RAPID: Does riparian vegetation state mediate consequences of climate change-induced extreme flooding for stream-riparian food webs and communities?

于二零二二年六月，北方黄石国家公园经历雨雪事件，导致500年一遇的洪水，摧毁当地基础设施，并引起公众关注，成为人为气候变化的重大后果。 极端干扰，无论是5级飓风，严重的野火还是极端干旱，都变得越来越频繁和强烈。 自然资源管理者和政策制定者需要了解这种极端干扰的后果，并找到支持生态系统复原力的方法。 从历史上看，生态学家认为，尽管生态系统对轻度或中度干扰具有弹性，甚至从中受益，但极端干扰会将生态系统“重置”到某种统一的基线状态。 NSF已经批准了RAPID对这个项目的支持，以评估北方黄石公园的极端干扰。 该研究区包含相当大的生物多样性在整个马赛克的不同的栖息地。 这种复杂性的一个来源来自于狼和灰熊等食肉动物的恢复，它们与麋鹿和野牛等食草动物的相互作用，以及随后对植物群落的改变。 结果，柳树和赤杨在一些小溪和河流周围重新生长，而几英里外的其他地方仍然被草和莎草占据。 以前的调查表明，不同的植物群落影响溪流和河流的多样性和生产力，但在当地的情况下，导致在马赛克的生态系统状态介导的方式。 正如捕食者的恢复并没有均匀地改变这个生态系统，对最近极端洪水的反应可能是由当地环境介导的。 反过来，这项研究的结果可能会为管理决策提供信息，并影响公众对这种干扰后果的看法，就像过去的生态研究对该地区野火所做的那样。通过利用自然实验的机会，并通过比较极端洪水前后的河流-河岸生态系统，本项目将评估河流-河岸生态系统是否发生了同质的“重置”，或者，影响河岸植被状态的陆生野生动物动态，以及水生群落的洪水前特征，介导了河流河岸生物和生态系统过程的异质性反应。 该项目将收集洪水后与洪水前平行的测量数据，包括河流-河岸生境特征、食草动物和河岸植物群落组成和结构、河流生态系统有机物动态、水生无脊椎动物和鱼类的生产力和食物网相互作用，以及河岸蜘蛛和鸟类群落。 如果生物体、群落或食物网特征在极端洪水之后塑造了抵抗力、复原力和变化轨迹，这将提供一个机会来评估这种“生态记忆”如何约束对未来极端事件的反应。 如果生物体和群落的特征对于调节对极端干扰的反应确实很重要，那么这个项目可能会突出在面对气候变化和生物多样性危机时保护这种复杂性的重要性。这个奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

In June 2022, Northern Yellowstone National Park experienced rain-on-snow events leading to a 1 in 500-year flood, devastating local infrastructure and capturing public attention as a high-profile consequence of human-caused climate change. Extreme disturbances, whether they be category 5 hurricanes, severe wildfires, or extreme droughts, are becoming more frequent and intense. Natural resource managers and policy makers need to understand the consequences of such extreme disturbances and find ways to support ecosystem resiliency. Historically, ecologists thought that though ecosystems were resilient to, or even benefitted from, mild or moderate disturbances, extreme disturbances “reset” ecosystems to some uniform, baseline state. NSF has approved RAPID support for this project, to evaluate extreme disturbance in the context of Northern Yellowstone. The study area contains considerable biodiversity throughout a mosaic of distinct habitats. One source of this complexity comes from the restoration of predators like wolves and grizzly bears, their interactions with herbivores such as elk and bison, and the subsequent changes to plant communities. As a result, willows and alders have regrown around some streams and rivers while others, just miles away, remain dominated by grasses and sedges. Previous investigations showed that different plant communities influence the diversity and productivity of streams and rivers, but in ways mediated by local context that result in a mosaic of ecosystem states. Just as the restoration of predators has not uniformly changed this ecosystem, responses to the recent extreme flooding may have been mediated by local context. In turn, results from this study may inform management decisions and influence public perceptions regarding consequences of such disturbances, as indeed past ecological studies have done for wildfire in this region.Through the opportunistic use of a natural experiment and by comparing stream-riparian ecosystems before and after the extreme flooding, this project will evaluate whether a homogenous “reset” of stream-riparian ecosystems occurred, or if terrestrial wildlife dynamics that influence riparian vegetation state, as well as pre-flood traits of aquatic communities, mediated heterogeneous responses of stream-riparian organisms and ecosystem processes. This project will collect parallel measurements after flooding to those collected before, including stream-riparian habitat characteristics, herbivory and riparian plant community composition and structure, stream ecosystem organic matter dynamics, productivity and food web interactions of aquatic invertebrates and fish, and riparian spider and bird communities. If organism, community, or food web traits shape resistance, resilience, and trajectories of change following the extreme flood, this will provide an opportunity to evaluate how such “ecological memory” constrains responses to future extreme events. If traits of organisms and communities are indeed important to mediating responses to extreme disturbances, this project may highlight the importance of conserving such complexity in the face of climate change and the biodiversity crisis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.