Fuels & Fuel Treatments
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Increasing impacts from wildfires are reshaping fire policies worldwide, with expanded investments in a wide range of fuel reduction strategies. In many fire prone regions, especially in the Mediterranean basin, fuel management programs have relied on fuel break networks for decades to facilitate fire suppression and reduce area burned and damage. By contrast, on the fire prone federal forests in the western United States, fuel management is guided primarily by landscape restoration goals, including improving fire resiliency such that wildfires can be managed for ecological benefit, and suppression is used more as a tool to shape burn patterns and less to extinguish fires. New policies in both fire systems are now calling for hybrid approaches that rely on both types of investments and efficient allocation of alternative spatial treatment patterns: linear networks versus patches across the landscape. However, studies that combine these strategies and examine alternative co-prioritization outcomes and potential synergies are largely non-existent. Here, we analyzed scenarios for implementing both types of treatments in concert while varying the prioritization metrics for one type or the other on a western United States national forest.
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Prescribed Burn Associations are critical for restoring fire adapted landscapes, imparting knowledge, and sharing resources. Join Ryan Mitchell and George Jensen from Tall Timbers as they discuss ways to regionally encourage and support private landowners to create sustainable and effective PBAs.
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We evaluated the responses of forest structure, regeneration, old-tree mortality, and tree growth to forest restoration for 21 years in a landscape-scale (2114 ha) experiment in a ponderosa pine-Gambel oak forest in northern Arizona, United States. Relative to the start of the experiment in 1996, tree density and basal area (BA) in the treated area were reduced by 56 and 38%, respectively, at the end of the study period compared to the untreated control. Conifer seedling densities generally declined and sprouting hardwoods increased following treatment. Mortality of old oak trees was significantly higher in the treated area compared to the control, likely due to fire-caused injury during the prescribed burning. Mean annual BA increment of individual trees was 93% higher in the treated area than in the control. Our study provides new information on ponderosa pine forest responses to restoration treatments at broad spatial scales and under realistic operational conditions. Results from this study can help inform landscape-scale restoration projects in dry, fire-dependent forests.
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To evaluate forest restoration and fuel treatment benefits and costs, we conducted a meta-analysis of benefit-cost ratios for restoration benefit types documented in the literature for Western U.S. dry mixed conifer forests at risk of uncharacteristic wildfires. A total of 120 observations were collated from 16 studies conducted over the last two decades, with benefits ranging from enhanced ecosystem services to extensively avoided wildfire costs. Significant variation in the value of restoration and fuel treatment benefit types was found, indicating that restoration benefits differ in value based on societal importance. Overall, 17 individual benefit types were aggregated to show that in the most valuable and at-risk watersheds, every dollar invested in forest restoration can provide up to seven dollars of return in the form of benefits and provide a return-on-investment of 600%.
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Our pinyon jay abundance model allowed abundance relationships with pinyon pine and juniper to vary by ecoregion, thereby accounting for potential regional differences in habitat associations. We found pinyon jay abundance was generally positively associated with pinyon pine and juniper cover; however, habitat relationships varied by ecoregion. Additionally, we found positive associations between jay abundance and grass cover, sagebrush cover, and percent bare ground. Our results agree with prior research suggesting mechanical removal of pinyon pine and juniper trees for sagebrush restoration or fuel treatments may negatively affect pinyon jay. Managers wishing to reduce pinyon and juniper tree cover without negatively affecting pinyon jay may benefit from targeting sites where both large-scale distribution models and our local habitat relationships suggest pinyon jay are likely to occur in low numbers. Additionally, our modeled relationships indicate restoration that increases grass cover, sagebrush cover, and bare ground, while maintaining pinyon and (or) juniper cover, may lead to increased local densities of pinyon jay.
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Forest management offers a diverse toolkit for delivering carbon benefits, with biochar fitting in as a cornerstone in combination with other climate-smart practices. For example, selective thinning can help promote healthier stands that capture more carbon while reducing fire risk. In turn, this generates more merchantable timber, which when used
sustainably, can also serve as a long-term carbon store, further offsetting emissions. Additionally, forests can be strategically managed to promote reforestation and afforestation efforts, expanding overall carbon sequestration potential.
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Mechanical thinning of forests is one method used to prevent high intensity wildfire and create a more open overstory. This Science You Can Use outlines how this treatment benefits native understory plants like grasses and sedges. Forests that were treated had higher understory species diversity, and native understory plants were more abundant. This research helps to inform restoration and forest management practices.
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This guide identifies seven primary components that largely determine the outcomes of vegetation treatments to reduce fuels and maintain or increase resilience to disturbance and resistance to invasive annual plants. The components are (1) characteristics of the ecological type, (2) current, pre-treatment vegetation, (3) disturbance and management history, (4) fuel characteristics and appropriate treatments, (4) treatment severity and ecological response, (6) seeding considerations, and (7) post-treatment monitoring and management. Key questions and a set of tools are provided to assess the components. The guide provides information to (1) evaluate resilience and resistance for potential treatment areas, (2) determine likely effects of treatments on fuels, fire behavior, and ecological response, and (3) select appropriate treatments, including the need to seed. An evaluation score sheet is included for assessing relative resilience and resistance and seeding needs. The Pine Valley Ranger District of the Dixie National Forest, part of a USDA Forest Service “Wildfire Crisis Landscape,” is used as a case study. Maps and data summaries included for the district are dominant shrubland and pinyon-juniper ecological types, burn probabilities, cover of the invasive annual, cheatgrass, proxy soil temperature and moisture regimes, relative resilience and resistance, pinyon-juniper stand characteristics, and habit for mule deer and pinyon jay.
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Prescribed fire implementation is subject to multiple constraints, including the number of days characterized by weather and vegetation conditions conducive to achieving desired outcomes. Here, we quantify observed and projected trends in the frequency and seasonality of western United States prescribed fire days. We find that while ~2 C of global warming by 2060 will reduce such days overall (−17%), particularly during spring (−25%) and summer (−31%), winter (+4%) may increasingly emerge as a comparatively favorable window for prescribed fire especially in northern states.
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A recently published review, led by Kimberley Davis, Research Ecologist at the USDA Forest Service’s Rocky Mountain Research Station, and collaborators at the University of Montana and The Nature Conservancy, brings together results from 40 studies for a rigorous analysis of fuel treatment efficacy.