Evolution Trend And Driving Force Of Ecological Security In Resource-exhausted Cities In China

Ecological security is an important issue that needs to be solved in the transformation and development of resource-exhausted cities in China.As the problem of resource depletion of resource cities is becoming more and more serious,the relevant research in China began to emerge in the 1990s.Currently,most of the relevant studies are objects in a single or certain area of resource-exhausted cities,there are few researches on the ecological security of resource-exhausted cities as a whole.To reveal the evolutionary trends and key factors of the ecological security of resource-exhausted prefecture-level cities,this study constructed and tested a evaluation index system of resource-exhausted cities in China and analyzed and summarized the evolution characteristics of the ecological security of 24 resource-exhausted prefecture-level cities and the driving force sequence of evaluation indexes during 2011-2019.The evolutionary trend of ecological security in 2020-2030 was predicted.The main research contents and conclusions are as follows:(1)When constructing the evaluation index system,the study used a combination of frequency statistics,sensitivity analysis,and grey correlation clustering to reduce the 30 evaluation indicators commonly used in the study of resource-exhausted urban ecological security to 15.After redundancy,sensitivity,and case verifications,the validity of the method was verified.Thus,a relatively refined ecological security evaluation index system was constructed for resource-exhausted cities in China.(2)The study on the evolutionary trend of ecological security in 24 resourceexhausted prefecture-level cities in China from 2011 to 2019 concluded that the evolution trend of ecological security can be roughly divided into four forms:gentle development,ladder rise,"V" type development,and shock development.The overall trend was divided into two stages:the ecological security level in the first half(20112015)was low and the development was slow,while the ecological security level in the second half(2016-2019)was rapid.By 2019,the ecological security levels of all cities in the study area were above the critical security level.(3)In the study of the trend characteristics of the spatiotemporal evolution of ecological security,the ecological security of 24 resource-exhausted prefecture-level cities in China gradually improved from 2016 to 2019.However,from 2011 to 2018,the geographical and spatial evolutionary trends were not significant.Until 2019,it was relatively obvious feature of high in the south and low in the north.(4)In the study of the driving forces of ecological security,the grey correlation analysis model was used to determine the order relationship of ecological security driving forces for each evaluation index by analyzing the grey comprehensive correlation matrix between the 24 resource-exhausted prefecture-level cities and evaluation indexes.The results showed that the relationships between the driving forces of ecological security in a single city were not the same.The perspective of the whole,individual,and geographical space resulted in the same conclusion.Namely,three indicators:R2(the proportion of education expenditure in public budget expenditure),P2(the amount of agricultural fertilizer applied),and P7(carbon emissions),and similar clustering factors:P5(energy consumption per unit of GDP),S4(GDP growth rate),R5(beds in health institutions),S3(urbanization rate),and R6(the proportion of science and technology expenditure in public budget expenditure)represent the dominant factors in the driving force of ecological security in resource-exhausted prefecture-level cities in China.(5)In the study of ecological security trend prediction,the grey prediction GM(1,1)model suitable for "small data and poor information" was used in this study.By comparing the simulation errors of the four basic forms of the GM(1,1)model,prediction models for the 24 resource-exhausted cities were determined.In view of the situation that the prediction results of some cities exceeded the theoretical upper limit of the ecological security index,this study proposed a regulation method combining the prediction upper limit with the order of buffer operator,which can quantize the order originally determined by experience and effectively solve the problem of unreasonable prediction results.The results showed that,except for a few cities,the ecological security of resource-exhausted prefecture-level cities in China will realize an overall growth trend during 2020-2030,and the growth rate of ecological security will be lower than that during 2011-2019.This study made beneficial attempts to build a refined and effective multi-object ecological security evaluation index system.The relatively refined evaluation index system provides convenience for ecological security researchers in resource-exhausted cities in China and reduces the difficulty of data collection and the calculation workload to a large extent.Simultaneously,it also reduces the problem of maintenance disasters caused by excessive evaluation indices with similar information and lays a foundation for further improvement of the subsequent evaluation index system.In this study,the GM(1,1)model was used to determine the order of the buffer operators in multi-object ecological security index predictions,which can provide a reference for related research.In a practical sense,at the present urbanization stage of "urban disease" and the exploration stage of resource-exhausted city transformation and development,this study provides a reference for understanding and solving the problem of the ecological security of resource-exhausted city,and can also provide decision-making support services for governments at all levels to formulate relevant policies,which is conducive to the optimization of resource allocation and improvement of resource utilization efficiency.