长江经济带城市生态效率的时空分异及其驱动因素

Spatial-temporal differentiation of urban eco-efficiency in the Yangtze River Economic Belt and its driving factors

厘清城市生态效率的时空分异及其驱动因素是实现长江经济带协同绿色发展的基本前提。本文基于2003-2018年城市数据,采用MinDS模型测度了长江经济带城市生态效率水平,从投入产出视角揭示了城市生态无效率的具体来源,进一步利用Theil指数及地理探测器等方法实证考察了城市生态效率的时空分异特征及其驱动因素。研究发现:①样本考察期内,长江经济带总体及上、中、下游城市生态效率水平呈现波动上升趋势,且下游地区始终高于中、上游地区。期望产出不足和非期望产出冗余是造成城市生态无效率的重要原因。②地区内差异是长江经济带城市生态效率空间差异的主要来源。2011年之前下游地区内部生态效率差异对总体差异的影响最大;2011年之后下游与上游地区内差异贡献交替位于前两位。③长江中、下游地区城市生态效率的绝对差异呈显著缩小态势,但上游地区稍有扩大。除中游地区外,长江经济带城市生态效率具有一定的梯度效应,且下游地区的两极分化现象最为明显。④长江经济带城市生态效率的空间分异受到多种因素的综合影响,从结构因素来看,经济发展差异对长江经济带城市生态效率空间差异的决定力始终最高,能源投入差异和污染排放差异的作用强度相对较小;从社会经济因素来看,人口密度差异对城市生态效率空间分异的决定力显著强于其他因素。

Clarifying the spatial-temporal differentiation of urban eco-efficiency and its driving factors is the primary task to achieve green and sustainable development in the Yangtze River Economic Belt.Based on the urban panel data from 2003 to 2018,this paper used the MinDS model to measure the eco-efficiency of cities in the Yangtze River Economic Belt,revealed the specific sources of urban ecological inefficiency from the perspective of input-output,and further used the Theil Index and geographic detectors to empirically investigate the spatial-temporal differentiation characteristics and driving factors of its urban eco-efficiency.The study found that:①During the sample period,the overall eco-efficiency of the Yangtze River Economic Belt and the cities in the upper,middle and lower reaches showed a rising trend of fluctuation,and the downstream area was always higher than the middle and upstream areas.Insufficient expected output and undesired output redundancy were the root causes of urban ecological inefficiency.②Intra-regional differences were the main source of spatial differences in urban eco-efficiency in the Yangtze River Economic Belt.Before 2011,the differences in internal eco-efficiency in the downstream regions had the greatest impact on the overall differences;after 2011,the differences in the downstream and upstream regions alternately ranked first and second in the contribution list.③The absolute difference in urban eco-efficiency in the middle and lower reaches of the Yangtze River had decreased significantly,but the upstream area expanded slightly.Except for the middle reaches of the Yangtze River,urban eco-efficiency in the Yangtze River Economic Belt demonstrated a certain gradient effect,and the polarization in the downstream areas was the most obvious.④The spatial differentiation of urban eco-efficiency in the Yangtze River Economic Belt was affected by a variety of factors.From the perspective of structural factors,the difference in economic development had always been the most decisive factor for the spatial differences in the urban eco-efficiency of the Yangtze River Economic Belt.The difference in energy input and pollution emissions had a relatively small effect;from the perspective of socioeconomic factors,the difference between population density and the spatial differentiation of urban eco-efficiency was significantly stronger than other factors.