Numerical Simulation of Crown Fire Hazard Immediately after Bark Beetle-Caused Mortality in Lodgepole Pine Forests

Hoffman, Chad; Morgan, Penelope; Mell, William E.; Parsons, Russell A.; Strand, Eva K.; Cook, Stephen P.

doi:10.5849/forsci.10-137

Cited by 58 publications

(76 citation statements)

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“…At higher mortality levels, the abundance of burning dead trees begins to affect the burning of live trees, and the canopy begins to support some active crown fire activity even at low wind speeds. Simulations in lodgepole pine by Hoffman et al (2012b) showed a similar increase in canopy fuel consumption, as did observations by Harvey et al (2014b) in the earliest phases of a bark beetle outbreak in lodgepole pine in Wyoming, USA, and observations by Prichard and Kennedy (2014) following wildfires that burned through red-phase mortality in mixed conifer stands in Washington, USA. Here, we showed that this increase was not only due to fuel consumption of dead trees, but also due to fuel consumption of the live trees that survived the bark beetle outbreak, revealing the synergy between the two disturbances.…”

Section: Discussionmentioning

confidence: 51%

“…Linn et al (2012) found that the addition of dead needles during the gray phase provided greater surface fuel continuity, and therefore sustained simulated fire spread in patchy pinyon-juniper woodlands. The study by Hoffman (2011) in lodgepole pine forests found that simulated crown consumption was higher in stands expe-riencing between 20 % and 55 % mortality compared to green-phase stands, which they also attributed to the combination of increased wind penetration and surface fuels with adequate levels of crown continuity. Agne et al (2016) also noted that high-severity fire was more prevalent in lodgepole pine stands with lower levels of mountain pine beetle-caused tree mortality during the gray phase that burned in an Oregon, USA, wildfire.…”

Section: Discussionmentioning

confidence: 99%

“…Theoretical frameworks and some studies predict higher fire severity in the red phase and lower in the gray phase (Jenkins et al 2008, Hicke et al 2012, Prichard and Kennedy 2014, Meigs et al 2016. However, other studies have suggested that fires during the gray phase may be more severe than fires in green-phase forests, or they may be less severe or have little effect on fire severity in either phase (Hoffman 2011;Simard et al 2011;Donato et al 2013;Harvey et al 2014aHarvey et al , 2014b. These varying fuel effects across the temporal phases thus can potentially alter both the severity of a subsequent fire as well as type and magnitude of the bark beetle−fire interaction.…”

Section: Introductionmentioning

confidence: 99%

“…For example, several studies have suggested that the severity and rate of bark beetle-caused mortality plays a pivotal role in the severity of a subsequent fire (DeRose and Long 2009;Hoffman et al 2012b;Harvey et al 2014aHarvey et al , 2014bHoffman et al 2015). Thus, varying levels and rates of mortality may alter subsequent fire severity, whether the disturbances are linked or not, and even the type and magnitude of the interaction across different phases.…”

Section: Introductionmentioning

confidence: 99%

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2017

Fire Ecology

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Previous studies have suggested that bark beetles and fires can be interacting disturbances, whereby bark beetlecaused tree mortality can alter the risk and severity of subsequent wildland fires. However, there remains considerable uncertainty around the type and magnitude of the interaction between fires following bark beetle attacks, especially in drier forest types such as those dominated by ponderosa pine (Pinus ponderosa Lawson & C. Lawson). We used a full factorial design across a range of factors thought to control bark beetle−fire interactions, including the temporal phase of the RESUMENEstudios previos han sugerido que los escarabajos de la corteza y el fuego pueden ser disturbios interactivos, por lo que la mortalidad de árboles causada por estos escarabajos puede alterar el riesgo y la severidad de incendios subsecuentes. Sin embargo, una considerable incertidumbre persiste en torno al tipo y magnitud de la interacción entre los incendios que siguen al ataque de insectos, especialmente en tipos de bosques secos como los dominados por pino ponderosa (Pinus ponderosa Lawson & C. Lawson). Usamos un diseño factorial a través de un rango de factores que pensamos controlaban la interacción entre el escarabajo de la corteza y los incendios, incluyendo la fase temporal del estallido del insecto, el nivel Fire Ecology Volume 13, Issue 3, 2017 doi: 10.4996/fireecology.130300123 Sieg et al.: Bark Beetle-Fire Disturbance Interactions Page 2 outbreak, level of mortality, and wind speed. We used a three-dimensional physics-based model, HIGRAD/FIRE-TEC, to simulate fire behavior in fuel beds representative of 60 field plots across five national forests in northern Arizona, USA. The plots were dominated by ponderosa pine, and encompassed a gradient of bark beetlecaused mortality due to a mixture of both Ips and Dendroctonus species. Non-host species included two sprouting species, Gambel oak (Quercus gambelii Nutt.) and alligator juniper (Juniperus deppeana Steud.), as well as other junipers and pinyon pine (Pinus edulis Engelm.). The simulations explicitly accounted for the modifications of fuel mass and moisture distribution caused by bark beetle-caused mortality. We first analyzed the influence of the outbreak phase, level of mortality, and wind speed on the severity of a subsequent fire, expressed as a function of live and dead canopy fuel consumption. We then computed a metric based on canopy fuel loss to characterize whether bark beetles and fire are linked disturbances and, if they are, if the linkage is antagonistic (net bark beetle and fire severity being less than if the two disturbances occurred independently) or synergistic (greater combined effects than independent disturbances). Both the severity of a subsequent fire and whether bark beetles and fire are linked disturbances depended on the outbreak phase of the bark beetle mortality and attack severity, as well as the fire weather (here, wind). Greater fire severity and synergistic interactions were generally associated with the "red phase"...

