城市边缘区碳源碳汇用地空间扩张模式研究

Research on spatial expansion mode of land used for carbon source and sink at urban fringe areas

城市边缘区是城市碳源碳汇平衡的核心载体之一，是碳汇碳源用地转换的集中地。本文提出了碳源碳汇用地概念，总结了城市边缘区碳源碳汇用地空间结构扩张的六种基本模式，探讨了边缘区碳源碳汇用地空间结构变化规律。选取南宁市为研究对象，对南宁市遥感影像进行了监督分类，利用 ArcGIS 人机交互目视判读的方法，提取南宁市四个时间点边缘区的范围及其碳源碳汇用地构成。1990~2000年，南宁市边缘区碳源碳汇用地空间结构扩张模式以蔓延为主、指状为辅；2000~2006年，以指状型及独立型为主；2006~2013年，扩张模式为连片型。城市边缘区形态按“破碎-规则-发散-规则”方向变化，不同阶段具有的不同扩张模式对边缘区碳汇用地影响不同。边缘区碳汇用地主要以耕地与园地构成，保护耕地与园地成为增加碳汇用地的核心任务。城市边缘区的扩张方向受到城市未来发展方向的明显指引，其扩张方向体现了城市未来的发展方向。

Urban fringe areas is one of the core carriers for the balance of carbon source and sink in urban regions and the concentration areas for the conversion of land used for carbon source and sink. In order to obtain the change of spatial structure of the land used for carbon source and sink, and to guide low-carbon city development, expansion modes of spatial structure of the land used for carbon source and sink at urban fringe areas were studied. There are six expansion modes of spatial struc-tures of urban fringe areas. The remote sensing images of Nanning, capital of Guangxi province, are classified. Using ArcGIS, the range of fringe areas of Nanning is extracted by visual interpretation. From 1990 to 2000, expansion mode of spatial structure of the land used for carbon source and sink at Nanning fringe areas was rotary; from 2000 to 2006, the mode was finger and stand-alone; from 2006 to 2013, the mode returned to contiguity. Urban morphology changes according to the rule“broken-regulation-divergent-regulation”, and carbon sink land was made up of cultivated lands and gardening plots. The direction of urban fringe expansion reflects the future development direction of the city.