基于分形的城市体系经济规模等级演变研究

The Evolution of The Level of Economic Scale of Urban System Based on Fractal Analysis

利用区域城市体系经济规模等级分形理论,选取长江三角洲1995-2009期间4个年份的县级以上行政单位经济发展数据,计算了经济规模等级分形维数。以该地区城市体系经济规模等级分形维数的演变特征为载体,探讨了长江三角洲地区城市体系经济规模等级演变规律。结果表明：①虽然当前长三角地区各城市的经济社会发展水平差异较大,中心城市垄断性仍然较强,但其均匀化趋势明显。②经济规模等级的空间梯度特征明显,经济规模等级的均匀性随着距离区域核心城市距离的扩大而降低。③产业空间布局层次化逐步分明,中心城市的第三产业比重不断提升,区域控制能力不断增强,与以第二产业为主导的中小城市形成有机整体,区域经济竞争力整体得到提升。

According to the fractal theory of economic scale in regional urban system,we select four-year economic data of the administrative units that above the county level in the Changjiang River Delta between 1995 and 2009,and calculate the fractal dimensions of the economic scales.Under the evolving characteristics of the fractal dimensions of the Changjiang River Delta,we explore the evolving law of economic scale levels in the urban system of the Changjiang River Delta.The results show： 1） Although the differences of levels of economic and social development between cities in the Changjiang River Delta are quite big currently and the central city has more monopoly,the trend of homogenization is obvious.Overall,the fractal dimensions of the economic gross data and economic density data have shown a rising trend among all the economic sectors.Furthermore,the evolution pattern of fractal dimensions for both data demonstrated a strong consistency.The trends of variations can be summarized into three types： decreased at first and then increased,fluctuating increased and sustainable increased.The type of decreasing at first and then increasing is evidently demonstrated in the evolution of the fractal dimensions of the economic gross data,while the fluctuating increasing type is evidently demonstrated in the evolution of the fractal dimensions of economic density data.The sustainable increasing type is evidently demonstrated in the evolution of the fractal dimensions of the foreign trade data.Under the cooperation of the various economic departments,the trend of homogenization for spatial pattern of the regional GDP is obviously revealed.2） The levels of economic scale have a significant gradient feature in space,and the uniformity of the level of economic scale is reducing with increasing distance from the core cities of the region.The cities in the core region,which have higher level of economic scale,constitute the first non-scaling interval.The fractal dimensions of the first non-scaling interval are higher than the corresponding dimensions of all the cities in the same region.This result indicates that,along with the enhancement of the economic develop zone,the pattern of regional control evolves gradually from core cities leading to economic development zone leading.3） The hierarchy of spatial layout of the regional industrials is gradually clear.The proportions of the foreign trade and the tertiary industry of central cities are improving constantly,and the ability of the regional control of central cities are improving,while the secondary industry has been put in leading position in medium and small cities.The central,medium and small cities all contribute to the formation of an organic whole,which result in improving of overall competitiveness of regional economy.