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Windows of opportunity for allowing wilderness fires to burn

Date: September 13, 2016

Many ignitions that occur inside wilderness have very low likelihoods of escaping the wilderness boundary, especially early and late in the fire season. We quantified this probability of escape and mapped these “windows” of opportunity


Background

A goal of fire management in wilderness is to allow fire to play its natural ecological role without intervention. Unfortunately, most unplanned ignitions in wilderness are suppressed, in part because of the risk they might pose to values outside of the wilderness. We capitalize on recent advances in fire risk analysis to demonstrate a risk-based approach for revealing where unplanned ignitions in wilderness pose little risk to non-wilderness values and therefore where fire can be managed for its longer term ecological benefits. Although this approach was demonstrated in the context of wilderness fire management, it has broad applicability and could support spatial fire and fuels management planning efforts in non-wilderness settings.

Research

The fire management community has embraced the concept of risk assessment for all fire and fuels management activities, and geospatial analysis tools are commonly used to map where fire is likely to cause damage. We are adapting these concepts and tools for use in the wilderness context, where the goal of fire management is to allow fire to play its natural ecological role. We used spatial risk analysis tools to map the likelihood that an unplanned ignition in wilderness would escape the wilderness boundary or reach the wildland-urban interface and to identify where and when “windows of opportunity” exist for allowing wilderness fires to burn. Importantly, these maps can reveal opportunities for managing wildfires for their resource benefits and thus integrate well with land management plans and spatial fire management plans. In addition, output from the analysis can be used to summarize escape probability in terms of escaped fire size, distance to the boundary, and month of ignition. We propose to refine and streamline these methods so that maps depicting “windows of opportunity” can be readily generated for any management unit and be used to inform forest and fire management planning.

Key Findings

  • In the wilderness areas we studied, there were large zones where fires had a very low likelihood of escape. These are zones where unplanned ignitions can be allowed to burn naturally and used to meet resource objectives.

  • The risk of escape depends on the proximity of the ignition to the wilderness boundary, and on when the fires start in the fire season.

  • Mid-season fires were more likely to become large and spread outside the wilderness boundary compared to early or late season fires.

  • The methods integrate well with spatial fire planning activities that are increasingly being adopted to support pre-season planning and real-time incident management decision environments.

Maps of the likelihood of unsuppressed ignitions spreading outside the wilderness study area boundary for each month of ignition in simulated fire seasons.
Maps of the likelihood of unsuppressed ignitions spreading outside the wilderness study area boundary for each month of ignition in simulated fire seasons.

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Principal Investigators: 
Forest Service Partners: 
Don Helmbrecht, technician
External Partners: 
Kevin Barnett, University of Montana
Joe Scott, Pyrologix LLC