Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed-conifer forest
Document Type: Journal Article
Author(s): Dylan W. Schwilk; Eric E. Knapp; Scott M. Ferrenberg; Jon E. Keeley; Anthony C. Caprio
Publication Year: 2006

Cataloging Information

  • Abies concolor
  • Abies spp.
  • air quality
  • bark
  • bark beetle
  • Calocedrus decurrens
  • char
  • coniferous forests
  • Cornus nuttallii
  • Dendroctonus
  • Dendroctonus ponderosae
  • Dendroctonus valens
  • fire exclusion
  • fire intensity
  • fire management
  • firing techniques
  • forest management
  • fuel accumulation
  • fuel moisture
  • insects
  • Ips
  • moisture
  • mortality
  • Nevada
  • old growth forests
  • phenology
  • pine
  • Pinus
  • Pinus jeffreyi
  • Pinus lambertiana
  • Pinus ponderosa
  • plant diseases
  • population density
  • Quercus kelloggii
  • Scolytus
  • Scolytus ventralis
  • scorch
  • season of fire
  • Sierra Nevada
  • size classes
  • statistical analysis
  • surface fuels
  • trees
Record Maintained By:
Record Last Modified: December 13, 2018
FRAMES Record Number: 45003
Tall Timbers Record Number: 20452
TTRS Location Status: In-file
TTRS Call Number: Fire File
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy 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 the Tall Timbers Research Station and Land Conservancy.


Over the last century, fire exclusion in the forests of the Sierra Nevada has allowed surface fuels to accumulate and has led to increased tree density. Stand composition has also been altered as shade tolerant tree species crowd out shade intolerant species. To restore forest structure and reduce the risk of large, intense fires, managers have increasingly used prescription burning. Most fires prior to EuroAmerican settlement occurred during the late summer and early fall and most prescribed burning has taken place during the latter part of this period. Poor air quality and lack of suitable burn windows during the fall, however, have resulted in a need to conduct more prescription burning earlier in the season. Previous reports have suggested that burning during the time when trees are actively growing may increase mortality rates due to fine root damage and/or bark beetle activity. This study examines the effects of fire on tree mortality and bark beetle attacks under prescription burning during early and late season. Replicated early season burn, late season burn and unburned control plots were established in an old-growth mixed conifer forest in the Sierra Nevada that had not experienced a fire in over 120 years. Although prescribed burns resulted in significant mortality of particularly the smallest tree size classes, no difference between early and late season burns was detected. Direct mortality due to fire was associated with fire intensity. Secondary mortality due to bark beetles was not significantly correlated with fire intensity. The probability of bark beetle attack on pines did not differ between early and late season burns, while the probability of bark beetle attack on firs was greater following early season bums. Overall tree mortality appeared to be primarily the result of fire intensity rather than tree phenology at the time of the burns. Early season burns are generally conducted under higher fuel moisture conditions, leading to less fuel consumption and potentially less injury to trees. This reduction in fire severity may compensate for relatively modest increases in bark beetle attack probabilities on some tree species, ultimately resulting in a forest structure that differs little between early and late season prescribed burning treatments. © 2006 Elsevier B.V.

Schwilk, D. W., E. E. Knapp, S. M. Ferrenberg, J. E. Keeley, and A. C. Caprio. 2006. Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed-conifer forest. Forest Ecology and Management, v. 232, no. 1-3, p. 36-45. 10.1016/j/foreco.2006.05.036.