闽三角城市群生态安全格局构建及城镇扩展模拟

在快速城镇化背景下,构建生态安全格局并探讨城镇用地扩展格局已成为保障区域生态安全和缓解生态保护与土地开发矛盾的重要手段。以闽三角城市群为例,基于景观安全格局原理和ArcGIS空间分析法,从综合水安全、生物保护安全、地质灾害安全以及游憩安全四个方面叠加构建"底线安全格局-缓冲安全格局-最优安全格局"三种不同安全水平的综合生态安全格局;然后结合SLEUTH模型,将不同生态安全格局情景作为约束条件融入其排除图层,对研究区2015-2030年的城镇用地空间扩展进行多情景模拟。研究表明：①底线安全格局、缓冲安全格局以及最优安全格局的面积为9305.51、7576.28、3482.73 km²,分别占闽三角城市群总面积的36.89%、30.03%、13.81%;②三种生态安全格局情景模拟下城镇用地均呈增长趋势,但增长速度均小于历史用地的增长速度,高安全格局约束下的新增城镇用地面积和增长速度均最小,表明将生态安全格局作为城镇发展的约束条件,在城镇土地开发中能够增强对生态空间的保护力度,维护区域生态安全,控制城镇蔓延。相关研究成果可为城镇开发边界管控与国土空间规划的编制提供技术支撑与决策辅助。

Construction of ecological security pattern and simulation of urban sprawl in the Urban Agglomeration of Min Delta

Set against the backdrop of rapid urbanization in China, urban ecological environment suffers the elevated pressure of high-intensity human activities and unreasonable land development. Since urban ecological environment has been raised as an issue in relation to regionally ecological security, it is important to construct ecological security pattern and accordingly simulate the urban sprawl as a way to satisfy the requirements of both urban development and environment protection. Taking the Urban Agglomeration of Min Delta (Xiamen-Zhangzhou-Quanzhou) as the study area, this paper provides three scenarios of ecological security pattern, namely, basic security pattern, intermediate security pattern, and optimal security pattern. Basic security pattern represents that the protected area will not be occupied by built-up land use. Both intermediate security pattern and optimal security pattern locate the transition area between urban area and the protected area with the potential to be transformed into urban built-up area on the prerequisite that the urban ecological environment and urban ecosystem cannot be jeopardized. Compared to intermediate security pattern, the optimal security pattern covers the areas closer to urban area to security the ecological environment to the greatest extent. In the process of constructing the three scenarios of ecological security pattern, grounded in the theory of landscape security, by using a set of spatial analytic approaches in ArcGIS platform, we incorporate four aspects, including water safety, biological safety, geological safety and recreation safety to establish a comprehensive evaluation of ecological security. In addition, drawing on the SLEUTH model, we simulate three types of urban growth from 2015 to 2030, in which the three scenarios of ecological security pattern are combined to form three levels (i.e. low, medium, high) of eco-constraints. The results show that the area of basic security pattern is 9305.51 km², while intermediate security pattern is 7576.28 km² and optimal security pattern turns out 3482.73 km². The three patterns account for 36.89%, 30.03% and 13.81% of the total area of the Min Delta urban agglomeration, respectively. In terms of simulation modelling results, it shows that under all three scenarios of ecological pattern, urban area will keep growing by 2030 but the growth rate will be lower than the historical records. Under high level of eco-constraints, both urban growth area and urban growth rate are smaller than the other two settings of constraints. This reveals that ecological security pattern, as urban growth constraint, should be considered in our spatial planning to enhance the protection of urban ecological environment and prevent unreasonable urban sprawl. We argue our research is important to better inform urban planner on (re)designating urban growth boundary with the capacity of providing reliable technical support and scientific basis.