Study On Land Ecological Security Assessment And Land Use Pattern Of Caofeidian New District

Caofeidian new district was one of the rapidest economical developing areas in China in recent years. Affected by a variety of power systems of ocean, land and rivers, land-use of this area changed complexly and the ecological environment was fragile. Rapid urbanization constitutes a serious challenge to regional and even more larger area’s land ecological security. Under the background of current rapid urbanization, deeply analyze the relationship and the interaction mechanism of ecological security and land use, comprehensively analyze the variation characteristics of land use structure and layout, systematically assess the current situation of security and the impact of rapid urbanization to regional ecological security,construct comprehensive ecological security pattern to maintain regional basic ecological service, and in-depth study the prediction and simulation method of land use change under the restrict of comprehensive ecological security pattern, were of great significance to the rational allocation of land resources, protection of regional ecological security, and the realization of ecological environmental goal of ecological livable city construction.Therefore, this paper takes Caofeidian new district as an example, based on the in-depth analysis of the interaction mechanism of ecological security and regional land use, and under the basis of the theory of soil ecology, landscape ecology and sustainable development, comprehensively utilization of remote sensing data, GIS technology and programming techniques, in accordance with the research thought of “land use pattern dynamic change”-“ecological security Response”- “construction of ecological security pattern”-”land use change simulation under the ecological constraints”, deeply analyzed the change of land use and landscape patterns during the rapid urbanization of Caofeidian new district, and also analyzed the change of ecological security status during the rapid urbanization, Meanwhile deeply studied the construction method of comprehensive ecological security pattern to maintain the basic ecologcial service and the land use change prediction and simulation method under the constraint of ecological security patterns, and also explore and analyze the land use change and its rationality under the constrain of different scenarios. The main conclusions are as follows:(1) analysis of the land use pattern change of Caofeidian new districtBy means of 3 land use remote sensing interpretation maps of the year 1995, 2005 and 2013, the analysis of land use structure and landscape pattern change of Caofeidian new district was conducted, and the result indicate that Land use change of Caofeidain new district during 1995 to 2005 can be divided into two stages, the period of 1995 to 2005 can be regarded as a slowly changing stage, and the integrated land use dynamic degree is 0.33%; from 2005 to 2013 can be regarded as the fast changing stage, the integrated land use dynamic degree is 3.30%. This is consistent with the period of Caofeidian new district’s urbanization。During the period of 2005 to 2013, which is also the rapid urbanization period of Caofeidian new district, the main land use change type are construction land and beaches, presented that beaches were greatly occupied by construction lands, the relative dynamics of the construction land was 6.38%, and the relative dynamics of the beach was 3.41%, while relative dynamics of the other classes are all no more than 0.5%.Analysis of landscape-level pattern index of Caofeidian new district showed that landscape of Caofeidian new district becomes increasingly fragmented, while gradually shift from dominant landscape to the homogeneous landscape. Analysis of the class-level landscape indices indicate that, construction land and beaches change greatly, while cultivated land, saltern and water changes relatively little. Largest patch index of construction land raised from 0.79% in 1995 to 5.17% in 2013, indicating that there are some consolidated urbanized areas in which some intra-urban open space are gradually buildout, thus creating some larger urban patches and the layout was irrational.(2) Land ecological security assessment of Caofeidian new districtAssessment and early warning of land ecological security in rapidly urbanizing coastal area is an important content to ensure sustainable land use and effective maintenance of land ecological security. Based on the Pressure-State-Response(PSR) model,an index system for land ecological security(LES) in rapidly urbanizing coastal area was suggested.The index system includes eight factors, among which, construction development intensity, distance to major transportation, population density and distance to major commercial centers belong to “pressure” dimension, mainly describe the pressure that human activities exert on the environment. And another three factors, landscape patch density, ecological service value and ecological resilience, belong to the land ecological security “state” dimension, mainly describe the quality of land environment. And the last factor, land ecological regulating response, belongs to “response” dimension, mainly reflects the reaction of human beings to land ecology dynamics.By means of remote sensing data and GIS methods, 