滇中元江栲林下土壤活性有机碳空间分布特征.

In order to investigate the vertical distribution characteristics of soil organic carbon and its influence mechanism in Castanopsis orthacantha evergreen broad-leaved forest in Central Yunnan Plateau, we selected Castanopsis orthacantha forest at different altitudes(2 090-2 490 m) and different slope directions as objective to investigate the spatial distribution characteristics of organic carbon(SOC), microbial biomass carbon(MBC), soluble organic carbon(DOC), easily oxidized organic carbon(ROC), and granular organic carbon(POC) at 0-60 cm depths of soil. The results revealed:the contents of SOC, MBC, ROC, and POC initially increased and then decreased with increase of elevation, and the content of DOC decreased gradually with increase of elevation; the contents variation of the four active organic carbon fractions were followed as POC>ROC>MBC>DOC. The contents of soil organic carbon and active fractions were higher on the shady slope compared to the sunny slope, and decreased with soil depth significantly, the contents in 0-20 cm depth were higher obviously than that in 20-40 cm and 40-60 cm depth. The proportion of each soil active organic carbon component in soil organic carbon was POC/SOC>ROC/SOC>MBC/SOC>DOC/SOC, the particulate organic carbon(POC) was the main carbon pool among the four active carbon pools. The ratios of MBC/SOC have no significant variation with increase of elevation, while the ratios of ROC/SOC and POC/SOC finitially increased and then decreased. The contents of SOC, MBC, ROC and POC were positively correlated with each other, labile organic carbon was significantly negatively correlated with pH of soil. Altitude and soil depth have extremely significant impact on SOC, DOC, MBC, ROC and POC content. Slope direction highly significant effect on SOC, POC content and significantly affects DOC content. [ABSTRACT FROM AUTHOR]