Abstract:

The variation of forest soil organic carbon under the various communities and micro-habitats was investigated in karst rocky desertification areas of Guizhou Province. The results showed that the contents of soil total organic carbon and humic acid carbon in the broad-leaved forest soil were obviously higher than that of the soil in brush forest， brush-grass and sparse grass， but the content of soil dissolved organic carbon in those soils was on the contrary. The accumulation of soil organic carbon was reduced and the loss of soil organic carbon was increased with the karst forest degeneration. The results also showed that the soil total organic carbon and humic acid carbon under various micro-habitats were markedly different. The contents of total organic carbon and humic acid carbon in the soil from stone pit were markedly higher than that of the soils from rocky ditch， swallet or stone cavern. The principal component analysis (PCA) showed that the most important factor that influenced the variation of forest soil organic carbon was the community type,followed by micro-habitat.

Key words: forest soil, micro-habitats, total organic carbon, humic acid carbon, dissolved organic carbon, karst