Does increased forest protection correspond to higher fire severity in frequent‐fire forests of the western United States?

Bradley, Curtis M.; Hanson, Chad T.; DellaSala, Dominick A.

doi:10.1002/ecs2.1492

Cited by 45 publications

(32 citation statements)

References 65 publications

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“…Thus, in these landscapes, management strategies to conserve old‐growth characteristics may also reduce risk of high‐severity wildfire (Bradley et al. ) and serve as buffer to negative effects of climate change (Betts et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…In addition to the potential to mitigate negative effects of climate warming at local scales by creating refugia and enhancing biodiversity (Frey et al 2016), we suggest that northern spotted owl nesting/roosting habitat also has the potential to function as fire refugia (i.e., areas with higher probability of escaping high-severity fire compared to other areas on landscape) in areas with mixed-severity fire regimes under most weather conditions. Thus, in these landscapes, management strategies to conserve old-growth characteristics may also reduce risk of high-severity wildfire (Bradley et al 2016) and serve as buffer to negative effects of climate change (Betts et al 2018).…”

Section: Discussionmentioning

confidence: 99%

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Mixed‐severity wildfire and habitat of an old‐forest obligate

et al. 2019

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The frequency, extent, and severity of wildfire strongly influence the structure and function of ecosystems. Mixed‐severity fire regimes are the most complex and least understood fire regimes, and variability of fire severity can occur at fine spatial and temporal scales, depending on previous disturbance history, topography, fuel continuity, vegetation type, and weather. During high fire weather in 2013, a complex of mixed‐severity wildfires burned across multiple ownerships within the Klamath‐Siskiyou ecoregion of southwestern Oregon where northern spotted owl (Strix occidentalis caurina) demographics were studied since 1990. A year prior to these wildfires, high‐resolution, remotely sensed forest structural information derived from light detection and ranging (lidar) data was acquired for an area that fully covered the extent of these fires. To quantify wildfire impact on northern spotted owl nesting/roosting habitat, we fit a relative habitat suitability model based on pre‐fire locations used for nesting and roosting, and forest structure variables developed from 2012 lidar data. Our pre‐fire habitat suitability model predicted nesting/roosting locations well, and variable response functions followed known resource selection patterns. These forests had typical characteristics of old‐growth forest, with high density of large live trees, high canopy cover, and complex structure in canopy height. We projected the pre‐fire model onto lidar data collected two months post‐fire to produce a post‐fire suitability map, which indicated that >93% of pre‐fire habitat that burned at high severity was no longer suitable forest for nesting and roosting. We also quantified the probability that pre‐fire nesting/roosting habitat would burn at each severity class (unburned/low, low, moderate, high). Pre‐fire nesting/roosting habitat had lower probability of burning at moderate or high severity compared to other forest types under high burning conditions. Our results indicate that northern spotted owl habitat can buffer the negative effects of climate change by enhancing biodiversity and resistance to high‐severity fires, which are predicted to increase in frequency and extent with climate change. Within this region, protecting large blocks of old forests could be an integral component of management plans that successfully maintain variability of forests in this mixed‐ownership and mixed‐severity fire regime landscape and enhance conservation of many species.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Mixed‐severity wildfire and habitat of an old‐forest obligate

et al. 2019

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“…), and that reduced levels of forest legal protection (a proxy for more active management) have been associated with increased fire severity in the western U.S. (Bradley et al. ). These conflicting results further complicate the development of fire governance and management strategies for increasing social‐ecological resilience in a rapidly changing fire environment.…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have hypothesized that intensive forest management reduces fire behavior and effects (Hirsch et al 2001, Rodr ıguez y Silva et al 2014. However empirical results have been mixed, with evidence that intensive forest management can either reduce (Lyons-Tinsley andPeterson 2012, Prichard andKennedy 2014) or increase fire severity (Odion et al 2004, Thompson et al 2007, and that reduced levels of forest legal protection (a proxy for more active management) have been associated with increased fire severity in the western U.S. (Bradley et al 2016). These conflicting results further complicate the development of fire governance and management strategies for increasing social-ecological resilience in a rapidly changing fire environment.…”

Section: Introductionmentioning

confidence: 99%

Severe fire weather and intensive forest management increase fire severity in a multi‐ownership landscape

