Assessing canopy fuel stratum characteristics in crown fire prone fuel types of western North America

Cruz, Miguel G.; Alexander, Martin E.; Wakimoto, Ronald H.

doi:10.1071/wf02024

Cited by 170 publications

(187 citation statements)

References 44 publications

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“…In recent studies, the term "crown" is applied to describe aerial fuels at the tree level and "canopy" at the stand level [23]. Computer systems and models that simulate crown fire behavior need a quantitative description of the canopy fuels; available canopy fuel load (CFL), canopy bulk density (CBD) and canopy base height (CBH) [31,32,70].…”

Section: Canopy Fuelsmentioning

confidence: 99%

“…Nevertheless, current research efforts state that in certain fuel complexes, other fuel categories, such as the fine twigs, may significantly contribute to the heat released from the flaming zone of a crown fire [19,70,76]. Although numerous studies correlate crown or foliage biomass with tree dendrometric characteristics [13,37,46,51,53,55,56], only few studies measure crown fuel load by diameter size class at tree level [15,39,40,73] and at stand level [9,23], as it is required in crown fire behavior modeling.…”

Section: Cflmentioning

confidence: 99%

“…CBD is difficult to measure because it requires detailed knowledge of the vertical distribution of crown fuel biomass. For uniform stands, CBD can be computed as the available canopy fuel load divided by canopy depth [1,6,23,33,42]. This method carries the implicit assumption that canopy biomass is distributed uniformly within the stand canopy, which is unlikely to be true even in stands with very simple structure; multi-storied stands are probably even more poorly represented by this procedure [70].…”

Section: Cbdmentioning

confidence: 99%

Section: Cbhmentioning

confidence: 99%

“…One of the main problems is the lack of a universally accepted definition for the lower limit of the canopy fuel layer [23]. Several authors [23,45,52,79] consider as CBH the distance from the forest floor to the live crown base. Wilson and Baker [83] used the midpoint between the minimum CBH from the ground and the average live crown height for calculating crown fire initiation risk in multi-layered stands.…”

Section: Cbhmentioning

confidence: 99%

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Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

Mitsopoulos

Dimitrakopoulos

2007

Ann. For. Sci.

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-Canopy fuel characteristics that influence the initiation and spread of crown fires were measured in representative Aleppo pine (Pinus halepensis Mill.) stands in Greece. Vertical distribution profiles of canopy fuel load, canopy base height and canopy bulk density are presented. Aleppo pine canopy fuels are characterized by low canopy base height (3.0−6.5 m), while available canopy fuel load (0.96−1.80 kg/m 2 ) and canopy bulk density (0.09−0.22 kg/m 3 ) values are similar to other conifers worldwide. Crown fire behavior (probability of crown fire initiation, crown fire type, rate of spread, fireline intensity and flame length) in Aleppo pine stands with various understory fuel types was simulated with the most updated crown fire models. The probability of crown fire initiation was high even under moderate burning conditions, mainly due to the low canopy base height and the heavy surface fuel load. Passive crown fires resulted mostly in uneven aged stands, while even aged stands gave high intensity active crown fires. Assessment of canopy fuel characteristics and potential crown fire behavior can be useful in fuel management and fire suppression planning.canopy fuels / crown fires / fire behavior / Aleppo pine (Pinus halepensis Mill.) / Mediterranean Basin Résumé -Caractéristiques des combustibles de la canopée et comportement du potentiel de feu des couronnes de forêts de Pin d'Alep (Pinus halepensis Mill.). Les caractéristiques des combustibles qui influencent le démarrage et la propagation des feux de couronnes ont été mesurées dans des peuplements représentatifs de Pinus halepensis Mill. en Grèce. Des profils verticaux de la charge en combustible de la canopée, la hauteur de la base de la canopée et la densité volumique de la canopée sont présentés. La charge combustible de la canopée est caractérisée par une faible hauteur de la base de la canopée (3,0−6,5 m), tandis que la charge en combustible disponible (0,96−1,80 kg/m 2 ) et la densité volumique de la canopée (0,09−0,22 kg/m 3 ) sont similaires à celles des autres conifères dans le monde. Le comportement du feu de couronne (probabilité de démarrage du feu dans les couronnes, type de feu de couronne, taux de propagation, intensité de la ligne de feu et longueur des flammes) dans les peuplements de Pinus halepensis avec différents types de combustibles de sous-bois a été simulé avec le maximum de modèles actuels de feux de couronnes. La probabilité de démarrage de feu de couronne était forte même en conditions de faible embrasement, principalement en relation avec la faible hauteur de la base des couronnes et la forte charge en combustible au sol. Des feux passifs de couronnes se produisent principalement dans les peuplements inéquiennes tandis que les peuplements équiennes ont présenté de fortes intensités de feux actifs de couronnes. L'évaluation des caractéristiques des combustibles de la canopée et le comportement du potentiel de feu peuvent être très utiles pour la gestion des combustibles et la planification de la lutte contre les feux. c...

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Section: Canopy Fuelsmentioning

confidence: 99%

Section: Cflmentioning

confidence: 99%

Section: Cbdmentioning

confidence: 99%

Section: Cbhmentioning

confidence: 99%

Section: Cbhmentioning

confidence: 99%

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Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

Mitsopoulos

Dimitrakopoulos

2007

Ann. For. Sci.

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Landscape variation in tree regeneration and snag fall drive fuel loads in 24‐year old post‐fire lodgepole pine forests

Nelson

Turner

Romme

2016

Ecological Applications

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Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires.

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Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios

et al. 2022

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Increasing wildfire activity has spurred ecological resilience‐based management that aims to reduce the vulnerability of forest stands to wildfire by reducing the probability of crown fire. Targeted grazing is increasingly being used to build forest resilience to wildfire, either on its own or in combination with treatments such as mechanical thinning; however, it is unclear how effective this method is at altering the probability of crown fire in forest stands. We use crown fire simulation models to quantify to what extent targeted grazing, mechanical thinning targeting the vertical fuel stratum, and a combination of both treatments alter eastern ponderosa pine savanna stand resilience to wildfire by modeling their relative impacts on the fuel stratum gap and subsequent crown fire occurrence under six different wildfire risk scenarios generated by altering wind and fuel moisture conditions. We then model changes in the probability of crown fire occurrence resulting from treatments across 75 field‐sampled sites in the Pine Ridge region of Nebraska relative to predicted crown fire occurrence when sites are left untreated. We find that mechanical (vertical) thinning has the potential to alter the probability of crown fire in ponderosa pine stands to a much greater extent than targeted grazing. Combining both approaches had a slightly higher probability of reducing crown fire risk across the greatest range of wildfire risk scenarios. Across 75 sample sites, targeted grazing was only predicted to prevent crown fire occurrence at two sites expected to experience crown fire under observed stand conditions across all six of our wildfire risk scenarios. In contrast, targeted grazing combined with mechanical thinning was predicted to prevent crown fire at approximately half of the sites expected to experience crown fire under observed conditions for mild and moderate wildfire risk scenarios. Thus, targeted grazing should be combined with mechanical thinning to best enhance forest resilience to wildfire. No combination of targeted grazing or mechanical thinning was able to alter the probability of crown fire under wildfire risk scenarios most conducive to wildfire, confirming that relying solely on vertical thinning and targeted grazing is unlikely to sufficiently enhance resilience of forest stands to future wildfire conditions.

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Assessing canopy fuel stratum characteristics in crown fire prone fuel types of western North America

Cited by 170 publications

References 44 publications

Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

Landscape variation in tree regeneration and snag fall drive fuel loads in 24‐year old post‐fire lodgepole pine forests

Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios

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