中国城市群“圈层”结构对能源强度影响实证

Empirical Analysis of Circling-layering of Urban Agglomerations on Energy Intensity

借助于经济地理学的理论视角,利用2000-2011年十大城市群99个城市数据,首先结合城市引力模型来计算中心城市与腹地城市引力强度与中心城市自身引力强度之比来描述城市群中心城市与腹地城市经济联系转化的相对程度,通过给出设定的0.4-0.6之间的边界标准并使获得的比值与之相比较,比较结果可以描述中心城市规模密度及中心城市与腹地城市规模密度转换差异并对城市群"圈层"结构进行测度;其次在城市层面建立实证模型对城市群"圈层"结构降低能源强度的影响程度及作用机制进行分析,在控制了一系列能源强度影响因素后,回归结果显示,城市群由于集聚程度的饱和而出现向外扩张的趋势,随着次一级经济发展带的不断形成,这种循环运动增强了中心城市的影响力,从而使得中心城市和周围城市所在区域形成了表征区域集聚的城市群"圈层"结构,该圈层结构是在聚集效应和拥挤效应共同作用下通过合理布局从而最终达到降低能源强度的目标。但随着集聚程度的饱和,在0.45边界标准之后,拥挤效应的约束性作用显现,降低能源强度程度显著变小,在0.6边界标准降低能源强度程度达到了最低,控制政府干预的核心影响因素城市市区个数变量发现,"行政区经济"会间接通过增强行政成本而提高了能源强度,最后对研究结论进行了一系列的稳健性检验。这些实证研究结果具有显著的政策含义,通过进一步探寻空间和市场力量共同降低能源强度的可行选择,推动空间节约式的布局道路,使得城市群的层级形成为提升能源效率提供了一个合理的实现途径。

On the perspective of economic geography theory and based on 99 cities from 2000 to 2011,this paper caculates ratio betweeen the strength of gravity of key city and surrounding cities and the strength of gravity of key city,and gives the standard border of 0.4-0.6 to be compared with the ratio,the result will analyze conversion differences between the size of the key city and the surrounding cities and measure ＂circle-layering＂ economy structure of urban agglomerations with the gravity model.Secondly,this paper builds an empirical model to analyze the impact and mechanisms of ＂circle-layering＂ economy structure to energy intensity.After control a series of factors,the results show that urban agglomeration occurs the trend of outward expansion and formation of sub-level economic development zone,the circular motion will enhance the influence of key city and formation of ＂circle-layering＂,which can significantly reduce energy intensity with reasonable layout.But congestion effects appear to raise energy intensity significantly after 0.45 border standards and it reached the lowest on the 0.6 border.From the result we also found ＂administrative economy＂ will raise the energy intensity indirectly through enhanced administrative costs.Finally,the result is robust to a number of specification tests.With Viable option of market and space strength,those results have significant policy implications,which means we can promote layout roads of space-saving style and provide a reasonable way to achieve ＂circle-layering＂ economy structure to reduce the energy intensity.