Abstract: In Wuchang Fenghuangshan Forest Farm on the west slope of Zhangguangcai Mountain, we studied the seasonal dynamics of soil carbon input and output of three different forests of secondary broad-leaved natural forest(C), Larch and broad-leaved mixed forest(H), and Larch(Larix olgensis)(L) in different origins(artificial regeneration, artificial-natural regeneration, and natural regeneration) to explore the effect of different forest origins on soil carbon-budget. The soil organic carbon content of H was significantly higher than that of L(P＜0.05) with C in the middle, which showed no significant difference from H or L(P＞0.05). The sequence of litter-full leaf biomass of three different origin stands was C>H>L, with C significantly higher than L(P＜0.05). The sequence of litter-full decomposition rate of three different origin stands was C>H>L. C presented the highest soil respiration rate between three different origin stands in different seasons, and L presented the lowest. The June-October average of soil microbial biomass carbon(MBC) and soil readily oxidized organic carbon(ROC) both showed H>C>L, whereas water-soluble organic carbon(WSOC) showed the tendency of C>H>L. Litter decomposition weight loss rate was significantly correlative(P<0.05) with soil active carbon in three different origin stands, and highly negatively correlative between soil respiration rate, ROC and WSOC(P<0.01). Therefore, in the soil carbon-budget processes the artificial-natural regeneration was conductive to the turnover and storage of soil carbon.

Key words: forest origin, soil carbon, litter decomposition, soil respiration, soil active carbon