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We studied the impact of forest vegetation on soil erosion,surface runoff,and sediment generation by using field simulated rainfall apparatus.We measured runoff and sediment generation of five 4.5 × 2.1m runoff plots (a bare soil as a control; two Pinus tabulaeformis forest plots and two Platycladus orientalis forest with row spacing of 1m × 1m and 1.5 m × 1.5 m,respectively) in Beijing Jiu Feng National Forest Park under three rainfall intensities (0.42,0.83,1.26 mm per minute).Forest vegetation significantly reduced soil erosion and sediment yield.Mean total runoff volume in the four tree stand plots was 93％ of that in the control plot,demonstrating the limited effectiveness of forest vegetation in runoff control.With increasing rainfall intensity,runoff reduction in forest plots declined from 28.32％ to 2.1％.Similar trends in runoff coefficient and the relationship between runoffvolume and rainfall duration was observed.Mean total sediment yield and mean sediment yield reduction rate under different treatments was 55.05％ and 43.17％ of those in the bare soil control plot,respectively.Rainfall intensity played an important role in runoffand sediment generation processes,and had a greater impact on runoff than on soil erosion and sediment generation.When considering several factors in runoff and sediment transport processes,the P.tabulaeform plot with row spacing at 1 × 1 m had a greater effect on soil and water conservation than did other forested plots.