1km×1km sampling blocks were built up and index values for each block were calculated. Each index was spatial interpolated and mapped individually, and then the spatial-processed indicators were overlaid with weights for the creation of the comprehensive land ecological security map. According to assessment results of 2005 and 2013,coupled with current tendencies, the early warning type of Caofeidian new district was classified into four categories: early warning for security and degradation,early warning for sub-security and slow degradation, early warning for sub-security and rapid degradation, and early warning for insecurity.And the result indicates that,(1)the mean value of LES in 2005 was 0.551,indicating medium security level, while in 2013 it was 0.517, a medium-low security level, and the statistical result of different towns indicates that there has total 6 towns whose LES value raised and 8 towns whose LES value reduced, indicates the degradation trend and spatial uneven distribution of LES within Caofeidian new district.(2)according to the early warning result,the insecurity and slow degradation early warning area and the insecurity and rapid degradation early warning area were mainly distributed in the south coastal area of Caofeidian new district, which was also the rapid urbanization area, illustrates that the rapid expansion of urban construction land is the most important factor which leading to the deterioration of the regional land ecological security.(3)The LES of three towns—Industrial District, Shilihai town and Nanpu saltern—were in stages of high early warning given that the percentage of land in these districts that showed early warning of insecurity, sub-security and rapid degradation,and sub-security and slow degradation was58.26%、98.93% and 81.15%, respectively. And land ecological security evaluation and regulation of the two towns should be strengthened in future.(3)Construction of comprehensive ecological security pattern in Caofeidian new districtBased on the theory of landscape security patterns and GIS method, ecological security patterns was constructed to maintain the basic ecosystem services of Caofeidian new district which including flood regulation, freshwater supply, biodiversity protection and cultural services. And all these patterns were integrated into a comprehensive ecological security pattern with different security levels. The results indicate that the area of the comprehensive ecological security pattern was 1058.80km2, which accounted for about 53.53% of the study area. Among all levels of ecological security patterns, the area of baseline ecological security pattern which was also the forbidden areas for construction was 312.67km2, accounted for about 15.81% of the study area. And the satisfied and ideal ecological security pattern was 308.15km2 and 437.98km2 respectively.(4) Simulation of land use change based on the constrain of ecological security patternBased on the remote sensing data and GIS method, a land use scenario simulation methodology was developed to intergrate CA-Markov chain and ecological security pattern at a regional scale. Two scenarios were developed to compare the impact of our land use modeling approach. No ecological conservation scenario is a continuation of the current trends and involves only limited constraints on development. The ecological security pattern conservation scenario(ESP conservation scenario) incorporates an different levels ecological security pattern conservation network. The results indicate that under ESP conservation scenario, there are 74.07km2 newly-increasing construction land within the range of overall ecological security patterns, while it is 91.54km2 under no ecological conservation scenario,a increase of 17.47km2, indicates that the ecological security patterns was effectively protected under the ESP conservation scenario. Especially within the range of baseline ecological security pattern, the quantity of newly-increasing construction land is 0 under ESP conservation scenario, while it is 31.07km2, indicating an entirely conservation of baseline ecological security pattern under ESP conservation scenario.Comparative analysis of each scenario with landscape metrics indicated that under the ESP conservation scenario, the number of urban patches increased, indicating that a slightly more fragmented landscape. The value of the Shannon’s Diversity Index(SHDI) for no ecological conservation scenario and ESP conservation scenario does not change because under both scenarios the number of classes remains the same, and there are no large differences in the proportional distribution of the area covered by each land use class. The values of the Shannon’s Evenness Index(SHEI) are a slight increased under ESP conservation scenario suggests that the landscape composition has become more even, indicating a transition from a dominant land cover class towards a more diversified landscape. PSCo V for cultivated land, water, beach and saltern changed little under both scenarios, but PSCo V for construction land was obviously increased under no ecological conservation scenario, suggest that under no ecological conservation scenario there are some consolidated urbanized areas in which some intra-urban open space are gradually buildout, thus creating some larger urban patches and significant variability in patch size.