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Permanent URI for this collectionhttps://hdl.handle.net/10217/240633

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Open Access
Climate influences on future fire severity: a synthesis of climate-fire interactions and impacts on fire regimes, high-severity fire, and forests in the western United States
(Colorado State University. Libraries, 2023) Wasserman, Tzeidle N., author; Mueller, Stephanie E., author
Background Increases in fire activity and changes in fire regimes have been documented in recent decades across the western United States. Climate change is expected to continue to exacerbate impacts to forested ecosystems by increasing the frequency, size, and severity of wildfires across the western United States (US). Warming temperatures and shifting precipitation patterns are altering western landscapes and making them more susceptible to high-severity fire. Increases in large patches of high-severity fire can result in significant impacts to landscape processes and ecosystem function and changes to vegetation structure and composition. In this synthesis, we examine the predicted climatic influence on fire regimes and discuss the impacts on fire severity, vegetation dynamics, and the interactions between fire, vegetation, and climate. We describe predicted changes, impacts, and risks related to fire with climate change and discuss how management options may mitigate some impacts of predicted fire severity, and moderate some impacts to forests, carbon, and vegetation changes post fire. Results Climate change is increasing fire size, fire severity, and driving larger patches of high-severity fire. Many regions are predicted to experience an increase in fire severity where conditions are hotter and drier and changes in fire regimes are evident. Increased temperatures, drought conditions, fuels, and weather are important drivers of fire severity. Recent increases in fire severity are attributed to changes in climatic water deficit (CMD), vapor pressure deficit (VPD), evapotranspiration (ET), and fuels. Fire weather and vegetation species composition also influence fire severity. Future increases in fire severity are likely to impact forest resilience and increase the probability of forest type conversions in many ecosystems. Conclusions Increasing warming and drying trends are likely to cause more frequent and severe disturbances in many forested ecosystems in the near future. Large patches of high-severity fire have lasting legacies on vegetation composition and structure, and impacts on tree regeneration. In some ecosystems and under certain fire-weather conditions, restoration and fuel treatments may reduce the area burned at high severity and reduce conversions from forest to non-forest conditions, increasing forest resistance and resilience to wildland fire. Thinning and prescribed fire treatments can be effective at reducing the potential for crown fire, reducing fuels, and promoting forest resilience.
Open Access
Strategic fire zones are essential to wildfire risk reduction in the western United States
(Colorado State University. Libraries, 2024) North, Malcolm P., author; Bisbing, Sarah M., author; Hankins, Don L., author; Hessburg, Paul F., author; Hurteau, Matthew D., author; Kobziar, Leda N., author; Meyer, Marc D., author; Rhea, Allison E., author; Stephens, Scott L., author; Stevens?Rumann, Camille S., author
Background Over the last four decades, wildfires in forests of the continental western United States have significantly increased in both size and severity after more than a century of fire suppression and exclusion. Many of these forests historically experienced frequent fire and were fuel limited. To date, fuel reduction treatments have been small and too widely dispersed to have impacted this trend. Currently new land management plans are being developed on most of the 154 National Forests that will guide and support on the ground management practices for the next 15 20 years. Results During plan development, we recommend that Strategic Fire Zones (SFZs) be identified in large blocks (? 2,000 ha) of Federal forest lands, buffered (? 1 2.4 km) from the wildland-urban interface for the reintroduction of beneficial fire. In SFZs, lightning ignitions, as well as prescribed and cultural burns, would be used to reduce fuels and restore ecosystem services. Although such Zones have been successfully established in a limited number of western National Parks and Wilderness Areas, we identify extensive remote areas in the western US (8.3 12.7 million ha), most outside of wilderness (85 88%), where they could be established. Potential wildland fire Operational Delineations or PODs would be used to identify SFZ boundaries. We outline steps to identify, implement, monitor, and communicate the use and benefits of SFZs. Conclusions Enhancing collaboration and knowledge-sharing with Indigenous communities can play a vital role in gaining agency and public support for SFZs, and in building a narrative for how to rebuild climate-adapted fire regimes and live within them. Meaningful increases in wildland fire use could multiply the amount of beneficial fire on the landscape while reducing the risk of large wildfires and their impacts on structures and ecosystem services.
