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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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Baker WL. Restoration of forest resilience to fire from old trees is possible across a large Colorado dry-forest landscape by 2060, but only under the Paris 1.5℃ goal. GLOBAL CHANGE BIOLOGY 2021; 27:4074-4095. [PMID: 34018287 DOI: 10.1111/gcb.15714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
Fire-prone dry forests often face increasing fires from climate change with low resistance and resilience due to logging of large, old fire-resistant trees. Their restoration across large landscapes is constrained by limited mature trees, physical settings, and protection. Active restoration has been costly and shown limited effectiveness, but lower cost passive restoration is less studied. I used GIS and machine learning to see whether passive restoration of old trees could overcome constraints in time, by 2060, across 667,000 ha of montane forests in the San Juan Mountains, Colorado, where temperatures are increasing faster than the global average. Random Forest models of physical locations of reconstructed historical old growth (OG) and relatively frequent fire (RFF) show historical OG with RFF was favored between 6.1 and 7.9℃ annual mean temperatures. Random Forest models projected that similar temperature-suitable locations were moved into the current middle montane ca 2015, and would be extended to just below the upper limit of the montane if the Paris 1.5℃ goal is reached, but beyond if not. US Forest Service common stand exam data, which covered ~15% of the study area and included 26,149 tree ages, show the highest potential for restoring resistance and resilience from old trees is a ≥120-year age class. This class could become a ≥160-year age class, which meets old-growth age criteria, over 81% of the area by ca 2060, nearly fully restoring historical old-growth levels. Half this age class is already protected, and much of the remainder could be retained using evidence-based diameter caps. Datasets thus are sufficient to show that passive restoration of old-tree resistance and resilience to fire is feasible by ca 2060 across a large montane landscape, although contingent on global success in achieving the Paris 1.5℃ goal. Passive restoration may be viable elsewhere.
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Variable Forest Structure and Fire Reconstructed Across Historical Ponderosa Pine and Mixed Conifer Landscapes of the San Juan Mountains, Colorado. LAND 2019. [DOI: 10.3390/land9010003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Late-1800s land surveys were used to reconstruct historical forest structure and fire over more than 235,000 ha in ponderosa pine and mixed conifer landscapes of the San Juan Mountains, Colorado, to further understand differences among regional mountain ranges and help guide landscape-scale restoration and management. Historically, fire-resistant ponderosa pine forests with low tree density and relatively frequent fire, the most restorable forests, covered only the lower 15%–24% of the study area. The other 76%–85% had dominance by mixed- to high-severity fires. Both ponderosa pine and dry mixed conifer had generally pervasive, often dense understory shrubs, and ~20% of pine and ~50%–75% of mixed conifer forests also had high historical tree density. Intensive fuel reduction and mechanical restoration are infeasible and likely ineffective in the upper part of the pine zones and in mixed conifer, where restoring historical fire and creating fire-adapted communities and infrastructure may be the only viable option. Old-growth forests can be actively restored in the lower 15%–24% of the montane, likely increasing landscape resistance and resilience to fire, but mixed- to high-severity fires did also occur near these areas. This imperfect resistance suggests that fire-adapted human communities and infrastructure are needed throughout the study area.
