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Type: Journal Article
Author(s): Emily J. Francis; Pariya Pourmohammadi; Zachary L. Steel; Brandon M. Collins; Matthew D. Hurteau
Publication Date: 2023

Context: In western US forests, the increasing frequency of large high-severity fires presents challenges for society. Quantifying how fuel conditions influence high-severity area is important for managing risks of large high-severity fires and understanding how they are changing with climate change. Fuel availability and heterogeneity influence high-severity fire probability, but heterogeneity is insensitive to some aspects of forest connectivity that are important to potential high-severity fire transmission and thus high-severity area.

Objectives: To quantify the effects of fuel availability, heterogeneity, and connectivity on the proportion of forest area burned at high-severity (high-severity burn area). To use the extreme 2020 fire season to consider how climate change could affect high-severity burn area relationships.

Methods: We used datasets derived from remote sensing to quantify effects of forest fuel availability, heterogeneity, and connectivity on extreme (95th percentile) high-severity burn areas in western US coniferous watersheds from 2001 to 2020. We developed a connectivity metric to quantify potential high-severity fire transmission.

Results: High-severity burn area increased with increasing fuel availability and connectivity and decreased with increasing heterogeneity. In 2020, multiple large high-severity burn areas occurred in forests with high fuel availability, which only had small high-severity burn areas prior to 2020.

Conclusions: In forests with an annual fire season, management to limit forest connectivity and fuel accumulation and increase heterogeneity could mitigate the potential for large high-severity fires. In forests where climate usually limits fire, large high-severity fires may occur more frequently if climate change increases the frequency of years with inadequate climatic barriers to wildfire.

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Citation: Francis, Emily J.; Pourmohammadi, Pariya; Steel, Zachary L.; Collins, Brandon M.; Hurteau, Matthew D. 2023. Proportion of forest area burned at high-severity increases with increasing forest cover and connectivity in western US watersheds. Landscape Ecology 38(10):2501-2518.

Cataloging Information

  • climate change
  • connectivity
  • disturbance
  • fire severity
  • forest continuity
  • forest structure
  • wildfires
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Record Maintained By: FRAMES Staff (
FRAMES Record Number: 68839