Hydrological effects of forest litter and soil of three kinds of forest stands in Yanchi District,Ningxia of northwestern China.

A study of hydrological effects of litter layer and soil layer was carried out in two artificial forest stands (Populus bolleana and Pinus sylvestris var. mongolica) and one natural forest stand (Hedysarum scoparium) in Yanchi County, Ningxia of northwestern China. Its hydrological function of litter and soil was evaluated quantitatively through investigating standard spots, determining soil physical characteristics and water-olding capacity, and experimenting on soil infiltration, determining litter and soil water-olding capacity. The results showed that: 1) the litter total storage capacity of P. sylvestris var. mongolica was the largest, up to 7.6 t/hm2; P. sylvestris var. mongolica stand had both the maximum water capacity and available water capacity, which were 23.3 and 18.6 t/hm2, equivalent to water depth of 2.37 and 1.83 mm separately. 2)The P. sylvestris var. mongolica stand had strong soil water-lding capacity and the maximum of which was 349.2 t/hm2, equivalent to 34.91 mm water depth. The available soil water-holding capacity of P. sylvestris var. mongolica stand was 85.75 t/hm2, which was 3.24 times of H. scoparium stand, equivalent to 8.58 mm water depth. 3) Power function model can better reflect both water absorption speed of ground cover and its immersing time, and soil infiltrating rate and infiltrating time under different rainfall conditions, which had high correlation coefficient. 4) Using Philip infiltration model fitting the soil infiltration process(1 m deep soil), soil infiltration characteristicsof different forest stands were obtained.