基于物种分布的北京平原生态网络构建

高强度的城市化活动导致了生物栖息地破碎化、退化和消失，是生物多样性减少的主要原因。建立城市地区生态网络是保护生物多样性的重要途径。因其他物种数据可获得性差，以观测的典型鸟类群落为指示物种，探讨构建生态网络，可为城市生物多样性保护提供新思路。以北京市平原区为研究范围，重点基于86种鸟类分布大数据，通过Maxent模型掩膜生成栖息地源地并进行分级，在GIS技术的支撑下，以土地利用数据建立鸟类活动阻力面，采用最小累积阻力模型算法，模拟并形成了平原地区分级的生物多样性保护网络。研究结果表明，河湖湿地和城市公园组成了北京平原地区生态网络的优势景观类型，占平原区生态空间的81%。基于景观类型大小与物种数量的线性关系筛选出分级生物栖息地，其中一级生物栖息地58个，二级生物栖息地146个，通过模型模拟形成了平原地区生物多样性保护的一二级生态网络，共948条网络，长3760km。筛选出重要生态节点12处，关键生态廊道6条，是保护平原地区生物多样性的重要生态设施。该生态网络的实施对于提升首都平原区的生物多样性具有重要价值，研究结果可为国土生态空间优化提供重要科学依据和参考。

Building ecological networks in Beijing Plain based on local species distribution

Rapid urbanization has been reshaping terrestrial ecosystems worldwide in last few decades, and this process has resulted in habitat fragmentation, deterioration and even habitat loss, which is considered to be one of key drivers of biodiversity reduction in global scale. In this context, building ecological networks to increase habitat connectivity in urban scale is vitally important for effective conservation. Because the data of other species is inaccessible, taking the observed bird population as focal species and to build ecological networks provides us a novel idea for protecting local biodiversity. This paper takes Beijing plain as study area to build a systematic ecological network. Based on the data of spatial distribution of typical 86 kinds of bird that are in the list of threatened species, we explore the potential habitats as source patches under the support of Maxent model. Then we utilize the land use data to create resistance surface which symbolizes the degree of difficulty of species'' passing through among habitats, by means of that we integrate the spatial data with the minimum cumulative resistance model, and a classified ecological network is constructed. The result shows that wetlands and public gardens are the dominant habitats, which represent 81% natural areas in Beijing plain. The identified habitat sources are classified two types according to the linear relation of species richness and the extent of habitats, and the number of primary and the secondary habitats are 58 and 146, respectively. Similarly, the modelled ecological corridors are also classified into the primary and secondary types. The former represents the corridors among primary habitats, and the latter are corridors that connects the primary habitats with the secondary habitats. Totally, the number of corridors is 948 and the length is 3760 kilometers. Moreover, 12 essentially ecological nodes are selected by kernel density analysis, and 6 key corridors are confirmed according to their ecological attributes. These nodes and corridors are important ecological infrastructures in biodiversity conservation on Beijing plain. In conclusion, building up 948 corridors are believed to be beneficial for biodiversity conservation. Additionally, the ecological network is also an optional solution and reference for local decision makers to draw up scientifically and rationally a spatial optimized planning for human-nature harmonious Beijing.