Abstract: Soil dissolved organic carbon (DOC) and microbial biomass carbon (MBC) play an important role in ecosystem carbon cycle. In order to better understand the characteristics of soil DOC contents and MBC  and their controlling factors in urban forest, three forest types including Metasequoia glyptostroboides, Cinnamomum camphora, and Cedrus deodara were selected in Hefei City. The results showed that soil DOC contents were significantly influenced by forest type (P<0.05). The annual averages of soil DOC contents at the depth of 0-30 cm in M. glyptostroboides, C. deodara and C. camphora forests were 80.35, 60.13, and 43.36 mg·kg-1 respectively, and decreased with the increase of soil depth in general. The DOC contents in M. glyptostroboides and C. deodara forest soils were higher in summer and autumn than in winter, while a minimum DOC value was observed in C. camphora forest soil in June. The annual average values of MBC at the depth of 0-30 cm were in the order of M. glyptostroboides (412.84 mg·kg^-1) > C. deodara (358.85 mg·kg^-1) > C. camphora (283.40 mg·kg^-1). The soil MBC was significantly influenced by soil layer (P < 0.05), and generally decreased as the soil depth increased. The MBC values of different forest types were higher in summer and autumn than in winter. The correlation analysis showed that DOC contents and MBC were significantly positively correlated with the contents of soil organic carbon in M. glyptostroboides and C. camphora forests (P<0.01), while significantly positively correlated with root biomass in C. deodara forest (P<0.01), which suggested that exudates and decomposition of roots might be important sources of soil carbon for C. deodara forest.

Key words: drought resistance, relationship between root and leaf, spring drought stress, physiological characteristics.