Fuels & Fuel Treatments

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Complexity of biological disturbance agents, fuels heterogeneity, and fire in coniferous forests of the western US

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Forest biological disturbance agents (BDAs) are insects, pathogens, and parasitic plants that affect tree decline, mortality, and forest ecosystems processes. BDAs are commonly thought to increase the likelihood and severity of fire by converting live standing trees to more flammable, dead and downed fuel. However, recent research indicates that BDAs do not necessarily increase, and can reduce, the likelihood or severity of fire. This has led to confusion regarding the role of BDAs in influencing fuels and fire in fire-prone western United States forests. Here, we review the existing literature on BDAs and their effects on fuels and fire in the western US and develop a conceptual framework to better understand the complex relationships between BDAs, fuels and fire. We ask: 1) What are the major BDA groups in western US forests that affect fuels? and 2) How do BDA-affected fuels influence fire risk and outcomes? The conceptual framework is rooted in the spatiotemporal aspects of BDA life histories, which drive forest impacts, fuel characteristics and if ignited, fire outcomes. Life histories vary among BDAs from episodic, landscape-scale outbreaks (bark beetles, defoliators), to chronic, localized disturbance effects (dwarf mistletoes, root rots). Generally, BDAs convert aboveground live biomass to dead biomass, decreasing canopy fuels and increasing surface fuels. However, the rate of conversion varies with time-since-event and among BDAs and forest types, resulting in a wide range of effects on the amount of dead fuels at any given time and place, which interacts with the structure and composition of the stand before and subsequent to BDA events. A major influence on fuels may be that BDAs have emerged as dominant agents of forest heterogeneity creation. Because BDAs play complex roles in fuels and fire heterogeneity across the western US which are further complicated by interactions with climate change, drought, and forest management (fire suppression), their impacts on fuels, fire and ecological consequences cannot be categorized simply as positive or negative but need to be evaluated within the context of BDA life histories and ecosystem dynamics.

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Comparing land manager and community perceptions: Case study from CO Rx fire outreach

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We found that many community members were initially drawn to learn about wildfre risk mitigation, but their informational needs shifted toward broader forest ecology over time, suggesting that communication strategies and topics must also evolve over time. Some common terms used by land management professionals were unclear to public audiences, sometimes leading to feelings of dissatisfaction with outreach. One-on-one meetings and experiential group learning were perceived by information providers and community members to be useful strategies for outreach. Our fndings can be used to improve ongoing outreach in this study area and inform similar efforts elsewhere.

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Management to improve forest resilience and reduce wildfire risk

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Past practices, such as fire suppression, have created densely packed forests with an overabundance of woody vegetation. Live or dead, this vegetation can fuel severe wildfire. Overcrowded growing conditions also prevent  trees and other plants from obtaining sufficient nutrients, light, or water to bounce back and remain healthy following a stressful event. The warming climate further stresses vegetation and can foster tinderbox conditions on the landscape, especially under widespread persistent drought.

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Landscape-scale Rx burning supported by science

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The Wildfire Crisis Strategy calls for ramping up forest treatments on Federal, State, Tribal, and private lands well above current levels. Public and stakeholder engagement, consultation, and collaboration are critical to successful implementation of the strategy. Best available science can inform how to improve the way we engage with communities and help us collectively determine the right treatment locations and tools.

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Pinyon-Juniper Encroachment Education Project Website

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Around the world, woodlands and forests are replacing native grasslands and shrublands which impacts wildlife and people. In the sagebrush biome of the American West, pinyon pine, juniper, and other native conifer trees are expanding into imperiled shrublands. Learn more about the implications of this woodland encroachment and what communities are doing to restore healthy and resilient shrublands.

