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Mood BJ, Laroque CP. Forward modelling of white spruce radial growth at trailing edge demonstrates high plasticity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 957:177695. [PMID: 39579906 DOI: 10.1016/j.scitotenv.2024.177695] [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: 08/01/2024] [Revised: 10/29/2024] [Accepted: 11/19/2024] [Indexed: 11/25/2024]
Abstract
Climate conditions throughout the 21st century across much of western Canada's boreal forest have been drier than normal leading to significant impacts on forest productivity and tree growth. Determining the limiting factors of radial growth in common boreal tree species under current and future conditions is crucial to reconcile how they will continue to respond to climate change. In this study, we used a network of 26 white spruce tree-ring chronologies south of its natural range as an artificially constructed trailing edge to assess climate-growth relationships and limiting factors by identifying seasonal climate relationships and using the Vaganov-Shashkin Lite (VS-Lite) model, respectively. Analysis revealed that white spruce in the study region is positively correlated to precipitation and negatively associated with temperature from the current and previous growing seasons. VS-Lite showed that moisture was the primary limiting factor in growth across the entire study area. The modelled radial growth from the VS-Lite model showed moderate success (14 of 26 site models were significant) and was more variable than measured tree-ring index values. The model systematically overestimated drought-related impacts on radial growth, especially during the middle portion of the growth season (June-August) indicating white spruce likely employs a conservative approach to carbohydrate storage as the region is much more susceptible to moisture deficits. The outcome of our research illustrates that white spruce may be resilient to hotter, drier conditions through environmental plasticity in the Boreal Plains.
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Affiliation(s)
- Bryan J Mood
- Mistik Askwin Dendrochronology Laboratory, Department of Soil Science, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada.
| | - Colin P Laroque
- Mistik Askwin Dendrochronology Laboratory, Department of Soil Science, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada
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2
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Wion AP, Stevens JT, Beeley K, Oertel R, Margolis EQ, Allen CD. Multidecadal vegetation transformations of a New Mexico ponderosa pine landscape after severe fires and aerial seeding. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024; 34:e3008. [PMID: 39034303 DOI: 10.1002/eap.3008] [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: 07/18/2023] [Revised: 12/14/2023] [Accepted: 04/22/2024] [Indexed: 07/23/2024]
Abstract
Wildfires and climate change increasingly are transforming vegetation composition and structure, and postfire management may have long-lasting effects on ecosystem reorganization. Postfire aerial seeding treatments are commonly used to reduce runoff and soil erosion, but little is known about how seeding treatments affect native vegetation recovery over long periods of time, particularly in type-converted forests that have been dramatically transformed by the effects of repeated, high-severity fire. In this study, we analyze and report on a rare long-term (23-year) dataset that documents vegetation dynamics following a 1996 post-fire aerial seeding treatment and a subsequent 2011 high-severity reburn in a dry conifer landscape of northern New Mexico, USA. Repeated surveys between 1997 and 2019 of 49 permanent transects were analyzed for differences in vegetation cover, richness, and diversity between seeded and unseeded areas, and to characterize the development of seeded and unseeded vegetation communities through time and across gradients of burn severity, elevation, and soil-available water capacity. Seeded plots showed no significant difference in bare ground cover during the initial years postfire relative to unseeded plots. Postfire seeding led to a clear and sustained divergence in herbaceous community composition. Seeded plots had a much higher cover of non-native graminoids, primarily Bromus inermis, a likely contaminant in the seed mix. High-severity reburning of all plots in 2011 reduced native graminoid cover by half at seeded plots compared with both prefire levels and with plots that were unseeded following the initial 1996 fire. In addition, higher fire severity was associated with increased non-native graminoid cover and reduced native graminoid cover. This study documents fire-driven ecosystem transformation from conifer forest into a shrub-and-grass-dominated system, reinforced by aerial seeding of grasses and high-severity reburning. This unique long-term dataset illustrates that post-fire seeding carries significant risks of unwanted non-native species invasions that persist through subsequent fires-thus alternative postfire management actions merit consideration to better support native ecosystem resilience given emergent climate change and increasing disturbance. This study also highlights the importance of long-term monitoring of postfire vegetation dynamics, as short-term assessments miss key elements of complex ecosystem responses to fire and postfire management actions.
