| Litter is an important part of forest ecosystem, and it plays a vital role on ecological service function of the forest ecosystem. Litter can retain water and conserve soil, and also through decomposition it makes matter cycling and nutrient flow. This paper based on the Quercus Forests of Purple Mountain, researching from litter decomposition characteristics, water holding characteristics, interception of precipitation, blocking surface runoff, inhibition of soil evaporation and influences on physical and chemical properties of soil, studied the hydrological characteristics of litter and its function on improving soil The results found:(1) Litter decomposition rate is closely related to C/N and C/P, the weightlessness rate of litter has negative correlation with C/N(P<0.01) and C/P(P<0.01) respectively, and litter decomposition rate has significant positive correlation with organic C release(P < 0.01), and N release(P<0.05). Fitting litter decomposition rate, nutrient and organic carbon release rate with modified Olson exponential attenuation model, we found that the half-life of Quercus forest leaf litter is 12 months, and 95% decomposition time is 58.24 months, Except to K, half decay time of other nutrients ordered as P > Mg > N > Ca > organic C, and the differences are significant, among them, the half-life of Ca and N is close, and there is little difference in the half-life of P and Mg, 95% decomposition time of nutrients and organic C also showed significant differences, they performed as P>Mg>N>organic C>Ca.(2) Through the indoor litter immersion experiment,we found that water holding rate was logarithmically increased with time, and performed as semi decomposed layer > whole litter layer > undecomposed litter layer; as the same time, the litter water absorption rate curve showed that water absorption rate of litter increased at a exponential function with time increase, and ordered as semi decomposed layer > whole litter layer > undecomposed litter layer.(3) The ability of litter on rainfall interception is corrected with litter natural water holding rate and litter biomass. The bigger of the difference between litter natural water holding rate before and after rainfall, or the greater the litter biomass, the stronger ability on rainfall interception litter is. Litter can largestly intercept precipitation as 1.23 times as its dry weight. But based on the fact that in the natural environment precipitation reached the ground is easily seeping into the soil, or forming the surface runoff, which makes litter not be completely immersed in water, so the largest natural moisture content get from water immersion test can not express largest natural watering holding rate of litter, and the ratio different between them is 126.15%. The function of litter blocking surface runoff is corrected with litter cover thickness, depth of runoff and slope. the study found that with the same litter cover thickness, runoff depth affects the relationship between flow time and the slope, by the increase of runoff depth, the relationship between runoff time and the slope is gradually transferring from exponential function decreasing to Linear decreasing. Litter’s function of inhibiting soil evaporation is mainly related to litter cover thickness and soil moisture rate, the higher the soil water content, and the thicker the litter coverage, the stronger inhibition function is.(4) Litter decomposition has an impact on physicochemical properties and nutrient contents of soil. The study found that litter decomposition can reduce soil bulk density and p H, but not obviously. The research also found that litter decomposition has no correlation with soil total porosity, capillary porosity and non capillary porosity. N, P elements in the process of litter decomposition is obviously affected total N in soil(P<0.05), and litter release of P has obvious correction with available P in soil(P<0.05). |
