Balancing wildlife protection and wildfire threat mitigation using a network optimization approach

Abstract

In boreal forests of North America, land managers often carry out preventive treatments of forest fuel for the protection of human infrastructure from wildfires. However, these treatments may negatively affect other ecosystem services, such as the capacity to sustain wildlife populations. Here, we examine the efficacy of a strategy aimed at preserving a critical movement corridor for boreal woodland caribou (Rangifer tarandus caribou) in northern Québec, Canada, by raising high-voltage power line conductors above the forest canopy. To assess the interplay between the caribou protection objectives and a reduction in power line's exposure to wildfires, we developed an optimization model that combines the objectives of protecting the power line from wildfires via fuel treatments and maintaining a suitable movement corridor for caribou. The model combines a critical node detection (CND) problem with a habitat connectivity problem that allocates a minimum-resistance fixed-width habitat corridor between isolated wildlife refuges. Our results identify the best locations to perform fire fuel treatments to lessen the threat of fire damage to human infrastructure while maintaining a connectivity corridor for caribou in present and future climate scenarios. The selected fuel treatment locations aimed to mitigate wildfire exposure to a power line. In small-budget solutions, the exposure of power line infrastructure to wildfires was reduced by 36–39% in current climate conditions and by 20–31% in future climate, compared with no-treatment scenarios. Despite the detrimental effects of wildfire on both the industrial asset and caribou habitat, the approach provides strategies that help achieve a compromise between these two values. Such knowledge is timely to help mitigate the negative impacts of climate change on human livelihoods and natural ecosystems.

PostBP: A Python library to analyze outputs from wildfire growth models

“…This ensures that the function iterates through both Burn-P3 iterations and the fire IDs within each iteration. Note that the most common Burn-P3 scenarios simulate one fire spread event per iteration [ 19 , 22 ].…”

“…Another useful summary metric is the source-sink ratio [ 18 ] that defines the ratio between the expected number of fires originating from a given location and the expected number of fires spreading to that location from elsewhere. A more complex approach is to map the fire spread vectors and likelihoods between all pairs of locations across the landscape [ 13 , 19 ], which enables characterizing the directional spread of wildfires. For a given pair of forest patches i,j , this approach defines the likelihood that a fire ignited in i will spread to j .…”

“…For a given pair of forest patches i,j , this approach defines the likelihood that a fire ignited in i will spread to j . The landscape is characterized by a set of fire spread vectors between all pairs of locations; this set preserves information about prevailing fire spread directions and distances and thus helps better facilitate effective planning of wildfire risk mitigation and suppression activities [ 13 , 19 ]. The novelty of our approach is that it enables a detailed mapping of fire spread pathways, and the depiction of likely directions and fire spread distances, which provides important insights for managing wildfire risks and designing fire mitigation measures.…”