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Affiliation(s)
- Andreas P Wion
- U.S. Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Santa Fe, New Mexico, USA
| | - Jens T Stevens
- School of Environmental and Forest Science, University of Washington, Seattle, Washington, USA
| | - Kay Beeley
- National Park Service, Bandelier National Monument, Los Alamos, New Mexico, USA
| | - Rebecca Oertel
- U.S. Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Santa Fe, New Mexico, USA
| | - Ellis Q Margolis
- U.S. Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Santa Fe, New Mexico, USA
| | - Craig D Allen
- Department of Geography and Environmental Studies, University of New Mexico, Albuquerque, New Mexico, USA
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3
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Crockett JL, Hurteau MD. Ability of seedlings to survive heat and drought portends future demographic challenges for five southwestern US conifers. TREE PHYSIOLOGY 2024; 44:tpad136. [PMID: 37935402 DOI: 10.1093/treephys/tpad136] [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: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023]
Abstract
Climate change and disturbance are altering forests and the rates and locations of tree regeneration. In semi-arid forests of the southwestern USA, limitations imposed by hot and dry conditions are likely to influence seedling survival. We examined how the survival of 1-year seedlings of five southwestern US conifer species whose southwestern distributions range from warmer and drier woodlands and forests (Pinus edulis Engelm., Pinus ponderosa Douglas ex C. Lawson) to cooler and wetter subalpine forests (Pseudotsuga menziesii (Mirb.) Franco, Abies concolor (Gord. & Glend.) Lindl. Ex Hildebr. and Picea engelmannii Parry ex Engelm.) changed in response to low moisture availability, high temperatures and high vapor pressure deficit in incubators. We used a Bayesian framework to construct discrete-time proportional hazard models that explained 55-75% of the species-specific survival variability. We applied these to the recent climate (1980-2019) of the southwestern USA as well as 1980-2099 CMIP5 climate projections with the RCP8.5 emissions pathway. We found that the more mesic species (i.e., P. menziesii, A. concolor and P. engelmannii) were more susceptible to the effects of hot and dry periods. However, their existing ranges are not projected to experience the conditions we tested as early in the 21st century as the more xeric P. edulis and P. ponderosa, leading to lower percentages of their existing ranges predicted to experience seedling-killing conditions. By late-century, extensive areas of each species southwestern range could experience climate conditions that increase the likelihood of seedling mortality. These results demonstrate that empirically derived physiological limitations can be used to inform where species composition or vegetation type change are likely to occur in the southwestern USA.
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Affiliation(s)
- Joseph L Crockett
- Department of Biology, MSC03-20201, University of New Mexico, Albuquerque, NM 87131-0001
| | - Matthew D Hurteau
- Department of Biology, MSC03-20201, University of New Mexico, Albuquerque, NM 87131-0001
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4
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Nelson AR, Fegel TS, Danczak RE, Caiafa MV, Roth HK, Dunn OI, Turvold CA, Borch T, Glassman SI, Barnes RT, Rhoades CC, Wilkins MJ. Soil microbiome feedbacks during disturbance-driven forest ecosystem conversion. THE ISME JOURNAL 2024; 18:wrae047. [PMID: 38502869 PMCID: PMC11650388 DOI: 10.1093/ismejo/wrae047] [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: 11/07/2023] [Revised: 01/12/2024] [Accepted: 03/17/2024] [Indexed: 03/21/2024]
Abstract
Disturbances cause rapid changes to forests, with different disturbance types and severities creating unique ecosystem trajectories that can impact the underlying soil microbiome. Pile burning-the combustion of logging residue on the forest floor-is a common fuel reduction practice that can have impacts on forest soils analogous to those following high-severity wildfire. Further, pile burning following clear-cut harvesting can create persistent openings dominated by nonwoody plants surrounded by dense regenerating conifer forest. A paired 60-year chronosequence of burn scar openings and surrounding regenerating forest after clear-cut harvesting provides a unique opportunity to assess whether belowground microbial processes mirror aboveground vegetation during disturbance-induced ecosystem shifts. Soil ectomycorrhizal fungal diversity was reduced the first decade after pile burning, which could explain poor tree seedling establishment and subsequent persistence of herbaceous species within the openings. Fine-scale changes in the soil microbiome mirrored aboveground shifts in vegetation, with short-term changes to microbial carbon cycling functions resembling a postfire microbiome (e.g. enrichment of aromatic degradation genes) and respiration in burn scars decoupled from substrate quantity and quality. Broadly, however, soil microbiome composition and function within burn scar soils converged with that of the surrounding regenerating forest six decades after the disturbances, indicating potential microbial resilience that was disconnected from aboveground vegetation shifts. This work begins to unravel the belowground microbial processes that underlie disturbance-induced ecosystem changes, which are increasing in frequency tied to climate change.
