Fuel treatments reduce the severity of wildfire effects in dry mixed conifer forest, Washington, USA

2010 ◽  
Vol 40 (8) ◽  
pp. 1615-1626 ◽  
Author(s):  
Susan J. Prichard ◽  
David L. Peterson ◽  
Kyle Jacobson
Keyword(s):  
Prescribed Burning ◽  
Fire Severity ◽  
Large Diameter ◽  
Severity Index ◽  
Prescribed Burn ◽  
Conifer Forest ◽  
Fuel Treatments ◽  
Quantitative Evidence ◽  
Control Units ◽  
And Control

To address hazardous fuel accumulations, many fuel treatments are being implemented in dry forests, but there have been few opportunities to evaluate treatment efficacy in wildfires. We documented the effectiveness of thinning and prescribed burning in the 2006 Tripod Complex fires. Recent fuel treatments burned in the wildfires and offered an opportunity to evaluate if two treatments (thin only and thin and prescribed burn) mitigated fire severity. Fire severity was markedly different between the two treatments. Over 57% of trees survived in thin and prescribed burn (thinRx) units versus 19% in thin only (thin) and 14% in control units. Considering only large-diameter trees (>20 cm diameter at breast height), 73% survived in thinRx units versus 36% and 29% in thin and control units, respectively. Logistic regression modeling demonstrates significant reductions in the log-odds probability of tree death under both treatments with a much greater reduction in thinRx units. Other severity measures, including percent crown scorch and burn severity index, are significantly lower in thinRx units than in thin and control units. This study provides strong quantitative evidence that thinning alone does not reduce wildfire severity but that thinning followed by prescribed burning is effective at mitigating wildfire severity in dry western forests.

scholarly journals Comparing Modeled Emissions from Wildfire and Prescribed Burning of Post-Thinning Fuel: A Case Study of the 2016 Pioneer Fire

Fire ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 22
Author(s):  
Josh Hyde ◽  
Eva K. Strand
Keyword(s):  
Air Quality ◽  
Prescribed Fire ◽  
Prescribed Burning ◽  
Effective Means ◽  
National Forest ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Fuel Treatments ◽  
Mixed Conifer Forest

Prescribed fire is often used by land managers as an effective means of implementing fuel treatments to achieve a variety of goals. Smoke generated from these activities can put them at odds with air quality regulations. We set out to characterize the emission tradeoff between wildfire and prescribed fire in activity fuels from thinning in a case study of mixed conifer forest within the Boise National Forest in central Idaho. Custom fuelbeds were developed using information from the forest and emissions were modeled and compared for four scenarios, as follows: Untreated fuels burned in wildfire (UNW), prescribed fire in activity fuels left from thinning (TRX), a wildfire ignited on the post-treatment landscape (PTW), and the combined emissions from TRX followed by PTW (COM). The modeled mean total emissions from TRX were approximately 5% lower, compared to UNW, and between 2–46% lower for individual pollutants. The modeled emissions from PTW were approximately 70% lower than UNW. For the COM scenario, emissions were not significantly different from the UNW scenario for any pollutants, but for CO2. However, for the COM scenario, cumulative emissions would have been comprised of two events occurring at separate times, each with lower emissions than if they occurred at once.

Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest

2006 ◽  
Vol 15 (1) ◽  
pp. 37 ◽  
Author(s):  
Eric E. Knapp ◽  
Jon E. Keeley
Keyword(s):  
Sierra Nevada ◽  
Prescribed Burning ◽  
Fire Severity ◽  
Basal Area ◽  
Conifer Forest ◽  
Fuel Loading ◽  
Early Season ◽  
Late Season ◽  
Fuel Loads ◽  
In Fire

Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.

Prescribed-fire effects on fine-root and tree mortality in old-growth ponderosa pine

1991 ◽  
Vol 21 (5) ◽  
pp. 626-634 ◽  
Author(s):  
D. Michael Swezy ◽  
James K. Agee
Keyword(s):  
Ponderosa Pine ◽  
Tree Mortality ◽  
Prescribed Burning ◽  
Fine Root ◽  
Soil Depth ◽  
Fire Severity ◽  
Dry Weight ◽  
Prescribed Burn ◽  
Old Growth ◽  
Root Dry Weight

Old-growth Pinusponderosa Dougl. stands were surveyed at Crater Lake National Park to investigate potential accelerated mortality of large pines due to prescribed burning. Mortality of P. ponderosa greater than 22 cm diameter at breast height was higher in burned areas (19.5%) than in unburned areas (6.6%), and early-season burns had over 30% mortality. Mortality was associated with fire severity, as measured by scorch height and ground char, season of burning, and tree vigor. Pines of high, moderate, and low vigor were subjected to a prescribed burn in June; half of the trees had debris raked from tree bases as an additional treatment. Lethal heat loads (>60 °C) occurred in >75% of samples at the soil surface and at 5 cm soil depth, with duration exceeding 5 h. Burning reduced fine-root dry weight 50–75% 1 and 5 months after burning; raking and burning reduced fine-root dry weight more than burning alone after 1 month and had similar effects to burning after 5 months. A low-vigor tree that had been raked and burned died by the beginning of the fourth dry season after burning. Present fuel loads may be too high to burn during spring if old-growth P. ponderosa are to be protected.

