武汉市耕地非农化的空间非均衡发展与空间扩散路径分析

在5 期时间跨度20 多年的武汉市土地利用数据基础上,利用ArcGIS 的空间统计和空间分析功能,拟合出武汉市耕地非农化的空间洛仑兹曲线并制作了基于耕地非农化速度分级的重心曲线,结合统计数据分析耕地非农化扩散路径及其与经济、人口重心曲线变化的相关关系。研究结果表明:①武汉市是个典型的单中心城市,其耕地分布不均衡,耕地非农化仍是在围绕城市中心进行,耕地非农化在乡镇级别上是非均衡发展的,但非均衡程度在逐年减缓;②基于耕地非农化速度分级的耕地非农化重心曲线表明,耕地非农化速度快的点到速度慢的点的密度有逐步降低的趋势,并且速度快的点到速度慢的点还有向外围扩散的趋势;③武汉市耕地非农化扩散路径、GDP重心变化路径和人口重心变化路径在移动方向上大体上都符合在南北向是向北,转而向南又复向北;而在东西向是先向西然后向东,武汉市的耕地非农化与经济和人口的相关性表明武汉市的耕地非农化在空间上是有序发展的。研究结果能较好地揭示武汉市耕地非农化的空间非均衡发展状况,实现了武汉市耕地非农化空间非均衡发展的可视化,反映了武汉市耕地非农化、经济和人口之间的关系。

Spatial Unbalanced Development and Diffusion Route of Farmland Conversion inWuhan City

The alteration of land use spatial pattern includes not only historical information of land use, but also trends of land use in the future. It is significant to use proper information to analyze the process of farmland conversion. This paper conducts a study of the spatial unbalanced development of farmland conversion in Wuhan city based on the land use data from 1990 to 2011. By using spatial statistics and spatial analyst functions in ArcGIS, a spatial Lorenz curve of farmland conversion in Wuhan city was fitted and a curve of farmland conversion gravity centers which was classification based on speed of farmland conversion was formed. Meanwhile, the correlation among the diffusion route of farmland conversion, GDP gravity centers curve and population gravity centers curve was discussed. The main conclusions are as follows: Firstly, Wuhan city was a typical mono-centric city, not a multi-center city which was traditional considered. The spatial distribution of farmland was unbalanced in Wuhan city, and the farmland conversion mainly occurred around the city center. The speed of farmland conversion in Wuhan city was unbalanced and the degree of this unbalanced development was declining from 0.8285 to 0.5289 measured by Gini coefficient. Secondly, during urban land expansions from 1990 to 2011, 36.15% of the expansion land comes from farmland. The fastest speed of farmland conversion is up to 55.58 km² per year during 2005 to 2011. The multi-layer superposition based on the speed of farmland conversion classification shows that with the increasing of farmland conversion speed, the farmland conversion gravity centers of different layers move from the fringe to the center of Wuhan city and have a tendency of becoming dense. Thirdly, the trajectories of farmland conversion diffusion route, GDP and population gravity centers curves were following the same law that they moved to the north, then south and again north in south-north direction, and to the west, then east in east-west direction. The correlation among farmland conversion, GDP, and population indicated farmland conversion in Wuhan city was carried out orderly in space. This paper explores the spatial pattern of farmland conversion from several aspects, and the results perfectly reveal the unbalanced development of farmland conversion in Wuhan city and achieve this unbalance a visualization, moreover, explores the relationship among farmland conversion, GDP and population.