Chin J Plan Ecolo ›› 2016, Vol. 40 ›› Issue (10): 1064-1076.

• Reviews •

### Seasonal dynamics of active soil organic carbon in four subtropical forests in Southern China

Xiang GU1, Shi-Ji ZHANG2, Wen-Hua XIANG1,3,4, Lei-Da LI1, Zhao-Dan LIU1, Wei-Jun SUN1, Xi FANG1,3,4,*()

1. 1School of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410004, China

2School of Material Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China

3National Engineering Laboratory of South China Forestry Ecology Applicable Technologies, Changsha 410004, China
and
4Huitong National Field Station for Scientific Observation and Research of Chinese Fir Plantation Ecosystem in Hunan Province, Huitong, Hunan 438107, China
• Online:2016-11-02 Published:2016-10-10
• Contact: Xi FANG E-mail:fangxizhang@sina.com

Abstract:

Aims The objective of this paper was to quantify the seasonal variation of active soil organic carbon in the subtropical forests for better understanding of the underline mechanisms in controlling soil organic carbon storage and dynamics in natural and restored forests in the region. Methods The study was conducted in a one-hectare permanent plot at Dashanchong Forest Park in Changsha County, Hunan Province, China. Four types of subtropical forests were selected as our study sites: (1) Cunninghamia lanceolata plantation, (2) Pinus massoniana-Lithocarpus glaber mixed forest, (3) Choerospondias axillaries deciduous broad-leaved forest, and (4) L. glaber-Cyclobalanopsis glauca evergreen broad-leaved forest. The soil samples were taken from 0-15 cm and 15-30 cm depths within each of the forests from December 2011 to September 2012. Soil microbial biomass carbon (MBC), mineralized organic carbon (MOC), readily oxidized carbon (ROC), and dissolved organic carbon (DOC) were analyzed for their seasonal changes. Important findings There existed a considerable seasonal variations of soil MBC, MOC, ROC, DOC among the forests, with a similar patterns of active organic carbon fraction. Soil MBC, MOC and ROC were significantly higher in the summer and the autumn than those in the spring and winter, while soil DOC was higher in the spring, summer and winter than that in the autumn. The seasonal variations of different active organic carbon fractions appeared different within the same forest type. Significantly-positive correlations were found between soil MBC, MOC, ROC, DOC and soil moisture content, soil organic carbon (SOC), total N, hydrolysis N, total P (except for MBC, MOC and ROC in Cunninghamia lanceolata plantation), available P, but not between soil MBC, MOC, ROC, DOC concentrations and soil pH, total K and available K. The results indicated that the differences of exogenous carbon devotion, physicochemical properties were responsible for the significant differences of soil active organic carbon, and the growth rhythm of tree species, soil moisture content, the availability of nutrient (SOC, N and P), and the sources of soil active organic carbon fractions made a major contribution to seasonal variations of soil active organic carbon. Soil MBC, MOC, ROC, and DOC could be used as sensitivity indexes to assess the dynamics of soil C, N and P.