| The nature of ecological efficiency(eco-efficiency)is about extracting the maximum economic output from the least consumption of natural resources and environmental degradation.Not only does this idea show that eco-efficiency plays an important role in analyzing the efficiency of economic activity,but also portrays a green development system,which is resource saving and environmentally friendly.Academia has delved into the measurement methods,influencing factors,convergence analysis,and so on,of eco-efficiency.However,in the context of the country's regional development strategies led by metropolitan area,urban agglomeration and cross-region national economic zones,it is difficult for provincebased analysis to meet the demands of China's eco-environmental issues.At the same time,cities are relatively complete fundamental spatial units and important regions for economic development in China;however,they are also the greatest sources of energy consumption and greenhouse gas emissions.The existing research mainly focuses on the analysis of the ecoefficiency and its differences in a specific region,while less attention is paid to the problem of spatial spillover of eco-efficiency,which is precisely the prominent feature of the ecological environment problem.Therefore,it is necessary to research the spatial spillover of ecoefficiency and its driving mechnisums on the basis of the scientifically measure eco-efficiency,from the perspective of cities.The in-depth study of these issues has important practical significance in promoting urban eco-efficiency,driving the sustainable and green development of China's economy and society as well as building “Beautiful China”.On the basis of summarizing and analyzing the relevant literature from both foreign and domestic perspectives,we extend the convex metafrontier to non-convex metafeontier one and measure the urban eco-efficiency using a dataset of 251 prefectural-and-above cities in China during the years 2003-2016 based on the proposed data envelopment analysis model,along with investigating their spatiotemporal evolution.Secondly,based on the advanced theories and methods of spatial econometrics,this paper measures and analyzes the spatial spillover of ecoefficiency and its regional disparity,and deeply analyzes eco-efficiency convergence and the spatial effects in the precence of the spatial spillovers.Thirdly,following relevant theories,the paper studies the four driving paths of urban eco-efficiency spatial spillover,i.e.,driving ecoefficiency spatial spillover(including symmetry and asymmetry)through the paths and mechanisms of economic interactions,transportation development,regional innovation and environmental regulation.The two driving forces,i.e.,the eco-efficiency of the neighboring prefectures is at a high level(low level)compared to the local prefectures,and this gap will extert an upward pressure(downward suction)on the local city,thus forming a high pressure and a low suction.There are four kinds of driving effects,i.e.,the effects of “WitnessingExcellence-And-Emulating(WEE)”,“Make-No-Attempt-To-Make-Progress(MAMP)”,“Dominate-And-Make-Further-Progress(DMFP)”,“Witnessing-Inferiority-And-Emulating(WIE)”.Finally,the driving mechanism and theoretical hypothesis of eco-efficiency spatial spillover are empirically tested by using simultaneous equations seemingly unrelated regression method,interactive effect model and mediation effect model,and the effective boundary of ecoefficiency spatial spillover with different urban types and sizes,and relevant policy suggestions are presented based on the theoretical and empirical results.This thesis reaches the following main conclusions:(1)During the study sample period,the eco-efficiency shows the trend of “U” type with characteristics of first descending and then rising,and it has remarkable regional heterogeneity,and compared to prefectures located in Central/Western regions,prefectrues not listed as Key Environmental Protection(KEP)cities,prefectures listed as Resource-based(RB)cities and prefectures not listed as Two Control Zones(TCZ),intertemporal growth of eco-efficiency scores of prefectures located in Eastern region,prefectures listed as KEP,prefectures listed as Non-RB and prefectures listed as TCZ is more significant.(2)The high pressure and low suction of eco-efficiency spatial spillover have significant regional differences,and the Kernel density curve of high pressure of different urban ecoefficiency spatial spillover is symmetrical distribution,while the Kernel density curve of low suction of eco-efficiency spatial spillover is shown as left-skewed distribution.Although the spatial spillover gap of eco-efficiency inter cities has widened,it is gradually decreasing intra cities.Without considering spatial spillover,urban eco-efficiency has the characteristics of periodical ? convergence and ? convergence,while it has remarkable club ? convergence characteristics with considering spatial spillover.On the contrary,KEP and Non-RB cities with faster intertemporal growth of eco-efficiency have slower convergence speed.Furthermore,based on the Two-Regime spatial Durbin model,the effect of spatial spillover on regional ecoefficiency is verified,and the positive spillover of eco-efficiency from neighboring prefectures is more significant to eco-efficiency promotion of local prefectures.Similarly,the estimation results of sub samples show that the greater the positive spillover of eco-efficiency from neighboring prefectures listed as KEP and TCZ cities,the more conducive to eco-efficiency promotion of local prefectures.But the positive spillover of eco-efficiency from neighboring prefectures is not significant for the eco-efficiency promotion of prefectures located in Eastern and Central/Western regions.