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Tortorelli CM, Latimer AM, Young DJN. Moderating effects of past wildfire on reburn severity depend on climate and initial severity in Western US forests. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024; 34:e3023. [PMID: 39148306 DOI: 10.1002/eap.3023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/27/2024] [Accepted: 05/10/2024] [Indexed: 08/17/2024]
Abstract
Rising global fire activity is increasing the prevalence of repeated short-interval burning (reburning) in forests worldwide. In forests that historically experienced frequent-fire regimes, high-severity fire exacerbates the severity of subsequent fires by increasing prevalence of shrubs and/or by creating drier understory conditions. Low- to moderate-severity fire, in contrast, can moderate future fire behavior by reducing fuel loads. The extent to which previous fires moderate future fire severity will powerfully affect fire-prone forest ecosystem trajectories over the next century. Further, knowing where and when a wildfire may act as a landscape-scale fuel treatment can help direct pre- and post-fire management efforts. We leverage satellite imagery and fire progression mapping to model reburn dynamics within forests that initially burned at low/moderate severity in 726 unique fire pair events over a 36-year period across four large fire-prone Western US ecoregions. We ask (1) how strong are the moderating effects of low- to moderate-severity fire on future fire severity, (2) how long do moderating effects last, and (3) how does the time between fires (a proxy for fuel accumulation) interact with initial fire severity, day-of-burning weather conditions, and climate to influence reburn severity. Short-interval reburns primarily occurred in dry- and moist-mixed conifer forests with historically frequent-fire regimes. Previous fire moderated reburn severity in all ecoregions with the strongest effects occurring in the California Coast and Western Mountains and the average duration of moderating effects ranging from 13 years in the Western Mountains to >36 years in the California Coast. The strength and duration of moderating effects depended on climate and initial fire severity in some regions, reflecting differences in post-fire fuel accumulation. In the California Coast, moderating effects lasted longer in cooler and wetter forests. In the Western Mountains, moderating effects were stronger and longer lasting in forests that initially burned at higher severity. Moderating effects were largely robust to fire weather, suggesting that previous fire can mediate future fire severity even under extreme conditions. Our findings demonstrate that low- to moderate-severity fire buffers future fire severity in historically frequent-fire forests, underlining the importance of wildfire as a restoration tool for adapting to global change.
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Affiliation(s)
- Claire M Tortorelli
- Department of Plant Sciences, University of California, Davis, California, USA
| | - Andrew M Latimer
- Department of Plant Sciences, University of California, Davis, California, USA
| | - Derek J N Young
- Department of Plant Sciences, University of California, Davis, California, USA
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2
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Kennedy MC, Johnson MC, Harrison SC. Model analysis of post-fire management and potential reburn fire behavior. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119664. [PMID: 38042073 DOI: 10.1016/j.jenvman.2023.119664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 11/07/2023] [Accepted: 11/19/2023] [Indexed: 12/04/2023]
Abstract
Recent trends in wildfire area burned have been characterized by large patches with high densities of standing dead trees, well outside of historical range of variability in many areas and presenting forest managers with difficult decisions regarding post-fire management. Post-fire tree harvesting, commonly called salvage logging, is a controversial management tactic that is often undertaken to recoup economic loss and, more recently, also to reduce future fuel hazard, especially when coupled with surface fuel reduction. It is unclear, however, whether the reductions in future fuels translate to meaningful changes to reburn fire behavior, particularly in the context of potentially detrimental effects of harvest on other ecosystem services. We used observed post-fire snag structure in four high severity burn scars located in the Western United States that had variable post-fire snag basal area (13.3-63.9 mg ha-2) to initialize a simulation study of future coarse and fine woody fuel hazard and associated reburn fire behavior and effects. We compared untreated controls to intensive and intermediate intensity harvest treatments, both simulated and actual. All treatments showed some number of years of extreme fire behavior during which flame lengths exceeded thresholds associated with wildfire resistance to control, implying that future fuel reductions achieved by the treatments did not translate to conditions conducive for effective reburn fire management. Harvested stands had less severe soil fire effects (soil heating and smoldering duration) than untreated controls, explained by lower predicted peak coarse woody fuels (CWD) in the harvested stands. At higher pre-treatment snag basal area, harvested stands better maintained CWD within the range desired to maintain ecosystem functions such as nutrient cycling and wildlife habitat. These simulation results indicate that, even with reduced fuel hazard, salvage treatments may still be associated with severe fire behavior for some time after wildfire, but achieved reductions in coarse woody fuels may also reduce some soil fire effects. Tradeoffs in the effects of post-fire harvest must be considered carefully in the context of forest regeneration, local conditions that govern salvage methods, snag fall and decomposition, and associated potential reburn fire effects.
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Affiliation(s)
- Maureen C Kennedy
- University of Washington, Tacoma, School of Interdisciplinary Arts and Sciences, Division of Sciences and Mathematics, 1900 Commerce St, Tacoma, WA, 98402, USA.
| | - Morris C Johnson
- US Forest Service, Pacific Northwest Research Station, 400 North 34th Street, Suite 201, Seattle, WA, 98103, USA
| | - Sarah C Harrison
- US Forest Service, Pacific Northwest Research Station, 400 North 34th Street, Suite 201, Seattle, WA, 98103, USA; University of Washington, Seattle, School and Environmental and Forest Sciences, PO Box 352100, Seattle, WA, 98195, USA
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3
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Wu X, Sverdrup E, Mastrandrea MD, Wara MW, Wager S. Low-intensity fires mitigate the risk of high-intensity wildfires in California's forests. SCIENCE ADVANCES 2023; 9:eadi4123. [PMID: 37948522 PMCID: PMC10637742 DOI: 10.1126/sciadv.adi4123] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 10/12/2023] [Indexed: 11/12/2023]
Abstract
The increasing frequency of severe wildfires demands a shift in landscape management to mitigate their consequences. The role of managed, low-intensity fire as a driver of beneficial fuel treatment in fire-adapted ecosystems has drawn interest in both scientific and policy venues. Using a synthetic control approach to analyze 20 years of satellite-based fire activity data across 124,186 square kilometers of forests in California, we provide evidence that low-intensity fires substantially reduce the risk of future high-intensity fires. In conifer forests, the risk of high-intensity fire is reduced by 64.0% [95% confidence interval (CI): 41.2 to 77.9%] in areas recently burned at low intensity relative to comparable unburned areas, and protective effects last for at least 6 years (lower bound of one-sided 95% CI: 6 years). These findings support a policy transition from fire suppression to restoration, through increased use of prescribed fire, cultural burning, and managed wildfire, of a presuppression and precolonial fire regime in California.
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Affiliation(s)
- Xiao Wu
- Department of Biostatistics, Columbia University, New York, NY, USA
| | - Erik Sverdrup
- Graduate School of Business, Stanford University, Stanford, CA, USA
| | | | - Michael W. Wara
- Woods Institute for the Environment, Stanford University, Stanford, CA, USA
| | - Stefan Wager
- Graduate School of Business, Stanford University, Stanford, CA, USA
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4
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García-Redondo C, Fernández-Moure P, Cánibe M, Tapia L, Gil-Carrera A, Lombao A, Díaz-Raviña M, Regos A. Burn severity and land-use legacy influence bird abundance in the Atlantic-Mediterranean biogeographic transition. ENVIRONMENTAL RESEARCH 2023; 233:116510. [PMID: 37385415 DOI: 10.1016/j.envres.2023.116510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/22/2023] [Accepted: 06/24/2023] [Indexed: 07/01/2023]
Abstract
Fire regimes in mountain landscapes of southern Europe have been shifting from their baselines due to rural abandonment and fire exclusion policies. Understanding the effects of fire on biodiversity is paramount to implement adequate management. Herein, we evaluated the relative role of burn severity and heterogeneity on bird abundance in an abandoned mountain range located in the biogeographic transition between the Eurosiberian and Mediterranean region (the Natural Park 'Baixa Limia-Serra do Xurés'). We surveyed the bird community in 206 census plots distributed across the Natural Park, both inside and outside areas affected by wildfires over the last 11 years (from 2010 to 2020). We used satellite images of Sentinel 2 and Landsat missions to quantify the burn severity and heterogeneity of each fire within each surveyed plot. We also accounted for the past land use (forestry or agropastoral use) by using a land cover information for year 2010 derived from satellite image classification. We recorded 1735 contacts from 28 bird species. Our models, fitted by using GLMs with Poisson error distribution (pseudo-R2-average of 0.22 ± 0.13), showed that up to 71% of the modeled species were linearly correlated with at least one attribute of the fire regime. The spatiotemporal variation in burnt area and severity were relevant factors for explaining the local abundance of our target species (39% of the species; Akaike weights >0.75). We also found a quadratic effect of at least one fire regime attribute on bird abundance for 60% of the modeled species. The past land use, and its legacy after 10 years, was critical to understand the role of fire (Akaike weights >0.75). Our findings confirm the importance of incorporating remotely sensed indicators of burn severity into the toolkit of decision makers to accurately anticipate the response of birds to fire management.
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Affiliation(s)
- Concepción García-Redondo
- Área de Edafoloxía e Química Agrícola, Departamento de Bioloxía Vexetal e Ciencia do Solo, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, s/n 32004, Ourense, Spain
| | - Paula Fernández-Moure
- Departamento de Zooloxía, Xenética e Antropoloxía Física, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Miguel Cánibe
- Departamento de Zooloxía, Xenética e Antropoloxía Física, Universidade de Santiago de Compostela, Santiago de Compostela, Spain; BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal; CIBIO-InBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório Associado, Universidade do Porto, Campus de Vairão, Vila do Conde, 4485-661, Portugal
| | - Luis Tapia
- Departamento de Zooloxía, Xenética e Antropoloxía Física, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Alberto Gil-Carrera
- EBX, Estación Biolóxica do Xurés, Vilameá de Riocaldo 121, 32870, Lobios, Galicia, Spain; GREFA, Monte del Pilar S/N, 28220, Majadahonda, Spain
| | - Alba Lombao
- Misión Biológica de Galicia del Consejo Superior de Investigaciones Científicas (MBG-CSIC), Sede Santiago de Compostela, Avda de Vigo s/n, 15705, Santiago de Compostela, Spain
| | - Montserrat Díaz-Raviña
- Misión Biológica de Galicia del Consejo Superior de Investigaciones Científicas (MBG-CSIC), Sede Santiago de Compostela, Avda de Vigo s/n, 15705, Santiago de Compostela, Spain
| | - Adrián Regos
- Centre de Ciència i Tecnologia Forestal de Catalunya. Ctra. St. Llorenç de Morunys km 2, 25280, Solsona, Spain; Departamento de Zooloxía, Xenética e Antropoloxía Física, Universidade de Santiago de Compostela, Santiago de Compostela, Spain; BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal; CIBIO-InBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório Associado, Universidade do Porto, Campus de Vairão, Vila do Conde, 4485-661, Portugal.
