| The Three Gorges Reservoir area is the important natural ecological barrier of protection forest system in the Yangtze River Basin. As an optimal allocation of the comprehensive benefits of the protection forest system in the reservoir area, it is an important component of regional ecological-economic-social systems. In particular, the Shelterbelts space played a key technology of ecological protection benefit. The construction of the shelter forest system would ensure ecological functions and economic and social benefits of small watershed. This would meet the multi-objectively, demand for wide use, high-valuely.This study has selected two typical small watersheds in the Three Gorges Reservoir Area (artificial and natural). In the ARCGIS9.3platform, using the spatial data analysis of land suitability evaluation, we could built on the slope scale on a community scale field and field these various technology. On the small watershed scale, the use of multi-objective planning theory and the use of tools such as MATLAB, LINGO9.0, it would build a lot of quantitative adjustments of the small watershed vegetation structure from the slope scale, community scale and a small watershed scale for building a scientific and rational system. The typical configuration determine the multi-scale in the small watershed model. In this paper, advanced the theory, methods and techniques, we could explore the ecological forest ecosystem and agroforestry ecosystem-based in two typical small watershed optimization vegetation pattern. The main research results are:(1) Land suitability evaluation in the small watershed. The watershed would consider a small basin site conditions, select the elevation, such as slope, soil thickness, humus thickness, and accessibility of land suitability evaluation factor. It could build a scientific evaluation system to carry out a scientific and rational and typical small watershed land suitability evaluation, Lan Ling River small watershed:it is in the most appropriate grade area for4.8566km2, accounting for23.74%of the total area of the basin. This is more appropriate level area7.314375km2, accounting for35.76%of the total area of the basin. The basically suitable for the rating area is5.362025km2, accounting for26.21%of the total area of the basin. And the not suitable for the rating area is2.92235km2, accounting for14.29%of the total area of the basin. Sha Mu River small watershed:The fir basin is the most appropriate rating area0.881392km2, accounting for15.69%of the total area of the basin. The more appropriate for the rating area is2.206127km2, accounting for39.26percent of the watershed’s total area. The basic suitability rating area is1.447277km2, accounting for25.76%of the total area in the watershed. The not suitable for the rating area is1.084004km2, accounting for19.29%of the total area of the basin.(2) On the slope scale, the key factors is soil erosion analysis and comparison of innovation vegetation. We could analysis the key factors that affect soil erosion analysis and comparison. The slope-scale soil loss evaluation index is put forward, and determined the optimal allocation of the small watershed slope scale model:Sha Mu River small watershed, forest-ecological-forest, bush-forest-ecological forest; Lan Ling River small watershed when the slope is15°, shrubs-ecological forest-farming-ecological forest, shrub-farming-forest-forests and farming-forest-ecological forest ecological forest-farming-ecological forest; When the slope is25°, shrubs-ecological forest-forest-ecological forest. In a small watershed, the farming of this type of configuration is suitable for upper and middle slope positions layout The best way to effective erosion control is erosion control.(3) On a community scale, through field surveys and data statistics, the small watershed is determined8vegetation types of4typical community optimization c-onfiguration mode:the mode of irrigation-grass, coniferous mixed mode, mixed coniferous mode, mixed composite mode of economic forest, forest-the composite mode of biological measures, forest-grass composite model, forest-farming patterns. Then we could determine the main shrub species and the economic forest species.(4) This study reference the combination of multi-objective planning methodology, and calculate the ecological benefits, economic and social benefits in small watershed currency calculations. The small watershed goal programming objective function F (x) and the constraints set could define. Small watershed is configured to determine the ideal configuration mode in the type of30cultivation. In the ARCGIS9.3platform, divisioning of the slope, computing and re-classificating the grids, the small watershed protection forest space to optimize the configuration diagram. Then we could contrast and analysis the optimization results of a detailed comparison before and after in the Lan Ling Creek small watershed and Sha Mu Creek small watershed:Lan Ling Creek small watershed basin shrub area of0.6970km2, in reduced1.0728km2; the ecological forest area of3.8752km2in a decrease of2.1119km2; the forest area of8.1867km2in an increase of2.93km2in the farming area of2.0244km2in an increase of0.2547km2;in Sha Mu Creek small watershed, the shrub area of0.4014km2in reducing0.5791km2; the ecological forest area of1.8742km2in an increase of0.2733km2; the forest area of3.3432km2in an increase of0.8799km2. It reduced soil erosion40811.344605and20488.8109, and overall efficiency of the added value of42,083,148.25and$20,403,124.19yuan. Then all aspects of benefits have been greatly improved. |
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