Abstract: With the acceleration of urbanization in the Yangtze River Basin, the contradiction between resources and the environment is highlighted, and the reduction in ecological and environmental vulnerability has become an important way for cities along the river to achieve high-quality development. The spatial differences in the ecological vulnerability of cities along the river are not conducive to the synergistic development of the Yangtze River Economic Belt. Therefore, a scientific assessment of the ecological vulnerability of cities along the river and exploration of its spatial and temporal evolution patterns, and coping strategies can help the overall high-quality development of cities along the river. Existing literature mostly adopts intuitive horizontal comparison and spatial autocorrelation analysis to study the spatial and temporal clustering characteristics of vulnerability. It is a challenge to further explore the spatial and temporal evolution of vulnerability and quantify the spatial spillover effect of vulnerability.
In view of this, based on the theoretical analysis framework of vulnerability “exposure-sensitivity-adaptability”, this paper constructs an urban ecological environment vulnerability index system from the dimension of the coupled system of city, society and nature, and utilizes the “layer by layer vertical and horizontal” gearing method, the Kriging interpolation, Kernel density estimation and Markov chain, to systematically investigate the spatial and temporal characteristics and evolution of the distribution of ecological environmental vulnerability of cities along the Yangtze River from 2013 to 2018.
Based on the analysis results, the following conclusions can be drawn: 1)during the sample period, the ecological environmental vulnerability of cities along the Yangtze River in the upper, middle and lower reaches of the river is characterized by non-equilibrium spatial differentiation, which is stable, active and weakened, respectively; 2)the ecological environmental vulnerability of cities along the Yangtze River as a whole is in a declining trend, and regional differences are the main influencing factors for the expanding trend of vulnerability differences; 3)the vulnerability as a whole is not mobile and has the characteristics of “club convergence” and “clubs convergence”. The overall mobility of vulnerability is not strong and has the characteristics of “club convergence”; 4)spatial factors have a significant impact on the transfer of ecological environment vulnerability, and an effect of “polarization neighborhood stabilization”.
Based on the above conclusions, this paper suggests: 1)Implementing gradient regional policy instruments. Each region should implement policy instruments according to local conditions to ensure the synergistic development of cities along the river. 2)Promoting the accelerated downgrading of heavily vulnerable cities. Heavily vulnerable cities in the middle and lower reaches of the river should be accelerated and downgraded, so that the ecological vulnerability of the cities along the river will be converged to a lower level as a whole. 3)Strengthening the radiation role of mildly vulnerable cities. On the one hand, we should actively guide the establishment of cooperation platforms between mildly vulnerable cities and neighboring cities; on the other hand, we should build a cross-space complementary system with heavily vulnerable cities to realize a win-win situation for the development of cities along the river and protect the ecological environment.

Key words: vulnerability, urban ecological environment, spatial and temporal differentiation, evolution

摘要： 探究长江沿线城市生态环境脆弱性时空分布特征及演进规律。基于脆弱性“暴露度-敏感性-适应力”理论分析框架,从城市、社会与自然耦合系统维度构建城市生态环境脆弱性指标体系;运用“逐层纵横向”拉开档次法、Kriging插值、Kernel密度估计和Markov链等方法系统考察2013—2018年间长江沿线城市生态环境脆弱性分布的时空特征和演进规律。实证结果表明:在样本考察期内,长江沿线上中下游城市生态环境脆弱性分别呈平稳、活跃和弱化的非均衡化空间分异特征;长江沿线城市生态环境脆弱性整体呈下降态势,地区差异是脆弱性差异趋势扩大的主要影响因素;脆弱性整体流动性不强且具“俱乐部趋同”特征;空间因素对生态环境脆弱性转移具有显著影响且具“极化邻近趋稳效应”。

关键词: 脆弱性, 城市生态环境, 时空分异, 演化