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Levine CR, Cogbill CV, Collins BM, Larson AJ, Lutz JA, North MP, Restaino CM, Safford HD, Stephens SL, Battles JJ. Estimating historical forest density from land-survey data: a response to Baker and Williams (2018). ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01968. [PMID: 31257657 DOI: 10.1002/eap.1968] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 05/20/2019] [Accepted: 06/14/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Carrie R Levine
- Department of Environmental Science and Policy, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
| | - Charles V Cogbill
- Harvard Forest, Harvard University, 324 North Main Street, Petersham, Massachusetts, 01366, USA
| | - Brandon M Collins
- USDA Forest Service, Pacific Southwest Research Station, 1731 Research Park Drive, Davis, California, 95618, USA
- Center for Fire Research and Outreach, College of Natural Resources, University of California, Berkeley, California, 94720-3114, USA
| | - Andrew J Larson
- Department of Forest Management, University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - James A Lutz
- S. J. & Jessie E. Quinney College of Natural Resources, Utah State University, 5230 Old Main Hill, Logan, Utah, 84322-5230, USA
| | - Malcolm P North
- USDA Forest Service, Pacific Southwest Research Station, 1731 Research Park Drive, Davis, California, 95618, USA
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
| | | | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
- USDA Forest Service, Pacific Southwest Region, 1323 Club Drive, Vallejo, California, 94592, USA
| | - Scott L Stephens
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, California, 94720-3114, USA
| | - John J Battles
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, California, 94720-3114, USA
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Baker WL, Williams MA. Estimating historical forest density from land-survey data: Response. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e02017. [PMID: 31596977 DOI: 10.1002/eap.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/30/2019] [Accepted: 09/16/2019] [Indexed: 06/10/2023]
Affiliation(s)
- William L Baker
- Department of Geography/Program in Ecology, University of Wyoming, Laramie, Wyoming, 82071, USA
| | - Mark A Williams
- Department of Geography/Program in Ecology, University of Wyoming, Laramie, Wyoming, 82071, USA
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7
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Zhu Y, Shan D, Wang B, Shi Z, Yang X, Liu Y. Floristic features and vegetation classification of the Hulun Buir Steppe in North China: Geography and climate-driven steppe diversification. Glob Ecol Conserv 2019. [DOI: 10.1016/j.gecco.2019.e00741] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Johnston JD, Dunn CJ, Vernon MJ, Bailey JD, Morrissette BA, Morici KE. Restoring historical forest conditions in a diverse inland Pacific Northwest landscape. Ecosphere 2018. [DOI: 10.1002/ecs2.2400] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- James D. Johnston
- College of Forestry; Oregon State University; 140 Peavy Hall, 3100 SW Jefferson Way Corvallis Oregon 97333 USA
| | - Christopher J. Dunn
- College of Forestry; Oregon State University; 140 Peavy Hall, 3100 SW Jefferson Way Corvallis Oregon 97333 USA
| | - Michael J. Vernon
- Department of Forestry and Wildland Resources; Humboldt State University; 1 Harpst Street Arcata California 95521 USA
| | - John D. Bailey
- College of Forestry; Oregon State University; 140 Peavy Hall, 3100 SW Jefferson Way Corvallis Oregon 97333 USA
| | - Brett A. Morrissette
- College of Forestry; Oregon State University; 140 Peavy Hall, 3100 SW Jefferson Way Corvallis Oregon 97333 USA
| | - Kat E. Morici
- Department of Forest and Rangeland Stewardship; Colorado Forest Restoration Institute; Colorado State University; 1472 Campus Delivery Fort Collins Colorado 80523 USA
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Hagmann RK, Stevens JT, Lydersen JM, Collins BM, Battles JJ, Hessburg PF, Levine CR, Merschel AG, Stephens SL, Taylor AH, Franklin JF, Johnson DL, Johnson KN. Improving the use of early timber inventories in reconstructing historical dry forests and fire in the western United States: Comment. Ecosphere 2018. [DOI: 10.1002/ecs2.2232] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- R. Keala Hagmann
- Applegate Forestry LLC; 28831 Tampico Road Corvallis Oregon 97330 USA
- School of Environmental and Forest Sciences; University of Washington; Seattle Washington 98195 USA
| | - Jens T. Stevens
- Ecosystem Sciences Division; Department of Environmental Science, Policy, and Management; University of California; Berkeley California 94720 USA
| | - Jamie M. Lydersen
- Ecosystem Sciences Division; Department of Environmental Science, Policy, and Management; University of California; Berkeley California 94720 USA
| | - Brandon M. Collins
- Center for Fire Research and Outreach; University of California; Berkeley California 94720 USA
| | - John J. Battles
- Ecosystem Sciences Division; Department of Environmental Science, Policy, and Management; University of California; Berkeley California 94720 USA
| | - Paul F. Hessburg
- School of Environmental and Forest Sciences; University of Washington; Seattle Washington 98195 USA
- USDA-FS, Pacific Northwest Research Station; Wenatchee Washington 98801 USA
| | - Carrie R. Levine
- Department of Environmental Science and Policy; University of California; Davis California 95616 USA
| | - Andrew G. Merschel
- Department of Forest Engineering Resources and Management; College of Forestry; Oregon State University; Corvallis Oregon 97333 USA
| | - Scott L. Stephens
- Ecosystem Sciences Division; Department of Environmental Science, Policy, and Management; University of California; Berkeley California 94720 USA
| | - Alan H. Taylor
- Department of Geography, Earth and Environmental Institute; The Pennsylvania State University; University Park Pennsylvania 16802 USA
| | - Jerry F. Franklin
- School of Environmental and Forest Sciences; University of Washington; Seattle Washington 98195 USA
| | - Debora L. Johnson
- Applegate Forestry LLC; 28831 Tampico Road Corvallis Oregon 97330 USA
| | - K. Norman Johnson
- Department of Forest Ecosystems and Society; Oregon State University; Corvallis Oregon 97331 USA