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Affiliation(s)
- Amelia R Nelson
- Department of Soil and Crop Sciences, Colorado State
University, Fort Collins, CO 80523, United States
| | - Timothy S Fegel
- Rocky Mountain Research Station, US Forest Service,
Fort Collins, CO 80526, United
States
| | - Robert E Danczak
- Division of Biological Sciences, Pacific Northwest National
Laboratory, Richland, WA 99354, United States
| | - Marcos V Caiafa
- Department of Microbiology and Plant Pathology, University of California
Riverside, Riverside, CA 92521, United States
| | - Holly K Roth
- Department of Chemistry, Colorado State University,
Fort Collins, CO 80523, United
States
| | - Oliver I Dunn
- The Environmental Studies Program, Colorado College,
Colorado Springs, CO 80946, United
States
| | - Cosette A Turvold
- The Environmental Studies Program, Colorado College,
Colorado Springs, CO 80946, United
States
| | - Thomas Borch
- Department of Soil and Crop Sciences, Colorado State
University, Fort Collins, CO 80523, United States
- Department of Chemistry, Colorado State University,
Fort Collins, CO 80523, United
States
- Department of Civil and Environmental Engineering, Colorado State
University, Fort Collins, CO 80523, United States
| | - Sydney I Glassman
- Department of Microbiology and Plant Pathology, University of California
Riverside, Riverside, CA 92521, United States
| | - Rebecca T Barnes
- The Environmental Studies Program, Colorado College,
Colorado Springs, CO 80946, United
States
| | - Charles C Rhoades
- Rocky Mountain Research Station, US Forest Service,
Fort Collins, CO 80526, United
States
| | - Michael J Wilkins
- Department of Soil and Crop Sciences, Colorado State
University, Fort Collins, CO 80523, United States
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Tarbill GL, White AM, Sollmann R. Response of pollinator taxa to fire is consistent with historic fire regimes in the Sierra Nevada and mediated through floral richness †. Ecol Evol 2023; 13:e10761. [PMID: 38107425 PMCID: PMC10721959 DOI: 10.1002/ece3.10761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/12/2023] [Accepted: 11/11/2023] [Indexed: 12/19/2023] Open
Abstract
Many fire-prone forests are experiencing wildfires that burn outside the historical range of variation in extent and severity. These fires impact pollinators and the ecosystem services they provide, but how the effects of fire are mediated by burn severity in different habitats is not well understood. We used generalized linear mixed models in a Bayesian framework to model the abundance of pollinators as a function of burn severity, habitat, and floral resources in post-fire, mid-elevation, conifer forest, and meadow in the Sierra Nevada, California. Although most species-level effects were not significant, we found highly consistent negative impacts of burn severity in meadows where pollinators were most abundant, with only hummingbirds and some butterfly families responding positively to burn severity in meadows. Moderate-severity fire tended to increase the abundance of most pollinator taxa in upland forest habitat, indicating that even in large fires that burn primarily at high- and moderate-severity patches may be associated with improved habitat conditions for pollinator species in upland forest. Nearly all pollinator taxa responded positively to floral richness but not necessarily to floral abundance. Given that much of the Sierra Nevada is predicted to burn at high severity, limiting high-severity effects in meadow and upland habitats may help conserve pollinator communities whereas low- to moderate-severity fire may be needed in both systems.