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Evaluating Effects of Post-Fire Climate and Burn Severity on the Early-Term Regeneration of Forest and Shrub Communities in the San Gabriel Mountains of California from Sentinel-2(MSI) Images. FORESTS 2022. [DOI: 10.3390/f13071060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Studying the early changes in post-fire vegetation communities may improve the overall resilience of forests. The necessity for doing so was demonstrated by the Bobcat Fire, which seriously threatened the central San Gabriel Mountains and the Angeles National Forest in California. This study aimed to monitor and quantify the effects of climatological and topographic conditions along with burn severity on early (within 1 year) post-fire forests and shrubs community regeneration. In this study, we used Sentinel-2(MSI) intensive time-series imagery (July 2020–October 2021) to make a confusion matrix combined with 389 vegetation sample points on Google Earth Pro. The overall accuracy (OA) and the Kappa coefficient, calculated from the confusion matrix, were used as evaluation parameters to validate the classification results. With multiple linear regression models and Environmental Systems Research Institute (ESRI) historical images, we analyzed the effects of climate and slope aspects on the regeneration of post-fire forest and shrub communities. We also quantitatively analyzed the regeneration rates based on five burn severity types. The results show that the normalized burning rate (NBR) was the most accurate vegetation classification indicator in this study (OA: 92.3–99.5%, Kappa: 0.88–0.98). The vegetation classification accuracy based on SVM is about 6.6% higher than K-Means. The overall accuracy of the burn area is 94.87%. Post-fire climate factors had a significant impact on the regeneration of the two vegetation communities (R2: 0.42–0.88); the optimal regeneration slope was 15–35°; and the fire severity changed the original competition relationship and regeneration rate. The results provide four main insights into the regeneration of post-fire vegetation communities: (1) climate factors in the first regenerating season have important impacts on the regeneration of forest and shrub communities; (2) daytime duration and rainfall are the most significant factors for forests and shrubs regeneration; (3) tolerable low burn severity promotes forests regeneration; and (4) forests have a certain ability to resist fires, while shrubs can better tolerate high-intensity fire ecology. This study could support the implementation of strategies for regionalized forest management and the targeted enhancement of post-fire vegetation community resilience.
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Braziunas KH, Abendroth DC, Turner MG. Young forests and fire: Using lidar–imagery fusion to explore fuels and burn severity in a subalpine forest reburn. Ecosphere 2022. [DOI: 10.1002/ecs2.4096] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Kristin H. Braziunas
- Department of Integrative Biology University of Wisconsin‐Madison Madison Wisconsin USA
| | | | - Monica G. Turner
- Department of Integrative Biology University of Wisconsin‐Madison Madison Wisconsin USA
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Hagmann RK, Hessburg PF, Prichard SJ, Povak NA, Brown PM, Fulé PZ, Keane RE, Knapp EE, Lydersen JM, Metlen KL, Reilly MJ, Sánchez Meador AJ, Stephens SL, Stevens JT, Taylor AH, Yocom LL, Battaglia MA, Churchill DJ, Daniels LD, Falk DA, Henson P, Johnston JD, Krawchuk MA, Levine CR, Meigs GW, Merschel AG, North MP, Safford HD, Swetnam TW, Waltz AEM. Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02431. [PMID: 34339067 PMCID: PMC9285092 DOI: 10.1002/eap.2431] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/04/2021] [Accepted: 03/22/2021] [Indexed: 05/06/2023]
Abstract
Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.
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Affiliation(s)
- R. K. Hagmann
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
- Applegate Forestry LLCCorvallisOregon97330USA
| | - P. F. Hessburg
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
- USDA‐FS, Forestry Sciences LaboratoryPacific Northwest Research StationWenatcheeWashington98801USA
| | - S. J. Prichard
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
| | - N. A. Povak
- USDA‐FS, Forestry Sciences LaboratoryPacific Northwest Research StationWenatcheeWashington98801USA
- USDA‐FS, Pacific Southwest Research StationPlacervilleCalifornia95667USA
| | - P. M. Brown
- Rocky Mountain Tree‐Ring ResearchFort CollinsColorado80526USA
| | - P. Z. Fulé
- School of ForestryNorthern Arizona UniversityFlagstaffArizona86011USA
| | - R. E. Keane
- Missoula Fire Sciences LaboratoryUSDA‐FS, Rocky Mountain Research StationMissoulaMontana59808USA
| | - E. E. Knapp
- USDA‐FS, Pacific Southwest Research StationReddingCalifornia96002USA
| | - J. M. Lydersen
- Fire and Resource Assessment ProgramCalifornia Department of Forestry and Fire ProtectionSacramentoCalifornia94244USA
| | | | - M. J. Reilly
- USDA‐FS, Pacific Northwest Research StationCorvallisOregon97333USA
| | - A. J. Sánchez Meador
- Ecological Restoration InstituteNorthern Arizona UniversityFlagstaffArizona86011USA
| | - S. L. Stephens
- Department of Environmental Science, Policy, and ManagementUniversity of California–BerkeleyBerkeleyCalifornia94720USA
| | - J. T. Stevens
- U.S. Geological SurveyFort Collins Science CenterNew Mexico Landscapes Field StationSanta FeNew Mexico87508USA
| | - A. H. Taylor
- Department of Geography, Earth and Environmental Systems InstituteThe Pennsylvania State UniversityUniversity ParkPennsylvania16802USA
| | - L. L. Yocom
- Department of Wildland Resources and the Ecology CenterUtah State UniversityLoganUtah84322USA
| | - M. A. Battaglia
- USDA‐FS, Rocky Mountain Research StationFort CollinsColorado80526USA
| | - D. J. Churchill
- Washington State Department of Natural ResourcesOlympiaWashington98504USA
| | - L. D. Daniels
- Department of Forest and Conservation SciencesUniversity of British ColumbiaVancouverBritish ColumbiaV6T 1Z4Canada
| | - D. A. Falk
- School of Natural Resources and the EnvironmentUniversity of ArizonaTucsonArizona85721USA
- Laboratory of Tree‐Ring ResearchUniversity of ArizonaTucsonArizona85721USA
| | - P. Henson
- Oregon Fish and Wildlife OfficeUSDI Fish & Wildlife ServicePortlandOregon97232USA
| | - J. D. Johnston
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - M. A. Krawchuk
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - C. R. Levine
- Spatial Informatics GroupPleasantonCalifornia94566USA
| | - G. W. Meigs
- Washington State Department of Natural ResourcesOlympiaWashington98504USA
| | - A. G. Merschel
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - M. P. North
- USDA‐FS, Pacific Southwest Research StationMammoth LakesCalifornia93546USA
| | - H. D. Safford
- USDA‐FS, Pacific Southwest RegionVallejoCalifornia94592USA
| | - T. W. Swetnam
- Laboratory of Tree‐Ring ResearchUniversity of ArizonaTucsonArizona85721USA
| | - A. E. M. Waltz
- Ecological Restoration InstituteNorthern Arizona UniversityFlagstaffArizona86011USA
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Prichard SJ, Hessburg PF, Hagmann RK, Povak NA, Dobrowski SZ, Hurteau MD, Kane VR, Keane RE, Kobziar LN, Kolden CA, North M, Parks SA, Safford HD, Stevens JT, Yocom LL, Churchill DJ, Gray RW, Huffman DW, Lake FK, Khatri‐Chhetri P. Adapting western North American forests to climate change and wildfires: 10 common questions. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02433. [PMID: 34339088 PMCID: PMC9285930 DOI: 10.1002/eap.2433] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/09/2021] [Accepted: 03/22/2021] [Indexed: 05/22/2023]
Abstract
We review science-based adaptation strategies for western North American (wNA) forests that include restoring active fire regimes and fostering resilient structure and composition of forested landscapes. As part of the review, we address common questions associated with climate adaptation and realignment treatments that run counter to a broad consensus in the literature. These include the following: (1) Are the effects of fire exclusion overstated? If so, are treatments unwarranted and even counterproductive? (2) Is forest thinning alone sufficient to mitigate wildfire hazard? (3) Can forest thinning and prescribed burning solve the problem? (4) Should active forest management, including forest thinning, be concentrated in the wildland urban interface (WUI)? (5) Can wildfires on their own do the work of fuel treatments? (6) Is the primary objective of fuel reduction treatments to assist in future firefighting response and containment? (7) Do fuel treatments work under extreme fire weather? (8) Is the scale of the problem too great? Can we ever catch up? (9) Will planting more trees mitigate climate change in wNA forests? And (10) is post-fire management needed or even ecologically justified? Based on our review of the scientific evidence, a range of proactive management actions are justified and necessary to keep pace with changing climatic and wildfire regimes and declining forest heterogeneity after severe wildfires. Science-based adaptation options include the use of managed wildfire, prescribed burning, and coupled mechanical thinning and prescribed burning as is consistent with land management allocations and forest conditions. Although some current models of fire management in wNA are averse to short-term risks and uncertainties, the long-term environmental, social, and cultural consequences of wildfire management primarily grounded in fire suppression are well documented, highlighting an urgency to invest in intentional forest management and restoration of active fire regimes.
