Abstract: Runoff and soil are two basic sides of soil erosion and water loss. The anti-scouring feature of forest land soil was examined by using the undisturbed soil sample washing experiment and the spot washing experiment. The results showed that in the undisturbed soil sample washing experiment, the relationship between sediment yield and time was a cubic equation. Furthermore, an increase in slope and runoff was accompanied by an increasing sediment yield. Its correlation equation with the dry weight of the roots was a quadratic equation. In comparison, in the spot washing experiment the relationship between the sediment yield and time was an exponential equation. There was a positive correlation between the sediment yield and the runoff. Both experiments indicated that the runoff process had single or multiple peaks.

Key words: undisturbed soil sample washing, spot soil washing, Pinus tabulaeformis forest, Badaling