Collaborative Research: Causes and consequences of fire-regime variability in Rocky Mountain forests

在美国，野火平均每年影响超过18万平方公里，面积是黄石国家公园的20倍。在落基山脉，自20世纪80年代中期以来，被大火烧毁的面积一直在增加，这一趋势很好地与春季和夏季气温变暖有关，预计将在未来几十年继续下去。社会计划和应对野火的方式，例如通过联邦政策和土地管理，在很大程度上取决于我们对不同生态系统中火灾的原因、生态后果和历史先例的理解。在这方面的重要问题包括：过去发生火灾的频率有多高，这种情况如何随气候和人类活动而变化；火灾对包括森林和水质在内的宝贵资源有何影响；生态系统需要多长时间才能恢复到火灾前的状况？研究森林和野火活动如何以及为什么在过去不同的气候和人类活动时期发生变化，为理解野火的影响提供了关键的基础。这种长期视角还有助于提供信息并改进模拟未来环境变化影响的模型，包括野火活动的变化。更广泛影响的机制包括通过嵌入研究团队的新闻学研究生记录和交流研究结果，通过为高中教育工作者开发森林和火灾生态学课程来推进STEM教育，以及培训研究生和本科生进行基于野外、实验室和模型的研究。本研究通过古生态重建和生态系统建模的独特组合，调查了过去2500年来气候、野火活动和生态系统变化之间的关系和反馈。利用两个研究区域(即落基山脉北部和南部1000平方公里范围内的9-12个湖泊)异常密集的湖泊沉积物记录网络，将表征过去火灾活动的频率、严重性和同步性，并与古气候记录进行比较，以评估过去火灾活动的驱动因素。古火灾记录将补充一些重点地点的植被和生物地球化学变化的高分辨率记录，以评估过去火灾活动对生态系统的影响。将通过一系列生态系统模拟模拟，在分水岭和次区域的空间尺度上研究气候--火--生态系统相互耦合的动态变化，这些模拟比较了古生态情景和平衡情景。

Wildfires affect more than 180,000 km2 in the Unites States every year, on average, an area 20 times the size of Yellowstone National Park. In the Rocky Mountains, the amount of area burned in large wildfires has been increasing since the mid-1980s, a trend well linked to warming spring and summer temperatures, and expected to continue in upcoming decades. The way society plans for and reacts to wildfires, for example through federal policy and land management, is strongly shaped by our understanding of the causes, ecological consequences, and historical precedence of fire in different ecosystems. Important questions in this context include: how often have fires occurred in the past and how has this varied with climate and human activity, how have fires impacted valued resources including forests and water quality, and how long does it take for ecosystems to recover to pre-fire conditions? Studying how and why forests and wildfire activity have varied in the past, over periods of varying climate and human activity, provides a critical foundation for understanding the implications of wildfires. This long-term perspective also helps inform and improve models that simulate the impacts of future environmental change, including changes in wildfire activity. Mechanisms for broader impacts include documenting and communicating research results via a journalism graduate student embedded with the research team, advancing STEM education through the development of forest and fire ecology curricula for high school educators, and training graduate and undergraduate students in field-, lab-, and modeling-based research.This research investigates the relationships and feedbacks among changes in climate, wildfire activity, and ecosystems over the past 2500 years through a unique combination of paleoecological reconstructions and ecosystem modeling. Using an unusually dense network of lake-sediment records in two study regions (i.e., 9-12 lakes within 1000 km2 in the N. and S. Rockies), the frequency, severity, and synchrony of past fire activity will be characterized and compared to paleoclimate records to assess the drivers of past fire activity. Paleofire records will be supplemented with high-resolution records of vegetation and biogeochemical change at a subset of focal sites, to assess the ecosystem impacts of past fire activity. Coupled climate-fire-ecosystem dynamics will be examined at watershed and sub-regional spatial scales through a set of ecosystem modeling simulations that compare paleo-informed to equilibrium scenarios.