| Chongming distract is located in the northern hemisphere subtropical zone, that is in the Yangtze River Estuary, surrounded on the three side and east to the East China Sea, which is a typical marine climate. It is including the Chongming Island, the Changxing Island and Hengsha Island. Because of the geographical limitation and external traffic conditions, there haven’t been a large-scale development and construction activities, retaining the pattern of farming feature. In the past twenty years, with the development of urbanization, Human activities interfere with the ecological system more and more obviously, which will affect the status of ecological system.In this paper, according to the remote sensing image from Landset TM and Landset ETM+in year1989, in2005and2008of Chongming area, interpret by the United States SRTM3digital elevation model data, then get the corresponding land use type data, and make land use thematic map of three phase of the land. The author analysis the transfer matrix land use, select the number of patches, mean seven landscape pattern index-patch area, the total edge density, fractal dimension, diversity, dominance and evenness, and analysis of landscape pattern change. Based on this data, combined with the statistical data:population density, land reclamation rate, human disturbance degree, NDVI index, landscape diversity index, landscape evenness index, patch area, restoring force, the function value of ecosystem services, which is total nine indications. According to these data, establishment the ecosystem heath evaluation model of "pressure-state-response", and regard the Chongming county administrative division as the evaluation unit. In the finally, to evaluate the ecosystem heath, and reflect the temporal and spatial variation of Chongming County in the recent twenty years, the purpose is providing the basis theory for the sustainable development of Chongming area. The result is that:(1)During the twenty years, the land use situation of Chongming has changed so much. The area of agricultural and woodland reduced, but the urban and rural construction land increased significantly, that indicate the process of the urbanization accelerating. Before the year of2005, the urban and rural construction land is mainly from agricultural land, but after the year of2005, which is mainly from the woodland.(2)During the1989to2008, the landscape structure of Chongming changed obviously, Overall, various types of patch dominance decreased, the overall landscape diversity enhanced, more heterogeneity. Agricultural land fragmentation degree increased; the number of patch increased firstly and then decreased, but the average area of patch changed little, which have gathered trend.(3)During the year of1989to2001, the ecosystem health of Chongming area reduced significantly, the variation area accounted for18.93%of the total area, then remained stable during the year of2001to2008. Reasons for the decline of ecosystem heath mainly are urbanization, farm development and reclamation. Later because some ecological and environmental protection measures were implemented, heath status remained stable.(4) The ecological heath of northern and eastern Chongming was great, evaluation grade remained at two (good), the status of south-central was poor, evaluation grade is the forth, the reason is that the large construction area and the fragmented residential lead to the fragmentation.When during the overall planning of Ecological County, the government should be based on the maintenance of the eastern, northern district ecological heath, they should focus on recovering the ecological heath of central and southern, plan the land use reasonable, strengthen the urban greening, promote healthy city concept. |
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