Hydro-Ecological Effects Of Agro-Forestry System In The Loess Plateau

Rare plant makes frequent natural disasters, serious soil erosion and fragile ecological environment in the Loess Plateau. In order to improve ecological environment and agricultural production, our country scholars worded on this job for 60 years, and made great achievement. Currently, agroforestry system mainly concentrated in a single ecosystem, that is, the parameters of the hydro-ecological changes under the same types of land uses. There are many researches on hydro-ecological effect in different ecosystem, however, the research on boundary of different ecosystem is less. Studies on the law of hydro-ecological parameters under different agroforestry structure, which take a positive effect on artificial vegetation restoration and construction.The research conclusions are shown as follows:(1) In different vegetation cover, the average of soil moisture at depth of 0-200cm for fallow is 17.56%, which is the highest. And the arbor and apple orchard's soil moisture is between 15.22%-16.59%. The soil moisture of winter wheat and shrub is the lowest; it is 14.33% and 12.99%. Because of the root of arbor and apple orchard go deep and mainly use the soil moisture in great depth, the soil moisture in great depth is lower; By the contrary, the winter white use shallow layer soil moisture.Agroforestry can improve the surface coverage, develop a reasonable Root distribution structure, reduce soil water evaporization, and increase using of soil water.(2) Muddy infiltration can reduce soil water infiltration rate, and reduce range of forest land is more than that of apple orchard, agricultural land and fallow land. The Kostiakov exponential functions descript clearly soil water infiltration. Value a represent initial infiltration rate, and it is related with the thicker of forest floor, Soil density,soil moisture. value a is most in forest, the second in agriculture land, the third in fallow and the least in apple orchard, respectively. Value b represent soil water infiltration intensity, and it is significantly related with stable infiltration rate and initial infiltration rate, size order of b in different land using is forest, fallow, agricultural land and apple orchard(3) Based on split-window techniques to analyze soil water distance of edge influence for different agroforestry pattern. The result is: The distance of edge influence to soil water content were 8m & 6m for winter wheat– apple tree compound boundary respectively, 6m & 8m for Chinese pine - Black locust compound boundary, 6m & 10m apple tree– grassland compound boundary,8m & 10 m grassland–shrubbery compound boundary. The distance of edge influence to muddy infiltration were 6m & 4m for winter wheat– apple tree compound boundary respectively, 4m & 6m for Chinese pine - Black locust compound boundary, 6m & 8m apple tree– grassland compound boundary.(4) We analyzed the distance of edge influence to soil water and muddy infiltration for different compound boundary, based on efficient use of soil water, can decide width of plants at compound boundary: we can decide 16m & 12m for winter wheat– apple tree compound boundary, 12m & 16m for Chinese pine - Black locust compound boundary.