Evaluation And Optimization Of Urban Ecological Resilience In Changchun Based On Landscape Pattern

Ecosystem resilience,together with economic resilience,social resilience and resilience of other factors,constitutes the basic guarantee for the healthy operation of urban system and is an important part of urban system resilience.China's rapid urbanization and the lag of urban ecological environment construction lead to frequent ecological environment problems,threaten urban ecological security and become important factors restricting urban development.Therefore,the construction of ecological civilization is incorporated into the tasks and objectives of urbanization.Cities are faced with the disturbance and impact of natural disasters,climate changes and other uncertainties,which further aggravates urban risks and threatens urban ecological security.To cope with the internal pressure accumulated in the long-term development of cities and the impact of external uncertain risks,the concept of resilient city puts forward solutions for the development of urban ecological security,which has become a hot topic in the field of urban research and practice.This study takes Changchun city as a case city.Starting from the perspective of landscape ecology,it is based on the dual supporting functions inside and outside the urban ecosystem,namely,the ability to maintain the landscape matrix and meet the supply demand of the ecosystem for urban resilience development.This paper attempts to build an evaluation model of ecosystem resilience based on the perspective of internal development and the perspective of "exposure and adaptation".Through the quantitative measurement of the ecosystem resilience of Changchun city,the evolution rules and characteristics of its ecological resilience are summarized.The multi-scenario simulation and ecological resilience evaluation of Changchun's urban expansion in 2030 were carried out by using the simulation model,and the suggestions for the optimization of ecosystem resilience were put forward.The paper mainly contains three parts:The first part: the theoretical research part,composed of chapter one and chapter two.This paper mainly defines the concept of urban ecosystem resilience,sorts out the related literature and theories of urban ecological resilience and urban ecological security,and puts forward the significance,technical methods and research framework of ecosystem resilience.The second part: the empirical research part,from chapter three to chapter six.The third chapter quantitatively depicts the land use and landscape pattern evolution of Changchun city from the cognitive basis.The fourth and fifth chapters,based on the theories and methods of landscape ecology,construct the model of urban ecosystem resilience from the perspective of landscape matrix and the perspective of "risk-connection-potential",and conclude the evolution rules and characteristics of ecosystem resilience of Changchun from three aspects of mathematical analysis,spatial pattern and correlation pattern.The sixth chapter,combined with PCP model and ERS model,comprehensively evaluates the ecosystem resilience of Changchun,analyzes its evolution pattern,and predicts the ecosystem resilience of Changchun under multi-scenario simulation by using simulation model in 2030.The third part: application and conclusion,which consists of chapter seven and chapter eight.Chapter seven,based on the above theories and empirical analysis,summarizes the experience of typical cases of ecological resilience at home and abroad,and establishes the optimization principles of ecological resilience and the spatial optimization approaches of "patch-corridor-basement".From the aspect of central city,urban area,multi-scale network construction and land space planning and implementation,this paper puts forward the optimization strategies of Changchun ecosystem resilience.Chapter eight is the conclusion and discussion part of this paper,which mainly summarizes the main conclusions of this paper,analyzes the innovation points,and makes relevant prospects for the follow-up researches and deficiencies.Research findings :(1)From 1985 to 2015,the substantial expansion of construction land in Changchun city caused continuous compression of ecological land and intensified the frequency,speed and spatial range of conversion from natural ecological landscape to cultural landscape.The spreading expansion of the central urban area increasingly threatens the ecological barrier in the south of the city,while the key towns further accelerate the fragmentation of the ecological landscape pattern and destroy the integrity and stability of the ecosystem.(2)The resilience level of the ecosystem in Changchun showed a significant downward trend,both from the perspective of landscape matrix and the perspective of "risk-connection-potential".And it presents a regional spatial pattern of "high in the east and low in the west,good in the south and bad in the north".The low resilience area is mainly distributed in the western plain area,the southern valley plain and the eastern edge area of the urban area.The resilience level of the ecological barrier area with Dahei mountain as the main body is relatively good.The ecosystem resilience has the characteristic of "cold in the west and hot in the east".(3)The resilience level of the integrated ecosystem in Changchun city is at a relatively low level for a long time,and the overall trend is decreasing.The spatial distribution presents a stable pattern of "high in the east and low in the west",the distribution pattern of high and low resilience is relatively stable,and the characteristic of spatial heterogeneity is significant.Different stages of urbanization have direct influence on the corresponding adaptive cycle stages of the ecosystem.The multi-scenario simulation shows that the northeast direction and the urban traffic line will become the leading directions of urban expansion.Under the dual effects of construction land expansion and human activities,the urban ecological conservation area faces many ecological threats and gradually becomes the ecological fragile and sensitive area of Changchun.(4)Based on the typical case experience of ecological resilience at home and abroad,the principles of redundancy,diversity and multi-scale network connectivity of optimization of ecosystem resilience are established,and the main approaches of optimization of ecosystem resilience are proposed from the perspective of landscape pattern "patch-corridor-basement".According to the principles and ways of optimization of ecological resilience,Changchun resilience evolution,from the view of central city and the urban area,puts forward the specific optimization strategies,such as the setting of green patches,the construction of green corridor,the green energy conservation of production and life,and the protection of ecological integrity,and pays attention to the connection of the multi-scale ecological network.Finally,from the aspect of land spatial planning,the management measures of optimization of ecosystem resilience are put forward.(5)The following conclusions are drawn in this paper: the influence of the distribution pattern of landscape types on the spatial pattern of the ecosystem resilience presents typical heterogeneity characteristics.Ecosystem is an important way to mitigate or eliminate urban risks.The natural ecological space is the main contributor to the ecosystem resilience and the intensity of human activities has a negative effect on it.The ecosystem resilience is closely related to the quality of the ecosystem landscape matrix.The element system of multi-scale landscape is an important way to optimize the resilience of ecosystem.