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Science x Forests USFS webinar series

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  • Monday, November 14 SCIENCE x Forests: Silviculture for the present and future
    A compendium of silviculture treatments for forest types in the United States: Silviculture guidance to support modeling, scenario planning, and large-scale simulations, presented by Thomas Schuler
    Prescribed burning considerations following mechanical treatments, presented by Sharon Hood
    Reforestation in an era of megafires: A wicked problem for the Forest Service in Region 5 and elsewhere, presented by Martin Ritchie
  • Tuesday, November 15 SCIENCE x Forests: Forests and climate change
    Preparing our forests for the future, presented by Mike Battaglia
    The Pacific Northwest carbon dynamics research initiative: Co-production to assist land managers and policy makers, presented by Andrew Gray
    Sink, swim, or surf: Surging climate change impacts and the role of climate-adaptive silviculture, presented by Alejandro Royo
  • Wednesday, November 16 SCIENCE x Forests: Innovations in forest research
    From the forest to the faucet: Tools and data linking surface water from forested lands to public water systems, presented by Peter Caldwell
    Cloud computing advances regional old-growth forest monitoring for the Northwest Forest Plan, presented by David M Bell
    What is resilience in frequent-fire forests and how can it be measured?, presented by Malcolm North
  • Thursday, November 17 SCIENCE x Forests: Urban forestry, community, and wood utilization
    The science and practice of urban silviculture, presented by Nancy Sonti and Rich Hallett
    Expanding urban wood utilization, presented by Charlie Becker
    Not by trees alone: Centering community in urban forestry, presented by Lindsay Campbell
  • Friday, November 18 SCIENCE x Forests: Invasion and outbreaks in forests
    Species home-making in ecosystems: Toward place-based ecological metrics of belonging, presented by Susan Cordell
    Invasion and outbreak within an epidemiological model, presented by Rima Lucardi
    Mapping Armillaria-killed trees with high-resolution remote sensing, presented by Benjamin Bright
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Using virtual fencing to create fuel breaks in the sagebrush steppe

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Cows were fitted with VF collars (calves not collared) that use Global Positioning System positioning to contain cattle inside fuel break boundaries and record animal locations at 5-min intervals. End-of-trial forage utilization was 48.5% ± 3.7% and 5.5% ± 0.7% for areas inside and outside of the fuel break, respectively. Daily percentage of cattle locations inside the fuel break was initially > 94% but declined to approximately 75% by the end of the trial. Percentage daily locations of dry cows and cow/calf pairs inside the fuel break was 98.5% ± 0.5% and 80.6% ± 1.1%, respectively (P < 0.001). Our data suggest virtual fencing can be a highly effective method of concentrating grazing to reduce herbaceous fuel biomass within linear fuel breaks. Efficacy of this method could be substantially impacted by use of dry versus cow/calf pairs.

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A systematic review of empirical evidence for landscape-level fuel treatment effectiveness

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It is clear that the state of knowledge based on empirical evidence is at its infancy. This is likely because of the vast challenges associated with designing and implementing sampling designs that account for combinations of spatial and temporal configurations prior to wildfire occurrence. We also suspect part of the reason empirical evidence is lacking is because the distinction between site-level and landscape-level effects is not well recognized in the literature. All papers used the term landscape, but rarely defined the landscape, and some specified identifying landscape-level effects that were truly site-level effects. Future research needs to develop innovative ways to interpret the role of fuel treatments at the landscape level to provide insight on strategic designs and approaches to maximize fuel treatment effectiveness.

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Weeds, fire risk, and resilient forest landscapes – An infographic

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Nonnative species can be introduced or exacerbated by fire and fuels treatments. This resource describes how this can happen and what can be done to minimize the occurrence of nonnative species on burned sites or following fuels management.

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Effectiveness of fuel treatments at the landscape scale: State of understanding and key research gaps

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Maximizing the effectiveness of fuel treatments at the landscape scale is a key research and management need given the inability to treat all areas at risk from wildfire, and there is a growing body of scientific literature assessing this need. We synthesized existing scientific literature on landscape-scale fuel treatment effectiveness in North American ecosystems through a systematic literature review. We identified 127 studies that addressed this topic using one of three approaches: simulation modeling, empirical analysis, or case studies. Of these 127 studies, most focused on forested landscapes of the western United States. Together, they generally provided evidence that fuel treatments reduced negative outcomes of wildfire and in some cases promoted beneficial wildfire outcomes, although these effects diminished over time following treatment and were influenced by factors such as weather conditions at the time of fire. The simulation studies showed that fuel treatment extent, size, placement, timing, and prescription influenced the degree of effectiveness.

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