Open Access
Tree regeneration spatial patterns in ponderosa pine forests following stand-replacing fire: influence of topography and neighbors
(Colorado State University. Libraries, 2017-10-14) Ziegler, Justin P., author; Hoffman, Chad M., author; Fornwalt, Paula J. author; Sieg, Carolyn H., author; Battaglia, Mike A., author; Chambers, Marin E., author; Iniguez, Jose M., author
Shifting fire regimes alter forest structure assembly in ponderosa pine forests and may produce structural heterogeneity following stand-replacing fire due, in part, to fine-scale variability in growing environments. We mapped tree regeneration in eighteen plots 11 to 15 years after stand-replacing fire in Colorado and South Dakota, USA. We used point pattern analyses to examine the spatial pattern of tree locations and heights as well as the influence of tree interactions and topography on tree patterns. In these sparse, early-seral forests, we found that all species were spatially aggregated, partly attributable to the influence of (1) aspect and slope on conifers; (2) topographic position on quaking aspen; and (3) interspecific attraction between ponderosa pine and other species. Specifically, tree interactions were related to finer-scale patterns whereas topographic effects influenced coarse-scale patterns. Spatial structures of heights revealed conspecific size hierarchies with taller trees in denser neighborhoods. Topography and heterospecific tree interactions had nominal effect on tree height spatial structure. Our results demonstrate how stand-replacing fires create heterogeneous forest structures and suggest that scale-dependent, and often facilitatory, rather than competitive, processes act on regenerating trees. These early-seral processes will establish potential pathways of stand development, affecting future forest dynamics and management options.
Open Access
Overlapping bark beetle outbreaks, salvage logging and wildfire restructure a lodgepole pine ecosystem
(Colorado State University. Libraries, 2018-02-27) Rhoades, Charles C., author; Pelz, Kristen A., author; Fornwalt, Paula J., author; Wolk, Brett H., author; Cheng, Antony S., author
The 2010 Church's Park Fire burned beetle-killed lodgepole pine stands in Colorado, including recently salvage-logged areas, creating a fortuitous opportunity to compare the effects of salvage logging, wildfire and the combination of logging followed by wildfire. Here, we examine tree regeneration, surface fuels, understory plants, inorganic soil nitrogen and water infiltration in uncut and logged stands, outside and inside the fire perimeter. Subalpine fir recruitment was abundant in uncut, unburned, beetle-killed stands, whereas lodgepole pine recruitment was abundant in cut stands. Logging roughly doubled woody fuel cover and halved forb and shrub cover. Wildfire consumed all conifer seedlings in uncut and cut stands and did not stimulate new conifer regeneration within four years of the fire. Aspen regeneration, in contrast, was relatively unaffected by logging or burning, alone or combined. Wildfire also drastically reduced cover of soil organic horizons, fine woody fuels, graminoids and shrubs relative to unburned, uncut areas; moreover, the compound effect of logging and wildfire was generally similar to wildfire alone. This case study documents scarce conifer regeneration but ample aspen regeneration after a wildfire that occurred in the later stage of a severe beetle outbreak. Salvage logging had mixed effects on tree regeneration, understory plant and surface cover and soil nitrogen, but neither exacerbated nor ameliorated wildfire effects on those resources.
Open Access
Forest roads and operational wildfire response planning
(Colorado State University. Libraries, 2021-01-20) Thompson, Matthew P., author; Gannon, Benjamin M., author; Caggiano, Michael D., author
Supporting wildfire management activities is frequently identified as a benefit of forest roads. As such, there is a growing body of research into forest road planning, construction, and maintenance to improve fire surveillance, prevention, access, and control operations. Of interest here is how road networks directly support fire control operations, and how managers incorporate that information into pre-season assessment and planning. In this communication we briefly review and illustrate how forest roads relate to recent advances in operationally focused wildfire decision support. We focus on two interrelated products used on the National Forest System and adjacent lands throughout the western USA: potential wildland fire operational delineations (PODs) and potential control locations (PCLs). We use real-world examples from the Arapaho-Roosevelt National Forest in Colorado, USA to contextualize these concepts and illustrate how fire analytics and local fire managers both identified roads as primary control features. Specifically, distance to road was identified as the most important predictor variable in the PCL boosted regression model, and 82% of manager-identified POD boundaries aligned with roads. Lastly, we discuss recommendations for future research, emphasizing roles for enhanced decision support and empirical analysis.
