城市蔓延、多中心集聚与生产率

Urban Sprawl, Multi-center Agglomeration and Productivity

水平的蔓延和立体的多中心集聚是城市空间扩张的两种形态,它们如何影响城市生产率,对中国新型城镇化建设中土地集约化利用有重要参考价值。现有文献仅停留在分析城市蔓延对生产率的影响,并认为蔓延不利于生产率提高。本文认为,现代城市扩张不是过去那种单一住宅部门围绕市中心向外水平蔓延的模式,而是呈多中心集聚的模式,如服务业集聚于市中心而制造业集聚于外围次中心,并通过空间结构优化,在不显著增加通勤成本的同时,充分发挥集聚效应,有利于生产率提高。本文运用1997—2013年中国286个城市数据进行实证分析,结果表明:水平蔓延对城市生产率影响不显著,但不一定是负面影响;多中心集聚显著提高城市生产率,主要源自制造业次中心集聚及其与生产性服务业的互动效应。结果还表明,多中心集聚效应在不同发展阶段、不同类型的城市存在差异:在多中心城市加速发展期最为显著,大约对应2003—2011年城市生产率的变化;其对单中心向多中心转变的城市正向影响显著,而对规模过大的城市影响不显著。因此,加强多中心集聚并适度控制蔓延以优化空间结构是城市扩张中经济高效运行的关键。

Horizontal sprawl and multi-center agglomeration are two patterns of urban spatial expansion, and it is meaningful to evaluate how they affect urban productivity in order to promote land-use more efficiency in the process of new-type urbanization in China. The existing literature only analyzes the impact of sprawl on urban productivity and considers that it negatively affects productivity. This paper argues modern urban expansion is not only the former pattern that the single residential sector gradually sprawls outward city center, but the latter one of multi-center agglomeration that service sector clusters in city center and manufacturing sector agglomerates in peripheral sub-centers. The new expansive pattern produces positive agglomeration effects whereas affecting little commuting cost, therefore it could improve productivity. Based on data in the period from 1997 to 2013 of 286 Chinese prefecture-level cities, the empirical results show that muhi-center agglomeration significantly improves urban productivity through the effects of manufacturing sector clustering in sub-centers and its interaction with producer services, while sprawl has no evident impact. The results also demonstrate that the effects of multi-center agglomeration vary under different circumstances. It is significant in the period of 2003 to 2011, which is the speeding-up stage of urban expansion, and significantly promotes productivity for those cities transited from monocenter to multi-center while having no sign for those too large cities. Therefore, the key factor is multi-center agglomeration instead of horizontal sprawl that maintains high economic efficiency in the process of urban expansion.