基于多尺度协同的长沙市生态网络构建与层级优化

城市化背景下人类与自然环境的矛盾呈现出多尺度、层级化特征,而传统生态网络的构建方式较少考虑不同尺度下生态要素的关系,无法从区域落实到中心城区,难以形成系统性的解决方案。研究在综合梳理各尺度生态网络构建方法的基础上,以长沙市为例,基于形态学空间格局分析（Morphological Spatial Pattern Analysis,MSPA）、景观连通性原理和生态斑块重要性评价识别生态源地,并通过多层级生态阻力面的确定,综合运用最小费用路径（Least-cost path method,LCP）、电路理论、层级传导理论、尺度嵌套等方法对市域、都市区、中心城区的生态网络进行了协同构建和层级优化,最后基于不同尺度生态网络的特点应用并落实到多层级的国土空间规划体系中。研究结果表明：（1）长沙市域生态网络和都市区生态网络具有较好的层级嵌套特征;共识别两尺度生态叠合源地14个、生态叠合廊道15条,主要通过中心城区内的湘江、浏阳河和捞刀河部分河段与外围生态绿圈相衔接,形成"外环内楔"的空间格局。（2）确定市域重要廊道、市域潜在廊道、生态叠合廊道、都市区重要廊道、都市区潜在廊道的核心保护面积共501.14 km²,并提取位于生态廊道核心保护区范围内的生态夹点和生态障碍点,以进一步落实生态保护修复策略。（3）得到具有重要生态连通功能的中心城区生态绿道长度441.2 km,生态修复单元56个,并结合生态阻力值划分为5级进行针对性修复。（4）基于不同尺度生态网络的衔接、嵌套,最终构建"市域总体生态安全格局-都市区城市生态空间发展格局-以城市绿道为基础的中心城区生态修复单元",并与不同层级的国土空间规划体系相对应。研究结果将为以大城市为中心的跨尺度生态系统修复和生态安全格局构建提供科学参考。

Construction and hierarchical optimization of Changsha ecological network based on multi-scale collaboration

In the context of urbanization, contradictions between human beings and the natural environment have shown the characteristics of multi-scale and hierarchy. While the traditional construction of ecological network paid little attention on the relationship between ecological elements at different scales which could not be implemented from the region to the central city. So it was difficult to form a systematic solution to these problems. Based on a comprehensive review of ecological network construction methods at different scales, taking Changsha City as an example, we identified ecological sources through Morphological Spatial Pattern Analysis (MSPA), landscape connectivity theory and the evaluation of the importance of ecological patches. After determining the multi-level ecological resistance surfaces, we used the least cost path method (LCP), circuit theory, hierarchical transmission theory, scale nesting and other methods to study the coordinated construction and hierarchical optimization of ecological networks in the urban area, metropolitan area and central urban area. Finally, based on the characteristics of ecological networks at different scales, the research results were applied to the multi-level land spatial planning system. The results showed that:(1) the urban ecological network and metropolitan ecological network had good hierarchical nesting characteristics. The number of ecological overlapping sources and corridors on the two scales were 14 and 15, respectively, which were mainly connected with the peripheral ecological green circles through the Xiangjiang River, Liuyang River and Laodao River in the central urban area, forming the spatial pattern of "outer ring and inner wedge". (2) The core protection area of important corridors in the urban area, potential corridors in the urban area, ecological overlapping corridors, important corridors in the metropolitan area, and potential corridors in the metropolitan area was 501.14 km², from which we extracted ecological pinch points and ecological barriers for further ecological protection and restoration. (3) The length of ecological greenway in the central urban area with important ecological connectivity functions was 441.2 km. And the number of ecological restoration units was 56, which was divided into 5 levels combined with the ecological resistance value for the targeted restoration. (4) Based on the connection and nesting of ecological sources, corridors and node patches at different scales, we finally constructed the overall ecological security pattern of the urban area-the urban ecological spatial development pattern of the metropolitan area-the ecological restoration unit of the central urban area based on the urban greenways, which corresponded to the land spatial planning system at different levels. The research results could provide a scientific reference for the cross-scale ecosystem restoration and ecological security pattern construction centered on large cities.