RAPID: Food webs of 10 lakes before and after a mega-wildfire

在过去的二十年里，野火在美国西部森林山脉的规模和强度上都有所增加。虽然对它们对森林本身的影响进行了大量调查，但几乎没有研究评估它们对这些生态系统中嵌入的山地湖泊的影响。野火烧毁分水岭后，大量的有机碎片会被冲进湖泊。尽管淡水分类群可能对火灾影响特别敏感，但人们对与火灾有关的影响（如这些有机投入）在多大程度上改变淡水物种和生态系统知之甚少。2021年夏天，迪克西大火烧毁了北加州约100万英亩的森林。该研究项目利用了在烧伤疤痕内10个冰川湖泊的鱼类和食物网上收集的独特的野火前（2020年）数据，旨在对火灾后这些相同的生态系统进行重新采样，以了解流域火灾的严重程度如何影响湖泊生态。特别是，研究人员将调查这场大型野火是否会杀死湖泊中的鱼类种群，以及这是否取决于湖泊大小或盆地特征。此外，他们将评估鱼类数量的减少是如何通过食物网影响湖泊生态系统的整体健康的。通过这项研究获得的见解将有助于在严重野火之后更好地管理湖泊渔业和遗产物种（例如本地青蛙）。此外，从这项研究中收集的数据将为决策者提供未来如何管理这些系统的信息，包括何时以及是否要放养湖泊，以及火灾如何更广泛地影响淡水生态系统。研究人员将参与一项旨在唤起公众对这项工作的关注的科学传播策略，并将招募来自历史上被排斥背景的学生参与这项研究的整个生命周期。本研究将调查一场大型野火（迪克西大火）对美国加州驯鹿荒野拉森国家森林10个湖泊生态系统的影响。具体来说，我们将研究1)在大型野火后，鱼类是否在部分或所有湖泊中被消灭；2)鱼类的消失是否改变了营养级联；3)营养级联强度是否随生态系统规模而变化；4)流域燃烧后湖泊食物网结构和功能如何变化。该项目使用对鱼类、无脊椎动物和湖泊化学特征的地面测量，并使用稳定同位素来评估不断变化的食物网。这些评估将用于检验生态学理论，即扰动介导的营养级联的作用，以及它们对湖泊食物网结构和功能的控制。这项工作的结果将对对气候变化介导的干扰的影响感兴趣的各种生态学家，特别是在人类主导的景观中努力管理这些分类群的湖泊学家和淡水科学家有用。来自不同背景的本科生将被纳入研究过程。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Wildfires have grown in size and intensity across the forested mountains of the western USA in the last two decades. While there is much investigation of their impacts of forests themselves, almost no studies evaluate their impacts on the mountain lakes that are embedded in these ecosystems. After wildfires burn through a watershed, large quantities of organic debris can wash into lakes. Little is known about the extent to which fires-related effects such as these organic inputs, alter freshwater species and ecosystems, even though freshwater taxa may be notably sensitive to fire impacts. During summer 2021, the Dixie Fire burned ~1 million acres of forest in Northern California. This research project takes advantage of unique pre-wildfire (2020) data collected on the fish and food webs of 10 glacial lakes within the burn scar, and aims to resample these same ecosystems post-fire to understand how severity of fire in watershed impacts lake ecology. In particular, researchers will investigate whether this large wildfire kills fish populations in lakes and whether this depends on lake size or basin characteristics. Additionally they will evaluate how reductions in fish populations cascade through the food webs to affect the overall health of lake ecosystems. Insights gained through this study will enable better management of lake fisheries and heritage species (e.g., native frogs) following severe wildfire. Further, data collected from this study will inform decision makers on how to manage these systems into the future, including when and whether to stock lakes, and how fires impact freshwater ecosystems more generally. Researchers will engage in a science communication strategy aimed at calling public attention to this work, and will recruit students from historically-excluded backgrounds to participate in the full life-cycle of this research.This research will investigate the effects of a mega-wildfire (the Dixie Fire) on 10 lake ecosystems in the Lassen National Forest, Caribou Wilderness, California, USA. Specifically, we will examine 1) whether fishes are eradicated in some or all lakes following mega-wildfires,2) whether fish removal changes a trophic cascade, 3) if trophic cascade strength varies with ecosystem size, and 4) how lake food web structure and function shifts following watershed burning. This project uses both on the ground measurements of fish, invertebrates and lake chemical features, and uses stable isotopes to evaluate changing food webs. These assessments will be used to test ecological theory, namely the role of disturbance-mediated trophic cascades, and their control over lake food web structure and function. Results from this work will be useful to diverse ecologists interested in effects of climate change mediated disturbances, but especially limnologists and freshwater scientists struggling to manage these taxa in human dominated landscapes. Undergraduate students from diverse backgrounds will be included in the research process.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.