| Based on the results from the laboratory experiment and the field-test measurement, the function of hydrologic information and water and soil conversation of Quercus acutissima Carruth, (Sawtooth Oak) firewood forest of the low hills in the east of Anhui is studied. Through the analysis of the microcosmic indexes ,the paper establishes the regression model by comprehensive index of soil erosion modulus as the dependent variable, the indicated index of the soil resistance coefficient, the permeability coefficient and the disintegration coefficient as the independent variables. And it studies in detail the hydrologic information of forest stand, including the canopy layers ,the litter layers and the root zone soil mixture ,and examines systematically the redistribution of rainfall, surface runoff and soil erosion, the results are as follows:(1)There are differences among the 12 forest-stands as far as canopy interception of rainfall is concerned, and seasonal rainfall changed the interception of rainfall. The interception of rainfall for natural forest stands at its highest, with a maximum interception rate of 63.40 percent; while the interception of rainfall for one-year Quercus acutissima Carruth has an interception rate of 0.36 percent. The interception of rainfall of 8 different types of Sawtooth Oak increases with the age and crown density of the forest.(2)As is the different in stocks capacity of litter layer and decomposer, so is water-holding capacity and interception capacity. In this survey, the eight years Sawtooth Oak in the forest interception capacity is strong, the effective interception capacity amounts to 34.48t/hm2 , equivalent to a water depth of 3.44mm. The effective interception capacity for the seventh-year Quercus acutissima Carruth surpasses that of the fourteenth-year Masson, and its stocks capacity of litter for the eighth-year exceeds that of local main vegetation,it possesses better water conservation ability.(3)Through the analysis of root-system and physical properties of soil, it is discovered that they affect soil erosion resistance ability, and the relative model between them is established. Three indices, i.e., root length, root volume, and root density of less than 1mm core diameter, influence greatly the soil antierodibility. Whereas thick core diameter of more than 1mm, however, can improve soil pore volume, and increase amount of infiltrating water. The generation of runoff bears directly on the rate of soil infiltration property, the strength of soil anti-scourability and the well-functioning of antierodibility. The greater the runoff, the greater the soil erosion.The root system less than 1.0mm in diameter significantly increases internal environment, and enhances soil resistance,but the root system greater than 1.0mm in diameter improves soil water infiltration.(4) In the utilization of land, the mode of interplanting of trees and crops increases the capacity of waterstable aggregate, thereby strengthening reunion content of soil structure stability. In this system,the lands of the first year and the third year Quercus acutissima Carruth,slop soil interplant crops, all the rotten interplanting roots system strengthen the soil structure, increase the porosity and permeability of soil, so the function of the soil and water conservation is outstanding.(5)In the comprehensive evaluation of soil and water conservation function, the pure forest of Quercus acutissima Carruth and the mixed forest of Quercus acutissima Carruth and Pinus elliottii,the water and soil erosion resistance properties are better than other local plantations.(6)As the main mixed forest, the Sawtooth Oak gives full play to its hydrologic benefits.Quercus acutissima, the primary sources of industrial tree, is not only one of the most important economic tree species, but also an important ecological species.
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