Vertical distribution of soil active carbon and soil organic carbon storage under different forest types in the Qinling Mountains.

Adopting field investigation and indoor analysis methods, the distribution patterns of soil active carbon and soil carbon storage in the soil profiles of Quercus aliena var. acuteserrata (Matoutan Forest, I), Pinus tabuliformis (II), Pinus armandii (III), pine-oak mixed forest (IV), Picea asperata (V), and Quercus aliena var. acuteserrata (Xinjiashan Forest, VI) of Qinling Mountains were studied in August 2013. The results showed that soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and easily oxidizable carbon (EOC) decreased with the increase of soil depth along the different forest soil profiles. The SOC and DOC contents of different depths along the soil profiles of P. asperata and pine-oak mixed forest were higher than in the other studied forest soils, and the order of the mean SOC and DOC along the different soil profiles was V>IV>I>II>III>VI. The contents of soil MBC of the different forest soil profiles were 71. 25-710. 05 mg.kg^-1, with a content sequence of I>V>IV>III>II>VI. The content of EOC along the whole soil profile of pine-oak mixed forest had a largest decline, and the order of the mean EOC was IV>V>I>II>III>VI. The sequence of soil organic carbon storage of the 0-60 cm soil layer was V>I>IV>III>VI>II. The MBC, DOC and EOC contents of the different forest soils were significanty correlated to each other. There was significant positive correlation among soil active carbon and TOC, TN. Meanwhile, there was no significant correlation between soil active carbon and other soil basic physicochemical properties. [ABSTRACT FROM AUTHOR]