Simulation Study On Urban Land Expansion Based On Ecological Security Pattern

Applying a dynamic simulation method to model an urban land expansion under different scenarios from the perspective of ecological security and select the optimal control measures can effectively coordinate and resolve the contradiction between rapid urban development and ecological protection,thus improving the efficiency of urban land use.Therefore,this study takes the Liangjiang New Area of Chongqing as an example and builds an ecological security pattern of the study area based on the minimum cumulative resistance model according to the land use data in the study area for the periods in 2010,2014 and 2018.In the meantime,it analyzed land use changes in Liangjiang New Area from 2010 to 2018 and explored its driving factors according to the third phase of land use data.By integrating the ecological security pattern and the driving factors of land use changes in the study area,suitability maps for restrictive conditions and types of land use were developed.Then,the expansion of urban land in the study area in 2026 was simulated by the use of the CA-Markov model under the three scenarios of"Inertial Development","Ecological Protection"And"Strong Ecological Constraints"were created.Finally,through performing statistical operations on areas and calculating landscape indexes based on the simulation results,it conducted a comprehensive evaluation of these three simulation scenaris in a bid to select the optimal one for urban land expansion in Liangjiang New Area in 2026.The main methods and conclusions of the study are as follows:1.A total of 28 ecological source patches were identified by constructing the evaluation index system of"importance of ecological service function-ecological sensitivity",accounting for 22.17%of the total land area in the study area.With an obvious banded structure,the ecological sources are mainly distributed in the forest and cultivated land areas of four mountains in the Liangjiang New Area-Zhongliang Mountain,Longwangdong Mountain,Tongluo Mountain,and Mingyue Mountain.On the basis of identifying the ecological source land,the minimum cumulative resistance model is used to construct the resistance surface,so as to identify the ecological buffer zone is 60,087.78 hm~2,of which the ecological source area covers 26,018.92 hm~2.Due to high sensitivity to human activities,the ecological buffer zone in Liangjiang New Area is not suitable for development and construction.Meanwhile,based on the constructed resistance surface and the GIS hydrological analysis module,32 ecological corridors,with a total length of 197.40 km,were selected,which are mainly composed of natural rivers and some green spaces and belts in the cities.Finally,two types of ecological nodes were identified through the ecological corridor,that is,type A(5)and type B(11).For type A,these ecological nodes are primarily located around the intersection of rivers in the area,with a higher probability of biological circulation.For type B,this type of ecological nodes poses the greatest threat to resist ecological circulation,mainly located in the areas where urban construction land is relatively concentrated.2.Based on the land use data of the third phase of Liangjiang New Area,the land use change situation in the area is analyzed by statistical analysis method and GIS spatial analysis method.The results show that the main land use types of Liangjiang New Area in 2010-2018 are cultivated land,woodland and construction land,and the three areas change significantly.Specifically,the area of construction land in Liangjiang New Area increased significantly during the study period,the main sources of which were cultivated land and woodland,and the spatial distribution showed a trend of expansion to the north and east.At the same time,using the binary logistic regression model to explore the driving factors of land use change in Liangjiang New Area,the results show that the change of cultivated land and woodland in Liangjiang New Area is mainly affected by elevation,slope,construction density,population density and distance from railway;grassland change is mainly affected by slope;water area change is mainly affected by elevation,slope and population density;the main factor leading to the change of unused land is the distance from subway,river and district center;The change of construction land is mainly affected by construction density,population density and distance from highway and railway,and the expansion of construction land is also restricted by natural conditions such as slope.3.Three development scenarios were created to simulate the urban land expansion of Liangjiang New Area in 2026 and the landscape pattern index was used for an overall evaluation.The evaluation results show that the fragmentation degree of each land type under the"inertial development"scenario is high,and the overall connectivity and diversity are low.Under the“Ecological Protection”scenario,the landscape fragmentation of each land type is low,with a high degree of connectivity and rich diversity,and the demand for construction land development can be greatly met.Under this scenario,the regional economic development and ecological protection can be better coordinated,demonstrating that it is the best option among the three development scenarios.At the same time,compared with the"ecological protection"scenario,the excessive compression of construction land area under the"strong ecological constraints"scenario leads to the increasing of fragmentation degree of each land type and decreasing of overall connectivity and diversity,which will affect the stability of the urban interior landscape pattern to a certain extent.So,the use of moderate ecological protection policies for urban planning can better improve economic and ecological benefits.