County-scale Research On Spatial Differentiation Of Land Ecological Quality And Main Controlling Factors Identification:

Land ecosystem is a complex of society, economy and nature and is also the material carrier of human survival and development. Since China is at the stage of rapid urbanization and industrialization, human activity is deeply influencing and changing the land ecosystem in an unprecedented intensity. People often ignore the ecological service function of land in pursuit of short-term economic and social benefits, thus leading to a series of land ecological problems. In the area of rapid economic development, the intensity of land ecosystem disturbance from human activities is increasing, casting a great threat to people’s living environment and regional sustainable development. Therefore, systematical evaluation of regional land ecological quality and identification the main controlling factors of land ecological quality become an urgent issue.Based on the perspectives of land ecology and management and the idea of "method-phenomenon-mechanism-application", the study took Jintan City of Jiangsu Province as study area and established a detailed index system and method of land ecological evaluation. Through making full use of GIS technology, integrating social and economic data, sample monitoring data and remote sensing data, we systematically evaluated the land ecological quality. On this basis, further analysis was made. We analyzed the spatial differentiation of land ecological quality in Jintan City and the urban-rural gradient distribution law. And then the main controlling factors were identified in order to divide the land ecological protection and management zone and in turn put forward relevant policy suggestions for rational management and scientific decision-making of land use. The main conclusions are as follows:1) An index system including4criterion layers of basis, stress, structure and efficiency and15indicators was established to represent the evaluation system of land ecological quality. Among them, according to land quality indicators and focusing on ecological perspective, we choose8typical indicators to represent basis factors including terrain niche, soil thickness, organic matter content, the annual average precipitation, water supply reliability and vegetation fraction. With regards to the land ecological status quo and problems of Jintan City, we choose4key indicators to represent stress factors including annual decrease rate of wetland, construction land occupation of cultivated land rate, comprehensive pollution index of soil, and soil pH value, dominance index of ecological land、ecological connectivity, landscape diversity index are chose to represent the structure factors from the respects of patch, corridor and landscape in Landscape Ecology. And we quantify land ecological efficiency through comprehensive ecological service value. After that, taking administrative village.as evaluative unit, we integrate point, plaque, grid, statistical data and systematically evaluate land ecological quality evaluation of Jintan City via GIS technology and comprehensive index method, combine point, plaque, grid, statistical data, the land ecological quality evaluation system of Jintan City.2) Through land ecological evaluation, we find that land ecological quality of western hilly area in Jintan city is generally better than that of eastern plain area and became continuously better from the urban center to all around in terms of land ecology index. According to ring gradient analysis and stripe gradient analysis, we find that the spatial variation of land ecological quality shows an obvious rule of urban-rural gradient. From the city business core to periphery, every increase of2400meter in distance leads to a rise of1.6%in land ecological index and urbanization is one of the most important reasons to this rule.3) Through the econometric model, classification and regression tree model and stepwise regression method, we quantitatively analyzed the influence of urbanization factors and ecological factors on the spatial variation of land ecological quality in Jintan City, and further analyzed the main controlling factors of different land ecotypes. As far as the whole region of Jintan is concerned, economic development and construction land occupation of cultivated land are the key factors affecting land ecological spatial differentiation. As for the five land ecotypes, different ecotype has different main controlling factors due to different level of urbanization.4) Based on the foregoing analysis of land ecotypes and controlling factors, according to topography and land use character of Jintan, a management and protection zoning is made finally which divides Jintan into three parts:the western hills mountain ecological control zone,the central plain urban-rural ecological coordination area,and the esatern plain ecological optimization area.