(3)On the basis of the empirical tests of the spatial spillover of urban eco-efficiency driven by economic interaction,the empirical results show that the effects of economic interaction on promoting eco-efficiency have marked heterogeneity in terms of urban characteristics and sizes;specifically,economic competition significantly restrains the promotion of urban eco-efficiency,while economic cooperation significantly facilitates it.In addition,economic interaction inhibits the high pressure caused by the spatial spillover of eco-efficiency of nearby cities,while it significantly facilitates low attraction.Furthermore,obvious distance effects and remarkable regional heterogeneity characterize the effects of economic interaction on the spatial spillover of eco-efficiency of nearby cities.With regard to influencing mechanisms,the high pressure and low attraction caused by the symmetric spatial spillover of nearby cities' eco-efficiency,inhibit and facilitate the promotion of eco-efficiency local cities,respectively,that is,the MAMP effect and the DMFP effect.On the other hand,the high pressure and low attraction caused by asymmetric spatial spillover play a limited role in promoting the eco-efficiency of local cities.(4)On the basis of the empirical tests of the spatial spillover of urban eco-efficiency driven by transportation development,the empirical results show that transportation development facilitates the promotion of eco-efficiency,and the extent of impact of transportation development on the promotion of eco-efficiency has significant distance effects.Research findings also suggest the development of high-speed rail can significantly boost the impact of low attraction on eco-efficiency,yet inhibit that of high attraction on eco-efficiency.This conclusion is significantly tenable in different robustness tests.(5)On the basis of the empirical tests of the spatial spillover of urban eco-efficiency driven by regional innovation,the empirical results show that the regional innovation level significantly promotes urban eco-efficiency,and this promoting effect increases with increase in urban size.According to the estimation results of the full sample investigation into the impact of regional innovation on the symmetric spatial spillover of urban eco-efficiency,regional innovation has a significantly negative impact on the high pressure caused by symmetric spatial spillover of eco-efficiency of nearby cities,while it impacts the low attraction caused by symmetric spatial spillover significantly positively.The high pressure and low attraction will inhibit and facilitate the promotion of eco-efficiency of local cities,respectively,with significant distance effects,and the intensity of influence weakens as distance increases.According to the estimation results based on the split sample investigation into the impact of regional innovation on the symmetric spatial spillover of urban eco-efficiency,the direction and extent of the impact of regional innovation on the spatial spillover of nearby cities' ecoefficiency have significant regional heterogeneity.(6)On the basis of the empirical tests of the spatial spillover of urban eco-efficiency driven by environmental regulation,the empirical results show that greater environmental regulation significantly promotes urban eco-efficiency with significant heterogeneity in terms of urban characteristics and sizes.According to the estimation results of the full sample investigation into the impact of environmental regulation on the spatial spillover of urban eco-efficiency,environmental regulation has a significantly positive effect on the high pressure caused by the symmetric spatial spillover of eco-efficiency of nearby cities,while it has a significantly weak positive effect on the low attraction caused by symmetric spatial spillover.The high pressure and low attraction caused by the symmetric spatial spillover of eco-efficiency of nearby cities inhibit and facilitate,respectively,the promotion of eco-efficiency of local cities,with significant distance effects.Environmental regulation has a significant negative effect on the high pressure caused by the asymmetric spatial spillover of eco-efficiency of nearby cities,while its impact on the low attraction caused by asymmetric spatial spillover is not significant.According to the estimation results based on the split sample investigation into the impact of environmental regulation on the spatial spillover of urban eco-efficiency,the direction and extent of the impact of environmental regulation on the spatial spillover of eco-efficiency of nearby cities have significant regional heterogeneity.However,the high pressure and low attraction caused by the spatial spillover of eco-efficiency of nearby cities promote ecoefficiency of different cities significantly,denoted by Highs Inhibit and Lows Facilitate.Therefore,the lower the eco-efficiency of nearby cities in relation to that of local ones,the more advantageous it will be for the eco-efficiency of local cities to improve.Finally,this study proposes several concrete and feasible policy recommendations for the promotion of urban eco-efficiency based on the research conclusions above,and the status quo in China's eco-environment.These proposals are from the perspectives of leading regional development with high quality coordination,pioneering cooperation based on competition,effective utilization of high-speed rail in growth,stimulating internally dynamic mechanisms for boosting regional innovation,strengthening cooperation in environmental regulation and increasing efforts in joint prevention and control,and so on. |
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