Zald

Dunn

2018

Ecological Applications

136

120

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Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi-owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting management objectives, providing a unique experimental landscape to understand how different management practices influence wildfire severity. Leveraging Landsat based estimates of fire severity (Relative differenced Normalized Burn Ratio, RdNBR) and geospatial data on fire progression, weather, topography, pre-fire forest conditions, and land ownership, we asked (1) what is the relative importance of different variables driving fire severity, and (2) is intensive plantation forestry associated with higher fire severity? Using Random Forest ensemble machine learning, we found daily fire weather was the most important predictor of fire severity, followed by stand age and ownership, followed by topographic features. Estimates of pre-fire forest biomass were not an important predictor of fire severity. Adjusting for all other predictor variables in a general least squares model incorporating spatial autocorrelation, mean predicted RdNBR was higher on private industrial forests (RdNBR 521.85 ± 18.67 [mean ± SE]) vs. BLM forests (398.87 ± 18.23) with a much greater proportion of older forests. Our findings suggest intensive plantation forestry characterized by young forests and spatially homogenized fuels, rather than pre-fire biomass, were significant drivers of wildfire severity. This has implications for perceptions of wildfire risk, shared fire management responsibilities, and developing fire resilience for multiple objectives in multi-owner landscapes.

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“…Disturbances such as fire, windstorms and floods can have a major influence on both natural and human-modified ecosystems and affect the abundance and diversity of species, nutrient and energy cycling, biomass accumulation, hydrological regimes and other key ecosystem processes (Fairman, Nitschke, & Bennett, 2016;Pulsford, Lindenmayer, & Driscoll, 2016;Sousa, 1984;Swanson et al, 2011). The severity, intensity or frequency of natural disturbance regimes can be altered directly and indirectly by human activities (Bradley, Hanson, & DellaSala, 2016;Parisien et al, 2016) such as patterns of land use (Cochrane & Laurance, 2008;Taylor, McCarthy, & Lindenmayer, 2014;Thompson, Spies, & Ganio, 2007), climate change (Abatzoglou & Williams, 2016;Westerling, Hidalgo, Cayan, & Swetnam, 2006) and the establishment of invasive species (Johnstone et al, 2016;Jones et al, 2016;Setterfield, Rossiter Rachor, Hutley, Douglas, & Williams, 2010). Thus, there can be additive or interactive effects of human and natural disturbances in biodiversity and key ecosystem processes (Buma, 2015;Kishchuk et al, 2015;Lindenmayer, Thorn, & Banks, 2017).…”

Section: Introductionmentioning

confidence: 99%

From unburnt to salvage logged: Quantifying bird responses to different levels of disturbance severity

Lindenmayer

McBurney

Blair

et al. 2018

Journal of Applied Ecology

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Forests world‐wide are increasingly subject to natural and human disturbances, including wildfires and logging of varying intensity and frequency. Understanding how biodiversity responds to different kinds and combinations of natural and human disturbance is critical to enhanced forest management. We completed an 8‐year study of bird responses across a spectrum of disturbance types in Australian mountain ash (Eucalyptus regnans) forests following wildfires in 2009. We found evidence of a gradient in bird species richness over the study duration. It was highest in unlogged and unburned (least disturbed) sites, decreasing through burnt unlogged forest (subject to high or low intensity fire), lower still in logged forest, and lowest in the most disturbed sites (subject to salvage logging without island retention). Retention of uncut islands within logged areas increased bird species richness above that found in areas that had been clearcut. The greatest rate of increase per year after disturbance in bird species richness was on sites burnt by high‐severity fire but which were not subject to any form of logging. The level of disturbance affected the composition of the bird assemblage. Sites that were unlogged and unburned were more likely to support species that were larger, more mobile, and nested at greater heights above the ground. Synthesis and applications. All forms of logging on burned sites impaired recovery in bird species richness relative to sites subject to high‐severity fire. Alterations in stand structure and plant species composition (and hence modification in bird habitat suitability) due to logging are the most likely reasons for reduced bird species richness and delayed patterns of recovery. This study highlights the importance for native bird species of retaining patches of unlogged forest not only within otherwise clearcut forest, but also in areas that are burned and subject to salvage logging. We therefore suggest that the adoption of retention harvesting be expanded to include stands disturbed by wildfires.

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Does increased forest protection correspond to higher fire severity in frequent‐fire forests of the western United States?

Cited by 45 publications

References 65 publications

Mixed‐severity wildfire and habitat of an old‐forest obligate

Mixed‐severity wildfire and habitat of an old‐forest obligate

Severe fire weather and intensive forest management increase fire severity in a multi‐ownership landscape

From unburnt to salvage logged: Quantifying bird responses to different levels of disturbance severity

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