大都市区生态源地识别体系构建及国土空间生态修复关键区诊断

构建生态安全格局是保障城市生态安全的必要手段,科学识别生态源地是构建生态安全格局的基础。以高度城市化的大都市区--上海市为研究对象构建生态源地识别体系,探究不同土地利用数据源与指标权重对生态源地识别的影响。在此基础上,基于最小累积阻力模型(MCR)与电路理论构建生态阻力面,识别生态保护与修复优先区域,对已有研究仅关注保护/修复的情况进行补充。结果表明：(1)自然生态本底仍是识别生态源地的重要指标,加入人类需求指标可填补已有研究对高度城市化源地识别针对性和丰富性的不足。生态系统服务格局、生态环境安全格局与环境友好格局权重为5 ∶ 2 ∶ 1时,源地识别效果最佳。(2)上海市生态源地空间和数量分布极不均匀,破碎化是首要问题。上海市现有(2017年)生态源地202个,共920.96 km²,占总面积14.53%,其中微型源地(面积<3 km²)数量高达82.67%。城市化水平影响生态源地分布,外环是源地数量与总面积的分水岭,郊环是源地平均面积的重要界线。(3)上海市以"面(源地)-线(廊道)-点(优先点)"组成生态保护网络,其中生态廊道442条,生态保护优先点306个,重要点线分布集中于中心城区边界。上海市生态修复优先区域325.47 km²,其中障碍点309.78 km²,需优化的非生态斑块95个(15.69 km²),大都市区的生态修复重点区域应聚焦于城市化扩散的阻力区域,且应多关注生态价值适中的草地与耕地。研究工作可为其他高度城市化区域,以及处于高速城市化发展进程城市的国土空间生态修复关键区识别提供借鉴与参考。

Construction of ecological sources identification system for metropolitan areas and diagnosis of key areas for ecological restoration in nationally spatial areas

Construction of ecological security pattern is a necessary means to ensure urban ecological security. Accurate identification of ecological sources is the basis for the construction of ecological security pattern. In this study, ecological source identification system is constructed in Shanghai, a highly urbanized metropolitan area. The influences of different land use data sources and index weights on the identification of ecological sources are investigated. On the basis of this identification, ecological resistance surfaces are constructed with the minimum cumulative resistance model (MCR) and circuit theory to identify priority areas for ecological protection and restoration, which could complement the existing studies that focus only on protection/restoration. The results show that (1) the naturally ecological background is still an important indicator for identifying ecological source areas, and the addition of human demand indicators can fill the lack of relevance and richness of existing studies for identifying highly urbanized source areas. The best recognition is reached when the weighting of ecosystem service pattern, ecological and environmental safety pattern and environmentally friendly pattern is 5:2:1. (2) The spatial and quantitative distribution of ecological sources in Shanghai is extremely uneven, and fragmentation is the primary problem. There were 202 ecological source sites in Shanghai in 2017, totaling 920.96 km², accounting for 14.53% of the total area, of which the number of micro-source (area <3 km²) was 82.67%. The level of urbanization affects the distribution of ecological sources. The outer ring is the watershed between the number of source sites and the total area, and the suburban ring is the important boundary of the average area of source sites. (3) Shanghai''s ecological protection network is composed of surface (source sites)-line (corridors)-point (priority points), including 442 ecological corridors and 306 priority points for ecological protection, with important points and lines concentrated in the central urban boundary. The priority areas for ecological restoration in Shanghai are 325.47 km², including 309.78 km² of obstacle points, and 95 non-ecological patches (15.69 km²) need to be optimized. The priority areas for ecological restoration in the metropolitan area should focus on the areas of resistance to urbanization spreading, and more attention should be paid to grassland and arable land with moderate ecological value. The study can be used as a reference for identifying key areas for ecological restoration in other highly urbanized areas and cities in the process of rapid urbanization.