Abstract: Universal Soil Loss Equation(USLE)has been widely used to estimate the average annual soil loss.In most of the previous work on soil loss evaluation on forestland,cover management factor was calculated from the static forest landscape.The advent of spatially explicit forest landscape model in the last decade,which explicitly simulates the forest succession dynamics under natural and anthropogenic disturbances(fire,wind,harvest and so on)on heterogeneous landscape,makes it possible to take into consideration the change of forest cover,and to dynamically simulate the soil loss in different year(e.g.10 years and 20 years after current year).In this study,we linked a spatially explicit landscape model(LANDIS)with USLE to simulate the soil loss dynamics under two scenarios:fire and no harvest,fire and harvest.We also simulated the soil loss with no fire and no harvest as a control.The results showed that soil loss varied periodically with simulation year,and the amplitude of change was the lowest under the control scenario and the highest under the fire and no harvest scenario.The effect of harvest on soil loss could not be easily identified on the map;however,the cumulative effect of harvest on soil loss was larger than that of fire.Decreasing the harvest area and the percent of bare soil increased by harvest could significantly reduce soil loss,but had no significant effects on the dynamic of soil loss.Although harvest increased the annual soil loss,it tended to decrease the variability of soil loss between different simulation years.

Key words: Soil loss, USLE, RUSLE, Spatially explicit landscape model, LANDIS