高水平开放自贸区政策是否提升了城市绿色创新效率——基于中国276个城市的准自然实验

Has the policy of high-level opening-up free trade zones improved the urban green innovation efficiency?--A quasi-natural experiment based on 276 cities in China

使用2009—2022年中国276个地级市的平衡面板数据,以高水平开放自贸区政策的实施为准自然试验,采用多期DID方法和空间杜宾模型,探讨高水平开放自贸区政策对城市绿色创新效率的影响效果、作用机制和空间溢出效应。结果显示:①中国高水平开放自贸区政策通过规模效应和结构效应,显著提高了城市绿色创新效率,有利于城市高质量可持续发展;②沿海城市相对于内陆城市受惠于自贸区政策的绿色创新效率提升程度更大,并且城市等级越高,越能从自贸区设立的高水平开放实践中把握发展机会,进而有效提升城市绿色创新效率;③从空间创新溢出效应方面,高水平开放自贸区政策对城市绿色创新效率产生了正向的直接影响和间接影响,同时存在正向的空间溢出效应。

This paper used balanced panel data from 276 prefecture level cities in China from 2009 to 2022,and took the implementation of the policy of high-level opening-up free trade zones as a quasi-natural experiment.Using the multi-period DID method and spatial Durbin model,this paper explored the impact,mechanism,and spatial spillover effects of the policy of high-level opening-up free trade zones on the urban green innovation efficiency.The results indicated that:①The policy of high-level opening-up free trade zones in China has significantly improved the urban green innovation efficiency through scale and structural effects,which was conducive to high-quality and sustainable urban development.②Coastal cities benefited more from the green innovation efficiency improvement of the policy of free trade zones compared to inland cities.And the higher the city level was,the better it could seize development opportunities from the high-level opening-up practices represented by the establishment of free trade zones,finally improving the green innovation efficiency of cities effectively.③In terms of spatial innovation spillover effects,the policy of high-level opening-up free trade zones has had a positive direct and indirect impact on the urban green innovation efficiency,and there was also a positive spatial spillover effect.