Open Access
Potential operational delineations: new horizons for proactive, risk-informed strategic land and fire management
(Colorado State University. Libraries, 2022) Thompson, Matthew P., author; O'Connor, Christopher D., author; Gannon, Benjamin M. author; Caggiano, Michael D., author; Dunn, Christopher J., author; Schultz, Courtney A., author; Calkin, David E., author; Pietruszka, Bradley, author; Greiner, S. Michelle, author; Stratton, Richard, author; Morisette, Jeffrey T., author
Background: The PODs (potential operational delineations) concept is an adaptive framework for cross-boundary and collaborative land and fire management planning. Use of PODs is increasingly recognized as a best practice, and PODs are seeing growing interest from federal, state, local, tribal, and non-governmental organizations. Early evidence suggests PODs provide utility for planning, communication, coordination, prioritization, incident response strategy development, and fuels mitigation and forest restoration. Recent legislative action codifies the importance of PODs by devoting substantial financial resources to their expansion. The intent of this paper is to explore new horizons that would help land and fire management organizations better address risks and capitalize on opportunities. Specifically, we focus on how PODs are a natural platform for improvement related to two core elements of risk management: how we leverage preparation and foresight to better prepare for the future; and how we learn from the past to better understand and improve performance and its alignment with strategy. Results: We organize our exploration of new horizons around three key areas, suggesting that PODs can enable climate-smart forest and fire management and planning, inform more agile and adaptive allocation of suppression resources, and enable risk-informed performance measurement. These efforts can be synergistic and self-reinforcing, and we argue that expanded application of PODs at local levels could enhance the performance of the broader wildland fire system. We provide rationales for each problem area and offer growth opportunities with attendant explanations and illustrations. Conclusions: With commitment and careful effort, PODs can provide rich opportunities for innovation in both backward-looking evaluative and forward-looking anticipatory frameworks. In addition to continued improvement of core PODs elements, attention must be paid to being more inclusive and participatory in PODs planning, to building sufficient capacity to expand PODs applications in meaningful boundary spanning ways, to ensure their continuity and relevance over time through maintenance and updating, and to deliver necessary information to responders to inform the effective management of wildfires. Lastly, ongoing monitoring and evaluation of PODs and related initiatives is essential to support organizational learning and continual improvement.
Open Access
A horizon scan to inform research priorities on post-wildfire forest restoration and recovery in the western United States
(Colorado State University. Libraries, 2025-07-18) Jones, Kelly W., author; Cadol, Daniel, author; Morgan, Melinda, author; Stevens-Rumann, Camille, author; Agnew, Diane, author; BurneyOwen, author; Calabaza, James, author; Chambers, Marin E., author; Edgeley, Catrin M., author; Falk, Donald, author; Hughes, Lee G., author; Marsh, Chris, author; Schultz, Courtney A., author; McCarthy, Laura, author; Morrison, Ryan, author; Montoya, Manuel, author; Padowski, Julie, author; Piccarello, Matt, author; Pinto, Jeremiah R., author; Roach, Jesse, author; Roberts, Michael, author; Rodman, Kyle, author; Triepke, Jack, author; Tsinnajinnie, Lani, author; vonHedemann, Nicolena, author; Webster, Alex J., author; Buettner, William C., author; Leger, Abelino Fernandez, author; Mineau, Alyssa, author; Rotche, Lindsey, author; Russell, Gregory, author; Woolet, Jamie, author
The frequency, severity, and scale of extreme wildfire events is increasing globally, with certain regions such as the western United States disproportionately impacted. As attention shifts toward understanding how to adapt to and recover from extreme wildfire, there is a need to prioritize where additional research and evidence are needed to inform decision-making. In this paper, we use a horizon-scanning approach to identify key topics that could guide post-wildfire forest restoration and recovery efforts in the western United States over the next few decades. Horizon scanning is a method that uses an iterative and structured expert-elicitation process to identify emerging themes or set research agendas. Experts from across researcher and practitioner organizations identified 12 topics as having the greatest potential impact, and being the most time-sensitive to address, for advancing knowledge on post-wildfire forest restoration and recovery. Five topics fall under the social sciences, including institutional coordination, collaborative governance, pre-fire planning, community engagement and equity, and workforce development; four topics relate to forest management, including seed and seedlings, outplanting strategies, post-fire forest trajectories, and climate-informed reforestation; and three relate to hydrology, including soil erosion mitigation, flood and debris flow mitigation, and post-fire water quantity and quality trajectories. While conducted for the contiguous western United States, this analysis is relevant for other regions where both people and forests are impacted by extreme wildfire events. Addressing these topics has the potential to improve the equity, effectiveness, and efficiency of post-wildfire forest restoration and recovery responses.
