Aboveground biomass and corresponding carbon sequestration ability of four major forest types in south China

We estimated aboveground biomass carbon (T _ABC) and net carbon accumulation rates (T _NEP) for trees in four major forest types based on national forest inventory data collected in 1994–1998 and 1999–2003. The four types were Pinus massoniana forest, Cunninghamia lanceolata forest, hard broad-leaved evergreen forest and soft broad-leaved evergreen forest. We analyzed variations in T _ABC and T _NEP for five stand ages (initiation, young, medium, mature and old). In both time periods, estimated T _ABC in all four forest types increased consistently with forest stand age and the oldest stage had the largest T _ABC compared with other stages. Broad-leaved forests (hard and soft) had higher T _ABC than needle-leaved forests (Pinus massoniana and Cunninghamia lanceolata) for each of the five age stages. The difference of T _ABC between broad-leaved and needle-leaved forests increased with forest stand age. Comparison of estimated T _NEP by age category indicated T _NEP increased from the initiation stage to the young stage, and then decreased from the mature stage to old stage in all four forest types. T _NEP for any particular stage depended on the forest type; for instance, broad-leaved forests at both the mature and old stages had greater T _NEP than in needle-leaved forests. A logistic curve was applied to fit the relationship between T _ABC and forest stand age. In each period, correlations in all four forest types were all statistically significant (P < 0.01) with R ² > 0.95. T _ABC was therefore predicted by these regression functions from 2000 to 2050 and the mean T _NEP during the predicted period was estimated to be about 41.14, 31.53, 75.50 and 75.68 g C m^?2 a^?1 in Pinus massoniana forest, Cunninghamia lanceolata forest, hard broad-leaved forest and soft broad-leaved forest, respectively. Results from both forest inventory and regression prediction suggest broad-leaved forests are greater carbon sinks, and hence have greater carbon sequestration ability especially in the mature and old stages when compared to needle-leaved forests. Broad-leaved forests should have high levels of carbon sequestration when compared with needle-leaved forests in south China.