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Affiliation(s)
- Gina L. Tarbill
- Pacific Southwest Research StationUSDA, Forest ServiceDavisCaliforniaUSA
- Wildlife, Fish, & Conservation BiologyUniversity of California, DavisDavisCaliforniaUSA
| | - Angela M. White
- Pacific Southwest Research StationUSDA, Forest ServiceDavisCaliforniaUSA
| | - Rahel Sollmann
- Wildlife, Fish, & Conservation BiologyUniversity of California, DavisDavisCaliforniaUSA
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
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6
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Rodman KC, Davis KT, Parks SA, Chapman TB, Coop JD, Iniguez JM, Roccaforte JP, Sánchez Meador AJ, Springer JD, Stevens-Rumann CS, Stoddard MT, Waltz AEM, Wasserman TN. Refuge-yeah or refuge-nah? Predicting locations of forest resistance and recruitment in a fiery world. GLOBAL CHANGE BIOLOGY 2023; 29:7029-7050. [PMID: 37706328 DOI: 10.1111/gcb.16939] [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: 02/23/2023] [Revised: 08/25/2023] [Accepted: 08/31/2023] [Indexed: 09/15/2023]
Abstract
Climate warming, land use change, and altered fire regimes are driving ecological transformations that can have critical effects on Earth's biota. Fire refugia-locations that are burned less frequently or severely than their surroundings-may act as sites of relative stability during this period of rapid change by being resistant to fire and supporting post-fire recovery in adjacent areas. Because of their value to forest ecosystem persistence, there is an urgent need to anticipate where refugia are most likely to be found and where they align with environmental conditions that support post-fire tree recruitment. Using biophysical predictors and patterns of burn severity from 1180 recent fire events, we mapped the locations of potential fire refugia across upland conifer forests in the southwestern United States (US) (99,428 km2 of forest area), a region that is highly vulnerable to fire-driven transformation. We found that low pre-fire forest cover, flat slopes or topographic concavities, moderate weather conditions, spring-season burning, and areas affected by low- to moderate-severity fire within the previous 15 years were most commonly associated with refugia. Based on current (i.e., 2021) conditions, we predicted that 67.6% and 18.1% of conifer forests in our study area would contain refugia under moderate and extreme fire weather, respectively. However, potential refugia were 36.4% (moderate weather) and 31.2% (extreme weather) more common across forests that experienced recent fires, supporting the increased use of prescribed and resource objective fires during moderate weather conditions to promote fire-resistant landscapes. When overlaid with models of tree recruitment, 23.2% (moderate weather) and 6.4% (extreme weather) of forests were classified as refugia with a high potential to support post-fire recruitment in the surrounding landscape. These locations may be disproportionately valuable for ecosystem sustainability, providing habitat for fire-sensitive species and maintaining forest persistence in an increasingly fire-prone world.