Open Access
Restoring historical forest conditions in a diverse inland Pacific Northwest landscape
(Colorado State University. Libraries, 2018-07-16) Johnston, James D., author; Dunn, Christopher J., author; Vernon, Michael J., author; Bailey, John D., author; Morrissette, Brett A., author; Morici, Kat E., author
A major goal of managers in fire-prone forests is restoring historical structure and composition to promote resilience to future drought and disturbance. To accomplish this goal, managers require information about reference conditions in different forest types, as well as tools to determine which individual trees to retain or remove to approximate those reference conditions. We used dendroecological reconstructions and General Land Office records to quantify historical forest structure and composition within a 13,600 ha study area in eastern Oregon where the USDA Forest Service is planning restoration treatments. Our analysis demonstrates that all forest types present in the study area, ranging from dry ponderosa pine-dominated forests to moist mixed conifer forests, are considerably denser (273 316% increase) and have much higher basal area (60 176% increase) today than at the end of the 19th century. Historically, both dry pine and mixed conifer forest types were dominated by shade-intolerant species. Today, shade-tolerant tree cover has increased in dry pine stands, while mixed conifer stands are now dominated by shade-tolerant species. Federal managers in eastern Oregon are currently required to retain all live trees >53 cm diameter at breast height in the course of forest management activities because this size class is assumed to be under-represented on the landscape relative to historical conditions. However, we found the same or greater number of live trees >53 cm today than in the late 19th century. Restoring historical conditions usually involves removing shade-tolerant trees that established since Euro-American management significantly altered natural disturbance regimes. We evaluated a wide range of tree morphological and environmental variables that could potentially predict the age of grand fir and Douglas-fir, the most abundant shade-tolerant species found within the study area. We describe several morphological characteristics that are diagnostic of tree age and developed decision trees that predict the approximate age of trees using morphological characteristics that are easy to measure in the field such as height to live foliage or height to dead branches. Information about structural and compositional change over time combined with tree-age prediction tools provides a flexible framework for restoring historical conditions and meeting other resource management objectives.
Open Access
Mixed-severity fire fosters heterogeneous spatial patterns of conifer regeneration in a dry conifer forest
(Colorado State University. Libraries, 2018-01-20) Malone, Sparkle L., author; Fornwalt, Paula J., author; Battaglia, Mike A., author; Chambers, Marin E., author; Iniguez, Jose M., author; Sieg, Carolyn H., author
We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11 12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving) trees, in three 4-ha plots following the 2002 Hayman Fire. Residual tree density ranged from 167 to 197 trees ha 1 (TPH), and these trees were clustered at distances up to 30 m. Post-fire regenerating conifers, which ranged in density from 241 to 1036 TPH, were also clustered at distances up to at least 30 m. Moreover, residual tree locations drove post-fire regenerating conifer locations, with the two showing a pattern of repulsion. Topography and post-fire sprouting tree species locations further drove post-fire conifer regeneration locations. These results provide a foundation for anticipating how the reintroduction of mixed-severity fire may affect long-term forest structure, and also yield insights into how historical mixed-severity fire may have regulated the spatially heterogeneous conditions commonly described for pre-settlement dry conifer forests of Colorado and elsewhere.
