| Water cycling closely relate to the nutrient cycling in forest ecosystem. It is a medium and transport tools of nutrient cycling. The coordination role of water-nutrient cycling is important to the maintenance of stability and function of ecosystem. The impacts of forest vegetation on forest hydrology mainly manifests in two aspects. Those are water quantity and hydro-chemical properties.Pleioblastus amarus was one of the main bamboo species in Rainy Area of West China, it had important ecological, economic and social benefits to ecological barrier construction and regional economic development in upper-middle reaches of Yangtze River. The water quantity and hydro-chemical properties (DC, DOC, DN, NH4+, NO3-, SO42-,K+, Ca2+, Mg2+) of precipiation, through-fall, stem-flow, osmotic water of litter, surface runoff, osmotic water of soil in 0～40cm and 0～100cm were studied to reveal the precipiation redistribution and hydro-chemical characteristics of Pleioblastus amarus forest ecosystem in rainy area of west china, and also provide basic data to the effect of forest on water conservation and purification.The results showed as follows:1. The precipiation redistribution characteristics of Pleioblastus amarus forest ecosystem in Rainy Area of West China.(1) The annual precipiation outside the forest was 1986.0 mm, by the canopy, the throung-fall was 1877.0 mm, stem-flow was 223.9 mm.(2)The total forest precipiation was 2100.9 mm, it flowed to ground surface after the retention of litter, and the annual infiltration capacity was 1060.3 mm, the retention capacity of litter was 1040.6 mm, the retention rate was 49.5%.(3) The annual surface runoff was 14.2 mm and the runoff coefficient was 1.3%. The soil water infiltration amount in 40 cm was 161.2 mm and 100 cm was 44.5 mm.2. The hydro-chemical properties of Pleioblastus amarus forest ecosystem in Rainy Area of West China.(1) The hydro-chemical characteristics of precipiation outside the forest and forest precipitation.The monthly pH value variation of precipitation outside the forest, through-fall and stem flow showed a similar rule that was higher in spring and autumn, lower in summer and winter. The average pH value of precipitation outside the forest was 5.86, the average pH value of throung fall was 6.58 and it was higher than precipiation. While the average pH value of stem-flow was 5.13, it was lower than precipitation and appeared acidification.DC, DOC, DN, NH4+-N, NO3--N, SO42-, K+, Ca2+ and Mg2+:In the aspect of concentration, the monthly concenteation variation of each nutrient elements in precipitation outside the forest, throung-fall and stem-flow showed a similar rule that was higher in summer and lower in winter., The concenteation of other elements in throung-fall were higher than precipitation except for NO3--N The concenteation of each nutrient elementes in stem-flow were higher than precipiation except for Ca2+. In the aspect of total content, the other nutrient elements in forest precipitation (throung fall and stem-flow) were positively leaching except for NH4+-N.(2) The hydro-chemical characteristics of infiltration water of litterThe monthly pH value variation of infiltration water of litter showed that it was higher in spring and autumn, lower in summer and winter. The average pH value of infiltration water of litter was 6.17, it was higher than stem-flow and lower than throung-fall.DC, DOC, DN, NH4+-N, NO3--N, SO42-,K+, Ca2+ and Mg2+:In the aspect of concentration, the monthly concenteation variation of each nutrient elements in infiltration water of litter showed a similar rule that was higher in summer and lower in winter. But DC, DOC and NO3--N had a peak in May and June. the concenteation of other nutrient elements in infiltration water of litter were higher than forest precipitation except for NH4+-N, In the aspect of total content, DC,DOC and NO3--N were positively leaching, but DN,NH4+-N,SO42-,K+,Ca2+ and Mg2+ were negatively leaching.(3) The hydro-chemical characteristics of surface runoff, infiltration water of soil in 0～40 cm and 0～100 cm. The annual average pH value of surface runoff was 7.51, it was significantly higher than infiltration water of litter and soil, and its monthly variation had no significantly change law. The average pH value of infiltration water of soil in 0-40cm and 0-100cm were respectively 6.06 and 5.77, their monthly variation were consistent with infiltration water of litter.DC, DOC, DN, NH4+-N, NO3--N, SO42-, K+, Ca2+ and Mg2+:In the aspect of concentration, the monthly concenteation variation of each nutrient elements in surface runoff, infiltration water of soil in 0～40 cm and 0～100 cm showed a similar rule that was higher in summer and lower in winter. But DC and DOC in surface runoff had a peak in May and June, so did DC, DOC, DN, NH4+-N and NO3--N in infiltration water of soil in 0～40 cm and 0～100 cm. The concentration of DN, NH4+-N, NO3--N and SO42- in surface runoff were lower than infiltration water of litter, while the concentration of other elements were higher than infiltration water of litter. The concentration of each elements in infiltration water of soil in 0-40 cm and 0-100 cm were lower than infiltration water of litter except for SO42- and Ca2+, In the aspect of total content, each element of infiltration water of soil in 0～40 cm and 0～100 cm occurred adsorption effect.
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