Document


Title

A heat transfer model of crown scorch in forest fires
Document Type: Journal Article
Author(s): Sean T. Michaletz; Edward A. Johnson
Publication Year: 2006

Cataloging Information

Keyword(s):
  • buds
  • coniferous forests
  • crown scorch
  • fire intensity
  • fire management
  • flame length
  • foliage
  • forest management
  • heat
  • heat transfer
  • mortality
  • Picea glauca
  • Pinus banksiana
  • Pinus contorta
  • Pinus radiata
  • Pinus strobus
  • Pinus sylvestris
  • plant physiology
  • Quercus rubra
  • residence time
  • scorch
  • Sequoia sempervirens
  • statistical analysis
  • surface fires
  • temperature
  • Van Wagner's crown fire model
Record Maintained By:
Record Last Modified: May 17, 2019
FRAMES Record Number: 9276
Tall Timbers Record Number: 21181
TTRS Location Status: In-file
TTRS Call Number: Journals-C
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.

Description

The Van Wagner crown scorch model is widely used to estimate crown component necroses in surface fires. The model is based on buoyant plume theory but accounts for crown heat transfer processes using an empirical proportionality factor k. Crown scorch estimates have used k values for foliage, but k varies with heat transfer characteristics, and branch and bud necroses are more relevant to tree mortality. This paper derives and validates a more physically complete model of crown scorch in surface fires (I ≤ 2500 kW·m-1). The model links a buoyant plume model with a lumped capacitance heat transfer analysis applicable to branches, buds, and foliage (~1 cm maximum diameter). The lumped capacitance analysis is validated with vegetative-bud heating experiments, and the entire heat transfer model of crown scorch is validated with fireline intensity and foliage necrosis data. The model is more general than the Van Wagner model and is independent of experimental fire data. Predictions require measurements of fireline intensity, residence time, ambient temperature, and five thermophysical properties of crown components. The model predicts differences between bud and foliage necrosis heights, and illustrates why heat transfer processes should be considered in crown scorch models.

Online Link(s):
Citation:
Michaletz, Sean T.; Johnson, Edward A. 2006. A heat transfer model of crown scorch in forest fires. Canadian Journal of Forest Research 36(11):2839-2851.