| Liupan mountain lies on northwest loess plateau area, and in the intermediate belt which is from arid area to humid area, and ecological condition is extremely frail, and soil erosion and desertion is serious. The forest litter and soil have an important action in conservation of water and soil. To study the litter and soil in this area is helpful to the ecological construction in the half arid area and the restoring vegetation.Through studying five kinds of main vegetation of the eco-hydrological function of the litters and soil concretely, including Larix principris-upprechtii, Pinus armandii, Betula platyphylla, shrub forest, Quercus liaotungensis-Tilia panciostata, from May to October,2005, the primary conclusion was obtained:1. The hydrological function of litterLitters biomass of the five kinds of vegetation ranged from 5.96 t/hm~2 to 18.13t/hm~2, of which litters biomass of conifer is more than that of broadleaf forest, and the least is that of shrub. Litters thickness ranged from 2.72 cm to 4.87cm. The water-holding capacity of different litters ranged from 18.75 t/hm~2 to 46.19 t/hm~2. The effective water-holding depth of litters layer ranged from 0.58mm to 3.02mm. Those two items of Pinus armandii are the biggest.The experimentation of water-holding process indicated that the relational formula about the water-holding of the un-decomposed and semi-decomposed litter and the time of immersing is W=Aln(t)+B. The water-holding rate changed fast with 2 hours, and after 5-8 hours the water-holding of litter saturated.The water content of the un-decomposed and semi-decomposed litters in different vegetations ranged from 8.89% to 305.94% in the whole growth stage in 2005. The study indicated that precipitation influence the water content of litter.2. The hydrological function of forest soilAverage soil bulk density in lm soil layer of five kinds of main vegetation ranged from 1.03 g/cm~3 to 1.30g/cm~3, and the total porosity ranged from 50.63% to 60.48%. Compared with the water-retaining capacity of soil among different layers in the five kind of main vegetation, the biggest water-retaining capacity in 1m layer ranged from 506.34 mm to 604.81mm, and the available water-retaining capacity ranges from 117.08mm to 292.13mm. The available water-retaining capacity followed: Pinus armandii＞shrub forest＞Larix principris-upprechtii＞Betula platyphylla＞Quercus liaotungensis-Tilia panciostata.The infiltration of soil changed acutely with 0-10min, and decrease rapidly. With the change of time the infiltration was steady, and it becomed stable after 60min. The initial infiltration rates of soil in the five kinds of main vegetation ranged from 5.84 mm/min to 24.61mm/min, and the stable infiltration rates ranged from 3.15 mm/min to 15.35mm/min.The four kinds of the soil infiltration model are simulated, which showed the Horton model is prefect for soil infiltration. The influence factors on the soil infiltration were analyzed, and indicatd that the initial infiltration rates of soil was significant negative correlation with the stone fragments content. The stable infiltration rates of soil was significant negative correlation with the bulk density of soil and the stone fragments content, respectively, and there were significant positive correlation between the stable infiltration rates of soil and the total porosity of soil.According to the soil moisture dynamic characteristic in growth season, four periods of moisture change were divided: the consume period, the accumulate period, the fade period and the stable period.With the total growth stage the available water-holding capacity of the five kinds of main vegetation in 1m layer ranged from 283.59mm to 424.55mm. Besides 10-20, 20-40cm layer, the available water-holding capacity of Quercus liaotungensis-Tilia panciostata soil in capillary ratio is even, 41% water-holding of capillary change to the available water-holding of soil. In other plots the available water-holding of soil in capillary ratio decreased with the increasing of the soil depth.
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