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Affiliation(s)
- Kyle C Rodman
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Kimberley T Davis
- Fire Sciences Laboratory, Rocky Mountain Research Station, USDA Forest Service, Missoula, Montana, USA
| | - Sean A Parks
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, USDA Forest Service, Missoula, Montana, USA
| | - Teresa B Chapman
- Monitoring, Evaluation, and Learning Program, Chief Conservation Office, The Nature Conservancy, Arlington, Virginia, USA
| | - Jonathan D Coop
- Clark School of Environment and Sustainability, Western Colorado University, Gunnison, Colorado, USA
| | - Jose M Iniguez
- Rocky Mountain Research Station, USDA Forest Service, Flagstaff, Arizona, USA
| | - John P Roccaforte
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Andrew J Sánchez Meador
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
| | - Judith D Springer
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Camille S Stevens-Rumann
- Colorado Forest Restoration Institute, Colorado State University, Fort Collins, Colorado, USA
- Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado, USA
| | - Michael T Stoddard
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Amy E M Waltz
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Tzeidle N Wasserman
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
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7
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Tortorelli CM, Kim JB, Vaillant NM, Riley K, Dye A, Nietupski TC, Vogler KC, Lemons R, Day M, Krawchuk MA, Kerns BK. Feeding the fire: Annual grass invasion facilitates modeled fire spread across Inland Northwest forest‐mosaic landscapes. Ecosphere 2023. [DOI: 10.1002/ecs2.4413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- Claire M. Tortorelli
- Department of Forest Ecosystems and Society Oregon State University Corvallis Oregon USA
| | - John B. Kim
- Western Wildland Environmental Threat Assessment Center Corvallis Oregon USA
| | - Nicole M. Vaillant
- USDA Forest Service Rocky Mountain Research Station Wildland Fire Management Research, Development and Application Bend Oregon USA
| | - Karin Riley
- Rocky Mountain Research Station Missoula Fire Sciences Laboratory Missoula Montana USA
| | - Alex Dye
- USDA Forest Service Pacific Northwest Research Station Portland Oregon USA
| | - Ty C. Nietupski
- USDA Forest Service Pacific Northwest Research Station Portland Oregon USA
| | | | - Rebecca Lemons
- Department of Forest Ecosystems and Society Oregon State University Corvallis Oregon USA
| | - Michelle Day
- USDA Forest Service Rocky Mountain Research Station Fort Collins Colorado USA
| | - Meg A. Krawchuk
- Department of Forest Ecosystems and Society Oregon State University Corvallis Oregon USA
| | - Becky K. Kerns
- USDA Forest Service Pacific Northwest Research Station Portland Oregon USA
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8
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Young DJN, Slaton MR, Koltunov A. Temperature is positively associated with tree mortality in California subalpine forests containing whitebark pine. Ecosphere 2023. [DOI: 10.1002/ecs2.4400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- Derek J. N. Young
- Department of Plant Sciences University of California Davis California USA
| | - Michèle R. Slaton
- USDA Forest Service Pacific Southwest Region Remote Sensing Lab McClellan California USA
| | - Alexander Koltunov
- USDA Forest Service Pacific Southwest Region Remote Sensing Lab McClellan California USA
- Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources University of California Davis California USA
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9
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Coop JD. Postfire futures in southwestern forests: Climate and landscape influences on trajectories of recovery and conversion. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2725. [PMID: 36054332 PMCID: PMC10078526 DOI: 10.1002/eap.2725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 04/29/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
Southwestern ponderosa pine forests are vulnerable to fire-driven conversion in a warming and drying climate, yet little is known about what kinds of ecological communities may replace them. To characterize postfire vegetation trajectories and their environmental determinants, plant assemblages (361 sample plots including 229 vascular plant species, surveyed in 2017) were sampled within eight burns that occurred between 2000 and 2003. I used nonmetric multidimensional scaling, k-means clustering, principal component analysis, and random forest models to assess relationships between vegetation pattern, topographic and landscape factors, and gridded climate data. I describe seven postfire community types, including regenerating forests of ponderosa pine, aspen, and mixed conifers, shrub-dominated communities of Gambel oak and mixed species, and herb-dominated communities of native bunchgrasses and mixtures of ruderal, native, and nonnative species. Forest recovery was generally associated with cooler, mesic sites in proximity to forested refugia; shifts toward scrub and grassland types were most common in warmer, dryer locations distant from forested refugia. Under future climate scenarios, models project decreases in postfire forest recovery and increases in nonforest vegetation. However, forest to nonforest conversion was partially offset under a scenario of reduced burn severity and increased retention of forested refugia, highlighting important management opportunities. Burning trends in the southwestern United States suggest that postfire vegetation will occupy a growing landscape fraction, compelling renewed management focus on these areas and paradigm shifts that accommodate ecological change. I illustrate how management decisions around resisting, accepting, or directing change could be informed by an understanding of processes and patterns of postfire community variation and likely future trajectories.
