Area burned in the western United States is unaffected by recent mountain pine beetle outbreaks

Sarah J. Hart, Tania Schoennagel, Thomas T. Veblen, Teresa B. Chapman, Janet Franklin

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

In the western United States, mountain pine beetles (MPBs) have killed pine trees across 71,000 km2 of forest since the mid-1990s, leading to widespread concern that abundant dead fuels may increase area burned and exacerbate fire behavior. Although standlevel fire behavior models suggest that bark beetle-induced tree mortality increases flammability of stands by changing canopy and forest floor fuels, the actual effect of an MPB outbreak on subsequent wildfire activity remains widely debated. To address this knowledge gap, we superimposed areas burned on areas infested by MPBs for the three peak years of wildfire activity since 2002 across the western United States. Here, we show that the observed effect of MPB infestation on the area burned in years of extreme fire appears negligible at broad spatial extents. Contrary to the expectation of increased wildfire activity in recently infested red-stage stands, we found no difference between observed area and expected area burned in red-stage or subsequent gray-stage stands during three peak years of wildfire activity, which account for 46% of area burned during the 2002-2013 period. Although MPB infestation and fire activity both independently increased in conjunction with recent warming, our results demonstrate that the annual area burned in the western United States has not increased in direct response to bark beetle activity. Therefore, policy discussions should focus on societal adaptation to the effects of recent increases in wildfire activity related to increased drought severity.

Original languageEnglish (US)
Pages (from-to)4375-4380
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number14
DOIs
StatePublished - Apr 7 2015

Keywords

  • Bark beetle
  • Dendrocotnus ponderosae
  • Disturbance interactions
  • Lodgepole pine
  • Wildfire

ASJC Scopus subject areas

  • General

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