Using sentinel nodes to evaluate changing connectivity in a protected area network

It has been recognized that well-connected networks of protected areas are needed to halt the continued loss of global biodiversity. The recently signed Kunming-Montreal biodiversity agreement commits countries to protecting 30% of terrestrial lands in well-connected networks of protected areas by 2030. To meet these ambitious targets, land-use planners and conservation practitioners will require tools to identify areas important for connectivity and track future changes. In this study we present methods using circuit theoretic models with a subset of sentinel park nodes to evaluate connectivity for a protected areas network. We assigned a lower cost to natural areas within protected areas, under the assumption that animal movement within parks should be less costly given the regulation of activities. We found that by using mean pairwise effective resistance (MPER) as an indicator of overall network connectivity, we were able to detect changes in a parks network in response to simulated land-use changes. As expected, MPER increased with the addition of high-cost developments and decreased with the addition of new, low-cost protected areas. We tested our sentinel node method by evaluating connectivity for the protected area network in the province of Ontario, Canada. We also calculated a node isolation index, which highlighted differences in protected area connectivity between the north and the south of the province. Our method can help provide protected areas ecologists and planners with baseline estimates of connectivity for a given protected area network and an indicator that can be used to track changes in connectivity in the future.

学界已达成共识，需构建连通性优良的保护地网络，以遏制全球生物多样性的持续丧失。近日签署的《昆明-蒙特利尔生物多样性协定》要求各成员国到2030年将30%的陆地纳入连通性优良的保护地网络进行保护。为实现这一宏伟目标，土地利用规划者与保护从业者亟需相关工具，以识别对连通性至关重要的区域，并追踪未来的动态变化。本研究提出一种方法：采用电路理论模型，并选取哨兵保护地节点子集，对保护地网络的连通性开展评估。我们为保护地内的自然区域赋予更低的通行成本，其假设前提为：鉴于保护区内人类活动受到监管，动物在保护区内移动的“成本”应更低。研究结果显示，以平均成对有效阻抗（mean pairwise effective resistance, MPER）作为整体网络连通性的评估指标，我们能够检测出保护地网络在模拟土地利用变化下产生的响应变化。正如预期，随着高成本开发区域的增加，MPER值会上升；而新增低成本保护地则会使MPER值下降。我们以加拿大安大略省的保护地网络为研究对象，对所提出的哨兵节点方法进行了测试。此外，我们还计算了节点孤立指数，该指数清晰揭示了该省南北区域保护地连通性的差异。本研究提出的方法可为保护地生态学家与规划者提供特定保护地网络连通性的基线估算值，同时提供一个可用于未来追踪连通性变化的量化指标。