Arroyo-Esquivel Jorge, Adams Riley, Gravem Sarah, Whippo Ross, Randell Zachary, Hodin Jason, Galloway Aaron W E, Gaylord Brian, Baskett Marissa L
Department of Mathematics, University of California, Davis, California, USA.
California Department of Fish and Wildlife, West Sacramento, California, USA.
Ecology. 2024 Dec;105(12):e4453. doi: 10.1002/ecy.4453. Epub 2024 Oct 27.
Human-caused global change produces biotic and abiotic conditions that increase the uncertainty and risk of failure of restoration efforts. A focus of managing for resiliency, that is, the ability of the system to respond to disturbance, has the potential to reduce this uncertainty and risk. However, identifying what drives resiliency might depend on how one measures it. An example of a system where identifying how the drivers of different aspects of resiliency can inform restoration under climate change is the northern coast of California, where kelp experienced a decline in coverage of over 95% due to the combination of an intense marine heat wave and the functional extinction of the primary predator of the kelp-grazing purple sea urchin, the sunflower sea star. Although restoration efforts focused on urchin removal and kelp reintroduction in this system are ongoing, the question of how to increase the resiliency of this system to future marine heat waves remains open. In this paper, we introduce a dynamical model that describes a tritrophic food chain of kelp, purple urchins, and a purple urchin predator such as the sunflower sea star. We run a global sensitivity analysis of three different resiliency metrics (recovery likelihood, recovery rate, and resistance to disturbance) of the kelp forest to identify their ecological drivers. We find that each metric depends the most on a unique set of drivers: Recovery likelihood depends the most on live and drift kelp production, recovery rate depends the most on urchin production and feedbacks that determine urchin grazing on live kelp, and resistance depends the most on feedbacks that determine predator consumption of urchins. Therefore, an understanding of the potential role of predator reintroduction or recovery in kelp systems relies on a comprehensive approach to measuring resiliency.
人为引起的全球变化产生了生物和非生物条件，增加了恢复努力失败的不确定性和风险。对恢复力进行管理，即系统对干扰做出响应的能力，有可能降低这种不确定性和风险。然而，确定恢复力的驱动因素可能取决于衡量它的方式。一个能说明如何确定恢复力不同方面的驱动因素可以为气候变化下的恢复提供信息的系统例子是加利福尼亚州北部海岸，在那里，由于强烈的海洋热浪以及海带食草紫色海胆的主要捕食者向日葵海星的功能性灭绝，海带覆盖面积下降了95%以上。尽管该系统中针对海胆清除和海带重新引入的恢复工作仍在进行，但如何提高该系统对未来海洋热浪的恢复力这一问题仍然悬而未决。在本文中，我们引入了一个动态模型，该模型描述了海带、紫色海胆和紫色海胆捕食者（如向日葵海星）的三营养级食物链。我们对海带森林的三种不同恢复力指标（恢复可能性、恢复率和抗干扰能力）进行了全局敏感性分析，以确定它们的生态驱动因素。我们发现，每个指标最依赖于一组独特的驱动因素：恢复可能性最依赖于活海带和漂流海带的产量，恢复率最依赖于海胆产量以及决定海胆对活海带啃食的反馈，而抗干扰能力最依赖于决定捕食者对海胆消耗的反馈。因此，要理解捕食者重新引入或恢复在海带系统中的潜在作用，依赖于一种全面的恢复力测量方法。
