Abstract
A numerical model that describes CO2 gas environment in forest soil was created. The theory of the effect of environmental factors (temperature and moisture) on CO2 gas environment in soils was incorporated into this model, making it possible to simulate CO2 gas concentration of every depth that varies in response to time courses of environmental factors. Numerical simulation was performed to simulate the data observed in the Fukuroyama-sawa Watershed in the Tokyo University Forest in Chiba. The determined model parameters showed that the variation of CO2 gas concentration distribution with the observation points depended on CO2 gas production rate distribution in soils and gas diffusion properties at each point. The difference between the observed and the simulated time variations of CO2 gas concentration distribution in soils was very small, confirming the validity of this model. The numerical simulation provides information on the internal processes of a CO2 gas environment through the time variations of CO2 gas production rate and diffusion coefficient in response to varying environmental factors ; for example, it is the soil surface layer that environmental factors have a great influence on, whereas it is the CO2 gas concentration of the depths that fluctuate drastically.