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Affiliation(s)
- Susan J. Prichard
- University of Washington School of Environmental and Forest SciencesSeattleWashington98195‐2100USA
| | - Paul F. Hessburg
- University of Washington School of Environmental and Forest SciencesSeattleWashington98195‐2100USA
- U.S. Forest Service PNW Research StationWenatcheeWashington98801USA
| | - R. Keala Hagmann
- University of Washington School of Environmental and Forest SciencesSeattleWashington98195‐2100USA
- Applegate Forestry LLCCorvallisOregon97330USA
| | - Nicholas A. Povak
- U.S. Forest ServicePacific Southwest Research StationInstitute of Forest Genetics2480 Carson RoadPlacervilleCalifornia95667USA
| | - Solomon Z. Dobrowski
- University of Montana College of Forestry and ConservationMissoulaMontana59812USA
| | - Matthew D. Hurteau
- University of New Mexico Biology DepartmentAlbuquerqueNew Mexico87131‐0001USA
| | - Van R. Kane
- University of Washington School of Environmental and Forest SciencesSeattleWashington98195‐2100USA
| | - Robert E. Keane
- U.S. Forest Service Rocky Mountain Research StationMissoula Fire Sciences LaboratoryMissoulaMontana59808USA
| | - Leda N. Kobziar
- Department of Natural Resources and SocietyUniversity of IdahoMoscowIdaho83844USA
| | - Crystal A. Kolden
- School of EngineeringUniversity of California MercedMercedCalifornia95343USA
| | - Malcolm North
- U.S. Forest Service Pacific Southwest Research Station1731 Research ParkDavisCalifornia95618USA
| | - Sean A. Parks
- U.S. Forest Service Aldo Leopold Wilderness Research InstituteMissoulaMontana59801USA
| | - Hugh D. Safford
- U.S. Forest Service Pacific Southwest Research StationAlbanyCalifornia94710USA
| | - Jens T. Stevens
- U.S. Geological Survey Fort Collins Science CenterNew Mexico Landscapes Field StationSanta FeNew Mexico87544USA
| | - Larissa L. Yocom
- Department of Wildland Resources and Ecology CenterUtah State University College of Agriculture and Applied SciencesLoganUtah84322USA
| | - Derek J. Churchill
- Washington State Department of Natural Resources Forest Health ProgramOlympiaWashington98504USA
| | - Robert W. Gray
- R.W. Gray ConsultingChilliwackBritish ColumbiaV2R2N2Canada
| | - David W. Huffman
- Northern Arizona University Ecological Restoration InstituteFlagstaffArizona86011USA
| | - Frank K. Lake
- U.S. Forest Service Pacific Southwest Research StationArcataCalifornia95521USA
| | - Pratima Khatri‐Chhetri
- University of Washington School of Environmental and Forest SciencesSeattleWashington98195‐2100USA
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9
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Park IW, Mann ML, Flint LE, Flint AL, Moritz M. Relationships of climate, human activity, and fire history to spatiotemporal variation in annual fire probability across California. PLoS One 2021; 16:e0254723. [PMID: 34731170 PMCID: PMC8565767 DOI: 10.1371/journal.pone.0254723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 07/01/2021] [Indexed: 11/18/2022] Open
Abstract
In the face of recent wildfires across the Western United States, it is essential that we understand both the dynamics that drive the spatial distribution of wildfire, and the major obstacles to modeling the probability of wildfire over space and time. However, it is well documented that the precise relationships of local vegetation, climate, and ignitions, and how they influence fire dynamics, may vary over space and among local climate, vegetation, and land use regimes. This raises questions not only as to the nature of the potentially nonlinear relationships between local conditions and the fire, but also the possibility that the scale at which such models are developed may be critical to their predictive power and to the apparent relationship of local conditions to wildfire. In this study we demonstrate that both local climate-through limitations posed by fuel dryness (CWD) and availability (AET)-and human activity-through housing density, roads, electrical infrastructure, and agriculture, play important roles in determining the annual probabilities of fire throughout California. We also document the importance of previous burn events as potential barriers to fire in some environments, until enough time has passed for vegetation to regenerate sufficiently to sustain subsequent wildfires. We also demonstrate that long-term and short-term climate variations exhibit different effects on annual fire probability, with short-term climate variations primarily impacting fire probability during periods of extreme climate anomaly. Further, we show that, when using nonlinear modeling techniques, broad-scale fire probability models can outperform localized models at predicting annual fire probability. Finally, this study represents a powerful tool for mapping local fire probability across the state of California under a variety of historical climate regimes, which is essential to avoided emissions modeling, carbon accounting, and hazard severity mapping for the application of fire-resistant building codes across the state of California.
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Affiliation(s)
- Isaac W. Park
- Department of Ecology, Evolution, and Marine Biology, University of California–Santa Barbara, Santa Barbara, California, United States of America
| | - Michael L. Mann
- Department of Geography, George Washington University, Washington, D.C., United States of America
| | | | - Alan L. Flint
- U.S. Geological Survey, Sacramento, CA, United States of America
| | - Max Moritz
- University of California Cooperative Extension, Santa Barbara, CA, United States of America
- Bren School of the Environment, University of California–Santa Barbara, Santa Barbara, CA, United States of America
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10
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Taylor AH, Harris LB, Drury SA. Drivers of fire severity shift as landscapes transition to an active fire regime, Klamath Mountains, USA. Ecosphere 2021. [DOI: 10.1002/ecs2.3734] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Alan H. Taylor
- Department of Geography Earth and Environmental Systems Institute The Pennsylvania State University University Park Pennsylvania USA
| | - Lucas B. Harris
- Department of Geography Earth and Environmental Systems Institute The Pennsylvania State University University Park Pennsylvania USA
| | - Stacy A. Drury
- Pacific Southwest Research Station USDA Forest Service Davis California 95618 USA
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11
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Downing WM, Meigs GW, Gregory MJ, Krawchuk MA. Where and why do conifer forests persist in refugia through multiple fire events? GLOBAL CHANGE BIOLOGY 2021; 27:3642-3656. [PMID: 33896078 PMCID: PMC8362119 DOI: 10.1111/gcb.15655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/02/2021] [Accepted: 04/14/2021] [Indexed: 06/12/2023]
Abstract
Changing wildfire regimes are causing rapid shifts in forests worldwide. In particular, forested landscapes that burn repeatedly in relatively quick succession may be at risk of conversion when pre-fire vegetation cannot recover between fires. Fire refugia (areas that burn less frequently or severely than the surrounding landscape) support post-fire ecosystem recovery and the persistence of vulnerable species in fire-prone landscapes. Observed and projected fire-induced forest losses highlight the need to understand where and why forests persist in refugia through multiple fires. This research need is particularly acute in the Klamath-Siskiyou ecoregion of southwest Oregon and northwest California, USA, where expected increases in fire activity and climate warming may result in the loss of up to one-third of the region's conifer forests, which are the most diverse in western North America. Here, we leverage recent advances in fire progression mapping and weather interpolation, in conjunction with a novel application of satellite smoke imagery, to model the key controls on fire refugia occurrence and persistence through one, two, and three fire events over a 32-year period. Hotter-than-average fire weather was associated with lower refugia probability and higher fire severity. Refugia that persisted through three fire events appeared to be partially entrained by landscape features that offered protection from fire, suggesting that topographic variability may be an important stabilizing factor as forests pass through successive fire filters. In addition, smoke density strongly influenced fire effects, with fire refugia more likely to occur when smoke was moderate or dense in the morning, a relationship attributable to reduced incoming solar radiation resulting from smoke shading. Results from this study could inform management strategies designed to protect fire-resistant portions of biologically and topographically diverse landscapes.
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Affiliation(s)
- William M. Downing
- Department of Forest Ecosystems and SocietyCollege of ForestryOregon State UniversityCorvallisOR97331USA
| | - Garrett W. Meigs
- Washington State Department of Natural ResourcesOlympiaWA98504USA
| | - Matthew J. Gregory
- Department of Forest Ecosystems and SocietyCollege of ForestryOregon State UniversityCorvallisOR97331USA
| | - Meg A. Krawchuk
- Department of Forest Ecosystems and SocietyCollege of ForestryOregon State UniversityCorvallisOR97331USA
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12
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Abstract
Pyrodiversity or variation in spatio-temporal fire patterns is increasingly recognized as an important determinant of ecological pattern and process, yet no consensus surrounds how best to quantify the phenomenon and its drivers remain largely untested. We present a generalizable functional diversity approach for measuring pyrodiversity, which incorporates multiple fire regime traits and can be applied across scales. Further, we tested the socioecological drivers of pyrodiversity among forests of the western United States. Largely mediated by burn activity, pyrodiversity was positively associated with actual evapotranspiration, climate water deficit, wilderness designation, elevation and topographic roughness but negatively with human population density. These results indicate pyrodiversity is highest in productive areas with pronounced annual dry periods and minimal fire suppression. This work can facilitate future pyrodiversity studies including whether and how it begets biodiversity among taxa, regions and fire regimes.
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Affiliation(s)
- Zachary L Steel
- Department of Environmental Science, Policy and Management, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Brandon M Collins
- Center for Fire Research and Outreach, University of California, Berkeley, CA 94720, USA.,USDA Forest Service, Pacific Southwest Research Station, Davis, CA 95618, USA
| | - David B Sapsis
- California Department of Forestry and Fire Protection, Sacramento, CA 95814, USA
| | - Scott L Stephens
- Department of Environmental Science, Policy and Management, University of California-Berkeley, Berkeley, CA 94720, USA
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13
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Koplitz SN, Nolte CG, Sabo RD, Clark CM, Horn KJ, Thomas RQ, Newcomer-Johnson TA. The contribution of wildland fire emissions to deposition in the U S: implications for tree growth and survival in the Northwest. ENVIRONMENTAL RESEARCH LETTERS : ERL [WEB SITE] 2021; 16:10.1088/1748-9326/abd26e. [PMID: 33747119 PMCID: PMC7970516 DOI: 10.1088/1748-9326/abd26e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Ecosystems require access to key nutrients like nitrogen (N) and sulfur (S) to sustain growth and healthy function. However, excessive deposition can also damage ecosystems through nutrient imbalances, leading to changes in productivity and shifts in ecosystem structure. While wildland fires are a known source of atmospheric N and S, little has been done to examine the implications of wildland fire deposition for vulnerable ecosystems. We combine wildland fire emission estimates, atmospheric chemistry modeling, and forest inventory data to (a) quantify the contribution of wildland fire emissions to N and S deposition across the U S, and (b) assess the subsequent impacts on tree growth and survival rates in areas where impacts are likely meaningful based on the relative contribution of fire to total deposition. We estimate that wildland fires contributed 0.2 kg N ha-1 yr-1 and 0.04 kg S ha-1 yr-1 on average across the U S during 2008-2012, with maxima up to 1.4 kg N ha-1 yr-1 and 0.6 kg S ha-1 yr-1 in the Northwest representing over ~30% of total deposition in some areas. Based on these fluxes, exceedances of S critical loads as a result of wildland fires are minimal, but exceedances for N may affect the survival and growth rates of 16 tree species across 4.2 million hectares, with the most concentrated impacts occurring in Oregon, northern California, and Idaho. Understanding the broader environmental impacts of wildland fires in the U S will inform future decision making related to both fire management and ecosystem services conservation.
