Abstract:In order to determine the vertical contents and the seasonal variations of none-labile carbon (NLC) under different forest types, soils samples at 0～10, 10～20 and 20～40 cm depth were collected from six forests, including shrub-grass forest, masson pine forest, Eucalyptus forest, native-species forest, Acacia forest and monsoon evergreen broad-leaved forest, respectively, in Heshan. The results showed that soil NLC declined with the soil depth in the six types of forest with the highest NLC contents at the surface layer (0～10 cm depth). At the surface layer soil, the contents of NLC were significantly different among the forest types with the highest level in Acacia forest and the lowest level in masson pine forest. At the deeper layers (10～20 cm and 20～40 cm depth), the Acacia forest had the highest NLC while the other 5 forest types had the contents of NLC without significant differences. Among the six forest types, there were seasonal patterns of soil NLC with the higher ratios of NLC to soil organic carbon (SOC) in wet season than in dry season. The ratios of NLC/SOC among the six forest types indicated that Acacia forest and shrub-grass forest were helpful to increase the contents of soil NLC at all layers,while masson pine forest, Eucalyptus forest, native-species forest, and monsoon evergreen broad-leaved forest were helpful to stabilize the contents of SOC at deeper soils.