Land Function Change And Ecological Effect In The Hinterland Of The Three Gorges Reservoir Area

The Three Gorges area is not only the economic backward area, but the ecological fragile region.The vulnerability of ecology and the urgency of the development constitute a contradiction between protection and development. For nearly 30 years, the types of land use function in the Three Gorges area has changed a lot as well as the whole area. The hinterland of the Three Gorges area,the key area of the construction of the Three Gorges, land functional selection of which relates to the ecological construction and sustained development in the reservoir area. In this paper, the Fengjie and Wushan in the hinterland of the Three Gorges Reservoir area are selected as the research area with the support of GIS and RS technology, system analysis of the 1986-2015 years evolution of land function and its influencing factors, and constructs the structure of land function, function of land suitable and land use comprehensive function model, the ecological effects changes under the evolution of land use function.(1) The characteristics of land use global change in the study areaThe overall land mainly develop and the pace of development is accelerating. Due to the construction of the Three Gorges Project and the policy of Returning Farmland to Ecosystem, the transformation between forest, shrub and grassland at the same levels is strongest. Ecological land has been improved after degradation, the growth of Land use degree just like "peak". For Fengjie County, LA has experienced the first increase after the reduction, but Wushan County, LA continued to grow. According to the graph, it can be seen that the distribution of forest, shrub and grassland is controlled by the landform pattern, which is adjusted by the land closely connected with the residential area and the agricultural area. Mosaic of cultivated land in various patches dispersed in the region below 1200 m. With garden rapid growing, the waters expanding, the road network expansion is formed and with towns along the road agglomerating and contiguous township increasing, the county has enlarged.(2) The characteristics of land function evolutionFor structure, the proportion of production function in the study area decreased in a fluctuation, the function of living continuing to grow, and the ecological function firstly increased and then decreased. Spatially, production functions in the northeast and Southeast shrunk, and the southern patch density decreased. Functional areas of the life dispersed from the part of the northern township to the entire township, while the development of the western and southern township went rapidly. The ecological function area is in contrast with the production function area spatially, showing the characteristics of the whole aggregation but local fragmentation, and the degree of fragmentation has been descending in recent years. Ecological function areas continuously distributed in the South and northeast of high altitude in the study area. Land function has strong spatial heterogeneity, with discontinuous distribution in the middle-altitude region of the watershed, while life function areas distributed closely along the banks of the river in low altitude.(3)Main influencing factors of land use functionThe slope of the study area is restricted to the distribution of land function, and presents low of the proportion of regional ecological function is proportional to the slope, the production and life function is inversely proportional to the slope. Ecological function in the low slope area gradually give way to the production and living function of the rapid growth. Altitude have obvious influence on differentiation and change of land function, and have obvious gradient characteristics. In general, the distribution of production and life function is in inverse proportion to the altitude, on the contrary, the distribution of ecological function is proportional to the altitude. Lithology conditions not only play a important role on the pattern of agricultural distribution, and also influence the Industrial layout. The proportion of mudstone area of production and living function is relatively large and a small proportion of ecological function, the limestone area is instead of the mudstone area, the sandstone area is between them. The distribution of the production and life function decreased with the increase of the distance of the road buffer, but the ecological function increased with the increase of the distance of the road buffer. In early, road neighborhood play an important role in the distribution of life function. With the improvement of the road network, the function of agglomeration is enhanced.(4)Construct of land use function structure, suitability and comprehensive function modelThe study area is mainly based on the multifunction structure, which is the ecological dominant type and ecological production dominant type, and play an important role in ecological conservation, the vast majority of productive land to maintain ecological function. Through the interaction of each factor to form the cumulative coefficient of suitability, the suitability of land function suitability index was constructed to analyze the suitability of land function distribution. Simulate the complex mountainous area land function distribution based on the suitability index, and select the Fair town of Fengjie County and Guandu town of Wushan County for empirical research and analysis of the correction factors for sampling for estimating large area land function space distribution method. From the point of view of economic development and sustainable development,Base on land use to construction of land function composite index model by the analytic hierarchy process method, and the spatial distribution of CF in the study area of 2015 was analyzed by using the township as a unit.(5) The ecological effects Influence by the evolution of land function in the study areaThrough the RSEI index of 4 indexes of dry degree, green degree, humidity and heat to evaluate the ecological effects of the study area from 2000 to 2015, the result is that the ecological environment of the study area is improved in general. In the Yangtze River and its tributaries, the impact of land development and the expansion of life function area, the ecological environment degradation is large; other areas due to the impact of returning farmland to forest, the ecological environment is improved.