Firefighter Observations of “Surprising” Fire Behavior in Mountain Pine Beetle-Attacked Lodgepole Pine Forests

Abstract

The recent mountain pine beetle outbreak affecting lodgepole pine forests in the Rocky Mountains has created a novel fire environment for wildland firefighters. This paper presents results from an examination of firefighters’ observations of fire behavior in post-outbreak lodgepole pine forests, with a focus on what they considered surprising from a fire behavior standpoint and how this in turn affected their suppression tactics. The surprises in fire behavior experienced by firefighters during the red phase of post-outbreak forests included an elevated level of fire spread and intensity under moderate weather and fuel moisture conditions, increased spotting, and faster surface-to-crown fire transitions with limited or no ladder fuels. Unexpectedly, during the gray phase in mountain pine beetle-attacked stands, crown ignition and crown fire propagation was observed for short periods of time. Firefighters are now more likely to expect to see active fire behavior in nearly all fire weather and fuel moisture conditions, not just under critically dry and windy situations, and across all mountain pine beetle attack phases, not just the red phase. Firefighters changed their suppression tactics by adopting indirect methods due to the potential fire behavior and tree-fall hazards associated with mountain pine beetle-attacked lodgepole pine forests.

Simulating spatial complexity in dry conifer forest restoration: implications for conservation prioritization and scenario evaluation

“…Forest structure and fuels are described by canopy cover, canopy bulk density, canopy base height, canopy height, and categorical fire behavior fuel model (Scott and Burgan 2005). We adjusted the baseline data for lodgepole pine by lowering the canopy base height by 20% and changing the fire behavior fuel model from moderate load conifer litter to high load conifer litter (Scott and Burgan 2005) to better reflect recent fire behavior observations (Moriarty et al 2019). Starting with the baseline fuelscape, we simulated each conservation practice design by adjusting fuel structure data according to the expected changes in fuel structure for each treatment.…”

An Operationally Relevant Framework for Mapping Spot Fire Transmission Potential

“…Estimating EP based on canopy mass engaged in combustion is more consistent than the stochastic production of embers in fire spread models [16], but our assumed scaling relationship is unvalidated. We also did not account for several factors that may influence ember generation, including inter-species differences in bark, branch, foliage, cone, or wood characteristics and the presence of standing, dead, or downed trees from windthrow or insect mortality [35][36][37][38]. The focus on canopy fuels is clearly a limitation for SP assessment in non-forest environments.…”

Forest Roads and Operational Wildfire Response Planning

“…Managers likely exhibited a strong preference for roads and trails because accessibility is a major constraint on firefighting operations due to the rugged topography. Roads are also viewed as the safest locations to engage with fires in the large portion of the CLRD where abundant standing and fallen dead trees from recent outbreaks of mountain pine beetle and spruce beetle impede cross country travel and increase firefighter hazards [55]. Comparison of panel (b) and panel (c) in Figure 4 indicates the strong alignment of high PCL features with manager-selected POD boundaries.…”