Open Access
Spatial heterogeneity in thinned forests: using aerial imagery to evaluate forest management outcomes
(Colorado State University. Libraries, 2025) Edinger, Jackie, author; Mueller, Stephanie, author; Rhea, Allison, author; Slack, Andrew, author
Open Access
Creating boundary objects supports knowledge co-development processes: a case study evaluation from the Colorado Front Range
(Colorado State University. Libraries, 2024-04-27) Brown, Hannah L. C., author; Cheng, Antony S., author; Clark, Nehalem C., author; Slack, Andrew W., author; Wolk, Brett H., author
This qualitative case study evaluates manager and researcher perceptions of the impact of a place-based, collaborative knowledge co-development process and examines the outcomes of that co-development for changes to management approaches. The USDA Forest Service (Forest Service) Rocky Mountain Research Station General Technical Report 373 (GTR-373) is a codeveloped science synthesis that functions as a boundary object providing a framework for planning, designing, and implementing management action for restoration of ponderosa and dry mixed-conifer forests. The process of creating and socializing the GTR-373 framework fostered continual knowledge exchange and engagement between researchers and managers across different organizations and levels of decision-making. This built trust in the information, improved justification for management action, developed a common foundation for cross-boundary implementation, and increased communication. The framework has been applied across jurisdictions and has been used as a foundational tool for training staff and designing projects. However, adapting the GTR-373 framework across scales remains challenging. Study Implications: This qualitative case study evaluates a co-development process in which researchers and managers from multi¬ple organizations and agencies collaborated to produce a science-informed restoration framework to support forest management on the Colorado Front Range (GTR-373). The process built trust, improved justification for management action, developed a common foundation for implementation, and increased communication. However, cross-boundary management across spatial scales remains challenging, and managers interpret information through organizational mandates and site-specific context. Sustained collaboration between researchers and land managers can help make science actionable and relevant at the appropriate scale for planning and management across expertise and jurisdictional boundaries.
Open Access
Aspen impedes wildfire spread in southwestern United States landscapes
(Colorado State University. Libraries, 2025-04-16) Harris, Matthew P., author; Coop, Jonathan D., author; Balik, Jared A., author; McFarland, Jessika R., author; Parks, Sean A., author; Stevens-Rumann, Camille S., author
Aspen (Populus tremuloides) forests are generally thought to impede fire spread, yet the extent of this effect is not well quantified in relation to other vegetation types. We examined the influence of aspen cover on interpolated daily fire spread rates, the relative abundance of aspen at fire perimeters versus burn interiors, and whether these relationships shifted under more fire-conducive atmospheric conditions. Our study incorporated 314 fires occurring between 2001 and 2020 in the southwestern United States and a suite of gridded vegetation, topography, and fire weather predictor variables. We found that aspen slows fire progression: as aspen cover on the landscape increased, daily area burned and linear spread rate decreased. Where aspen cover was <10%, daily fire growth averaged 1112 ha/day and maximum linear spread was 2.1 km/day; where aspen exceeded 25%, these values dropped to 368 ha/day and 1.3 km/day. Aspen also serves as a barrier to fire spread, demonstrated through a higher proportion of aspen cover at fire perimeters than in burn interiors. Finally, though favorable fire weather conditions increased fire growth rates, differences between aspens and conifers persisted. Our results affirm that aspen stands can act as a firebreak, with clear applications for vegetation management. For example, interventions that shift conifer to aspen cover could lessen the risk of fire for nearby values at risk (e.g., communities, infrastructure) but still support forest ecosystem function. Further, wildfire-driven conversion from conifer to aspen forest types in some landscapes may produce a negative feedback that could dampen expected increases in fire activity under a warmer and drier climate.
Open Access
Interactions between climate and stand conditions predict pine mortality during a bark beetle outbreak
(Colorado State University. Libraries, 2021-03-18) Chisholm, Paul J., author; Stevens-Rumann, Camille S., author; Davis, Thomas Seth, author
In temperate coniferous forests, biotic disturbances such as bark beetle outbreaks can result in widespread tree mortality. The characteristics of individual trees and stands, such as tree diameter and stand density, often influence the probability of tree mortality during a bark beetle outbreak. However, it is unclear if these relationships are mediated by climate. To test this, we assembled tree mortality data for over 3800 ponderosa pine trees from Forest Inventory and Analysis (FIA) plots measured before and after a mountain pine beetle outbreak in the Black Hills, South Dakota, USA. Logistic models were used to determine which tree, stand, and climate characteristics were associated with the probability of mortality. Interactions were tested between significant climate variables and significant tree/stand variables. Our analysis revealed that mortality rates were lower in trees with higher live crown ratios. Mortality rates rose in response to increasing tree diameter, stand basal area (both from ponderosa pine and non-ponderosa pine), and elevation. Below 1500 m, the mortality rate was ~1%, while above 1700 m, the rate increased to ~30%. However, the association between elevation and mortality risk was buffered by precipitation, such that relatively moist high-elevation stands experienced less mortality than relatively dry high-elevation stands. Tree diameter, crown ratio, and stand density affected tree mortality independent of precipitation. This study demonstrates that while stand characteristics affect tree susceptibility to bark beetles, these relationships may be mediated by climate. Thus, both site and stand level characteristics should be considered when implementing management treatments to reduce bark beetle susceptibility.
