中国城市标度律及标度因子时空特征

城市标度律刻画了城市系统中城市要素与人口数量之间的规模缩放关系,但标度律在中国城市系统中的适用性和意义尚不明确。本文采用中国275个地级及以上城市数据,探究不同城市要素与人口规模的标度关系,并从时空维度探究标度因子的时空演化规律。结果表明：作为典型的快速城市化发展中国家,中国城市发展符合标度律,且呈现出与发达国家不同的特征：中国城市人口集聚带来的经济产出集聚效应显著,而土地利用、基础设施与公共服务的规模经济效应还有待增强。部分基础设施、生活设施要素与人口规模呈超线性或线性关系,与预期的次线性相悖,基础教育、医疗等要素的标度因子则远低于发达国家的次线性阈值,反映了公共资源向大城市聚集、不同规模城市发展不平衡等快速城镇化进程中城市系统的独特性。标度因子的区域分异反映城市发展协调程度差异,其中东北地区不同规模城市差异最为显著。主要城市要素标度因子随时间的变化表明,中国大城市的经济产出集聚效应在2009年最为显著,而后略有下降;中国大城市土地扩张总体上自2000年以来持续加速,2008年以后仍维持在较高水平,管控城市特别是大城市的外延式扩张、提高土地利用效率具有紧迫性。中国城市标度律研究有助于认知快速城市化地区城市系统特征和演化规律,为实现区域协调发展与落实新型城镇化发展战略提供支持。

Urban scaling and the spatio-temporal characteristics of scaling exponents in China

Urban scaling laws depict the nonlinear relationship between urban indicators and population size within an urban system, but its applicability and significance in China's urban system is not clear. This study applied the data of 275 prefecture-level cities in China to explore the scaling relationship between different urban indicators and population sizes. We also attempt to present an empirical analysis of spatio-temporal characteristics of urban scaling exponent (β) from 2000-2017 to enrich the understanding of urban scaling laws. The result shows that as a typical fast urbanizing country, China's urban development conforms to the urban scaling laws but presents some different characteristics from developed countries. There is a significant increasing return to population size of economic output brought by China's urban population agglomeration. Nevertheless, the economies of scale for land use, infrastructure and public service are supposed to be strengthened. Some infrastructure and living facilities indicators have a super-linear or linear relationship with the population size, which are contrary to the expected sublinear regime. The scaling exponents of education, medical and health care and other urban indicators are far below the sub-linear thresholds of developed countries, which reflects the uniqueness in a fast urbanizing country that large cities are given priority to infrastructure construction and the unbalanced development of different-sized cities. The spatial distribution characteristic of scaling exponent reflects the differences in the degree of coordination of urban development, with the most significant differences in Northeast China. We also analyzed the evolution of scaling exponents of major urban indicators over time. Economic increasing returns to population size effect of large cities in China was the most significant in 2009 before falling slightly. Urban land expansion in large cities has continued to accelerate since 2000 and still remains at a high level after 2008. It is urgent to control the extensive urban land expansion and improve land use efficiency, especially in large cities. This study on urban scaling in China contributes to fully understanding the characteristics and evolution of urban systems in the fast urbanizing country. This paper is supposed to provide a support for achieving a balanced regional development and implementing new urbanization development strategies as well.