进行城市空间扩展模拟分析研究,对于城市生态安全格局优化具有重要意义。基于Dyna-CLUE模型进行广州市的城市空间扩展模拟与分析,结果表明:城市化到现阶段,政府采取的土地利用数量调控对城市空间扩展的影响较为重要,空间区划的引导作用相对不明显;建设用地聚集度持续增大,单位面积内的斑块数则先增后减,二者揭示出的景观特征不完全一致;城市空间是外缘、飞地式和内填式三种空间扩展模式共同作用的结果,但在1990-2005年以外缘和飞地式为主,在2005-2020年则以外缘和内填式为主,此时新增斑块与原有斑块的建设用地连成大斑块,单位斑块上的建设用地数量呈降势,前后两个时段内,城市由"摊大饼"外延式逐渐转向集约节约的内填式扩展,城市生态文明建设初显成效。
Urban land expansion can be considered as direct manifestation of the regional space of urbanization, which is also a key ecological process that affects the urban ecological security patterns. It is of great significance to optimize urban ecological security patterns through simulation and forecast researches on the basis of ecological security oriented spatial expansion of cities. This paper tried to forecast urban landscape transition by establishing an ecological security oriented simulation model with Guangzhou as the sample site based on the framework of Dyna-CLUE model so as to explore the urban land expansion patterns. The results lead to three main conclusions: (1) The quantitative regulation of land use by government is more important than space zoning with the goal of ecological security under present urbanization level. (2) The percentage of adjacent index indicates a trend of aggregation of construction land patches while the patch density index shows another trend of increase then decrease, which reveals some kind of variation of urban spatial characteristics. (3) The results of analysis on landscape patterns and urban land expansion modes reveal that three urban expansion modes, namely infilling, edge-expanding and leapfrogging, have common effects on the city's space. And during 1990-2005, edge-expanding and leapfrogging are the main urban expansion modes while from 2005 to 2020 edge-expanding and infilling have become the main modes. In the former period, urban expansion results in a large number of construction land patches due to the increase of aggregation and patch number per unit area. In the latter period, urban expansion continues with land-use transition from non-construction to construction land use with the trend of aggregation. However, as urban expansion modes are changing, many patches of construction land, including existing patches and newly added patches, will be connected with others. That is the reason why no increase of patch quantity per unit area has been obse