Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.
National Engineering Laboratory of Forest Ecology and Applied Technology for Southern China, College of Biological Science and Technology, Central South University of Forest and Technology, Changsha, 410004, China.
Ecol Appl. 2018 Sep;28(6):1655-1668. doi: 10.1002/eap.1760. Epub 2018 Jul 5.
Most of the planet's population currently lives in urban areas, and urban land expansion is one of the most dramatic forms of land conversion. Understanding how cities evolve temporally, spatially, and organizationally in a rapidly urbanizing world is critical for sustainable development. However, few studies have examined the coevolution of urban attributes in time and space simultaneously and the adequacy of power law scaling across cities and through time, particularly in countries that have experienced abrupt, widespread, political and economic changes. Here, we show the temporal coevolution of multiple physical, demographic, socioeconomic, and environmental attributes in individual cities, and the cross-city scaling of urban attributes at six time points (i.e., 1978, 1990, 1995, 2000, 2005, and 2010) in 32 major Chinese cities. We found that power law scaling could adequately characterize both the cross-city scaling of urban attributes across cities and the longitudinal scaling describing the temporal coevolution of urban attributes within individual cities. The cross-city scaling properties demonstrated substantial changes over time signifying evolved social and economic forces. A key finding was that the cross-city linear or superlinear scaling of urban area with population contradicts the theoretical sublinear power law scaling proposed between infrastructure and population. Furthermore, the cross-city scaling between area and population transitioned from linear to superlinear over time, and the superlinear scaling in recent times suggests decreased infrastructure efficiency. Our results demonstrate a diseconomy of scale in urban areal expansion that indicates a significant waste of land resources in the urbanization process. Future planning efforts should focus on policies that increase urban land use efficiency before continuing expansion.
目前，地球上的大多数人口都居住在城市地区，城市土地扩张是土地转换最显著的形式之一。了解在快速城市化的世界中城市如何在时间、空间和组织上演变，对于可持续发展至关重要。然而，很少有研究同时考察城市属性在时间和空间上的共同演变，以及幂律标度在城市之间和时间上的充分性，特别是在经历了突然、广泛的政治和经济变革的国家。在这里，我们展示了单个城市中多个物理、人口、社会经济和环境属性的时间协同演变，以及在六个时间点（即 1978 年、1990 年、1995 年、2000 年、2005 年和 2010 年）的 32 个中国主要城市中城市属性的跨城市标度。我们发现，幂律标度可以充分描述城市属性在城市之间的跨城市标度以及描述单个城市内部城市属性时间协同演变的纵向标度。跨城市标度特性随时间发生了实质性变化，表明社会和经济力量不断演变。一个关键发现是，城市面积与人口之间的跨城市线性或超线性标度与基础设施与人口之间理论上的次线性幂律标度相矛盾。此外，城市面积与人口之间的跨城市标度随时间从线性转变为超线性，最近的超线性标度表明基础设施效率降低。我们的研究结果表明，城市面积扩张存在规模不经济，这表明城市化过程中土地资源的大量浪费。未来的规划工作应重点关注提高城市土地利用效率的政策，然后再继续扩张。
