Wildfire containment probability is not affected by eastern spruce budworm defoliation in Ontario, Canada

Kennedy Korkola; Jennifer L. Beverly; Patrick M. A. James

doi:10.1071/WF25058

RESEARCH ARTICLE (Open Access)

Previous Contents Vol 34(9)

Wildfire containment probability is not affected by eastern spruce budworm defoliation in Ontario, Canada

Kennedy Korkola ^A ^* , Jennifer L. Beverly

^B and Patrick M. A. James ^A

+ Author Affiliations

- Author Affiliations

^A Institute of Forestry and Conservation, John H. Daniels Faculty of Architecture, Landscape and Design, University of Toronto, Toronto, ON M5S 3B3, Canada.

^B Department of Renewable Resources, 751 General Services Building, University of Alberta, Edmonton, AB, T6G 2H1, Canada.

^* Correspondence to: kennedy.korkola@mail.utoronto.ca

International Journal of Wildland Fire 34, WF25058 https://doi.org/10.1071/WF25058

Submitted: 18 March 2025 Accepted: 24 July 2025 Published: 5 September 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Stand-replacing wildfires and eastern spruce budworm outbreaks (Choristoneura fumiferana; SBW) are important disturbances in the boreal forest. SBW defoliation can affect fire behaviour by altering fuel loads and connectivity, thereby promoting the transition of low-activity surface fires into crown fires. However, little is known about how these altered fuels impact the effectiveness of fire suppression.

Aims

To assess key drivers of initial attack (IA) success in Ontario’s boreal forest and determine if incorporating SBW defoliation data improves predictive models.

Methods

We developed random forest models of fire containment using established predictors including fire weather, fire size at IA and region. We then evaluated if the inclusion of time since SBW defoliation improved model performance.

Key results

Fire size at IA was the most influential variable for determining whether a fire escaped containment. Contrary to our hypothesis, we did not find evidence that SBW defoliation greatly improved model performance.

Conclusions and implications

The size of the fire at IA was the most important variable in determining successful containment. Although budworm defoliation has been shown to affect other aspects of fire hazard, we were unable to identify an influence on IA success. Future work could benefit from focused investigation into how historical SBW defoliation affects fire behaviour.

Keywords: containment probability, defoliation, fire containment, forest fire, initial attack success, machine learning, random forest, spruce budworm, wildland fire.

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