其他摘要：To clarify the effects of different forest management practices on the quantitative variation in surface soil (fine earth, sediment, and litter) movement, we used sediment traps to measure the transport of materials on a slope for 4 years before and after clear cutting, heavy thinning, and normal thinning. As indicators of the degree of topsoil erosion, the transport rates (g m−1 mm−1) of fine earth, sediment, and litter were compared. The transport rates of all three materials increased significantly after clear cutting. By contrast, the transport rates of fine earth and sediment did not change after heavy or normal thinning. The greater the cutting intensity in the order normal thinning, heavy thinning, and clear cutting, the greater the increase in the relative light intensity of the understory and floor vegetation. We showed that heavy or normal thinning had little effect on fine earth and sediment movements, as compared to clear cutting. At the clear cut and heavily thinned sites, the surface soil disturbance caused by handling the felled trees was thought to offset by the inhibitory effects of vegetation recovery on sediment transport. We believe that it is important to conserve forest soils in order to minimize surface disturbance during harvest and encourage rapid revegetation when managing forests on steep slopes in Chamaecyparis obtusa plantations.
