Assessing the probability of crown fire initiation based on fire danger indices
Document Type: Journal Article
Author(s): Miguel G. Cruz; Martin E. Alexander; Ronald H. Wakimoto
Publication Year: 2003

Cataloging Information

  • Canada
  • CFFDRS - Canadian Forest Fire Danger Rating System
  • CFIS - Crown Fire Initiation and Spread System
  • coniferous forests
  • conifers
  • crown fire initiation
  • crown fires
  • disturbance
  • drought
  • duff
  • ecosystem dynamics
  • experimental fire
  • fine fuels
  • fire danger indices
  • fire danger rating
  • fire intensity
  • fire management
  • fire suppression
  • forest management
  • fuel management
  • fuel moisture
  • fuel types
  • ignition
  • insects
  • logistic regression
  • moisture
  • overstory
  • plant diseases
  • rate of spread
  • size classes
  • statistical analysis
  • surface fires
  • wildfires
  • wind
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Record Maintained By:
Record Last Modified: November 5, 2019
FRAMES Record Number: 3835
Tall Timbers Record Number: 17291
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.


The initiation of crown fires in conifer stands was modelled through logistic regression analysis by considering as independent variables a basic physical descriptor of the fuel complex structure and selected components of the Canadian Forest Fire Weather Index (FWI) System. The study was based on a fire behavior research database consisting of 63 experimental fires covering a relatively wide range of burning conditions and fuel type characteristics. Four models were built with decreasing input needs. Significant predictors of crown fire initiation were: canopy base height, wind speed measured at a height of 10 m in the open, and four components of the FWI System (i.e., Fine Fuel Moisture Code, Drought Code, Initial Spread Index and Buildup Index). The models predicted correctly the type of fire (i.e., surface or crown) between 90% and 66% of the time. The C index, a statistical measure, varied from 0.94 to 0.71, revealing good concordance between predicted probabilities and observed events. A comparison between the logistic models and Canadian Forest Fire Behavior Prediction System models did not show any conclusive differences. The results of a limited evaluation involving two independent experimental fire data sets for distinctly different fuel complexes were encouraging. The logistic models built may have applicability in fire management decision support systems, allowing for the estimation of the probability of crown fire initiation at small and large spatial scales from commonly available fire environment and fire danger rating information. The relationships presented are considered valid for free-burning fires on level terrain in coniferous forests that have reached a pseudo steady-state and are not deemed applicable to dead conifer forests (i.e., insect-killed stands).

[This publication is referenced in the "Synthesis of knowledge of extreme fire behavior: volume I for fire managers" (Werth et al 2011).]

Online Link(s):
Cruz, Miguel G.; Alexander, Martin E.; Wakimoto, Ronald H. 2003. Assessing the probability of crown fire initiation based on fire danger indices. The Forestry Chronicle 79(5):976-983.