The Influence of Underground Surface of Karst Natural Slope on Soil Organic Carbon Components
[Purposes]A good understanding on the interaction of topographic factors and vegetation type on the contents of soil organic carbon and its labile fractions is necessary to detect more effective meth-ods for ecological restoration and soil organic carbon(SOC)sequestration.[Methods]In this study,soil samples(0～15 cm)were sampled from four natural-recovery peak-cluster slopes in a rocky desertifica-tion area of Wangjiazhai in Guizhou Province,and the underlay surface factors such as bare rock rate,vegetation types,soil depth were investigated.[Findings]The results showed that SOC average content in Sparse shrub was 59.04 g·kg-1,was 200%and 150%lower than in shrubs and thorny shrub,respec-tively(p<0.05).Ratio of dissolved organic carbon(DOC)and microbial biomass carbon(MBC)to SOC were 0.08%～0.1%and 0.13%～0.37%,respectively,and decreased significantly with the natural recov-ery from sparse shrubs to shrub(p<0.05).The structural equation modeling revealed that SOC decreased with soil depth,while DOC decreased with soil depth and increase of bare rock ratio.Vegetation type showed the largest direct contribution to SOC fractions.Slope and altitude indirectly affect the content of SOC components by affecting vegetation types.[Conclusions]In general,the increase in soil depth is conducive to the restoration of vegetation and the improvement of soil organic carbon stability.
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