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Type: Journal Article
Author(s): Robert A. Andrus; Thomas T. Veblen; Brian J. Harvey; Sarah J. Hart
Publication Date: 2016

Recent large and severe outbreaks of native bark beetles have raised concern among the general public and land managers about potential for amplified fire activity in western North America. To date, the majority of studies examining bark beetle outbreaks and subsequent fire severity in the U.S. Rocky Mountains have focused on outbreaks of mountain pine beetle (MPB; Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests, but few studies, particularly field studies, have addressed the effects of the severity of spruce beetle (Dendroctonus rufipennis Kirby) infestation on subsequent fire severity in subalpine Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) forests. In Colorado, the annual area infested by spruce beetle outbreaks is rapidly rising, while MPB outbreaks are subsiding; therefore understanding this relationship is of growing importance. We collected extensive field data in subalpine forests in the eastern San Juan Mountains, southwestern Colorado, USA, to investigate whether a gray-stage (<5 yr from outbreak to time of fire) spruce beetle infestation affected fire severity. Contrary to the expectation that bark beetle infestation alters subsequent fire severity, correlation and multivariate generalized linear regression analysis revealed no influence of pre-fire spruce beetle severity on nearly all field or remotely sensed measurements of fire severity. Findings were consistent across moderate and extreme burning conditions. In comparison to severity of the pre-fire beetle outbreak, we found that topography, pre-outbreak basal area, and weather conditions exerted a stronger effect on fire severity. Our finding that beetle infestation did not alter fire severity is consistent with previous retrospective studies examining fire activity following other bark beetle outbreaks and reiterates the overriding influence of climate that creates conditions conducive to large, high-severity fires in the subalpine zone of Colorado. Both bark beetle outbreaks and wildfires have increased autonomously due to recent climate variability, but this study does not support the expectation that post-beetle outbreak forests will alter fire severity, a result that has important implications for management and policy decisions.

Online Links
Citation: Andrus, Robert A.; Veblen, Thomas T.; Harvey, Brian J.; Hart, Sarah J. 2016. Fire severity unaffected by spruce beetle outbreak in spruce-fir forests in southwestern Colorado. Ecological Applications 26(3):700-711.

Cataloging Information

Partner Sites:
  • Abies lasiocarpa
  • Colorado
  • coniferous forest
  • Dendroctonus ponderosae
  • Dendroctonus rufipennis
  • disturbance
  • Engelmann spruce
  • fire intensity
  • fire management
  • fire severity
  • fire weather
  • forest management
  • insects
  • lodgepole pine
  • MPB - mountain pine beetle
  • Picea engelmannii
  • Pinus contorta
  • plant diseases
  • rate of spread
  • San Juan Mountains
  • spruce beetle
  • stand characteristics
  • subalpine fir
  • subalpine forests
  • subalpine forests
  • wildfires
Tall Timbers Record Number: 32258Location Status: In-fileCall Number: Journals - EAbstract Status: Fair use, Okay, Reproduced by permission
Record Last Modified:
Record Maintained By: FRAMES Staff (
FRAMES Record Number: 22109

This bibliographic record was either created or modified by Tall Timbers and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of Tall Timbers.
This document is part of the Southwest FireCLIME Annotated Bibliography, which includes published research related to the interactions between climate change, wildfire, and subsequent ecosystem effects in the southwestern U.S. The publications contained in the Bibliography have each been summarized to distill the outcomes as they pertain to fire and climate. Go to this document's record in the Southwest FireCLIME Annotated Bibliography.