Land Use Change And Ecological Security Evaluation In Yancheng Coastal Wetland Of Northern Jiangsu

In this paper, we took Yanchen coastal wetland of northern Jiangsu as the research object. The paper extracted the data of land use from the remote sensing images by using geographic information systems (GIS) technology and combined with some statistical yearbook data. We use some theories and methods, such as Ecosystem service value, Markov shift matrix forecast method, and P-S-R (Pressure-Status-Response) frame work to study the current status and temporal dynamics of the types of land-use. The paper evaluated the ecological safety from the time-series and analyzed the influence of land-use change on the ecological environment.Application of remote sensing (RS) and geographic information systems (GIS) technology, we got the land-use map of the Yancheng coastal wetland.According to the analysis of dynamic change of land use, we obtained 1983-2009 land use spatial-temporal evolution. Then evaluate ecosystem service value of Yancheng coastal areas in 1983,2001 and 2009, by using equivalent weight factor table of ecosystem services of terrestrial ecosystems in China. The ecosystem services value in 1983 was 25.283 billion RMB/year.It increased to 34,448 RMB/year in 2001, growth to 34,926 RMB/year in the year of 2009. The ecosystem services value showed ascendant trend.Markov model was utilized to simulate future land use structure assumes that external interference was constant.We predicted the land use structure of North Jiangsu coastal wetlands land from 2010 to 2050 and its stability. The results indicated that the percentage of town land and farmland increased gradually, meanwhile reed land and Marine aquaculture land percentage declined. Reduction of reed land was mainly changed to farmland. We used the theory of ecosystem service value to analyse prediction results. Land use patterns in this area changes are high value of types of land use, such as forest land, irrigation ditch and rivers increased, at the same time, low value of types, such as town land improved greatly. However, mudflats, reed land and grassland continually decreased, which had higher value than other types. To improve ecosystem service function value of North Jiangsu coastal wetlands land, we should use mudflats, reed land and grassland rationally, and control the land for residential housing construction appropriately in the following land use planning and ecological construction. In the end, land use change drivers were analyzed.Under the guidance of the P-S-R(Pressure-Status-Response) framework,we use AHP method to construct the target layer, rule layer and index layer three administrative levels,which includes 3 subsystems,14 indicators, that constituted ecological security evaluation index system of Yancheng wetland.We took administrative district (county-level city) for the evaluation unit, using AHP and entropy method of combination weighting method to determine the weight of each index.Then we multi-level weighted sum model to evaluate the ecological safety of the study area in 2001 and 2009. The results of regional ecological security showed that the northern Jiangsu coastal wetlands ecological security level was improved as a whole and eco-environment quality took on an ascending trend which coincided with ecosystem service value trends. But the ecological security indexes of some sections were also in alarm or warning status and the potential threat was serious. Some countermeasures were advanced to protect the ecological security of coastal wetland.In the end, the main conclusion and innovations in the dissertation are summarized.