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Cogbill CV, Thurman AL, Williams JW, Zhu J, Mladenoff DJ, Goring SJ. A retrospective on the accuracy and precision of plotless forest density estimators in ecological studies. Ecosphere 2018. [DOI: 10.1002/ecs2.2187] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
| | - Andrew L. Thurman
- Department of Internal Medicine University of Iowa Iowa City Iowa 52242 USA
| | - John W. Williams
- Department of Geography University of Wisconsin–Madison Madison Wisconsin 53706 USA
- Center for Climatic Research University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - Jun Zhu
- Department of Statistics University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - David J. Mladenoff
- Department of Forest and Wildlife Ecology University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - Simon J. Goring
- Department of Geography University of Wisconsin–Madison Madison Wisconsin 53706 USA
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Baker WL, Williams MA. Land surveys show regional variability of historical fire regimes and dry forest structure of the western United States. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:284-290. [PMID: 29345744 DOI: 10.1002/eap.1688] [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: 08/04/2017] [Revised: 12/03/2017] [Accepted: 12/21/2017] [Indexed: 06/07/2023]
Abstract
An understanding of how historical fire and structure in dry forests (ponderosa pine, dry mixed conifer) varied across the western United States remains incomplete. Yet, fire strongly affects ecosystem services, and forest restoration programs are underway. We used General Land Office survey reconstructions from the late 1800s across 11 landscapes covering ~1.9 million ha in four states to analyze spatial variation in fire regimes and forest structure. We first synthesized the state of validation of our methods using 20 modern validations, 53 historical cross-validations, and corroborating evidence. These show our method creates accurate reconstructions with low errors. One independent modern test reported high error, but did not replicate our method and made many calculation errors. Using reconstructed parameters of historical fire regimes and forest structure from our validated methods, forests were found to be non-uniform across the 11 landscapes, but grouped together in three geographical areas. Each had a mixture of fire severities, but dominated by low-severity fire and low median tree density in Arizona, mixed-severity fire and intermediate to high median tree density in Oregon-California, and high-severity fire and intermediate median tree density in Colorado. Programs to restore fire and forest structure could benefit from regional frameworks, rather than one size fits all.
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Affiliation(s)
- William L Baker
- Program in Ecology/Department of Geography, University of Wyoming, Department 3371, 1000 East University Avenue, Laramie, Wyoming, 82071, USA
| | - Mark A Williams
- Program in Ecology/Department of Geography, University of Wyoming, Department 3371, 1000 East University Avenue, Laramie, Wyoming, 82071, USA
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12
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Baker WL, Hanson CT. Improving the use of early timber inventories in reconstructing historical dry forests and fire in the western United States. Ecosphere 2017. [DOI: 10.1002/ecs2.1935] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- William L. Baker
- Program in Ecology/Department of Geography; University of Wyoming; Laramie Wyoming 82071 USA
| | - Chad T. Hanson
- Earth Island Institute; 2150 Allston Way, Suite 460 Berkeley California 94704 USA
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13
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Levine CR, Cogbill CV, Collins BM, Larson AJ, Lutz JA, North MP, Restaino CM, Safford HD, Stephens SL, Battles JJ. Evaluating a new method for reconstructing forest conditions from General Land Office survey records. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:1498-1513. [PMID: 28370925 DOI: 10.1002/eap.1543] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/10/2017] [Accepted: 02/22/2017] [Indexed: 06/07/2023]
Abstract
Historical forest conditions are often used to inform contemporary management goals because historical forests are considered to be resilient to ecological disturbances. The General Land Office (GLO) surveys of the late 19th and early 20th centuries provide regionally quasi-contiguous data sets of historical forests across much of the Western United States. Multiple methods exist for estimating tree density from point-based sampling such as the GLO surveys, including distance-based and area-based approaches. Area-based approaches have been applied in California mixed-conifer forests but their estimates have not been validated. To assess the accuracy and precision of plotless density estimators with potential for application to GLO data in this region, we imposed a GLO sampling scheme on six mapped forest stands of known densities (159-784 trees/ha) in the Sierra Nevada in California, USA, and Baja California Norte, Mexico. We compared three distance-based plotless density estimators (Cottam, Pollard, and Morisita) as well as two Voronoi area (VA) estimators, the Delincé and mean harmonic Voronoi density (MHVD), to the true densities. We simulated sampling schemes of increasing intensity to assess sampling error. The relative error (RE) of density estimates for the GLO sampling scheme ranged from 0.36 to 4.78. The least biased estimate of tree density in every stand was obtained with the Morisita estimator and the most biased was obtained with the MHVD estimator. The MHVD estimates of tree density were 1.2-3.8 times larger than the true densities and performed best in stands subject to fire exclusion for 100 yr. The Delincé approach obtained accurate estimates of density, implying that the Voronoi approach is theoretically sound but that its application in the MHVD was flawed. The misapplication was attributed to two causes: (1) the use of a crown scaling factor that does not correct for the number of trees sampled and (2) the persistent underestimate of the true VA due to a weak relationship between tree size and VA. The magnitude of differences between true densities and MHVD estimates suggest caution in using results based on the MHVD to inform management and restoration practices in the conifer forests of the American West.
