| The multi-level, connective and composite urban ecological network, which is based on grass land, wetland, farmland and forest, is an important carrier and foundation of ecological civilization, and also an important guarantee of sustainable economic and social development. Located in the Yangtze River Estuary, Pudong New Area is one of the most developed regions in china. Since1990, with the development and opening of Pudong New Area, the population and economic grows rapidly, and the built-up area expands unceasingly, which leads to significant land use change. With some natural and man-made factors, such as sea level rise, coastal erosion, the resource and environment is facing enormous pressure, basic ecological resource have been greatly affected, such as decrease in habitat resources, increase fragmentation of wetland and grassland, lower connectivity of ecological network, and gradual decline of ecological function.In2001, the Shanghai Government put forward the first ecological network plan, which is mainly for nature protection, meets variety functions of social, cultural and economic. It will meet the further implement the city development strategy of "giving priority to ecology and focusing on livable environment" with ecological land covering more than50%of the city’s land use. With the background of this plan and our country’s new urbanization, we should find out the amount, spatial distribution, structure and spatial-temporal evolution of ecological network resources. Besides, we should have an good known of the quality of ecological network, influence and stress, the future development. Then, we can providing scientific support for policy decision makers and ecological construction.So, this pager takes Pudong New Area as an example. With the help of RS and GIS, collectting more than20years’ Landsat TM/ETM+and FW2moderate or high resolution remote sensing data, together with topographic maps, we get the multidate land use classification by object oriented classification methord.Based on the multi aspect research of Pudong New Area land use, especially the landscape pattern and dirving mechanism of ecological elements, we use high-resolution RS image and field survey data to built an multi-level ecological network which is mainly consist of forest, grass, farmland and wetland. In this study, the following conclusions have been drawn:(1) During the20years in1989to2009, the land use in Pudong New Area changes a lot:the land for construction increased35959.94hm2, with an annual growth of5.00%;farmland decreased a lot, especially in the more urbanization area in the old Pudong distrct.Large amont of farmland have became constructions or forest;forest and grass decreased at first, while get large increase during the later of the time;the wetland in land, especially the herbaceous swamp, change closely with the construction of large project;with the influence of changes in water supply and sediment and offshore engineering, tidal wetland in coastal areas decrease while increase in Jiuduansha.(2) The increases in total number of ecological patches and Shannon’s diversity index, decreases in contagion index and cohesion index, show that, the landscape become more fragmentized and the connection of habitat get lower; area-weighted mean fractal dimension(AWMPFD) is becoming lower, which means the impacts of human being get bigger;the percentage of landscape index and the cohesion index of grass and forest rise, that mean the construction of grass land in Pudong New Area have a good effect.(3) Aming at specific species, we discuss the connectivity of forest land and wetland. With the spatial distribution and statistics of cumulative cost, we can draw the following conclusions:the connectivity of forest in the sourth is higher than that in north, and the connectivity of wetland offshore is higher than that in the land; at the beginning of Pudong New Area’s construction, the connectivity of forest decreases, with the number of high cost pixels increase and the number of low cost pixels decrease. With the construction of grass and forest land, the connectivity of forest increase during2000and2009. At the cost of mud flat reclamation, the connectivity of wetland decrease during2000and2009.(4) Pudong New Area’ coastal wetland is influence by hydrological condition upstream and offshore engineering, and the latter one is the key factor.The mud flat reclamation, planting in Jiuduansha, and the construction of the south jetty in deep water channel, change the coastal wetland, especially the mud flat.Besides, the rapid growth of population and economic, the expansion of urban areas, are also the key driving mechanism of land use change, which directly change the landscap pattern.(5) Based on the recognition of ecological elements by using high resolution RS image and field survey data, we extract the important corridors with the Least-Cost Path and Gravity Model.We find that,there are few large patches with strong ecological suitability, and most of them are located in the northeast;Jiuduansha play important roles in ecological niche; the grassland beside the outer hoop is good connectors between the patches in built-up area and outskirts;the forest lands is the superior landscape type in the ecological network of study area,while it’s very narrow and easily got influence by humen beings. |
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