白银市城市空间组织演化过程及其合理性分析

城市是一个复杂的自组织巨系统，但人类的干预作用几乎伴随其成长的整个过程。我国的资源型城市作为一类特殊城市在其空间发展变化中都留下了自组织与他组织的作用烙印，科学认识二者作用下的空间成长变化规律对实施转型发展具有积极意义。以白银市为例，选择白银城区1953年、1986年、2000年、2016年建设用地为数据源，运用GIS方法对白银城区空间扩展演化进行定量分析，结果表明：（1）白银市城市空间演变经历了城市兴起成长的他组织主导空间扩展期（1953-1986年）、城市波动发展的自-他组织共同作用的空间扩展期（1987-2000年）与转型发展的自组织主导空间扩展期（2000-2016年）三个阶段，虽然自组织机制在城市空间演变中的作用不断增强，但他组织机制仍发挥着不可或缺的引导管理作用。（2）城市空间扩展强度在纵向上不断增大，不同阶段各类型建设用地扩展强度差异显著，各有侧重，而在横向上方位分异性突出，各阶段有各自的主导扩展方向。表明在国家经济体制、城市经济转型和城市空间结构等变化过程中，自组织机制与他组织机制随其变化而影响到空间扩展强度和范围的变化。（3）各阶段白银市城市空间的建设用地结构不尽合理，工业用地占总建设用地的比例过大，虽凸显了资源型城市的特质，但严重超国家标准。同时，无论是单项人均居住与工业用地，还是人均建设用地都大幅超国家标准。（4）城市空间与城市人口和经济的相对增长关系趋好性显著，城市空间形态的离散程度与分形维数降低，空间紧凑度提升。表明城市空间扩展的演化方向是一个能够发挥自组织机制和他组织机制的优势互补的优化过程。

Self-organization process and rationality of urban spatial development of Baiyin City

The city is a complex giant self-organizing system,and it is also an other-organization system which is influenced by human intervention through its growth.Both the self-organization part and the other-organization part have left a deep mark on the resource-based cities and under their combined effects,how to understand scientifically the law of the urban spatial change can help set up the strategy to promote the transformation and development of those cities.Taking Baiyin City,Gansu Province,China as an example,this paper selected its construction land information in 1953,1986,2000 and 2016 as the data source,and quantitatively analyzed its urban spatial evolution using GIS technology.The results revealed as follows:(1) the urban spatial evolution had experienced three stages with the first stage being its growing-up stage (1953-1986) dominated by other-organization mechanism,the second stage,the stage of the fluctuations in its development (1986-2000) influenced jointly by self-organization and other-organization mechanism and the third,the transformation development stage (2000-2016) dominated by self-organization mechanism.The three stages indicated that not only the self-organization mechanism played a great role in the process of urban spatial expansion,but also the other-organization mechanism provided indispensable guidance and management throughout the evolution. (2) the intensity of urban spatial expansion is increased in general from the longitudinal time perspective with the obvious differences among the different types of urban construction lands.From the horizontal space point of view, each stage had its own dominant expansion direction and scope.All of these showed that the intensity and scope of urban spatial expansion under the self-organization mechanism or other-organization mechanism had been changing along with the changes in the national economic system,urban economic transition and urban spatial structure. (3) There were irrational construction land structures over the course which was reflected by the fact that the industrial land had a larger proportion and exceeded the national standard.Although it is shown as one of the characteristics of the resource-based cities,it exceeded significantly the national standard not only for the individual residential land per capita and industrial land per capita,but also for the construction land per capita. (4) The relative growth relation between the urban space and the city's population and economy was tending to become good.The space compactness was increased as the dispersion degree and fractal dimension of urban spatial form became decreased.All these indicated that the evolution of urban spatial expansion is an optimization process which can make their respective advantages complementary to each other for both self-organization mechanism and other-organization mechanism.