Abstract: With soil carbon cycle compartment model,this paper studied the carbon storage and flux of each carbon compartment of soil under Pinus tabulaeformis,a main forest type in the Huoditang forest region of Qinling Mountain.The results showed that the storage of soil organic carbon was 146.071 t·hm^-2，with 130.366 t·hm^-2 in mineral soil layer and 12.626 t·hm^-2 in litter layer.The storage was lower than the average value of forest soils in China and of oak Sharptooth forest soil in Huoditang,but higher than that of the soils under temperate coniferous forest and tropical forest.The annual carbon input into litter layer was 5.939 t·hm^-2,with 56.9% from above-ground litter and 43.1% from underground dead roots,while that into mineral soil layer via humic acid was 2.034 t·hm^-2.The annual amount of carbon released from the respiration of P.tabulaeformis forest soil system was 14.012 t·hm^-2,with litter layer,mineral soil layer,dead root system,and live root system occupied 15.7%,14.5%,11.7% and 58.1%,respectively.

Key words: Forest communities, Secondary succession, Interspecies covariation