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Affiliation(s)
- Shannon N Koplitz
- Center for Environmental Measurement and Modeling, US EPA, Research Triangle Park, NC, United States of America
- Current address: Office of Air Quality Planning and Standards, US EPA, Research Triangle Park, NC, United States of America
| | - Christopher G Nolte
- Center for Environmental Measurement and Modeling, US EPA, Research Triangle Park, NC, United States of America
| | - Robert D Sabo
- Center for Public Health and Environmental Assessment, US EPA, Washington, DC, United States of America
| | - Christopher M Clark
- Center for Public Health and Environmental Assessment, US EPA, Washington, DC, United States of America
| | - Kevin J Horn
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA, United States of America
| | - R Quinn Thomas
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA, United States of America
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14
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Contextualizing the 2019–2020 Kangaroo Island Bushfires: Quantifying Landscape-Level Influences on Past Severity and Recovery with Landsat and Google Earth Engine. REMOTE SENSING 2020. [DOI: 10.3390/rs12233942] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The 2019–2020 Kangaroo Island bushfires in South Australia burned almost half of the island. To understand how to avoid future severe ‘mega-fires’ and how vegetation may recover from 2019–2020, we can utilize information from the bulk of historical fires in an area. Landsat time-series of vegetation change provide this opportunity, but there has been little analysis of large numbers of fires to build a landscape-level understanding and quantify drivers in an Australian context. In this study, we built a yearly cloud-free surface reflectance normalized burn ratio (NBR) time-series (1988–2020) using all available summer Landsat images over Kangaroo Island. Data were collected in Google Earth Engine and fitted with LandTrendr. Burn severity and post-fire recovery were quantified for 47 fires, with a new recovery metric facilitating comparison where fire frequency is high. Variables representing the current burn, fire history, vegetation structure, and topography were related to severity and yearly recovery with random forest and bivariate analysis. Results show that the 2019–2020 bushfires were the most widespread and severe, followed by 2007–2008. Vegetation recovers quickly, with NBR stabilizing ten years post-fire on average. Severity is most influenced by fire frequency, vegetation capacity and land use with more severe burns in nature conservation areas with dense vegetation and a history of frequent fires. Influence on recovery varied with time since fire, with initial (year 1–3) faster recovery observed in areas with less surviving vegetation. Later (year 6–10) recovery was most influenced by a variable representing burn year and further investigation indicates that precipitation increases in later post-fire years likely facilitated faster recovery. The relative abundance of eucalypt woodlands also has a positive influence on recovery in middle and later years. These results provide valuable information to land managers on Kangaroo Island and in similar environments, who should consider adjusting practices to limit future mega-fire risk and potential ecosystem shifts if severe fires become more frequent with climate change.
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15
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García-Llamas P, Suárez-Seoane S, Fernández-Manso A, Quintano C, Calvo L. Evaluation of fire severity in fire prone-ecosystems of Spain under two different environmental conditions. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 271:110706. [PMID: 32778251 DOI: 10.1016/j.jenvman.2020.110706] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/11/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Severe fires associated to climate change and land cover changes are becoming more frequent in Mediterranean Europe. The influence of environmental drivers on fire severity, especially under different environmental conditions is still not fully understood. In this study we aim to determine the main environmental variables that control fire severity in large fires (>500 ha) occurring in fire-prone ecosystems under two different environmental conditions following a transition (Mediterranean-Oceanic)-Mediterranean climatic gradient within the Iberian Peninsula, and to provide management recommendations to mitigate fire damage. We estimated fire severity as the differenced Normalized Burn Ratio, through images obtained from Landsat 8 OLI. We also examined the relative influence of pre-fire vegetation structure (vegetation composition and configuration), pre-fire weather conditions, fire history and topography on fire severity using Random Forest machine learning algorithms. The results indicated that the severity of fires occurring along the transition (Mediterranean-Oceanic)-Mediterranean climatic gradient was primarily controlled by pre-fire vegetation composition. Nevertheless, the effect of vegetation composition was strongly dependent on interactions with fire recurrence and pre-fire vegetation structural configuration. The relationship between fire severity, weather and topographic predictors was not consistent among fires occurring in the Mediterranean-Oceanic transition and Mediterranean sites. In the Mediterranean-Oceanic transition site, fire severity was determined by weather conditions (i.e., summer cumulative rainfall), rather than being associated to topography, suggesting that the control exerted by topography may be overwhelmed by weather controls. Conversely, results showed that topography only had a major effect on fire severity in the Mediterranean site. The results of this study highlight the need to prioritise fuel treatments aiming at breaking fuel continuity and reducing fuel loads as an effective management strategy to mitigate fire damage in areas of high fire recurrence.
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Affiliation(s)
- Paula García-Llamas
- Biodiversity and Environmental Management Dpt., Faculty of Biological and Environmental Sciences, University of León, Campus de Vegazana s/n, 24071, León, Spain; Institute of Environmental Research (IMA), University of Léon, 24071, León, Spain.
| | - Susana Suárez-Seoane
- University of Oviedo. Department of Organisms and Systems Biology (Ecology Unit) and Research Unit of Biodiversity (UO-CSIC-PA), Oviedo, Mieres, Spain
| | - Alfonso Fernández-Manso
- Agrarian Science and Engineering Department, University of León, Av. Astorga s/n, 24400, Ponferrada, Spain
| | - Carmen Quintano
- Electronic Technology Department, Sustainable Forest Management Research Institute, University of Valladolid, Spanish National Institute for Agriculture and Food Research and Technology (INIA), C/Francisco Mendizábal s/n, 47014, Valladolid, Spain
| | - Leonor Calvo
- Biodiversity and Environmental Management Dpt., Faculty of Biological and Environmental Sciences, University of León, Campus de Vegazana s/n, 24071, León, Spain; Institute of Environmental Research (IMA), University of Léon, 24071, León, Spain
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16
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Martini L, Faes L, Picco L, Iroumé A, Lingua E, Garbarino M, Cavalli M. Assessing the effect of fire severity on sediment connectivity in central Chile. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 728:139006. [PMID: 32361584 DOI: 10.1016/j.scitotenv.2020.139006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
Chilean territory is recurrently affected by severe wildfires, which drastically reduce the forest cover and promote runoff, soil erosion and slope instabilities. To understand how the geomorphic system responds to wildfires in terms of sediment dynamics, the assessment of sediment connectivity, i.e. the property describing the relationships between compartments of a geomorphic system, is crucial. This study aims to quantify the spatial linkages between fire severity and sediment connectivity to identify common patterns and driving factors. The compound use of field data and open-source satellite imagery helped to apply the Relative differenced Normalized Burn Ratio (RdNBR) and the Index of Connectivity (IC) in the context of two consecutive wildfires, occurred in 2002 and 2015, in the Rio Toro catchment (Chile). The fire severity assessment showed that the 2002 event affected 90% of the catchment, with high severity areas representing around 70%. The 2015 wildfire instead, affected 76% of the catchment with moderate severity around 42%. Accordingly, as result of the sudden reduction in forest cover in severely affected areas, the IC changed after both wildfires with an overall increase of 1.07 and 0.54, respectively. However, only for the second disturbance, it was possible to observe a clear relationship between the RdNBR and the IC variations. The different degree of vegetation cover heterogeneity between the two pre-wildfire scenarios contributed to different fire severity and IC variability between the two disturbances. The use of open-source satellite data and the development of a weighting factor (W), to be used in IC and able to capture the land cover change driven by the wildfires, could make the application of this approach straightforward, promoting its reproducibility in other catchments for land management and risk mitigation purposes.
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Affiliation(s)
- Lorenzo Martini
- University of Padova, Department of Land, Environment, Agriculture and Forestry, Legnaro, Italy..
