中文摘要：

Based on the observation data of rainfall, vegetation, runoff and sediment yield in the experimental plots located in Hetian Town, Changting County of Fujian Province during 2007 -2010 , the changing characteristics and interrelation of live vegetation volume of grass, rainfall parameters,and water (soil) conservation effect RE(SE) were analyzed at four time scales of rainfall event, month, season, and year. The results showed that with the increase of time scales，the rainfall and vegetation indicators increased or decreased more or less，and the variation range of RE was small, while SE slowly decreased. The mean RE changed by 10% -20% at different time scales, and the observed water conservation effect of the grassland was the best at season scale while the worst at year scale. The soil conservation effect of the grassland was the best at month scale and the worst at season scale. The water conservation effect of the grass was mainly controlled by rainfall factors, including rainfall duration and precipitation at rainfall event scale, and the maximum intensity of precipitation within 30 min at longer time scales. However, the soil conservation effect of the grass was mainly controlled by vegetation factors, including the contribution of the litter on soil surface at rainfall event scale,the interaction of rainfall and vegetation at month and season scales, and the live vegetation volume of the grass at year scale. Consequently, at different time scales, the factors influencing water and soil conservation changed and interacted, and the observed water and soil conservation effects were also different, indicating that the influence of time scales deserves attention in both research and management practices.