面向连通性提升的旱区城市生态网络优化情景——以巴彦淖尔市及其周边地区为例

巴彦淖尔市作为典型的干旱区城市，经济发展与生态保护之间的矛盾突出，生态空间的破碎化日益严重。生态网络是景观连通性视角下耦合景观结构、生态过程和功能的有效途径。基于生态系统服务重要性、景观核心区与桥接区、自然保护区、重要湖泊湿地4个层面指标选取生态源地，使用最小耗费距离方法识别巴彦淖尔市及其周边区域的潜在生态网络，并设置了3种网络优化情景进行网络优化，包括情景一增加生态"踏脚石"、情景二清除生态障碍点、情景三保护生态夹点，结合"网络构建成本"及"生境连通效果"选取最佳优化方案。结果表明，研究区当前的生态网络由24处生态源地，44条生态廊道、39个生态障碍点和41个生态夹点组成。3种情景中生态夹点的保护对生态网络连通度的改善最明显，且相对保护成本较低。研究结果对干旱区城市生态网络构建提供了方法支撑。

Scenario analysis of urban ecological network optimization for connectivity improvement in arid area: A case study of Bayannur City and its surrounding areas

As a typical city in dryland, the contradiction between economic development and ecological protection is increasing in Bayannur City, which intensifies the fragmentation of ecological space. Ecological network is an effective way to couple landscape structure, ecological processes and functions from the perspective of landscape connectivity. The main purposes for constructing a landscape ecological network are to protect landscape sustainability, maintain habitat, and increase ecological connectivity. Identification and optimization of urban ecological networks guarantee the effective provision of urban ecosystem services and ensure the regional ecological security pattern. We selected the key ecological sources of Bayannur City through the importance of ecosystem services, the landscape core area and bridges, the lakes and wetlands with important ecological functions, and the nature reserves. Then we used the least cost path method to identify the potential ecological networks in Bayannur City and its surrounding areas. Three scenarios were developed to optimize the ecological network. Scenario 1 was increasing the ecological stepping stones; Scenario 2 was repairing the barrier points, and Scenario 3 was protecting the ecological pinch points. The three scenarios addressed the shortage of insufficient ecological nodes, inaccessible corridors and weak ecological flow in the current ecological network pattern, respectively. The best plan was chosen according to "cost of network construction" and "effect of landscape connectivity". The results showed that the current ecological network pattern in the study area consisted of 24 ecological sources, 44 corridors, 39 ecological barrier points, and 41ecological pinch points. Among the three scenarios, the Scenario 3 had the most significant improvement in ecological network connectivity and relatively low conservation costs. However, the new corridor in Scenario 1 was important for the migration and activities of Mongolian wild asses as well as biodiversity conservation and stopping the eastward migration of the western deserts. Therefore, the ecological network optimization process in Bayannur City should also focus on the construction and planning of ecological networks in the western desert and desert-steppe areas of the study area so as to promote the ecological network coverage in the whole area. The results are helpful to methodologically support the construction of ecological security patterns in dryland cities.