| | - Lorenzo Faes
- University of Padova, Department of Land, Environment, Agriculture and Forestry, Legnaro, Italy
| | - Lorenzo Picco
- University of Padova, Department of Land, Environment, Agriculture and Forestry, Legnaro, Italy.; Universidad Austral de Chile, Faculty of Engineering, Valdivia, Chile; Universidad Austral de Chile, RINA - Natural and Anthropogenic Risks Research Center, Valdivia, Chile
| | - Andrés Iroumé
- Universidad Austral de Chile, Faculty of Forest Sciences and Natural Resources, Valdivia, Chile
| | - Emanuele Lingua
- University of Padova, Department of Land, Environment, Agriculture and Forestry, Legnaro, Italy
| | - Matteo Garbarino
- University of Torino, Department of Agricultural, Forest and Food Sciences, Grugliasco, Italy
| | - Marco Cavalli
- National Research Council, Research Institute for Geo-Hydrological Protection, Padova, Italy
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17
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Prichard SJ, Povak NA, Kennedy MC, Peterson DW. Fuel treatment effectiveness in the context of landform, vegetation, and large, wind-driven wildfires. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02104. [PMID: 32086976 DOI: 10.1002/eap.2104] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/03/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
Large wildfires (>50,000 ha) are becoming increasingly common in semiarid landscapes of the western United States. Although fuel reduction treatments are used to mitigate potential wildfire effects, they can be overwhelmed in wind-driven wildfire events with extreme fire behavior. We evaluated drivers of fire severity and fuel treatment effectiveness in the 2014 Carlton Complex, a record-setting complex of wildfires in north-central Washington State. Across varied topography, vegetation, and distinct fire progressions, we used a combination of simultaneous autoregression (SAR) and random forest (RF) approaches to model drivers of fire severity and evaluated how fuel treatments mitigated fire severity. Predictor variables included fuel treatment type, time since treatment, topographic indices, vegetation and fuels, and weather summarized by progression interval. We found that the two spatial regression methods are generally complementary and are instructive as a combined approach for landscape analyses of fire severity. Simultaneous autoregression improves upon traditional linear models by incorporating information about neighboring pixel burn severity, which avoids type I errors in coefficient estimates and incorrect inferences. Random forest modeling provides a flexible modeling environment capable of capturing complex interactions and nonlinearities while still accounting for spatial autocorrelation through the use of spatially explicit predictor variables. All treatment areas burned with higher proportions of moderate and high-severity fire during early fire progressions, but thin and underburn, underburn only, and past wildfires were more effective than thin-only and thin and pile burn treatments. Treatment units had much greater percentages of unburned and low severity area in later progressions that burned under milder fire weather conditions, and differences between treatments were less pronounced. Our results provide evidence that strategic placement of fuels reduction treatments can effectively reduce localized fire spread and severity even under severe fire weather. During wind-driven fire spread progressions, fuel treatments that were located on leeward slopes tended to have lower fire severity than treatments located on windward slopes. As fire and fuels managers evaluate options for increasing landscape resilience to future climate change and wildfires, strategic placement of fuel treatments may be guided by retrospective studies of past large wildfire events.
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Affiliation(s)
- Susan J Prichard
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, Washington, 98195-2100, USA
| | - Nicholas A Povak
- USDA Forest Service, Pacific Northwest Research Station, Wenatchee Forestry Sciences Lab, Wenatchee, Washington, 98801, USA
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, Tennessee, 37830, USA
| | - Maureen C Kennedy
- Sciences and Mathematics, Division of the School of Interdisciplinary Arts and Sciences, University of Washington - Tacoma, Tacoma, Washington, 98801, USA
| | - David W Peterson
- USDA Forest Service, Pacific Northwest Research Station, Wenatchee Forestry Sciences Lab, Wenatchee, Washington, 98801, USA
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18
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Hansen WD, Abendroth D, Rammer W, Seidl R, Turner MG. Can wildland fire management alter 21st-century subalpine fire and forests in Grand Teton National Park, Wyoming, USA? ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02030. [PMID: 31674698 PMCID: PMC7612770 DOI: 10.1002/eap.2030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 08/09/2019] [Accepted: 09/16/2019] [Indexed: 06/10/2023]
Abstract
In subalpine forests of the western United States that historically experienced infrequent, high-severity fire, whether fire management can shape 21st-century fire regimes and forest dynamics to meet natural resource objectives is not known. Managed wildfire use (i.e., allowing lightning-ignited fires to burn when risk is low instead of suppressing them) is one approach for maintaining natural fire regimes and fostering mosaics of forest structure, stand age, and tree-species composition, while protecting people and property. However, little guidance exists for where and when this strategy may be effective with climate change. We simulated most of the contiguous forest in Grand Teton National Park, Wyoming, USA to ask: (1) how would subalpine fires and forest structure be different if fires had not been suppressed during the last three decades? And (2) what is the relative influence of climate change vs. fire management strategy on future fire and forests? We contrasted fire and forests from 1989 to 2098 under two fire management scenarios (managed wildfire use and fire suppression), two general circulation models (CNRM-CM5 and GFDL-ESM2M), and two representative concentration pathways (8.5 and 4.5). We found little difference between management scenarios in the number, size, or severity of fires during the last three decades. With 21st-century warming, fire activity increased rapidly, particularly after 2050, and followed nearly identical trajectories in both management scenarios. Area burned per year between 2018 and 2099 was 1,700% greater than in the last three decades (1989-2017). Large areas of forest were abruptly lost; only 65% of the original 40,178 ha of forest remained by 2098. However, forests stayed connected and fuels were abundant enough to support profound increases in burning through this century. Our results indicate that strategies emphasizing managed wildfire use, rather than suppression, will not alter climate-induced changes to fire and forests in subalpine landscapes of western North America. This suggests that managers may continue to have flexibility to strategically suppress subalpine fires without concern for long-term consequences, in distinct contrast with dry conifer forests of the Rocky Mountains and mixed conifer forest of California where maintaining low fuel loads is essential for sustaining frequent, low-severity surface fire regimes.
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Affiliation(s)
- Winslow D. Hansen
- Department of Integrative Biology, University of Wisconsin–Madison, Madison, Wisconsin 53706 USA
| | - Diane Abendroth
- Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna Austria
| | - Werner Rammer
- Grand Teton National Park, Teton Interagency Fire, Moose, Wyoming 83012 USA
| | - Rupert Seidl
- Grand Teton National Park, Teton Interagency Fire, Moose, Wyoming 83012 USA
| | - Monica G. Turner
- Department of Integrative Biology, University of Wisconsin–Madison, Madison, Wisconsin 53706 USA
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19
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Krofcheck DJ, Litvak ME, Hurteau MD. Allometric relationships for
Quercus gambelii
and
Robinia neomexicana
for biomass estimation following disturbance. Ecosphere 2019. [DOI: 10.1002/ecs2.2905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Dan J. Krofcheck
- Department of Biology University of New Mexico Albuquerque New Mexico USA
| | - Marcy E. Litvak
- Department of Biology University of New Mexico Albuquerque New Mexico USA
| | - Matthew D. Hurteau
- Department of Biology University of New Mexico Albuquerque New Mexico USA
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20
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Hessburg PF, Miller CL, Parks SA, Povak NA, Taylor AH, Higuera PE, Prichard SJ, North MP, Collins BM, Hurteau MD, Larson AJ, Allen CD, Stephens SL, Rivera-Huerta H, Stevens-Rumann CS, Daniels LD, Gedalof Z, Gray RW, Kane VR, Churchill DJ, Hagmann RK, Spies TA, Cansler CA, Belote RT, Veblen TT, Battaglia MA, Hoffman C, Skinner CN, Safford HD, Salter RB. Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00239] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Stockdale CA, Macdonald SE, Higgs E. Forest closure and encroachment at the grassland interface: a century‐scale analysis using oblique repeat photography. Ecosphere 2019. [DOI: 10.1002/ecs2.2774] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Christopher A. Stockdale
- Department of Renewable Resources Faculty of Agricultural, Life and Environmental Sciences University of Alberta Edmonton Alberta Canada
| | - S. Ellen Macdonald
- Department of Renewable Resources Faculty of Agricultural, Life and Environmental Sciences University of Alberta Edmonton Alberta Canada
| | - Eric Higgs
- School of Environmental Studies University of Victoria Victoria British Columbia Canada
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22
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Palomino J, Kelly M. Differing Sensitivities to Fire Disturbance Result in Large Differences Among Remotely Sensed Products of Vegetation Disturbance. Ecosystems 2019. [DOI: 10.1007/s10021-019-00367-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Bowman DMJS, Moreira-Muñoz A, Kolden CA, Chávez RO, Muñoz AA, Salinas F, González-Reyes Á, Rocco R, de la Barrera F, Williamson GJ, Borchers N, Cifuentes LA, Abatzoglou JT, Johnston FH. Human-environmental drivers and impacts of the globally extreme 2017 Chilean fires. AMBIO 2019; 48:350-362. [PMID: 30128860 PMCID: PMC6411810 DOI: 10.1007/s13280-018-1084-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 05/06/2023]
Abstract
In January 2017, hundreds of fires in Mediterranean Chile burnt more than 5000 km2, an area nearly 14 times the 40-year mean. We contextualize these fires in terms of estimates of global fire intensity using MODIS satellite record, and provide an overview of the climatic factors and recent changes in land use that led to the active fire season and estimate the impact of fire emissions to human health. The primary fire activity in late January coincided with extreme fire weather conditions including all-time (1979-2017) daily records for the Fire Weather Index (FWI) and maximum temperature, producing some of the most energetically intense fire events on Earth in the last 15-years. Fire activity was further enabled by a warm moist growing season in 2016 that interrupted an intense drought that started in 2010. The land cover in this region had been extensively modified, with less than 20% of the original native vegetation remaining, and extensive plantations of highly flammable exotic Pinus and Eucalyptus species established since the 1970s. These plantations were disproportionally burnt (44% of the burned area) in 2017, and associated with the highest fire severities, as part of an increasing trend of fire extent in plantations over the past three decades. Smoke from the fires exposed over 9.5 million people to increased concentrations of particulate air pollution, causing an estimated 76 premature deaths and 209 additional admissions to hospital for respiratory and cardiovascular conditions. This study highlights that Mediterranean biogeographic regions with expansive Pinus and Eucalyptus plantations and associated rural depopulation are vulnerable to intense wildfires with wide ranging social, economic, and environmental impacts, which are likely to become more frequent due to longer and more extreme wildfire seasons.