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Affiliation(s)
- Carrie R Levine
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, California, 94720, USA
| | - Charles V Cogbill
- Harvard Forest, Harvard University, 324 North Main Street, Petersham, Massachusetts, 01366, USA
| | - Brandon M Collins
- University of California Center for Fire Research and Outreach, College of Natural Resources, University of California, Berkeley, California, 94720, USA
| | - Andrew J Larson
- Department of Forest Management, University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - James A Lutz
- S. J. & Jessie E. Quinney College of Natural Resources, Utah State University, 5230 Old Main Hill, Logan, Utah, 84322, USA
| | - Malcolm P North
- USDA Forest Service, Pacific Southwest Research Station, 1731 Research Park Drive, Davis, California, 95618, USA
| | - Christina M Restaino
- Department of Environmental Science and Policy, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
| | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
- USDA Forest Service, Pacific Southwest Region, 1323 Club Drive, Vallejo, California, 94592, USA
| | - Scott L Stephens
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, California, 94720, USA
| | - John J Battles
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, California, 94720, USA
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Baker WL. Restoring and managing low-severity fire in dry-forest landscapes of the western USA. PLoS One 2017; 12:e0172288. [PMID: 28199416 PMCID: PMC5310858 DOI: 10.1371/journal.pone.0172288] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/02/2017] [Indexed: 11/19/2022] Open
Abstract
Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA and warrant restoration and management, but historical rates of burning remain uncertain. Past reconstructions focused on on dating fire years, not measuring historical rates of burning. Past statistics, including mean composite fire interval (mean CFI) and individual-tree fire interval (mean ITFI) have biases and inaccuracies if used as estimators of rates. In this study, I used regression, with a calibration dataset of 96 cases, to test whether these statistics could accurately predict two equivalent historical rates, population mean fire interval (PMFI) and fire rotation (FR). The best model, using Weibull mean ITFI, had low prediction error and R2adj = 0.972. I used this model to predict historical PMFI/FR at 252 sites spanning dry forests. Historical PMFI/FR for a pool of 342 calibration and predicted sites had a mean of 39 years and median of 30 years. Short (< 25 years) mean PMFI/FRs were in Arizona and New Mexico and scattered in other states. Long (> 55 years) mean PMFI/FRs were mainly from northern New Mexico to South Dakota. Mountain sites often had a large range in PMFI/FR. Nearly all 342 estimates are for old forests with a history of primarily low-severity fire, found across only about 34% of historical dry-forest area. Frequent fire (PMFI/FR < 25 years) was found across only about 14% of historical dry-forest area, with 86% having multidecadal rates of low-severity fire. Historical fuels (e.g., understory shrubs and small trees) could fully recover between multidecadal fires, allowing some denser forests and some ecosystem processes and wildlife habitat to be less limited by fire. Lower historical rates mean less restoration treatment is needed before beginning managed fire for resource benefits, where feasible. Mimicking patterns of variability in historical low-severity fire regimes would likely benefit biological diversity and ecosystem functioning.
