Collaborative Research: The Past, Present, and Future of Boreal Fire Feedbacks

北方森林环绕着全球，蕴藏着地球上一些最大的碳储量。这种碳被锁在树木和土壤中，与大气隔离开来。但是，随着气候变暖，火灾正变得越来越常见--虽然野火在北部地区并不罕见，但越来越频繁的燃烧正在超过森林进化所能容忍的范围，导致森林丧失和永久冻土融化。我们不知道接下来会发生什么。如果森林不能从频繁的火灾中恢复过来，草和灌木可能会接管森林，进一步增加易燃性。或者它们可能会抑制未来的火灾活动。这个项目对北部地区的火灾进行了独特的观察，通过湖泊沉积岩心调查火灾的深层历史，在那里你可以看到数千年的火灾历史，通过实地工作来确定现在的地形有多有弹性，并通过高性能的计算机模型来估计火灾在未来的行为。该项目跨越了许多时间尺度，将计算能力推到了极限，并将为这个生物群和地球的未来提供信息。该项目将培训研究生、本科生和博士后学者，组织为期两天的科学交流研讨会，并改进用于向高中生传授碳-植被-火相互作用的火灾教学模式。该项目将采用综合和动态的方法，结合现有的和新收集的沉积物数据来探索北部地区短时间间隔火灾的古史，并在短时间间隔火区进行共同定位的野外工作。尽管已知现代火灾频率正在超过历史标准，但该项目将更进一步，以确定当前的短时间间隔火灾是否正在创造新的结构。这些结构是未来火灾行为的基础，因此研究人员将把这些测量与基于物理的现代流体力学火灾行为模型相结合，这种流体动力学模型可以模拟近距离树冠和新型森林结构中的风，该模型将扩展到包括土壤效应，这在北部地区至关重要。这是探索似乎正在出现的真正新颖的物种组合和结构的火灾影响的唯一可用的方法。这项工作将共同探索与北方森林火灾行为相关的火灾可能性反馈和结构阈值，并提供有关该地区将如何在野火和能源平衡方面对气候变暖做出反应的预期。该项目将与非营利组织指南针合作，为更大学术界的研究生和科学家组织为期两天的科学交流研讨会。他们还将与协和联盟合作，为高中生开发一个教学模块工具，与教师合作征求反馈。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Boreal forests circle the globe and contain some of the largest carbon stocks on the planet. Locked in the trees and soil, this carbon is sequestered from the atmosphere. But as the climate warms, fires are becoming more and more common – and while wildfire is not unusual in the boreal, the increasing frequency of burning is surpassing what the forests have evolved to tolerate, leading to forest loss and permafrost thaw. We do not know what comes next. It is possible that if the forest fails to recover from high frequency fires, grasses and shrubs may take over, further increasing flammability. Or they may dampen future fire activity. This project takes a unique look at fires in the boreal, by investigating the deep history of fire through lake sediment cores where you can see the history of fire over thousands of years, through fieldwork to determine how resilient the landscape is now, and through high-performance computer models to estimate how fires will behave in the future. The project spans many timescales and pushes computing powers to the limit and will inform expectations of the future for this biome and the planet. The project will train graduate students, undergraduate students, and postdoctoral scholars, organize a two-day science communication workshop, and refine a fire teaching model used to teach high schoolers about carbon-vegetation-fire interactions. Using an integrative and dynamic approach, this project will combine existing and newly collected sediment data to explore the paleohistory of short interval fires in the boreal with co-located fieldwork in short-interval fire areas. Although it is known that modern fire frequency is passing historical norms, this project will go further, to determine if current short interval fires are creating novel structures. Those structures are the basis for fire behavior in the future, so the researchers will then combine those measurements with modern, physics-based fluid dynamics modeling of fire behavior that can simulate wind in close canopies and in novel forest structures Further, this model will be extended to incorporate soil effects, critical in the boreal. This is the only available way to explore the fire implications of truly novel species assemblages and structures that seem to be emerging. Together, this work will explore fire likelihood feedbacks and structural thresholds associated with fire behavior in the boreal forest and inform expectations about how the region will respond, in terms of wildfire and energy balance, to climate warming. The project will work with the non-profit COMPASS to organize a two-day science communication workshop for graduate students and scientists in the larger academic community. They will also work with Concord Consortium to develop a module tool for teaching highschoolers, working with teachers to solicit feedback.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.