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Affiliation(s)
- David M. J. S. Bowman
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001 Australia
| | - Andrés Moreira-Muñoz
- Instituto de Geografía, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2241 Valparaíso, Chile
| | - Crystal A. Kolden
- College of Natural Resources, University of Idaho, Moscow, ID 83844-1133 USA
| | - Roberto O. Chávez
- Instituto de Geografía, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2241 Valparaíso, Chile
| | - Ariel A. Muñoz
- Instituto de Geografía, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2241 Valparaíso, Chile
| | - Fernanda Salinas
- Fiscalía del Medio Ambiente (ONG FIMA), Mosqueto 491, of. 312, Santiago, Chile
| | - Álvaro González-Reyes
- Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, Casilla, 567 Valdivia, Chile
| | - Ronald Rocco
- Instituto de Geografía, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2241 Valparaíso, Chile
| | - Francisco de la Barrera
- Faculty of Architecture, Urbanism and Geography, Universidad de Concepcion, Victor Lamas 1290, Concepción, Chile
| | - Grant J. Williamson
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001 Australia
| | - Nicolás Borchers
- Menzies Institute for Medical Research, University of Tasmania, Private Bag 23, Hobart, TAS 7001 Australia
| | - Luis A. Cifuentes
- Industrial and Systems Engineering Department, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago, Chile
| | | | - Fay H. Johnston
- Menzies Institute for Medical Research, University of Tasmania, Private Bag 23, Hobart, TAS 7001 Australia
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24
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Harvey BJ, Andrus RA, Anderson SC. Incorporating biophysical gradients and uncertainty into burn severity maps in a temperate fire‐prone forested region. Ecosphere 2019. [DOI: 10.1002/ecs2.2600] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Brian J. Harvey
- School of Environmental & Forest Sciences University of Washington Campus Box 352100 Seattle Washington 98195 USA
| | - Robert A. Andrus
- Department of Geography University of Colorado Boulder GUGG 110, 260 UCB Colorado 80309 USA
| | - Sean C. Anderson
- Pacific Biological Station Fisheries and Oceans Canada 3190 Hammond Bay Rd. Nanaimo British Columbia V9T 6N7 Canada
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25
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Rodman KC, Veblen TT, Saraceni S, Chapman TB. Wildfire activity and land use drove 20th‐century changes in forest cover in the Colorado front range. Ecosphere 2019. [DOI: 10.1002/ecs2.2594] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Kyle C. Rodman
- Geography University of Colorado Boulder 260 UCB Boulder Colorado 80309 USA
| | - Thomas T. Veblen
- Geography University of Colorado Boulder 260 UCB Boulder Colorado 80309 USA
| | - Sara Saraceni
- Marche Polytechnic University Piazza Roma 22 Ancona, Marche 60121 Italy
| | - Teresa B. Chapman
- Geography University of Colorado Boulder 260 UCB Boulder Colorado 80309 USA
- The Nature Conservancy 2424 Spruce Boulder Colorado 80302 USA
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Roberts CP, Donovan VM, Wonkka CL, Powell LA, Allen CR, Angeler DG, Wedin DA, Twidwell D. Fire legacies in eastern ponderosa pine forests. Ecol Evol 2019; 9:1869-1879. [PMID: 30847078 PMCID: PMC6392404 DOI: 10.1002/ece3.4879] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/30/2018] [Accepted: 11/23/2018] [Indexed: 11/08/2022] Open
Abstract
Disturbance legacies structure communities and ecological memory, but due to increasing changes in disturbance regimes, it is becoming more difficult to characterize disturbance legacies or determine how long they persist. We sought to quantify the characteristics and persistence of material legacies (e.g., biotic residuals of disturbance) that arise from variation in fire severity in an eastern ponderosa pine forest in North America. We compared forest stand structure and understory woody plant and bird community composition and species richness across unburned, low-, moderate-, and high-severity burn patches in a 27-year-old mixed-severity wildfire that had received minimal post-fire management. We identified distinct tree densities (high: 14.3 ± 7.4 trees per ha, moderate: 22.3 ± 12.6, low: 135.3 ± 57.1, unburned: 907.9 ± 246.2) and coarse woody debris cover (high: 8.5 ± 1.6% cover per 30 m transect, moderate: 4.3 ± 0.7, low: 2.3 ± 0.6, unburned: 1.0 ± 0.4) among burn severities. Understory woody plant communities differed between high-severity patches, moderate- and low-severity patches, and unburned patches (all p < 0.05). Bird communities differed between high- and moderate-severity patches, low-severity patches, and unburned patches (all p < 0.05). Bird species richness varied across burn severities: low-severity patches had the highest (5.29 ± 1.44) and high-severity patches had the lowest (2.87 ± 0.72). Understory woody plant richness was highest in unburned (5.93 ± 1.10) and high-severity (5.07 ± 1.17) patches, and it was lower in moderate- (3.43 ± 1.17) and low-severity (3.43 ± 1.06) patches. We show material fire legacies persisted decades after the mixed-severity wildfire in eastern ponderosa forest, fostering distinct structures, communities, and species in burned versus unburned patches and across fire severities. At a patch scale, eastern and western ponderosa system responses to mixed-severity fires were consistent.
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Affiliation(s)
- Caleb P. Roberts
- Department of Agronomy & HorticultureUniversity of NebraskaLincolnNebraska
- School of Natural ResourcesNebraska Cooperative Fish and Wildlife Research UnitLincolnNebraska
| | | | - Carissa L. Wonkka
- Department of Agronomy & HorticultureUniversity of NebraskaLincolnNebraska
| | - Larkin A. Powell
- School of Natural ResourcesUniversity of NebraskaLincolnNebraska
| | - Craig R. Allen
- U.S. Geological Survey, Nebraska Cooperative Fish & Wildlife Research Unit, School of Natural ResourcesUniversity of NebraskaLincolnNebraska
| | - David G. Angeler
- Department of Aquatic Sciences and AssessmentSwedish University of Agriculture SciencesUppsalaSweden
| | - David A. Wedin
- School of Natural ResourcesUniversity of NebraskaLincolnNebraska
| | - Dirac Twidwell
- Department of Agronomy & HorticultureUniversity of NebraskaLincolnNebraska
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Harvey BJ, Donato DC, Turner MG. Burn me twice, shame on who? Interactions between successive forest fires across a temperate mountain region. Ecology 2018; 97:2272-2282. [PMID: 27859087 DOI: 10.1002/ecy.1439] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/22/2016] [Accepted: 03/25/2016] [Indexed: 02/05/2023]
Abstract
Increasing rates of natural disturbances under a warming climate raise important questions about how multiple disturbances interact. Escalating wildfire activity in recent decades has resulted in some forests re-burning in short succession, but how the severity of one wildfire affects that of a subsequent wildfire is not fully understood. We used a field-validated, satellite-derived, burn-severity atlas to assess interactions between successive wildfires across the US Northern Rocky Mountains a 300,000-km2 region dominated by fire-prone forests. In areas that experienced two wildfires between 1984 and 2010, we asked: (1) How do overall frequency distributions of burn-severity classes compare between first and second fires? (2) In a given location, how does burn severity of the second fire relate to that of the first? (3) Do interactions between successive fires vary by forest zone or the interval between fires? (4) What factors increase the probability of burning twice as stand-replacing fire? Within the study area, 138,061 ha burned twice between 1984 and 2010. Overall, frequency distributions of burn severity classes (low, moderate, high; quantified using relativized remote sensing indices) were similar between the first and second fires; however burn severity was 5-13% lower in second fires on average. Negative interactions between fires were most pronounced in lower-elevation forests and woodlands, when fire intervals were <10 yr, and when burn severity was low in the first fire. When the first fire burned as high severity and fire intervals exceeded 10-12 yr, burn-severity interactions switched from negative to positive, with high-severity fire begetting subsequent high-severity fire. Locations most likely to experience successive stand-replacing fires were high-elevation forests, which are adapted to high-severity fire, and areas conducive to abundant post-fire tree regeneration. Broadly similar severities among short-interval "re-burns" and other wildfires indicate that positive severity feedbacks, an oft-posited agent of ecosystem decline or state shift, are not an inevitable outcome of re-burning. Nonetheless, context-dependent shifts in both the magnitude and direction of wildfire interactions (associated with forest zone, initial burn-severity, and disturbance interval) illustrate complexities in disturbance interactions and can inform management and predictions of future system dynamics.
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Affiliation(s)
- Brian J Harvey
- Department of Geography, University of Colorado-Boulder, Boulder, Colorado, 80309, USA
| | - Daniel C Donato
- Washington Department of Natural Resources, Olympia, Washington, 98504, USA
| | - Monica G Turner
- Department of Zoology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
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28
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Davis KT, Higuera PE, Sala A. Anticipating fire‐mediated impacts of climate change using a demographic framework. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13132] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kimberley T. Davis
- Department of Ecosystem and Conservation Sciences University of Montana Missoula Montana
| | - Philip E. Higuera
- Department of Ecosystem and Conservation Sciences University of Montana Missoula Montana
| | - Anna Sala
- Division of Biological Sciences University of Montana Missoula Montana
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29
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Fire regimes approaching historic norms reduce wildfire‐facilitated conversion from forest to non‐forest. Ecosphere 2018. [DOI: 10.1002/ecs2.2182] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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30
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Barros AMG, Ager AA, Day MA, Krawchuk MA, Spies TA. Wildfires managed for restoration enhance ecological resilience. Ecosphere 2018. [DOI: 10.1002/ecs2.2161] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Ana M. G. Barros
- College of Forestry, Forest Ecosystems & Society Oregon State University 321 Richardson Hall Corvallis Oregon 97331 USA
| | - Alan A. Ager
- USDA Forest Service Rocky Mountain Research Station Missoula Fire Sciences Laboratory 5775 US Highway 10W Missoula Montana 59808 USA
| | - Michelle A. Day
- College of Forestry Forest Engineering, Resources & Management Oregon State University 280 Peavy Hall Corvallis Oregon 97331 USA
| | - Meg A. Krawchuk
- College of Forestry, Forest Ecosystems & Society Oregon State University 321 Richardson Hall Corvallis Oregon 97331 USA
| | - Thomas A. Spies
- USDA Forest Service, Pacific Northwest Research Station 3200 SW Jefferson Way Corvallis Oregon 97331 USA
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31
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32
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Halofsky JS, Donato DC, Franklin JF, Halofsky JE, Peterson DL, Harvey BJ. The nature of the beast: examining climate adaptation options in forests with stand-replacing fire regimes. Ecosphere 2018. [DOI: 10.1002/ecs2.2140] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Joshua S. Halofsky
- Washington State Department of Natural Resources; 1111 Washington Street SE, Box 47014 Olympia Washington 98504 USA
| | - Daniel C. Donato
- Washington State Department of Natural Resources; 1111 Washington Street SE, Box 47014 Olympia Washington 98504 USA
- School of Environmental and Forest Sciences; University of Washington; P.O. Box 352100 Seattle Washington 98195 USA
| | - Jerry F. Franklin
- School of Environmental and Forest Sciences; University of Washington; P.O. Box 352100 Seattle Washington 98195 USA
| | - Jessica E. Halofsky
- School of Environmental and Forest Sciences; University of Washington; P.O. Box 352100 Seattle Washington 98195 USA
| | - David L. Peterson
- U.S. Forest Service, Pacific Northwest Research Station; 400 N 34th Street Seattle Washington 98103 USA
| | - Brian J. Harvey
- School of Environmental and Forest Sciences; University of Washington; P.O. Box 352100 Seattle Washington 98195 USA
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33
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Predicting Potential Fire Severity Using Vegetation, Topography and Surface Moisture Availability in a Eurasian Boreal Forest Landscape. FORESTS 2018. [DOI: 10.3390/f9030130] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Parks SA, Parisien MA, Miller C, Holsinger LM, Baggett LS. Fine-scale spatial climate variation and drought mediate the likelihood of reburning. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:573-586. [PMID: 29280248 DOI: 10.1002/eap.1671] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/11/2017] [Indexed: 06/07/2023]
Abstract
In many forested ecosystems, it is increasingly recognized that the probability of burning is substantially reduced within the footprint of previously burned areas. This self-limiting effect of wildland fire is considered a fundamental emergent property of ecosystems and is partly responsible for structuring landscape heterogeneity (i.e., mosaics of different age classes), thereby reducing the likelihood of uncharacteristically large fires in regions with active fire regimes. However, the strength and longevity of this self-limiting phenomenon is not well understood in most fire-prone ecosystems. In this study, we quantify the self-limiting effect in terms of its strength and longevity for five fire-prone study areas in western North America and investigate how each measure varies along a spatial climatic gradient and according to temporal (i.e., annual) climatic variation. Results indicate that the longevity (i.e., number of years) of the self-limiting effect ranges between 15 yr in the warm and dry study area in the southwestern United States to 33 yr in the cold, northern study areas in located in northwestern Montana and the boreal forest of Canada. We also found that spatial climatic variation has a strong influence on wildland fire's self-limiting capacity. Specifically, the self-limiting effect within each study area was stronger and lasted longer in areas with low mean moisture deficit (i.e., wetter and cooler settings) compared to areas with high mean moisture deficit (warmer and drier settings). Last, our findings show that annual climatic variation influences wildland fire's self-limiting effect: drought conditions weakened the strength and longevity of the self-limiting effect in all study areas, albeit at varying magnitudes. Overall, our study provides support for the idea that wildland fire contributes to spatial heterogeneity in fuel ages that subsequently mediate future fire sizes and effects. However, our findings show that the strength and longevity of the self-limiting effect varies considerably according to spatial and temporal climatic variation, providing land and fire managers relevant information for effective planning and management of fire and highlighting that fire itself is an important factor contributing to fire-free intervals.