Open Access
Cultivating collaborative resilience to social and ecological change: an assessment of adaptive capacity, actions, and barriers among collaborative forest restoration groups in the United States
(Colorado State University. Libraries, 2022-01-05) Beeton, Tyler A., author; Cheng, Antony S., author; Colavito, Melanie M., author
Collaboration is increasingly emphasized as a tool to realize national-level policy goals in public lands management. Yet, collaborative governance regimes (CGRs) are nested within traditional bureaucracies and are affected by internal and external disruptions. The extent to which CGRs adapt and remain resilient to these disruptions remains under-explored. Here, we distill insights from an assessment of the Collaborative Forest Landscape Restoration Program (CFLRP) projects and other CGRs. We asked (1) how do CGRs adapt to disruptions? and (2) what barriers constrained CGR resilience? Our analysis is informed by a synthesis of the literature, case examples and exemplars from focus groups, and a national CFLRP survey. CGRs demonstrated the ability to mobilize social capital, learning, resources, and flexibility to respond to disruptions. Yet authority, accountability, and capacity complicated collaborative resilience. We conclude with policy and practice recommendations to cultivate collaborative resilience moving forward. Study Implications: Collaborative approaches between public lands management agencies and nongovernment organizations have become common in forest restoration. Yet collaborative progress may be affected by turnover, wildfire disturbances, or legal or policy changes. We assessed how forest collaboratives in the United States adapted to changes that affected their performance and documented the factors that constrained response. We found that forest collaboratives developed myriad strategies to adapt to these changes, although limited authority, capacity, and accountability constrain adaptation options. We offer policy and practice recommendations to overcome these constraints, increase adaptation options, and enhance the sustainability of forest collaboratives.
Open Access
Extreme fire spread events burn more severely and homogenize postfire landscapes in the southwestern United States
(Colorado State University. Libraries, 2025-01-28) McFarland, Jessika R., author; Coop, Jonathan D., author; Balik, Jared A., author; Rodman, Kyle C., author; Parks, Sean A., author; Stevens-Rumann, Camille S., author
Extreme fire spread events rapidly burn large areas with disproportionate impacts on people and ecosystems. Such events are associated with warmer and drier fire seasons and are expected to increase in the future. Our understanding of the landscape outcomes of extreme events is limited, particularly regarding whether they burn more severely or produce spatial patterns less conducive to ecosystem recovery. To assess relationships between fire spread rates and landscape burn severity patterns, we used satellite fire detections to create day-of-burning maps for 623 fires comprising 4267 single-day events within forested ecoregions of the southwestern United States. We related satellite-measured burn severity and a suite of high-severity patch metrics to daily area burned. Extreme fire spread events (defined here as burning > 4900 ha/day) exhibited higher mean burn severity, a greater proportion of area burned severely, and increased like adjacencies between high-severity pixels. Furthermore, increasing daily area burned also resulted in greater distances within high-severity patches to live tree seed sources. High-severity patch size and total high-severity core area were substantially higher for fires containing one or more extreme spread events than for fires without an extreme event. Larger and more homogenous high-severity patches produced during extreme events can limit tree regeneration and set the stage for protracted forest conversion. These landscape outcomes are expected to be magnified under future climate scenarios, accelerating fire-driven forest loss and long-term ecological change.
