Water Interception and Retarding Characteristics of Forest Litters in the Upper Streams of Miyun Reservoir, Beijing

Laboratory experiments were adopted to study the characteristics of three kinds of forest litters (Pinus tabulaeform is, Robinia pseudoacacia and Vitex negundo var. heterophylla) in intercepting rainfall and retarding surface runoff under different conditions. The results showed that forest litter inter-ception process experienced three stages:firstly, rising and sopping stage; secondly, almost stable interception stage; thirdly, declining or drainage stage.Roughness coefficient of forest floor increased as litter weight of per unit area increased. Regressive analysis show ed that the roughness coefficients of three kinds of forests litter significantly correlated with biomass weight of per unit area and fitted cubic multinomial.