Land ecological assessment of Jintan city in Yangtze River Delta with highly developed economy

Abstract: With the constant intensification of land use and the rapid expansion of construction land, people are confronted with a series of ecological problems such as soil pollution, land quality degradation, extreme climate, geological disaster, etc. which will cast a serious threat to the sustainable development of human beings. In view of scientific land management and regulation, we should not only emphasize land quantity and quality, but also pay attention to its ecology. Due to relative lack of comprehensive land ecological assessments focusing on land ecological status quo, especially in developed regions, we chose Jiantan as a typical city with a highly developed economy, and made an ecological assessment of land use in 2011 based on 3S technology and statistical analysis. First, the land ecological survey and assessment system was established including background layer, structure layer, stress layer, and efficiency layer aiming at studying the land ecosystem structure, function, effect, and problems. Then according to the index system, we used the Kriging model, linear spectrum decomposition model, landscape analysis model, GIS spatial statistical and calculation modeler, and field investigation to get data of all 26 indexes. The main processing software includes ArcGIS9.3, Envi4.5, Fragstats 3.3, SPSS13.0. After that, taking administrative villages as an independent unit, we assessed Jintan's land ecology through information mining, entropy weight methods, and overlay calculation. The result shows land ecology in the west was better than that in the east and became continuously better from the urban center to all around. Furthermore, we divided the study area into five ecotypes via cluster analysis of the 26 indexes; using a stepwise regression method, we figured out key controlling factors of each ecotype by taking the26 indexes as independent variables and the ecology score as the dependent variable. Finally, taking geomorphology into account, we put forward three ecological management zones: the western hills mountain ecological control zone, the east-central plain urban and rural ecological coordination area, and the center city plain ecological optimization area. In the western hills mountain ecological control zone, the land ecological background is good, its stress is low and its efficiency is high. Thus, the ecological score of land use is generally high. The east-central plain urban and rural ecological coordination area mostly covers the ecological buffer zone in ecology planning of Jintan and its ecological status quo is medium. In the center city plain ecological optimization area, the ecological score of land use is low; we should pay more attention to improve the ecology in this area as its land ecological background is not good and land use structure is not efficient. Moreover, its ecological stress is quite high. In this way, we diagnosed the main ecological problems in each zone that would provide a solid basis for government decision-making and land management.