以建成区面积表征的中国城市规模分布

选择1990－2000年中国城市用地面积位于前200位的地级及地级以上的城市用地资料，把运用城市人口规模上的位序－规模法则移植到城市用地上，分析了城市土地利用规模的变化规律。然后运用分形理论，阐释了城市用地的位序－规模曲线。结果显示：（1）以建成区面积作为衡量城市规模的指标，中国城市规模分布符合位序－规模法则，拟合曲线的判定系数都在0.95以上；（2）根据位序－规模曲线的形态，中国城市按建成区面积可分为3类：用地面积＞200km^2的大城市，50－200km^2的中等城市和＜50km^2的小城市；（3）城市建成区用地的位序－规模曲线有平行向前推进的特点，这为预测我国未来城市建成区用地规模提供很好的基础；（4）中国位于前200位的城市用地规模分布的均衡度不断增强，城市建成区用地规模总量持续增加。

Distribution of China City Size Expressed by Urban Built-up Area

China has experienced a rapid urbanization process during the past two decades because of its fast-growing economy. In the near future, the urbanization process will be accelerated due to promotion of governments at different levels. As a major type of land use change, urban expansion, because of its potential impact on croplands, has become one of the top concerns in land planning, land management and food security of China. This paper analyzed changes in urban built-up area of 200 major cities in the 1990s, using the rank-size law, which is often employed in the study of city's population size distribution. Then, we explained the rank-size curves using theory of fractal and the results include the following several aspects. Firstly, the city size distribution in terms of urban built-up area perfectly accorded with rank-size rule, and the coefficient of determination (R 2 ) were all more than 0.95. Secondly, according to the curve shape, we claimed that Chinese cities could be divided into three categories, i.e., large cities with an area of more than 200 km 2 , medium-sized cities with an area between 50 and 200 km 2 , and small cities, with an area of less than 50 km 2 . Thirdly, the China's city system in terms of built-up area is relatively well developed. and the rank-size distribution curve therefore moved in a parallel evolution manner from 1990 to 2000. Fourthly, the rank-size distribution curve revealed that the rate of urban land expansion was markedly different among these three groups of cities during the past decade. At last, this study suggested that the rank-size law could be a good tool to predict future urban expansion in China.