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Section: Discussionmentioning

confidence: 51%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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2017

Fire Ecology

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“…The primary motivation driving the study of canopy architecture comes from the radiative transfer domain (Oker-blom and Kellomaki 1983;Duursma and Mäkelä 2007;Da Silva et al 2008;Parveaud et al 2008), but the arrangement of crown material is also important across a diverse array of interests ranging from long-established forest growth and competition modeling (Vanclay 1994) to novel approaches in wildland fire modeling that attempt to understand fire behavior and effects at very fine grains (Parsons et al 2011;Hoffman 2012).…”

Section: Introductionmentioning

confidence: 99%

Conifer crown profile models from terrestrial laser scanning

Ferrarese¹,

Affleck²,

Seielstad³

2015

Silva Fenn.

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• Crown models are derived from terrestrial laser data for 3 NW USA conifer species.• Crown models require only crown length for implementation.• Beta and Weibull curves fit to 95th percentile widths describe crown extent.• Crown profile curves are species-specific and not interchangeable.• Crown shape is not strongly conditioned by tree size or site. AbstractRegional crown profile models were derived for three conifer species of the interior northwestern USA from terrestrial laser scans of eighty-six trees across a range of sizes and growing conditions. Equations were developed to predict crown shape from crown length for Pseudotsuga menziesii, Pinus ponderosa, and Abies lasiocarpa from parametric curves applied to crown-length normalized laser point clouds. The 95th width percentile adequately described each crown's outer limit; alternate width percentiles produced little profile shape variation. For P. menziesii and P. ponderosa, a scaling parameter-modified beta curve gave the most accurate fit (using cross-validated Mean Absolute Error) to aggregated 95th width percentile points. For A. lasiocarpa, beta and Weibull curves (equivalently modified) produced similar results. For all species, modified beta and Weibull curves fit crown points with less error than conic or cylindrical profiles. Crown profile curves were species-specific; interchanging among species increased error significantly. Laser-derived crown base metrics provided objectivity and consistency, but underestimated field-derived base heights through inclusion of dead branches. Profile curve parameters were not correlated with tree or stand characteristics suggesting that crown shape is not strongly conditioned by size and site factors. However, laser sampling necessarily favored more open growing conditions, potentially under-representing variations in crown shape associated with social position. Overall, Terrestrial Laser Scanning (TLS) lends itself to detailed measurements of external crown architecture with occlusion-imposed limits to characterization of internal features. Yet, the time and cost of collecting and processing individual tree data precludes use of TLS as a common field sampling tool.

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Recent bark beetle outbreaks influence wildfire severity in mixed‐conifer forests of the Sierra Nevada, California, USA

Wayman

Safford

2021

Ecological Applications

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In temperate forests, elevated frequency of drought related disturbances will likely increase the incidence of interactions between disturbances such as bark beetle epidemics and wildfires. Our understanding of the influence of recent drought and insect-induced tree mortality on wildfire severity has largely lacked information from forests adapted to frequent fire. A recent unprecedented tree mortality event in California's Sierra Nevada provides an opportunity to examine this disturbance interaction in historically frequent-fire forests. Using field data collected within areas of recent tree mortality that subsequently burned in wildfire, we examined whether and under what conditions wildfire severity relates to severity of prefire tree mortality in Sierra Nevada mixed-conifer forests. We collected data on 180 plots within the 2015 Rough Fire and 2016 Cedar Fire footprints (California, USA). Our analyses identified prefire tree mortality as influential on all measures of wildfire severity (basal area killed by fire, RdNBR, and canopy torch) on the Cedar Fire, although it was less influential than fire weather (relative humidity). Prefire tree mortality was influential on two of three fire-severity measures on the Rough Fire, and was the most important predictor of basal area killed by fire; topographic position was influential on two metrics. On the Cedar Fire, the influence of prefire mortality on basal area killed by fire was greater under milder weather conditions. All measures of fire severity increased as prefire mortality increased up to prefire mortality levels of approximately 30-40%; further increases did not result in greater fire severity. The interacting disturbances shifted a pine-dominated system (Rough Fire) to a cedar-pine-fir system, while the pre-disturbance fir-cedar system (Cedar Fire) saw its dominant species unchanged. Managers of historically frequent-fire forests will benefit from utilizing this information when prioritizing fuels reduction treatments in areas of recent tree mortality, as it is the first empirical study to document a relationship between prefire mortality and subsequent wildfire severity in these systems. This study contributes to a growing body of evidence that the influence of prefire tree mortality on wildfire severity in temperate coniferous forests may depend on other conditions capable of driving extreme wildfire behavior, such as weather.

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Numerical Simulation of Crown Fire Hazard Immediately after Bark Beetle-Caused Mortality in Lodgepole Pine Forests

Cited by 58 publications

References 36 publications

Untitled

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Conifer crown profile models from terrestrial laser scanning

Recent bark beetle outbreaks influence wildfire severity in mixed‐conifer forests of the Sierra Nevada, California, USA

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