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Affiliation(s)
- Sean A Parks
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, USDA Forest Service, 790 E. Beckwith Avenue, Missoula, Montana, 59801, USA
| | - Marc-André Parisien
- Northern Forestry Centre, Canadian Forest Service, Natural Resources Canada, 5320 122nd Street, Edmonton, Alberta, T5H 3S5, Canada
| | - Carol Miller
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, USDA Forest Service, 790 E. Beckwith Avenue, Missoula, Montana, 59801, USA
| | - Lisa M Holsinger
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, USDA Forest Service, 790 E. Beckwith Avenue, Missoula, Montana, 59801, USA
| | - Larry Scott Baggett
- Rocky Mountain Research Station, USDA Forest Service, 240 West Prospect Road, Fort Collins, Colorado, 80526, USA
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35
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Stand Age Influence on Potential Wildfire Ignition and Spread in the Boreal Forest of Northeastern Canada. Ecosystems 2018. [DOI: 10.1007/s10021-018-0235-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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36
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Whitman E, Parisien MA, Thompson DK, Hall RJ, Skakun RS, Flannigan MD. Variability and drivers of burn severity in the northwestern Canadian boreal forest. Ecosphere 2018. [DOI: 10.1002/ecs2.2128] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Ellen Whitman
- Department of Renewable Resources; University of Alberta; 751 General Services Building Edmonton Alberta T6G 2H1 Canada
- Northern Forestry Centre; Canadian Forest Service; Natural Resources Canada; 5320-122nd Street Edmonton Alberta T6H 3S5 Canada
| | - Marc-André Parisien
- Northern Forestry Centre; Canadian Forest Service; Natural Resources Canada; 5320-122nd Street Edmonton Alberta T6H 3S5 Canada
| | - Dan K. Thompson
- Northern Forestry Centre; Canadian Forest Service; Natural Resources Canada; 5320-122nd Street Edmonton Alberta T6H 3S5 Canada
| | - Ronald J. Hall
- Northern Forestry Centre; Canadian Forest Service; Natural Resources Canada; 5320-122nd Street Edmonton Alberta T6H 3S5 Canada
| | - Robert S. Skakun
- Northern Forestry Centre; Canadian Forest Service; Natural Resources Canada; 5320-122nd Street Edmonton Alberta T6H 3S5 Canada
| | - Mike D. Flannigan
- Department of Renewable Resources; University of Alberta; 751 General Services Building Edmonton Alberta T6G 2H1 Canada
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37
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Harris L, Taylor AH. Previous burns and topography limit and reinforce fire severity in a large wildfire. Ecosphere 2017. [DOI: 10.1002/ecs2.2019] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Lucas Harris
- Department of Geography; Pennsylvania State University; 302 Walker Building University Park Pennsylvania 16802 USA
| | - Alan H. Taylor
- Department of Geography; Pennsylvania State University; 302 Walker Building University Park Pennsylvania 16802 USA
- Earth and Environmental Systems Institute; Pennsylvania State University; 2217 Earth-Engineering Sciences Building University Park Pennsylvania 16802 USA
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38
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Adapt to more wildfire in western North American forests as climate changes. Proc Natl Acad Sci U S A 2017; 114:4582-4590. [PMID: 28416662 DOI: 10.1073/pnas.1617464114] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Wildfires across western North America have increased in number and size over the past three decades, and this trend will continue in response to further warming. As a consequence, the wildland-urban interface is projected to experience substantially higher risk of climate-driven fires in the coming decades. Although many plants, animals, and ecosystem services benefit from fire, it is unknown how ecosystems will respond to increased burning and warming. Policy and management have focused primarily on specified resilience approaches aimed at resistance to wildfire and restoration of areas burned by wildfire through fire suppression and fuels management. These strategies are inadequate to address a new era of western wildfires. In contrast, policies that promote adaptive resilience to wildfire, by which people and ecosystems adjust and reorganize in response to changing fire regimes to reduce future vulnerability, are needed. Key aspects of an adaptive resilience approach are (i) recognizing that fuels reduction cannot alter regional wildfire trends; (ii) targeting fuels reduction to increase adaptation by some ecosystems and residential communities to more frequent fire; (iii) actively managing more wild and prescribed fires with a range of severities; and (iv) incentivizing and planning residential development to withstand inevitable wildfire. These strategies represent a shift in policy and management from restoring ecosystems based on historical baselines to adapting to changing fire regimes and from unsustainable defense of the wildland-urban interface to developing fire-adapted communities. We propose an approach that accepts wildfire as an inevitable catalyst of change and that promotes adaptive responses by ecosystems and residential communities to more warming and wildfire.
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39
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O'Connor CD, Falk DA, Lynch AM, Swetnam TW, Wilcox CP. Disturbance and productivity interactions mediate stability of forest composition and structure. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:900-915. [PMID: 28029193 DOI: 10.1002/eap.1492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/06/2016] [Accepted: 12/12/2016] [Indexed: 06/06/2023]
Abstract
Fire is returning to many conifer-dominated forests where species composition and structure have been altered by fire exclusion. Ecological effects of these fires are influenced strongly by the degree of forest change during the fire-free period. Response of fire-adapted species assemblages to extended fire-free intervals is highly variable, even in communities with similar historical fire regimes. This variability in plant community response to fire exclusion is not well understood; however, ecological mechanisms such as individual species' adaptations to disturbance or competition and underlying site characteristics that facilitate or impede establishment and growth have been proposed as potential drivers of assemblage response. We used spatially explicit dendrochronological reconstruction of tree population dynamics and fire regimes to examine the influence of historical disturbance frequency (a proxy for adaptation to disturbance or competition), and potential site productivity (a proxy for underlying site characteristics) on the stability of forest composition and structure along a continuous ecological gradient of pine, dry mixed-conifer, mesic mixed-conifer, and spruce-fir forests following fire exclusion. While average structural density increased in all forests, species composition was relatively stable in the lowest productivity pine-dominated and highest productivity spruce-fir-dominated sites immediately following fire exclusion and for the next 100 years, suggesting site productivity as a primary control on species composition and structure in forests with very different historical fire regimes. Species composition was least stable on intermediate productivity sites dominated by mixed-conifer forests, shifting from primarily fire-adapted species to competition-adapted, fire-sensitive species within 20 years of fire exclusion. Rapid changes to species composition and stand densities have been interpreted by some as evidence of high-severity fire. We demonstrate that the very different ecological process of fire exclusion can produce similar changes by shifting selective pressures from disturbance-mediated to productivity-mediated controls. Restoring disturbance-adapted species composition and structure to intermediate productivity forests may help to buffer them against projected increasing temperatures, lengthening fire seasons, and more frequent and prolonged moisture stress. Fewer management options are available to promote adaptation in forest assemblages historically constrained by underlying site productivity.