Open Access
Restoration and fuel hazard reduction result in equivalent reductions in crown fire behavior in dry conifer forests
(Colorado State University. Libraries, 2022-03-18) Ritter, Scott M., author; Hoffman, Chad M. author; Battaglia, Mike A. author; Jain, Theresa B., author
Over the past several decades, the management of historically frequent-fire forests in the western United States has received significant attention due to the linked ecological and social risks posed by the increased occurrence of large, contiguous patches of high-severity fire. As a result, efforts are underway to simultaneously reduce potential fire and fuel hazards and restore characteristics indicative of historical forest structures and ecological processes that enhance the diversity and quality of wildlife habitat across landscapes. Despite widespread agreement on the need for action, there is a perceived tension among scientists concerning silvicultural treatments that modify stands to optimally reduce potential fire behavior (fuel hazard reduction) versus those that aim to emulate historical forest structures and create structurally complex stands (restoration). In this work, we evaluated thinning treatments in the Black Hills National Forest that exemplify the extremes of a treatment continuum that ranges from fuel hazard reduction to restoration. The goal of this work was to understand how the differing three-dimensional stand structures created by these treatment approaches altered potential fire behavior. Our results indicate that restoration treatments created higher levels of vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential crown fire behavior. There were some trade-offs identified as the restoration treatments created larger openings, which generated faster mean rates of fire spread; however, these increased spread rates did not translate to higher levels of canopy consumption. Overall, our results suggest that treatments can create vertical and horizontal complexity desired for restoration and wildlife habitat management while reducing fire hazard and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. We also provide some suggestions to land managers seeking to design and implement prescriptions that emulate historical structures and enhance forest complexity.
Open Access
Variability in mixed conifer spatial structure changes understory light environments
(Colorado State University. Libraries, 2019-11-13) Cannon, Jeffery B., author; Tinkham, Wade T., author; DeAngelis, Ryan K., author; Hill, Edward M., author; Battaglia, Mike A., author
In fire-adapted conifer forests of the Western U.S., changing land use has led to increased forest densities and fuel conditions partly responsible for increasing the extent of high-severity wildfires in the region. In response, land managers often use mechanical thinning treatments to reduce fuels and increase overstory structural complexity, which can help improve stand resilience and restore complex spatial patterns that once characterized these stands. The outcomes of these treatments can vary greatly, resulting in a large gradient in aggregation of residual overstory trees. However, there is limited information on how a range of spatial outcomes from restoration treatments can influence structural complexity and tree regeneration dynamics in mixed conifer stands. In this study, we model understory light levels across a range of forest density in a stem-mapped dry mixed conifer forest and apply this model to simulated stem maps that are similar in residual basal area yet vary in degree of spatial complexity. We found that light availability was best modeled by residual stand density index and that consideration of forest structure at multiple spatial scales is important for predicting light availability. Second, we found that restoration treatments differing in spatial pattern may differ markedly in their achievement of objectives such as density reduction, maintenance of horizontal and tree size complexity, and creation of microsite conditions favorable to shade-intolerant species, with several notable tradeoffs. These conditions in turn have cascading effects on regeneration dynamics, treatment longevity, fire behavior, and resilience to disturbances. In our study, treatments with high aggregation of residual trees best balanced multiple objectives typically used in ponderosa pine and dry mixed conifer forests. Simulation studies that consider a wide range of possible spatial patterns can complement field studies and provide predictions of the impacts of mechanical treatments on a large range of potential ecological effects.
Open Access
Effects of collaborative monitoring and adaptive management on restoration outcomes in dry conifer forests
(Colorado State University. Libraries, 2021-02-18) Barrett, Kevin J., author; Cannon, Jeffery B., author; Schuetter, Alex M., author; Cheng, Antony S., author
In response to large, severe wildfires across the western US, federal initiatives have been enacted to increase the pace, scale, and quality of ecological restoration in fire dependent forests. To address uncertainty and controversy in agreement among specific restoration prescriptions on national forest land, several initiatives adopt a collaborative adaptive management (CAM) strategy wherein monitoring data can inform stakeholder input into future management actions. It is unclear, however, how such approaches may change restoration outcomes. Here we assess the extent to which CAM strategies impact restoration outcomes that were implemented as part of the Collaborative Forest Landscape Restoration Program (CFLRP) in ponderosa pine-dominated forests of the Colorado Front Range. We assessed stand-level desired conditions across 24 projects over a 7-year period to determine how restoration treatments contribute to desired conditions, and compared treatment outcomes over implementation time to assess whether the CAM processes contribute towards treatments better approximating restoration. We found that restoration treatments improve aspects of forest structure related to stand density. However, meeting objectives related to forest composition and horizontal structural complexity goals were not met. Additionally, CAM processes were effective at improving outcomes related to forest density over implementation time, but novel tools and approaches may be required so that outcomes related to forest composition and horizontal structural complexity are more congruent with restoration objectives. Evaluating the success and challenges of CAM provides insight to improve collaborative and large-scale restoration.
