In the last few years, ecologists have paid much attention to the carbon cycle and hope to figure out the generation of catastrophes associated with the global warming. Forest, one of the largest terrestrial carbon sinks or source, may influence the concentration of carbon dioxide in the atmosphere by carbon exchange. Coarse woody debris (CWD), which is contributed by fallen and standing dead wood, has been a focus of ecological studies because it accounts for up to 30% of aboveground biomass of the forest ecosystem.

    In tropical and temperate areas, the role of CWD has been emphasized due to its fast dynamic rates. However, in subtropical regions, the research is sparse. Although most of studies have assumed that the dynamics of CWD is in a steady-state, the rhythm and dynamics were uncertain. Thus, one lowland subtropical rainforest is the Nanjenshan Natural Reserve in Taiwan was selected to conduct the CWD research. The aim is how the stock and dynamic changes of CWD in Taiwan.    The stock, the seasonal input rate and decomposition rate were measured for one year period. Five 100 m line-intercepts were set up within a 2.1ha plot. And 30 quadrats (each 10 by 10 m²) were randomly selected to measure decomposition rates. The decay degree of woody debris was classified into 5 levels by its hardness. Every three months the line-intercepts were resurveyed for seasonal inputs.

Results/Conclusions

The preliminary results showed that the stock in this plot is 10.88 Mg/ha (10.41 Mg/ha for fallen dead wood, 0.47 Mg/ha for standing dead wood). And the variance is high, which reflects the high heterogeneity within this forest. The maximum amount of input occurred in autumn, and mostly contributed by the second decay level of CWD. The large fallen branches also increased in this season. These phenomena are likely to be caused by the disturbances of typhoons during summer.