COS 195-1 - Examining the drivers of dry conifer forest resilience to extreme wildfire events

Wednesday, August 9, 2023

1:30 PM – 1:45 PM PDT

Location: D139

Presenting Author(s)

AD

Amy DeCastro

Project Scientist
National Center for Atmospheric Research, United States

Coauthor(s)

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Michael J. Koontz

Research Scientist/Lead Scientist: Ecosystem Monitoring and Forecasting
Cooperative Institute for Research in Environmental Sciences, United States
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Andrew Latimer

Professor, Plant Sciences
University of California, Davis, United States
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Malcolm North

University of California Davis, United States

Abstract: Rapid fire spread in extreme wildfire events (EWEs) is associated with high risk to life and property because when fires move very fast, there is little time for communication and evacuation, and because rapidly spreading forest fires produce many embers that ignite widespread spot fires. Ecological impacts of EWEs can also be severe. In conifer forest ecosystems, rapid fire spread is coupled with high fire intensity and extensive crown fire due to high surface and ladder fuel loads that build up in the absence of frequent fire. As a result, EWEs often produce large, high-severity patches, erasing fuel and structural heterogeneity across tens of thousands of acres at a time.

To determine which features and management actions in burning landscapes moderate fire intensity and increase tree survival, we combined Monitoring Trends in Burn Severity (MTBS) data with Landfire vegetation data. We examined the distribution of extreme events and their severity levels, as well as the patterns of severity within the daily burned areas of EWEs in dry conifer forests across the Western US. We coupled the intersecting spaces with terrain and atmospheric data to help determine the environmental drivers that distinguish between areas of large tree survival and areas of low resilience.

Results suggest there are strong associations between weather and topographic variables, and both pixel-scale and daily fire-scale severity for EWEs. In particular, vegetation and fuel heterogeneity play a key role in landscape resilience for dry conifer systems. Results of this work emphasize the importance of heterogeneity as a self-reinforcing structure fundamental to resilience. With limited budgets and workforce, managers might consider identifying leverage locations in fire-prone landscapes where targeted treatments may have a large-scale influence on limiting EWE events.