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Affiliation(s)
- William L. Baker
- Program in Ecology/Department of Geography, Dept. 3371, 1000 E. University Ave., University of Wyoming, Laramie, Wyoming, United States of America
- * E-mail:
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15
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Goring SJ, Mladenoff DJ, Cogbill CV, Record S, Paciorek CJ, Jackson ST, Dietze MC, Dawson A, Matthes JH, McLachlan JS, Williams JW. Novel and Lost Forests in the Upper Midwestern United States, from New Estimates of Settlement-Era Composition, Stem Density, and Biomass. PLoS One 2016; 11:e0151935. [PMID: 27935944 PMCID: PMC5147790 DOI: 10.1371/journal.pone.0151935] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 03/07/2016] [Indexed: 11/19/2022] Open
Abstract
Background EuroAmerican land-use and its legacies have transformed forest structure and composition across the United States (US). More accurate reconstructions of historical states are critical to understanding the processes governing past, current, and future forest dynamics. Here we present new gridded (8x8km) reconstructions of pre-settlement (1800s) forest composition and structure from the upper Midwestern US (Minnesota, Wisconsin, and most of Michigan), using 19th Century Public Land Survey System (PLSS), with estimates of relative composition, above-ground biomass, stem density, and basal area for 28 tree types. This mapping is more robust than past efforts, using spatially varying correction factors to accommodate sampling design, azimuthal censoring, and biases in tree selection. Changes in Forest Structure We compare pre-settlement to modern forests using US Forest Service Forest Inventory and Analysis (FIA) data to show the prevalence of lost forests (pre-settlement forests with no current analog), and novel forests (modern forests with no past analogs). Differences between pre-settlement and modern forests are spatially structured owing to differences in land-use impacts and accompanying ecological responses. Modern forests are more homogeneous, and ecotonal gradients are more diffuse today than in the past. Novel forest assemblages represent 28% of all FIA cells, and 28% of pre-settlement forests no longer exist in a modern context. Lost forests include tamarack forests in northeastern Minnesota, hemlock and cedar dominated forests in north-central Wisconsin and along the Upper Peninsula of Michigan, and elm, oak, basswood and ironwood forests along the forest-prairie boundary in south central Minnesota and eastern Wisconsin. Novel FIA forest assemblages are distributed evenly across the region, but novelty shows a strong relationship to spatial distance from remnant forests in the upper Midwest, with novelty predicted at between 20 to 60km from remnants, depending on historical forest type. The spatial relationships between remnant and novel forests, shifts in ecotone structure and the loss of historic forest types point to significant challenges for land managers if landscape restoration is a priority. The spatial signals of novelty and ecological change also point to potential challenges in using modern spatial distributions of species and communities and their relationship to underlying geophysical and climatic attributes in understanding potential responses to changing climate. The signal of human settlement on modern forests is broad, spatially varying and acts to homogenize modern forests relative to their historic counterparts, with significant implications for future management.
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Affiliation(s)
- Simon J. Goring
- Department of Geography, University of Wisconsin-Madison, Madison, Wisconsin, United States
- * E-mail:
| | - David J. Mladenoff
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Charles V. Cogbill
- Harvard Forest, Harvard University, Petersham, Massachusetts, United States
| | - Sydne Record
- Harvard Forest, Harvard University, Petersham, Massachusetts, United States
- Department of Biology, Bryn Mawr College, Bryn Mawr, Pennsylvania, United States
| | | | - Stephen T. Jackson
- Department of the Interior Southwest Climate Science Center, U.S. Geological Survey, Tucson, Arizona
- School of Natural Resources and the Environment and Department of Geosciences, University of Arizona, Tucson, Arizona, United States
| | - Michael C. Dietze
- Department of Earth and Environment, Boston University, Boston, Massachusetts, United States
| | - Andria Dawson
- Department of Statistics, University of California, Berkeley, California, United States
| | | | - Jason S. McLachlan
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States
| | - John W. Williams
- Department of Geography, University of Wisconsin-Madison, Madison, Wisconsin, United States
- Center for Climatic Research, University of Wisconsin-Madison, Madison, Wisconsin, United States
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16
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Baker WL, Williams MA. Bet-hedging dry-forest resilience to climate-change threats in the western USA based on historical forest structure. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2014.00088] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Faber-Langendoen D, Keeler-Wolf T, Meidinger D, Tart D, Hoagland B, Josse C, Navarro G, Ponomarenko S, Saucier JP, Weakley A, Comer P. EcoVeg: a new approach to vegetation description and classification. ECOL MONOGR 2014. [DOI: 10.1890/13-2334.1] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Baker WL. Historical forest structure and fire in Sierran mixed-conifer forests reconstructed from General Land Office survey data. Ecosphere 2014. [DOI: 10.1890/es14-00046.1] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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19
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Maxwell RS, Taylor AH, Skinner CN, Safford HD, Isaacs RE, Airey C, Young AB. Landscape-scale modeling of reference period forest conditions and fire behavior on heavily logged lands. Ecosphere 2014. [DOI: 10.1890/es13-00294.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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20
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Odion DC, Hanson CT, Arsenault A, Baker WL, DellaSala DA, Hutto RL, Klenner W, Moritz MA, Sherriff RL, Veblen TT, Williams MA. Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America. PLoS One 2014; 9:e87852. [PMID: 24498383 PMCID: PMC3912150 DOI: 10.1371/journal.pone.0087852] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 01/01/2014] [Indexed: 11/18/2022] Open
Abstract
There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.
