Model simulation of soil carbon dynamics with stand development in Japanese cedar (Cryptomeria japonica) plantations

Soil carbon cycling in Japanese cedar plantations after clear-cutting, and in chronological order, was calculated with and without the consideration of forest management (pruning and thinning) by a mathematical model. The model employed a daily time step, used daily air temperature and observed precipitation near the plantations. The result of the calculations was compared with field observations. There were few differences in the changes of aboveground biomass, carbon flow and carbon accumulation with the forest regeneration between the calculations with or without consideration of management and field observation (p>0.05, by a one-way analysis of variance), as suggested by the small standard error between them. For example, the carbon accumulation and total soil respiration rate calculated with the consideration of management for a 60-year-old stand were 104 tC ha-1 and 4.8 tC ha-1y-1 with a field observation of 110 tC ha-1 and 4.5 tC ha-1y-1, respectively. The effect of forest management on the soil carbon cycling was also examined, suggesting that the soil respiration rates and carbon accumulations changed little by the management except for the clear-cutting. Consequently, it was suggested that the dynamics of carbon cycling following the clear-cutting of a Japanese cedar plantation could be simulated exactly by the model even if forest management was considered or not. That is, it indicates that the model can simulate the chronological change in carbon cycling at cedar plantations easily and correctly even if the history of management in the plantations is unknown