Spatial-temporal Evolution Of Ecosystem Health And Its Dynamic Response To Urbanization In The Yangtze River Economic Belt

How to balance the relationship between ecological protection and economic development is a long-term important issue in the process of urbanization.As an important birthplace of the Chinese civilization,the Yangtze River Basin has always attracted attention for its ups and downs.The strategic orientation of "ecological priority and green development" highly summarizes the development direction and realization path between ecological protection and economic development,which is also an inevitable move to maintain the titles of "economic corridor" and "ecological corridor".However,although the "resource-exhausted development" has greatly promoted urbanization,the ecological health has deteriorated seriously,which has become a serious bottleneck restricting the sustainable development.Under the circumstance of tightening green constraints,how to restore and protect ecosystems,and develop while protecting and protect while developing are the difficult problems that must be faced and solved.Evaluating and analyzing spatiotemporal evolution of ecosystem health,and quantifying its dynamic response to urbanization are the objective requirements and inherent needs for solving this problem.Therefore,this study summarizes the experience of existing research by sorting out research results at home and abroad,analyzes the shortcomings of current research,and constructs evaluation index systems based on improved VOR model and comprehensive index method.Then,taking 130 cities in the Yangtze River Economic Belt as examples,comprehensively quantifying the health status of ecosystems and the level of urbanization,and focusing on analyzing the spatiotemporal evolution characteristics of ecosystem health and its components.Lastly,analyzing the influencing factors of the spatiotemporal evolution of ecosystem health,using the spatial econometric model to explore spatiotemporal dynamic response of ecosystem health to urbanization,with a view to provide theoretical basis and practical support for the realization of green development.The follows are the main conclusions of the study:(1)There are obvious spatiotemporal differences in the components of ecosystem health.The ecosystem vigor has obvious spatial heterogeneity,showing the distribution characteristics of "high in the south and low in the north".Ecosystem organization shows a steady downward trend in time,and the spatial distribution is relatively random.Ecosystem resilience has significant agglomeration characteristics,cities with high population and economic density and areas with high terrain have low habitat quality index and low level of resilience.Affected by the decline in the supply of ecosystem services and the increase in demand,the supply and demand balance index of ecosystem services shows a continuous downward trend,the deficit area is mainly concentrated in the northern part of the lower reaches and part of the urban agglomeration in space.(2)The average value of the ecosystem health index showed a slight fluctuation in a small decline,with significant spatial agglomeration characteristics.The “trough” in the lower reaches lowered the overall average value of the Yangtze River Economic Belt,which evolution was mainly affected by changes of the middle and upper reaches.In terms of spatial pattern,ecosystem health has a significant spatial autocorrelation relationship,which is reflected in the low-level agglomeration in the northern of the lower reaches,the high-level agglomeration in the western periphery of the mid-reaches region and the southern of the overall region,and the result shows that ecosystem health poor areas may have an increasing impact on the health of neighboring ecosystems.The decline in ecosystem health index is mainly concentrated between 2005 and 2010,mainly in some provincial capital cities and more developed areas.(3)The level of urbanization continued to rise.During the 13 years from 2005 to2018,the overall urbanization level increased by 46.7%,with an average annual growth rate of 2.97%.The overall growth rate and the average annual growth rate of the middle and lower reaches are higher than the average level.Among them,the low reaches has the largest growth rate and the fastest average annual growth rate,52.97% and 3.34%respectively.The level of development among the sub-systems of economy,population,land and social urbanization is very different,the economic urbanization is highest,and the coordination level between population and social is relatively high.The overall level of urbanization shows an increase in regional development differences from west to east.Except for a few cities limited by geographical location in the upper reaches,the rest of the cities have reached the average level of urbanization and above.(4)The urbanization has a significant negative impact on ecosystem health,but the negative impact is declining in general.The spatial autocorrelation results showed that the spatial correlation between urbanization and ecosystem health was mainly reflected in upper reaches and lower reaches.Among them,social urbanization is positively correlated with ecosystem health,while economic,population and land urbanization are significantly negatively correlated with ecosystem health.In quantifying the response model of ecosystem health to urbanization,the fitting effect of the spatial error model with control variables is the best.The negative impact of land and population urbanization on ecosystem health is significantly higher than the positive impact of social urbanization,making the overall negative impact of urbanization on ecosystem health.In addition,natural factors such as terrain relief,rainfall,and distance from rivers have a positive impact on ecosystem health,either directly benefiting ecosystem health or indirectly protecting ecosystem health by limiting urban sprawl.Based on the above research conclusions,the following suggestions are put forward: on the one hand,the ecological priority is the premise,the overall linkage,the integration of the central and the separate,the establishment of a long-term ecological protection mechanism,and the comprehensive consideration of the spatial externality,to jointly focus on ecological protection;on the other hand,green development as the orientation,promote the transformation of green industries,dislocate within the region,coordinate between regions,and build a new pattern of coordinated development.