国家级城市群建设对绿色创新的影响

National city group construction and green innovation

城市群崛起是经济发展到一定阶段的重要标志,同时对经济发展构成巨大带动作用。基于2003——2017年中国城市面板数据,本文采用双重差分等方法实证检验了国家级城市群建设对绿色创新的影响。本研究的边际贡献在于:评估国家级城市群建设对绿色创新影响的短期效果;考察国家级城市群建设对绿色生产率与绿色专利影响的异同;基于要素流动性与政策严格度等中介机制,剖析国家级城市群建设对绿色创新的作用途径。研究发现,国家级城市群建设对绿色生产率有显著的正向影响,但是对绿色专利没有显著影响。可见,城市群建设对绿色生产率与绿色专利的影响是异质性的,强波特假说成立、弱波特假说不成立,这意味着国家级城市群建设促进了绿色效率提升、而非绿色技术进步。在采取了PSM-DID、反事实分析、聚类标准差回归、动态面板回归、工具变量回归等一系列稳健性检验之后,本文证明该结果是稳健的。基于异质性分析发现,国家级城市群建设对于中低技术水平城市和外围城市的绿色生产率有显著的正向影响,但是,对高技术水平城市和中心城市的绿色生产率和绿色专利皆没有显著影响。从机制看,一方面,国家级城市群建设对绿色生产率的积极影响主要源于污染转移、而非本地创新;另一方面,国家级城市群建设对绿色专利并无裨益,原因主要在于要素流动性与政策严格度等中介机制不畅。政府应高度重视城市群自主创新能力的培养,规避“伪创新”现象,坚决破除地区之间利益藩篱和政策壁垒,努力推进绿色专利与绿色生产率的同步提升。

The rise of urban agglomerations is an important sign of economic development in a certain stage,and at the same time,it plays an important role in promoting economic development.Based on the city-level panel data of China from 2003 to 2017,this paper empirically tests the impact of national city group(NCG)construction on green innovation by using difference-in-difference method.The marginal contribution of this study is:evaluating the short-term effect of NCG construction on green innovation;investigating the similarities and differences of NCG construction on green productivity and green patents;analyzing the role of NCG construction on green innovation based on the intermediary effect of factor mobility and policy strictness.It is found that the construction of NCG is conducive to the improvement of green productivity,but not to the increase of green patents.After a series of robustness tests such as PSM-DID,counterfactual analysis,cluster standard error regression,dynamic panel regression and IV regression,this paper proves that the result is robust.Based on the heterogeneity analysis,it is found that the construction of NCG has a significantly positive impact on the green productivity of low-tech cities and peripheral cities,but has no significant impact on the green innovation level of high-tech cities and central cities.From the perspective of impact mechanism,on the one hand,the positive impact of NCG construction on green productivity mainly comes from pollution transfer rather than local innovation.On the other hand,the NCG construction is not beneficial to green patents,mainly because the intermediary effect of factor mobility and policy strictness does not work.As a result,the government should give high priority to the cultivation of independent innovation ability of NCG,avoid the phenomenon of‘pseudo innovation’,resolutely break down the barriers of interests and policy barriers between regions,and strive to promote the synchronous promotion of green patents and green productivity.