For a long time, fire research in the moist forests of the Pacific Northwest was dominated by two main assertions: that wildfires in the West Cascades are typically "high-severity, low frequency" (in other words, dominated by stand-replacing fires that don't happen very often), and that Indigenous burning largely took place in prairies, river valleys and low-lying oak ecosystems. But extensive tree ring sampling over the last decade has shown that, in fact, these assertions aren't telling the entire story. Our guest for this episode is Dr. Andrew Merschel, who is a post-doc at Oregon State University and lead scientist/co-director of the Tree Ring Lab at OSU. Andrew has spent years studying fire histories in the moist, doug fir, hemlock and cedar-dominated forests of the West Cascades. His findings through the Tree Ring Lab have brought to question many of our longest-held assumptions about how fires burned in the Pacific Northwest prior to colonization—and the takeaway is that it's not nearly as simple as we once thought.
For a long time, fire research in the moist forests of the Pacific Northwest was dominated by two main assertions: that wildfires in the West Cascades are typically "high-severity, low frequency" (in other words, primarily characterized by stand-replacing fires that don't happen very often), and that Indigenous burning largely took place in prairies, river valleys and low-lying oak ecosystems.
But extensive tree ring sampling over the last decade has shown that, in fact, these long-held assertions aren't telling the entire story.
Our guest for this episode is Dr. Andrew Merschel, who is a post-doc at Oregon State University and lead scientist/co-director of the Tree Ring Lab at OSU. Andrew has spent years studying fire histories in the moist, doug fir, hemlock and cedar-dominated forests of the West Cascades by analyzing stumps and tree core samples across the PNW. His work with the Tree Ring Lab has called to question many of our longest-held assumptions about how fires burned in the Pacific Northwest prior to colonization—and the takeaway is that it's not nearly as straightforward as we once thought.
Andrew spoke about how fire "edits" forests over time, how these "edits" are crucial to the development of biodiversity, mature trees and old growth stands, and how we can use what we now know about "Westside" fire histories to inform management practices and wildfire resilience measures. We also spoke about how fire history on the Westside is not spatially or temporally stable, and that it doesn't operate on a cyclical basis; he and his team of research assistants and grad students have found, time and again, that fire histories can change based on what side of a ridge they're on, what part of a watershed they're in, what aspect they're at—making it a fascinating place to research how fire has interacted with the landscape over the last millennia. As Andrew says in this episode: "[In the East Cascades], I can tell you we'll find fire every 15 years at every site we go to. On the Westside it's an adventure, you don't know the story of each place until you get out there."
We also spoke about how this research intersects with Indigenous history, how it can be used to inform management decisions, and how Andrew's team collaborates with community groups, tribes, land management agencies and others to help them establish a better understanding of fire history in specific areas.
If you've ever had questions about how research can inform forest management decisions, about how researchers discern between Indigenous fire use and lightning-caused fires, or how we come to understand a place's relationship with fire over time, this is the episode for you.
To learn more about the Tree Ring Lab, check out their website and consider reading up on some of their recent (and fascinating!) research from the West Cascades.
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