Abstract:

The soil thermal regime and the effect of forest harvest in the watershed were studied in virtue of thermal conductivity equation in soil and physical principle by 6 years data in Chinese Fir plantation. The results showed that the content of water in the soil determined the change of the thermal capacity, thermal diffusivity and thermal conductivity according to the time in the watershed. With the increasing of soil thermal capacity, the percent of solid and the decreasing of porosity, all thermal factors increased. After forest harvesting, the surface soil became more tighten because of the artificial strong disturbing. So the ratio of solid, liquid and?gas in the soil was changed and the soil thermal regimes were changed, especially the thermal diffusivity and thermal conductivity in 0～5 cm depth soil increased more than one times. The soil thermal regimes were affected by the soil structure and the soil components. But for the each factors of soil thermal regimes, the effect of each components was different, especially to the interaction of each components, which made the thermal diffusivity and thermal conductivity more complex. Therefore, it was very difficult to evaluate the effect of every soil structure and every component.

Key words: Soil thermal regimes, Volume thermal capacity, Thermal diffusivity, Thermal conductivity