三峡库区不同林型土壤的入渗能力研究

利用环刀入渗法，观测了三峡库区山地不同海拔地段森林土壤的入渗过程，对比分析了典型林型下土壤各发生层的入渗率和常用入渗模型的适宜性。结果表明：不同林型下土壤入渗能力的差异在各发生层内表现不一致；腐殖质层和淋溶淀积层的入渗率差异相似，温性落叶阔叶林山地棕壤<常绿落叶阔叶混交林山地黄棕壤<暖性针叶林山地黄壤，入渗主要受土壤质地的影响，质地较重的粉壤土入渗能力比质地较轻的砂质黄壤差；母质层则相反，山地棕壤>山地黄棕壤>山地黄壤，黄壤母质风化度低，土壤密度大，渗透性能较差；同一林型土壤的不同发生层相比较，山地棕壤和山地黄棕壤的入渗能力随土层深度增加而增大，腐殖质层<淋溶淀积层<母质层，而山地黄壤则呈相反趋势。温性落叶阔叶林山地棕壤和常绿落叶阔叶混交林山地黄棕壤的入渗率随时间下降明显，而暖性针叶林山地黄壤降低幅度较小，趋于稳定入渗的时间较短。入渗曲线拟合显示，Horton方程对3种森林土壤入渗过程的模拟效果较好，是描述三峡库区森林土壤入渗过程的适宜模型

RESEARCH ON THE SOIL INFILTRATION CAPACITY OF DIFFERENT FOREST TYPES IN THE THREE GORGES RESERVOIR AREA

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.〖