Class
Article
College
S.J. & Jessie E. Quinney College of Natural Resources
Department
Wildland Resources Department
Faculty Mentor
Larissa Yocom
Presentation Type
Poster Presentation
Abstract
Aspen trees (Populus tremuloides) are widely distributed across North America. They provide important wildlife habitat, livestock forage, understory biodiversity, landscape diversity, and aesthetic value. They have also been regarded as important for their ability to act as fuel breaks, at least under average conditions. There have been many qualitative accounts of crown fires dropping to surface fires or being extinguished when they encounter aspen stands. These observations of aspen reducing fire behavior (i.e., flame length, rate of spread, fire intensity) when compared to conifers has led to the idea that aspen could be strategically planted on the landscape, such as around wildland urban interface (WUI) communities, to reduce fire risk. However, aspen forests vary widely in structure and composition, and little quantitative data is available to guide managers regarding characteristics of aspen forests that would serve to modify fire behavior. This research provides a quantitative link between aspen composition and fire behavior. The metrics I used to measure fire behavior were flame length and tree mortality due to fire. Flame length represents the amount of energy released by the fire, which is fire intensity. Tree mortality due to fire indicates fire severity. Fire severity is measured by the effects of the fire on vegetation. I used the Forest Vegetation Simulator to simulate a forest fire in tree stands across two gradients: composition and successional stage. All other variables in the model were held constant. Composition varied from 0% aspen and 100% subalpine fir to 100% aspen and 0% subalpine fir. There were three successional stages – early (3-inch diameter subalpine fir), mid (6- and 9-inch diameter subalpine fir), and late (12-inch diameter subalpine fir). Increasing percentages of aspen correlate to a linear decrease in tree mortality. Increasing percentages of aspen correlate to a threshold decrease in flame length. Flame lengths are high across successional stages at 0% aspen in the stand, and they sharply decrease at 10% aspen in the stand. There are no clear correlations between successional stage and tree mortality or flame length. Managers may use aspen around communities to create fuel breaks. In differing compositions or successional stages, aspen could limit tree mortality or decrease fire intensity.
Location
Logan, UT
Start Date
4-12-2023 12:30 PM
End Date
4-12-2023 1:30 PM
Included in
How Aspen Trees Affect Fire Behavior
Logan, UT
Aspen trees (Populus tremuloides) are widely distributed across North America. They provide important wildlife habitat, livestock forage, understory biodiversity, landscape diversity, and aesthetic value. They have also been regarded as important for their ability to act as fuel breaks, at least under average conditions. There have been many qualitative accounts of crown fires dropping to surface fires or being extinguished when they encounter aspen stands. These observations of aspen reducing fire behavior (i.e., flame length, rate of spread, fire intensity) when compared to conifers has led to the idea that aspen could be strategically planted on the landscape, such as around wildland urban interface (WUI) communities, to reduce fire risk. However, aspen forests vary widely in structure and composition, and little quantitative data is available to guide managers regarding characteristics of aspen forests that would serve to modify fire behavior. This research provides a quantitative link between aspen composition and fire behavior. The metrics I used to measure fire behavior were flame length and tree mortality due to fire. Flame length represents the amount of energy released by the fire, which is fire intensity. Tree mortality due to fire indicates fire severity. Fire severity is measured by the effects of the fire on vegetation. I used the Forest Vegetation Simulator to simulate a forest fire in tree stands across two gradients: composition and successional stage. All other variables in the model were held constant. Composition varied from 0% aspen and 100% subalpine fir to 100% aspen and 0% subalpine fir. There were three successional stages – early (3-inch diameter subalpine fir), mid (6- and 9-inch diameter subalpine fir), and late (12-inch diameter subalpine fir). Increasing percentages of aspen correlate to a linear decrease in tree mortality. Increasing percentages of aspen correlate to a threshold decrease in flame length. Flame lengths are high across successional stages at 0% aspen in the stand, and they sharply decrease at 10% aspen in the stand. There are no clear correlations between successional stage and tree mortality or flame length. Managers may use aspen around communities to create fuel breaks. In differing compositions or successional stages, aspen could limit tree mortality or decrease fire intensity.