Abstract:

Cutting ring infiltration method was used to quantitatively measure the soil infiltration capacity under different forest types in the Three Gorges Reservoir area.The results indicated that the difference of soil infiltration rates among different forest types did not show the same trend in different soil layers.For Humus layers and leaching illuvial layers,the soil infiltration rate of mountain brown earth covered with temperate deciduous broadleaved forest was smaller than that of mountain yellow brown earth covered with mixed evergreendeciduous broadleaved forest,which was even smaller than that of mountain yellow earth covered with warm coniferous forest.This was caused by larger proportion of silt and clay particle content in two upper layers of mountain brown earth and mountain yellow brown earth than that of mountain yellow earth.However,the infiltration rate of soil parent material layers was exactly opposite to the humus layers and leaching illuvial layers.Soil infiltration rate of mountain brown soil covered with temperate deciduous broadleaved forest was bigger than that of mountain yellow brown soil covered with mixed evergreendeciduous broadleaved forest,which was even bigger than that of mountain yellow soil covered with warm coniferous forest.This may be caused by larger soil density and lower soil porosity in parent material layer of mountain yellow soil than that of mountain brown soil and mountain yellow brown soil.With comparison of different layers within the same type soil,the infiltration rate increased with the increasing of soil depth to mountain brown soil and mountain yellow brown soil,and that of humus layers were smaller than that of leaching illuvial layers,which were even smaller than that of parent material layers.While the infiltration rate of mountain yellow soil decreased with the increasing of soil depth, and that of humus layers were bigger than that of leaching illuvial layers,which were even bigger than that of parent material layers. The infiltration rate of all types forest soil decreased with time,but the decline rates were different.The infiltration rate of mountain brown soil and mountain yellow brown soil decreased rapidly with time,while the infiltration rate of mountain yellow soil and abandon cultivated land decreased slowly with time,and reached steady infiltration stage quickly.Simulation result of soil infiltration curve indicated that Horton equation simulated different forest land best,and was suitable to describe the infiltration process of forest soil in the Three Gorges Reservoir area.〖