than the fraction following changes in land use.