Spatial-Temporal Changes Of Land Ecological Security In Coastal Port Cities

Land is the carrier of biological activities and natural resources,the material basis for human survival,and the basic guarantee for social progress and economic development.In the21 st century,With the acceleration of economic globalization,coastal port cities have become the gathering center of global social and economic activities with their livable ecological environment and convenient traffic conditions.Population growth and large-scale land development activities also pose a threat to land ecological security.Therefore,revealing the law of land ecological security changes in coastal port cities and putting forward the countermeasures of land ecological security regulation will help to maintain the harmonious development of regional nature,economy and society.Firstly,based on the theory of ecology and system theory,combined with the impact mechanism of land ecological security in coastal port cities,and according to the characteristics of land ecological security,and based on P-S-R(Pressure-State-Response)model,this thesis constructs an evaluation index system of land ecological security suitable for coastal port cities;secondly,taking Lianyungang City as the research area,based on remote sensing data of four periods in 2000,2005,2010 and 2015 and other thematic elements data,each evaluation index is rasterized by ArcGIS software,and a single index raster layer with resolution of 30m’30m is established,and each index is standardized by extreme value method to obtain a single index Safety index.Then using the analytic hierarchy process to give it weight,and based on the ArcGIS software spatial analysis tool,weighted summation of each index weight and individual index safety index by comprehensive analysis method,the comprehensive value of land ecological security is obtained.Finally,the spatial and temporal changes of land ecological security in Lianyungang City in recent 15 years are graded and evaluated,and the countermeasures and suggestions of land ecological security regulation are given.The main conclusions are as follows:(1)The land ecological security situation in Lianyungang City in 2015 was improved compared with that in 2000.The comprehensive value of land ecological security increased stepwise from 69.38 in 2000 to 79.54 in 2015.The proportion of the area occupied by the fifth grade land ecological security zone increased from 23.13% in 2000 to 86.94% in 2015,which increased 2.76 times.The proportion of the area occupied by the fourth grade and below decreased by 83.01%.The main reason is that Lianyungang has strengthened the construction of ecological civilization,the pressure of land ecosystem has been gradually alleviated,the state of land ecosystem has been optimized and the response of land ecosystem has been strengthened.(2)From 2000 to 2015,the spatial variation of the comprehensive value of land ecological security is obvious in Lianyungang City.In 2000,the land ecological security in the eastern and southern parts of Lianyungang City was relatively poor.Except for Donghai County in the west,the area of safety zones of grade IV and below of land ecology accounted for a large proportion.The urban area and the main urban area of Guannan County were safety zones of grade II of land ecology.In 2005,the land ecological situation in northern,central and southern Lianyungang began to improve.The proportion of land area in grade III and IV security zones decreased,while that in grade V security zones increased.The land ecological situation in Donghai County in Western deteriorated.By 2010,because Lianyungang has strengthened the investment intensity of infrastructure construction,the land ecological security in its urban and eastern coastal areas has deteriorated,and the proportion of land area in Grade II security zone has increased greatly;the area of Grade IV security zone in the rest of the area occupies the dominant position.By 2015,Lianyungang City,the eastern coastal area of Guanyun County and other county main urban areas will be located in the level IV security zone of land ecology,while most of the other areas will be located in the level V security zone of land ecology.(3)Based on the characteristics of Land Ecological Security in Lianyungang City,this thesis puts forward the countermeasures and suggestions for the regulation and control of land ecological security in Lianyungang City from three aspects: alleviating the pressure of regional land ecosystem,optimizing the state of regional land ecosystem and strengthening the response of regional land ecosystem,with a view to improving the regional soil quality and ensuring the sustainable development of regional social economy.