Study On The Efficient Spatial Allocation And Stable Stand Structure Of Soil And Water Conservation Forest System

In the paper, the current situation and problems of soil and water conservation forest system in western Liaoning (SWCFSWL) are analysed, and the vegetation types and landscape patterns and developing trends of SWCFSWL are studied. According to researcli results of optimum proportion of vegetation types, optimum forest coverage, patches mosaic structure and site classification in western Liaoning, the spatial allocation with high benefit of SWCFSWL are advanced. Based on the drought resistance of common tree species, species structures of resisting pine caterpillars (Dendrolimus spp.), and the maximum stand densities on water balance in hilly areas in western Liaoning, the index of stable stand structure of SWCFSWL is brought forward and defined. On the basis of characteristics of climate and sites in western Liaoning, the constructing models and the constructing techniques of spatial allocation with high benefit and stable stand structure of SWCFSWL are put forward.Main research results are:On spatial allocation with high benefit of SWCFSWL The research result shows that three types can be divided in eco-environment on hilly in western Liaoning, The optimum vegetation types proportions of SWCFSWL is determined by applying layer analysis method. The optimum forest coverage of SWCFSWL is determined based on characteristic of soil and water losses in western Liaoning. It is the first lime to put forward that patches mosaic pattern is ideal structure of spatial allocation with high benefit of SWCFSWL. It is the first time to put forward the index and models of spatial allocation with high benefit of SWCFSWL.(1) The optimum forest coverage is 50 percent;(2) The optimum proportions of vegetation types of SWCFSWL is: 36.91 percent of mixed forest, 20.50 percent of shrub, 13.69 percent of cash tree with ecology; 5.69 percent of conifers; 8.56 percent of broad leaved forest; 14.43 percent of grasses;(3) Patches mosaic pattern are composed of 4 types of patches.On stable stand structure of SWCFSWL Drought resistance and suitable scopes of 20 common tree species are studied, and they were sorted accordingly. The stand density of SWCFSWL was determined. It is the first time to put forward the index of stable stand structure of SWCFSWL. The indices are as follows:(1) Proportion of main confers is below 50 percent;(2) Stand densities of arbor in one hectare are below 900, and stand densities of shrubs in one hectare are below 4000;(3) Structure is composed of more than 4 species;On constructing models and techniques of spatial allocation with high benefit and stable stand structure of SWCFSWL. 2 constructing models in western Liaoning are put forward. Constructing techniques on macro and micro scale are recommended. Sustainable techniques are advanced based on researches of selective cutting, improvement pure plantation and regeneration.