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Affiliation(s)
- Christopher D O'Connor
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, 85721, USA
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona, 85721, USA
| | - Donald A Falk
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, 85721, USA
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona, 85721, USA
| | - Ann M Lynch
- U.S. Forest Service, Rocky Mountain Research Station, Tucson, Arizona, 85721, USA
| | - Thomas W Swetnam
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona, 85721, USA
| | - Craig P Wilcox
- U.S. Forest Service, Coronado National Forest, Safford, Arizona, 85546, USA
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40
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Reilly MJ, Dunn CJ, Meigs GW, Spies TA, Kennedy RE, Bailey JD, Briggs K. Contemporary patterns of fire extent and severity in forests of the Pacific Northwest, USA (1985-2010). Ecosphere 2017. [DOI: 10.1002/ecs2.1695] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Matthew J. Reilly
- Department of Forest Ecosystems and Society; College of Forestry; Oregon State University; Corvallis Oregon 97331 USA
| | - Christopher J. Dunn
- Department of Forest Engineering and Resource Management; College of Forestry; Oregon State University; Corvallis Oregon 97331 USA
| | - Garrett W. Meigs
- Rubenstein School of Environment and Natural Resources; Gund Institute for Ecological Economics; University of Vermont; Burlington Vermont 05405 USA
| | - Thomas A. Spies
- USDA Forest Service; Pacific Northwest Research Station; Corvallis Oregon 97331 USA
| | - Robert E. Kennedy
- College of Earth, Ocean, and Atmospheric Sciences; Oregon State University; Corvallis Oregon 97331 USA
| | - John D. Bailey
- Department of Forest Engineering and Resource Management; College of Forestry; Oregon State University; Corvallis Oregon 97331 USA
| | - Kevin Briggs
- Department of Forest Ecosystems and Society; College of Forestry; Oregon State University; Corvallis Oregon 97331 USA
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41
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Nelson KN, Turner MG, Romme WH, Tinker DB. Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:2422-2436. [PMID: 27875007 DOI: 10.1002/eap.1412] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 06/22/2016] [Indexed: 06/06/2023]
Abstract
Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m3 (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires.
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Affiliation(s)
- Kellen N Nelson
- Program in Ecology and Department of Botany, University of Wyoming, Laramie, Wyoming, 82071, USA
| | - Monica G Turner
- Department of Zoology, University of Wisconsin, Madison, Wisconsin, 53706, USA
| | - William H Romme
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Daniel B Tinker
- Program in Ecology and Department of Botany, University of Wyoming, Laramie, Wyoming, 82071, USA
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42
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Stephens SL, Miller JD, Collins BM, North MP, Keane JJ, Roberts SL. Wildfire impacts on California spotted owl nesting habitat in the Sierra Nevada. Ecosphere 2016. [DOI: 10.1002/ecs2.1478] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Scott L. Stephens
- Division of Ecosystem Science Department of Environmental Science, Policy, and Management University of California 130 Mulford Hall Berkeley California 94720 USA
| | - Jay D. Miller
- USDA Forest Service Pacific Southwest Region, Fire and Aviation Management McClellan California 95652 USA
| | - Brandon M. Collins
- Pacific Southwest Research Station USDA Forest Service Davis California 95618 USA
- Center for Fire Research and Outreach University of California Berkeley California 94720 USA
| | - Malcolm P. North
- Pacific Southwest Research Station USDA Forest Service Davis California 95618 USA
| | - John J. Keane
- Pacific Southwest Research Station USDA Forest Service Davis California 95618 USA
| | - Susan L. Roberts
- University of California, Merced, Sierra Nevada Research Station 7799 Chilnualna Falls Road Wawona California 95389 USA
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43
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Stephens SL, Collins BM, Biber E, Fulé PZ. U.S.
federal fire and forest policy: emphasizing resilience in dry forests. Ecosphere 2016. [DOI: 10.1002/ecs2.1584] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Scott L. Stephens
- Division of Ecosystem ScienceDepartment of Environmental Science, Policy, and ManagementUniversity of California 130 Mulford Hall Berkeley California 94720 USA
| | - Brandon M. Collins
- Center for Fire Research and OutreachUniversity of California Berkeley California 94720 USA
| | - Eric Biber
- University of California, BerkeleySchool of Law 436 North Addition Berkeley California 94720 USA
| | - Peter Z. Fulé
- School of ForestryCollege of Engineering, Forestry, and Natural SciencesNorthern Arizona University Flagstaff Arizona 86011 USA
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44
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Beyond Fuel Treatment Effectiveness: Characterizing Interactions between Fire and Treatments in the US. FORESTS 2016. [DOI: 10.3390/f7100237] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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45
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46
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Coppoletta M, Merriam KE, Collins BM. Post-fire vegetation and fuel development influences fire severity patterns in reburns. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:686-699. [PMID: 27411243 DOI: 10.1890/15-0225] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In areas where fire regimes and forest structure have been dramatically altered, there is increasing concern that contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Our study utilized an extensive set of field plots established following four fires that occurred between 2000 and 2010 in the northern Sierra Nevada, California, USA that were subsequently reburned in 2012. The information obtained from these field plots allowed for a unique set of analyses investigating the effect of vegetation, fuels, topography, fire weather, and forest management on reburn severity. We also examined the influence of initial fire severity and time since initial fire on influential predictors of reburn severity. Our results suggest that high- to moderate-severity fire in the initial fires led to an increase in standing snags and shrub vegetation, which in combination with severe fire weather promoted high-severity fire effects in the subsequent reburn. Although fire behavior is largely driven by weather, our study demonstrates that post-fire vegetation composition and structure are also important drivers of reburn severity. In the face of changing climatic regimes and increases in extreme fire weather, these results may provide managers with options to create more fire-resilient ecosystems. In areas where frequent high-severity fire is undesirable, management activities such as thinning, prescribed fire, or managed wildland fire can be used to moderate fire behavior not only prior to initial fires, but also before subsequent reburns.
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Coop JD, Parks SA, McClernan SR, Holsinger LM. Influences of prior wildfires on vegetation response to subsequent fire in a reburned Southwestern landscape. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:346-354. [PMID: 27209778 DOI: 10.1890/15-0775] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Large and severe wildfires have raised concerns about the future of forested landscapes in the southwestern United States, especially under repeated burning. In 2011, under extreme weather and drought conditions, the Las Conchas fire burned over several previous burns as well as forests not recently exposed to fire. Our purpose was to examine the influences of prior wildfires on plant community composition and structure, subsequent burn severity, and vegetation response. To assess these relationships, we used satellite-derived measures of burn severity and a nonmetric multidimensional scaling of pre- and post- Las Conchas field samples. Earlier burns were associated with shifts from forested sites to open savannas and meadows, oak scrub, and ruderal communities. These non-forested vegetation types exhibited both resistance to subsequent fire, measured by reduced burn severity, and resilience to reburning, measured by vegetation recovery relative to forests not exposed to recent prior fire. Previous shifts toward non-forested states were strongly reinforced by reburning. Ongoing losses of forests and their ecological values confirm the need for restoration interventions. However, given future wildfire and climate projections, there may also be opportunities presented by transformations toward fire-resistant and resilient vegetation types within portions of the landscape.
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Katuwal H, Calkin DE, Hand MS. Production and efficiency of large wildland fire suppression effort: A stochastic frontier analysis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 166:227-236. [PMID: 26513321 DOI: 10.1016/j.jenvman.2015.10.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 09/18/2015] [Accepted: 10/15/2015] [Indexed: 06/05/2023]
Abstract
This study examines the production and efficiency of wildland fire suppression effort. We estimate the effectiveness of suppression resource inputs to produce controlled fire lines that contain large wildland fires using stochastic frontier analysis. Determinants of inefficiency are identified and the effects of these determinants on the daily production of controlled fire line are examined. Results indicate that the use of bulldozers and fire engines increase the production of controlled fire line, while firefighter crews do not tend to contribute to controlled fire line production. Production of controlled fire line is more efficient if it occurs along natural or built breaks, such as rivers and roads, and within areas previously burned by wildfires. However, results also indicate that productivity and efficiency of the controlled fire line are sensitive to weather, landscape and fire characteristics.
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Affiliation(s)
- Hari Katuwal
- The University of Montana, 32 Campus Drive, Missoula, MT 59812, USA.
| | - David E Calkin
- Rocky Mountain Research Station, USDA Forest Service, 800 E Beckwith, Missoula, MT 59801, USA
| | - Michael S Hand
- Rocky Mountain Research Station, USDA Forest Service, 800 E Beckwith, Missoula, MT 59801, USA
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Affiliation(s)
- Malcolm North
- USFS Pacific Southwest Research Station, Davis, CA 95618, USA
- University of California, Davis, CA 95616, USA
| | | | - Brandon Collins
- USFS Pacific Southwest Research Station, Davis, CA 95618, USA
- University of California, Berkeley, CA 94720, USA
| | - James Agee
- University of Washington, Seattle, WA 98195, USA
| | - Greg Aplet
- The Wilderness Society, Denver, CO 80202, USA
| | | | - Pete Fulé
- Northern Arizona University, Flagstaff, AZ 86011, USA
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Parks SA, Holsinger LM, Miller C, Nelson CR. Wildland fire as a self-regulating mechanism: the role of previous burns and weather in limiting fire progression. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2015; 25:1478-92. [PMID: 26552258 DOI: 10.1890/14-1430.1] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Theory suggests that natural fire regimes can result in landscapes that are both self-regulating and resilient to fire. For example, because fires consume fuel, they may create barriers to the spread of future fires, thereby regulating fire size. Top-down controls such as weather, however, can weaken this effect. While empirical examples demonstrating this pattern-process feedback between vegetation and fire exist, they have been geographically limited or did not consider the influence of time between fires and weather. The availability of remotely sensed data identifying fire activity over the last four decades provides an opportunity to explicitly quantify-the ability of wildland fire to limit the progression of subsequent fire. Furthermore, advances in fire progression mapping now allow an evaluation of how daily weather as a top-down control modifies this effect. In this study, we evaluated the ability of wildland fire to create barriers that limit the spread of subsequent fire along a gradient representing time between fires in four large study areas in the western United States. Using fire progression maps in conjunction with weather station data, we also evaluated the influence of daily weather. Results indicate that wildland fire does limit subsequent fire spread in all four study areas, but this effect decays over time; wildland fire no longer limits subsequent fire spread 6-18 years after fire, depending on the study area. We also found that the ability of fire to regulate, subsequent fire progression was substantially reduced under extreme conditions compared to moderate weather conditions in all four study areas. This study increases understanding of the spatial feedbacks that can lead to self-regulating landscapes as well as the effects of top-down controls, such as weather, on these feedbacks. Our results will be useful to managers who seek to restore natural fire regimes or to exploit recent burns when managing fire.
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