Open Access
Transcending parallel play: boundary spanning for collective action in wildfire management
(Colorado State University. Libraries, 2021-07-30) Davis, Emily Jane, author; Huber-Stearns, Heidi, author; Cheng, Antony S., author; Jacobson, Meredith, author
A key challenge in the United States is how to manage wildfire risk across boundaries and scales, as roles, responsibilities, and ability to act are distributed among actors in ways that do not always incentivize collective action. In this review paper, we provide several conceptual contributions to the understanding of wildfire management through the application of boundary spanning frameworks. This includes: (1) a characterization of four major types of boundaries in managing wildfire risk; (2) a review of major boundary spanning features and frameworks that integrate them; and (3) consideration of current and potential applications of the boundary spanning construct to the domain of wildfire management. Our goal is to advance knowledge of how actors in this arena may overcome "parallel play" to more collectively address wildfire risk. We generate new thinking about wildfire management, and offer potential implications and questions for future research, policy, and management.
Open Access
'Mind the gap' reforestation needs vs. reforestation capacity in the western United States
(Colorado State University. Libraries, 2024-05-29) Dobrowski, Solomon Z., author; Aghai, Matthew M., author; Chichilnisky du Lac, Ariella, author; Downer, Rebecca, author; Fargione, Joseph author; Haase, Diane L., author; Hoecker, Tyler author; Kildisheva, Olga A., author; Murdoch, Alix, author; Newman, Shaw, author; North, Malcolm, author; Saksa, Phil, author; Sjoholm, Matt, author; Baribault, Tom, author; Buonanduci, Michele S., author; Chambers, Marin E., author; Gonzales-Kramer, Lisa, author; Harvey, Brian J., author; Hurteau, Matthew D., author; Loevner, Jonathan, author; Safford, Hugh D., author; Sloan, Joshua, author
Tree establishment following severe or stand-replacing disturbance is critical for achieving U.S. climate change mitigation goals and for maintaining the co-benefits of intact forest ecosystems. In many contexts, natural post-fire tree regeneration is sufficient to maintain forest cover and associated ecosystem services, but increasingly the pattern and scale of disturbance exceeds ecological thresholds and active reforestation may be warranted. Our capacity to plant trees, however, is not keeping pace with reforestation needs. This shortfall is uniquely apparent in the western U.S., where wildfire size and severity have increased in recent decades and long-term divestment in the reforestation supply chain has limited our ability to respond to existing needs. Here we present an analysis of key facets of both the supply and demand side of reforestation in the western U.S. and address six questions: (1) What is the current backlog of potential reforestation needs driven by high-severity wildfire?; (2) How will increasing wildfire activity through the end of the century affect potential reforestation needs?; (3) What is our capacity to meet current and future reforestation needs?; (4) How can we scale the reforestation supply chain to meet current and future demands?; (5) What approaches to reforestation can promote forest resilience to climate change and wildfire?; and (6) Where are opportunities emerging from recent policy initiatives, innovative public-private partnerships, and natural capital markets for scaling reforestation? Between 1984 and 2000, annual tree planting capacity met post-fire needs but cumulatively over the last two decades (2000 to 2021) it has fallen short of fire-driven needs by an estimated 1.5 million ha (ca. 3.8 million ac). We anticipate this gap will increase 2 to 3 fold by 2050. Scaling up reforestation efforts to close this gap will require increased investment across all facets of the reforestation supply chain, public-private partnerships, and novel approaches to reforestation that increase the resilience of western forests to drought and wildfire. We highlight emerging opportunities from recent policy initiatives and conservation finance for expanding reforestation efforts.

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