Foliar moisture content of Pacific Northwest vegetation and its relation to wildland fire behavior

Agee, James K.; Wright, Clinton S.; Williamson, Nathan; Huff, Mark H.

doi:10.1016/s0378-1127(01)00690-9

Cited by 112 publications

(99 citation statements)

References 9 publications

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“…Ten samples of 1-year-old foliage, >1-year-old foliage, and small twigs (0.0-0.6 cm) for each species were collected from the lower crown on the south side of the tree between 1400 and 1700 h to minimize variation (Agee et al 2002). Samples were sealed in plastic bags, weighed wet, and then dried at 70°C for 48 h. Douglas-fir samples were approximately 25 g, and tanoak samples were approximately 45 g.…”

Section: Foliar Moisturementioning

confidence: 99%

Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA

Raymond¹,

Peterson²

2005

Can. J. For. Res.

144

131

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We had the rare opportunity to quantify the relationship between fuels and fire severity using prefire surface and canopy fuel data and fire severity data after a wildfire. The study area is a mixed-evergreen forest of southwestern Oregon with a mixed-severity fire regime. Modeled fire behavior showed that thinning reduced canopy fuels, thereby decreasing the potential for crown fire spread. The potential for crown fire initiation remained fairly constant despite reductions in ladder fuels, because thinning increased surface fuels, which contributed to greater surface fire intensity. Thinning followed by underburning reduced canopy, ladder, and surface fuels, thereby decreasing surface fire intensity and crown fire potential. However, crown fire is not a prerequisite for high fire severity; damage to and mortality of overstory trees in the wildfire were extensive despite the absence of crown fire. Mortality was most severe in thinned treatments (80%-100%), moderate in untreated stands (53%-54%), and least severe in the thinned and underburned treatment (5%). Thinned treatments had higher fine-fuel loading and more extensive crown scorch, suggesting that greater consumption of fine fuels contributed to higher tree mortality. Fuel treatments intended to minimize tree mortality will be most effective if both ladder and surface fuels are treated.Résumé : Les auteurs ont eu une occasion exceptionnelle de quantifier la relation entre les combustibles et la sévérité du feu en utilisant des données récoltées avant un incendie sur les combustibles de surface et dans la canopée ainsi que des données sur l'intensité du feu après un incendie de forêt. L'aire d'étude est une forêt mélangée de conifères du sud-ouest de l'Oregon avec un régime de feux d'intensité mixte. La modélisation du comportement du feu a montré que l'éclaircie a réduit les combustibles dans la canopée, ce qui a diminué le potentiel de propagation d'un feu de cime. Les risques d'initiation d'un feu de cime n'ont pas changé malgré la réduction des combustibles étagés parce que l'éclaircie a augmenté les combustibles de surface, ce qui a contribué à accentuer l'intensité du feu de surface. L'éclaircie suivie d'un brûlage au sol a réduit les combustibles dans la canopée, le long du tronc et en surface, diminuant par conséquent l'intensité du feu de surface et les possibilités d'un feu de cime. Cependant, un feu de cime n'est pas né-cessaire pour avoir un feu de forte intensité; les dommages et la mortalité chez les arbres de l'étage dominant causés par un incendie de forêt ont été importants malgré l'absence d'un feu de cime. La mortalité était la plus élevée dans les peuplements éclaircis (80-100 %), modérée dans les peuplements non traités (53-54 %) et la moins élevée dans les peuplements éclaircis et soumis à un brûlage dirigé (5 %). Les peuplements éclaircis avaient une quantité plus importante de combustibles fins et plus de roussissement des cimes, ce qui indique qu'une plus grande consommation de combustibles fins a contribué à une plus fort...

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Section: Foliar Moisturementioning

confidence: 99%

Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA

Raymond¹,

Peterson²

2005

Can. J. For. Res.

144

131

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“…Rates of resprouting vary widely depending on a plant's growth form, age, and resource availability (Bond and Midgley 2003;Vesk 2006). Fire causes mortality of riparian trees by combusting tissue or producing lethal internal temperatures, with the risk often lowest both for older trees and for those nearest the humid margin of perennial river channels (Agee et al 2002;Danehy and Kirpes 2000).…”

Section: Introductionmentioning

confidence: 99%

Effects of Fire on Riparian Forests Along a Free-Flowing Dryland River

Stromberg

Rychener

2009

Wetlands

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Riparian fire studies in the American Southwest have focused on flow-regulated rivers and typically show increase in introduced Tamarix, a species with high resprout capacity, and declines in Populus. Effects of fire, however, can vary with environmental setting. We examined riparian fire along the free-flowing Upper San Pedro River (Arizona) by making temporal comparisons supplemented by spatial contrasts between burned and unburned sites. Pre-fire, Populus fremontii and Salix gooddingii were dominant species, with Tamarix sparse in the understory. Species differed in mortality and resprout rates, producing post-fire vegetation change. Mortality was highest for Tamarix, intermediate for Salix, and lowest for Populus, and also varied among size classes. Resprout rate was low for Populus, high for Salix, and also high for the few surviving Tamarix. The net effect was changes in population size structure (relative shifts towards larger Populus but smaller individuals of other species) and forest composition (decreased abundance of Tamarix relative to Populus and Salix), and in spatial distribution of stems. Tamarix's low ability to survive fire resulted from competitive suppression by Populus and Salix, with their dominance a product of the site's flow regime. Results indicate that post-fire outcomes within the riparian Southwest are variable and context-dependent.

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“…Other types of live vegetation, like evergreen mature tree foliage without severe soil water deficit, will even usually maintain an approximately constant M l over the year (Pook & Gill, 1993;Agee et al, 2002). However, for the shrubs addressed by this study, the difference between minimum and maximum M l was 32.1% for average monthly means (Fig.…”

Section: Unifying Laboratory and Field Evidencementioning

confidence: 68%

Short communication: On the effect of live fuel moisture content on fire-spread rate

Rossa

Fernandes

2018

For. syst.

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Aim of study: To reconcile the effects of live fuel moisture content (FMC) on fire rate of spread (ROS) derived from laboratory and field fires.Methods: The analysis builds on evidence from previous fire-spread experimental studies and on a comparison between two functions for the FMC damping effect: one derived from field burns, based on dead FMC, and another derived from laboratory trials, based on a weighted FMC (dead and live fuels).Main results: In a typical Mediterranean shrubland, laboratory and field-derived FMC damping functions are linearly related, which is explained by the correlation between monthly average live and dead FMC variation throughout the year. This clarifies why the effect of live FMC on real-world fires ROS has remained elusive, although in fact it has an influence.Research highlights: By providing evidence that the most significant effect of FMC on ROS is independent of vegetation phenology (dead or live condition), and explaining why in specific situations dead FMC is sufficient to provide satisfactory ROS predictions, our results can assist future modelling efforts.Additional keywords: fire behaviour; forest fuels; plant phenology; combustion.

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Foliar moisture content of Pacific Northwest vegetation and its relation to wildland fire behavior

Cited by 112 publications

References 9 publications

Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA

Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA

Effects of Fire on Riparian Forests Along a Free-Flowing Dryland River

Short communication: On the effect of live fuel moisture content on fire-spread rate

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