| Forests and water are important compositions of forest ecosystem, moreover, they are the most fundamental condition for the life and development of human being. The relationship between forests and water is one of key problems of the present research in forestry and ecology.This paper on the basis of forest hydrological effect, the interaction between forests and water features, and the precipitation, interception, the temporal and spatial variation of soil moisture, water and other aspects of the chemical characteristics of a comprehensive study of forest vegetation in water conservation, water regulation, Reduce the runoff of sediment, improve water quality and other aspects of the important functions. The research of "Forests and Water" is from the aspects of the eco-hydrological models of forest ecosystem from, the viewpoint of forest ecosystem and combining with the research on forest structure, function, productivity, energy and material circulation, to explore the laws and internal relation of various forest hydrological phenomenon is the basic topic of research.The results show:1. In the period of observation annual rainfall is 716.4 mm, the rainy season accounted for 91.5%, 8.5 % of the dry season, the maximum rainfall in July, the minimum in December, the first time in the distribution pattern: the rainy season, rainfall Lin For 655.8 mm, interception of the canopy, tree trunks runoff, the penetration of rainfall respectively Lin rainfall of 51.62%, 0.15%, 48.23%; second distribution pattern: the rainy season rainfall in the forest for the 317.25 mm, surface runoff accounts Lin rainfall within the 0.31%, the flow of soil in the rain forest, or 0.14%, Lin, 99.56% of the rainfall in the preservation of forest litter layer and the soil layer (including the deep infiltration of), required for the growth of spruce .2.There is a linear relationship between canopy interception and precipitation, regression equation: y = 0.554x-0.0424, (r = 0.9236); It showed a logrithmic correlation between rate of canopy interception and rainfall outside of stands ,regression equation: y =-0.0857Ln ( x)+0.782, (R2 = 0.2574); Tree trunks and forest runoff, rainfall was related to power function, regression equation: y = 0.0004x1.4309, (R2 = 0.8192); Tree trunks and forest runoff, rainfall was related to power function,regression equation: y =-0.0004x2 +0.0172 x +0.002, (R2 = 0.614). Penetration of rainfall and rainfall in a forest outside the linear correlation,regression equation: y = 0.4181x+0.5005, (r = 0.8720).3. Nyingchi spruce virgin forest litter on the litter in the litter rhythm obviously, there are two in a year in litter peak, the first litter peak in the beginning of the rainy season (April or May), when the clouds in Nyingchi Shan focus for the period of the second peak of litter at the end of the rainy season (October or November), the proportion of spruce of the smaller, representing only all of the 24.29 percent of litter, branches and leaves of the total 50.36 %, miscellaneous items (mainly spruce cone, understory shrub leaves) accounted for 49.64 %. Moss and litter layer, the average thickness, the total volume of dry and saturated with water were reached 9.83 cm, 81.3 t/hm2 and 217.07 t/hm2; layer of decomposition, semi-decomposition of decomposition and has an average thickness of the layer, respectively 4.17cm, 3.33cm, 2.33cm; saturated aquifer rates were 420.44%, 374.02%, 174.94%; Nyingchi primitive spruce forest of moss and litter layer saturated with water can be reached 21.71 mm, while natural state with water Average of 5.95 mm, under normal circumstances moss and litter-effective water holding capacity of 15.76mm. Early in the litter layer of relatively dry conditions, the single market is less than 15.76 mm rainfall, does not produce runoff.4.Nyingchi original spruce forest soil with the soil bulk density increases with increasing depth, respectively 0.85,1.07,1.29. The largest with water, capillary water holding capacity, and the youngest A water holding capacity was 68.26%, 58.64%, 50.19%; B:47.79%, 37.10%, 32.22%, C: 36.17%, 27.90% , 25.21%, that the water-holding capacity of soil depth with the increase gradually weakened. Soil porosity of A, B, C respectively of 57.25 %, 50.01%, 46.47%, with gross porosity of 49.12%, 39.10 %, 35.76 %, non-capillary porosity of 8.13%, 10.92%, 10.71%, show that In the rainy season in one cubic meters of soil containing about 0.51 cubic meters of water, even in the dry part of still water quarter (41%) in the soil preservation5.Soil infiltration process can be roughly divided into three stages. The first stage, the infiltration rate big, big change in rates, the first non-capillary fill the gap, the second phase, the penetration rate decreased, the rate of change has become smaller, mainly by capillary force of the role of the third stage into the steady infiltration, At this time the water main affected by gravity.6.Nyingchi spruce forest of the original soil level of dynamic change in soil moisture trend analysis, can be divided into the following four stages: stage with moisture, the moisture loss stage, a smooth phase, water stage, with the depth of the increase, With the increasing depth of soil, water content decreases, 50 cm below has stabilized, soil water use can be divided into three levels:weak use of soil moisture; use of soil moisture, and the stability of the soil moisture content in 20% to 25 %.7.Through water quality contrasting analyses of the outer rainfall, penetrating rain, trunk runoff, runthrough , streams ,Nan Yi Qu water,the Yarlung Zangbo River water and so on of Nyingchi spruce virgin forest in Tibet , it shows : the muddy sand content of the outer rainfall is the least , which is 5.56 mg·L-1 ; that of the trunk runoff is the highest , which is 68.34 mg·L-1;The pH of the outer rainfall is 7.61, a neutral partial-basic.8.The chemical content of outer rainfall were S042->HC03- >Cl->Zn>Ca>N>Fe>Cu>Mg>P>Na,that of K was not found. After the outer rainfall through canopy, the canopy absorption S042-, Zn; that of canopy leaching factors: Na>P>Mg>Ca>HC03- >Cl- >N>Cu>Fe>S042->Zn;When the outer rainfall formed the rain runoff, trunk leaching factors: Na>P>Mg>Ca>HC03->Cl->N>Fe>Zn>Cu>S042-,On the case , Nyingchi spruce virgin forest ecosystems, the Chemical substances of Runoff output were higher than the outer rainfall', which HC03-, K, Na, Ca, Mg, Cu and so on is the amount of the loss, that of N, P, Fe, Zn, Cl-was negative, that is, the spruce forest ecosystem accumulation of the latter. elements or ions of the migration factor: Na>Mg>HC03- >Ca>Cu>S042->P>Fe>N>Cl->Zn.9. On the whole forest ecosystems, by elements and the size of the loss for the order: HC03->K>Na>Ca>Mg>Cu>P>Fe>N>Zn>Cl-, which, HC03-, K, Na, Ca, Mg, Cu Such as the amount of loss is that these elements or ion-stream out of spruce forest ecosystems, and P, Fe, N, Zn, Cl-was negative, that spruce forest ecosystem to have absorbed or adsorbed function. By elements of the migration factor and ion size: Na>Mg>HC03- >Ca>Cu>S042- >P>Fe>N>Cl->Zn。...
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