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Affiliation(s)
- Dennis C. Odion
- Earth Research Institute, University of California Santa Barbara, Santa Barbara, California, United States of America
- Environmental Studies Department, Southern Oregon University, Ashland, Oregon, United States of America
- * E-mail:
| | - Chad T. Hanson
- Earth Island Institute, Berkeley, California, United States of America
| | - André Arsenault
- Canadian Forest Service Natural Resources Canada, Corner Brook, N.L., Canada
| | - William L. Baker
- Program in Ecology and Department of Geography, University of Wyoming, Laramie, Wyoming, United States of America
| | | | - Richard L. Hutto
- Avian Science Center, Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Walt Klenner
- Wildlife Habitat Ecologist, FLNR, Thompson-Okanagan Region, Kamloops, B.C., Canada
| | - Max A. Moritz
- Ecosystem Sciences Division, Environmental Science, Policy, & Management Dept., University of California, Berkeley, California, United States of America
| | - Rosemary L. Sherriff
- Department of Geography, Humboldt State University, Arcata, California, United States of America
| | - Thomas T. Veblen
- Department of Geography, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Mark A. Williams
- Program in Ecology and Department of Geography, University of Wyoming, Laramie, Wyoming, United States of America
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Bukowski BE, Baker WL. Historical fire regimes, reconstructed from land-survey data, led to complexity and fluctuation in sagebrush landscapes. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2013; 23:546-564. [PMID: 23734485 DOI: 10.1890/12-0844.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sagebrush landscapes provide habitat for Sage-Grouse and other sagebrush obligates, yet historical fire regimes and the structure of historical sagebrush landscapes are poorly known, hampering ecological restoration and management. To remedy this, General Land Office Survey (GLO) survey notes were used to reconstruct over two million hectares of historical vegetation for four sagebrush-dominated (Artemisia spp.) study areas in the western United States. Reconstructed vegetation was analyzed for fire indicators used to identify historical fires and reconstruct historical fire regimes. Historical fire-size distributions were inverse-J shaped, and one fire > 100 000 ha was identified. Historical fire rotations were estimated at 171-342 years for Wyoming big sagebrush (A. tridentata ssp. wyomingensis) and 137-217 years for mountain big sagebrush (A. tridentata ssp. vaseyana). Historical fire and patch sizes were significantly larger in Wyoming big sagebrush than mountain big sagebrush, and historical fire rotations were significantly longer in Wyoming big sagebrush than mountain big sagebrush. Historical fire rotations in Wyoming were longer than those in other study areas. Fine-scale mosaics of burned and unburned area and larger unburned inclusions within fire perimeters were less common than in modern fires. Historical sagebrush landscapes were dominated by large, contiguous areas of sagebrush, though large grass-dominated areas and finer-scale mosaics of grass and sagebrush were also present in smaller amounts. Variation in sagebrush density was a common source of patchiness, and areas classified as "dense" made up 24.5% of total sagebrush area, compared to 16.3% for "scattered" sagebrush. Results suggest significant differences in historical and modern fire regimes. Modern fire rotations in Wyoming big sagebrush are shorter than historical fire rotations. Results also suggest that historical sagebrush landscapes would have fluctuated, because of infrequent episodes of large fires and long periods of recovery and maturity. Due to fragmentation of sagebrush landscapes, the large, contiguous expanses of sagebrush that dominated historically are most at risk and in need of conservation, including both dense and scattered sagebrush. Fire suppression in Wyoming big sagebrush may also be advisable, as modern fire rotations are shorter than their historical counterparts.
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Affiliation(s)
- Beth E Bukowski
- Department of Geography, Department 3371, 1000 E. University Avenue, University of Wyoming, Laramie, Wyoming 82072, USA
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Labbe T, Adams A, Conrad R. Historical Condition and Change in Riparian Vegetation, Hood Canal and Eastern Strait of Juan de Fuca, Washington. NORTHWEST SCIENCE 2013. [DOI: 10.3955/046.087.0103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Baker WL. Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades. Ecosphere 2012. [DOI: 10.1890/es11-00320.1] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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