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

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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.