A fuel treatment reduces fire severity and increases suppression efficiency in a mixed conifer forest

2007 ◽  
Vol 16 (6) ◽  
pp. 673 ◽  
Author(s):  
Jason J. Moghaddas ◽  
Larry Craggs
Keyword(s):  
Fire Severity ◽  
Private Land ◽  
Limited Information ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Fuel Treatments ◽  
Private Lands ◽  
Fuel Treatment ◽  
Public And Private ◽  
Spot Fires

Fuel treatments are being implemented on public and private lands across the western United States. Although scientists and managers have an understanding of how fuel treatments can modify potential fire behaviour under modelled conditions, there is limited information on how treatments perform under real wildfire conditions in Sierran mixed conifer forests. The Bell Fire started on 22 September 2005 on the Plumas National Forest, CA. This fire burned upslope into a 1-year old, 158-ha mechanical fuel treatment on private land. Prior to coming into contact with the fuel treatment, the main fire ignited spot fires 400 feet (122 metres) into the treated area. Overall, this fuel treatment resulted in: (1) increased penetration of retardant to surface fuels; (2) improved visual contact between fire crews and the Incident Commander; (3) safe access to the main fire; and (4) quick suppression of spot fires. This treatment was relatively small and isolated from other fuel treatments but resulted in decreased severity, suppression costs and post-fire rehabilitation needs, leading to cost savings for local public and private land managers.

Fuel treatment effects on tree mortality following wildfire in dry mixed conifer forests, Washington State, USA

2012 ◽  
Vol 21 (8) ◽  
pp. 1004 ◽  
Author(s):  
Susan J. Prichard ◽  
Maureen C. Kennedy
Keyword(s):  
Pinus Ponderosa ◽  
Tree Mortality ◽  
Prescribed Burning ◽  
Strong Predictor ◽  
Large Diameter ◽  
Lower Probability ◽  
First Year ◽  
Prescribed Burn ◽  
Fuel Treatment ◽  
Crown Scorch

Fuel reduction treatments are increasingly used to mitigate future wildfire severity in dry forests, but few opportunities exist to assess their effectiveness. We evaluated the influence of fuel treatment, tree size and species on tree mortality following a large wildfire event in recent thin-only, thin and prescribed burn (thin-Rx) units. Of the trees that died within the first 3 years, most died in the first year regardless of treatment. First-year mortality was much higher in control and thin-only units (65 and 52%) than in thin-Rx units (37%). Cumulative third-year mortality followed a similar trend (78 and 64% in control and thin-only units) v. 43% in thin-Rx units. Percentage crown scorch is a strong predictor of mortality and is highly dependent on fuel treatment. Across all treatments, Pinus ponderosa had a lower probability of post-fire mortality than did Pseudotsuga menziesii. Finally, the probability of beetle attack on surviving trees was highest in large-diameter trees within thin-only treatments and lowest within thin-Rx treatments. This study contributes further evidence supporting the effectiveness of thinning and prescribed burning on mitigating post-fire tree mortality. We also present evidence that a combination of thinning and prescribed burning is associated with lower incidence of post-fire bark beetle attack.

Stand- and landscape-level effects of prescribed burning on two Arizona wildfires

2005 ◽  
Vol 35 (7) ◽  
pp. 1714-1722 ◽  
Author(s):  
Mark A Finney ◽  
Charles W McHugh ◽  
Isaac C Grenfell
Keyword(s):  
Prescribed Fire ◽  
Ponderosa Pine ◽  
Prescribed Burning ◽  
Wildland Fire ◽  
Fire Severity ◽  
Prescribed Burn ◽  
Fire Size ◽  
Ponderosa Pine Forests ◽  
Model Predictions ◽  
Landsat 7

Performance of fuel treatments in modifying behavior and effects of the largest wildfires has rarely been evaluated, because the necessary data on fire movement, treatment characteristics, and fire severity were not obtainable together. Here we analyzed satellite imagery and prescribed fire records from two Arizona wildfires that occurred in 2002, finding that prescribed fire treatments reduced wildfire severity and changed its progress. Prescribed burning in ponderosa pine forests 1–9 years before the Rodeo and Chediski fires reduced fire severity compared with untreated areas, despite the unprecedented 1860-km2 combined wildfire sizes and record drought. Fire severity increased with time since treatment but decreased with unit size and number of repeated prescribed burn treatments. Fire progression captured by Landsat 7 enhanced thematic mapper plus (ETM+) clearly showed the fire circumventing treatment units and protecting areas on their lee side. This evidence is consistent with model predictions that suggest wildland fire size and severity can be mitigated by strategic placement of treatments.

Sign in / Sign up

Export Citation Format

Share Document