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Affiliation(s)
- Jonathan D. Coop
- Clark School of Environment and SustainabilityWestern Colorado UniversityGunnisonColoradoUSA
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10
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Fulé PZ, Sánchez Meador AJ, Moore MM, Covington WW, Kolb TE, Huffman DW, Normandin DP, Roccaforte JP. Forest restoration treatments increased growth and did not change survival of ponderosa pines in severe drought, Arizona. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2717. [PMID: 36184740 DOI: 10.1002/eap.2717] [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: 08/20/2021] [Revised: 05/15/2022] [Accepted: 06/13/2022] [Indexed: 06/16/2023]
Abstract
We report on survival and growth of ponderosa pines (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) 2 decades after forest restoration treatments in the G. A. Pearson Natural Area, northern Arizona. Despite protection from harvest that conserved old trees, a dense forest susceptible to uncharacteristically severe disturbance had developed during more than a century of exclusion of the previous frequent surface-fire regime that ceased upon Euro-American settlement in approximately 1876. Trees were thinned in 1993 to emulate prefire-exclusion forest conditions, accumulated forest floor was removed, and surface fire was re-introduced at 4-years intervals (full restoration). There was also a partial restoration treatment consisting of thinning alone. Compared with untreated controls, mortality of old trees (mean age 243 years, maximum 462 years) differed by <1 tree ha-1 and old-tree survival was statistically indistinguishable between treatments (90.5% control, 92.3% full, 82.6% partial). Post-treatment growth as measured by basal area increment of both old (pre-1876) and young (post-1876) pines was significantly higher in both treatments than counterpart control trees for more than 2 decades following thinning. Drought meeting the definition of megadrought affected the region almost all the time since the onset of the experiment, including 3 years that were severely dry. Growth of all trees declined in the driest 3 years, but old and young treated trees had significantly less decline. Association of tree growth with temperature (negative correlation) and precipitation (positive correlation) was much weaker in treated trees, indicating that they may experience less growth decline from warmer, drier conditions predicted in future decades. Overall, tree responses after the first 2 decades following treatment suggest that forest restoration treatments have led to substantial, sustained improvement in the growth of old and young ponderosa pines without affecting old-tree survival, thereby improving resilience to a warming climate.
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Affiliation(s)
- Peter Z Fulé
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
| | - Andrew J Sánchez Meador
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Margaret M Moore
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
| | - W Wallace Covington
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Thomas E Kolb
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
| | - David W Huffman
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Donald P Normandin
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - John Paul Roccaforte
- Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona, USA
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Abstract
How will increasing wildfire activity affect water resources in the water-limited western United States (WUS)? Among basins where >20% of forest burned, postfire streamflow is significantly enhanced by an average of approximately 30% for 6 y. Over 2015 to 2020, several large WUS basins experienced >10% of forest burned. Climate projections and an exponential forest fire response to climate-induced drying suggest the next 3 decades will see repeated years when WUS forest fire area exceeds that of 2020, which set a modern record for forest area burned. If so, entire regions will likely experience more streamflow than expected, potentially enhancing human access to water but posing hazard management challenges. Projections of water supply and runoff-related hazards must account for wildfire. Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Significance is assessed by comparing prefire and postfire streamflow responses to climate and also to streamflow among 107 control basins that experienced little to no wildfire during the study period. The streamflow response scales with fire extent: among the 29 basins where >20% of forest area burned in a year, streamflow over the first 6 water years postfire increased by a multibasin average of 0.38 SDs, or 30%. Postfire streamflow increases were significant in all four seasons. Historical fire–climate relationships combined with climate model projections suggest that 2021 to 2050 will see repeated years when climate is more fire-conducive than in 2020, the year currently holding the modern record for WUS forest area burned. These findings center on relatively small, minimally managed basins, but our results suggest that burned areas will grow enough over the next 3 decades to enhance streamflow at regional scales. Wildfire is an emerging driver of runoff change that will increasingly alter climate impacts on water supplies and runoff-related risks.
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12
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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: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [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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13
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Crausbay SD, Sofaer HR, Cravens AE, Chaffin BC, Clifford KR, Gross JE, Knapp CN, Lawrence DJ, Magness DR, Miller-Rushing AJ, Schuurman GW, Stevens-Rumann CS. A Science Agenda to Inform Natural Resource Management Decisions in an Era of Ecological Transformation. Bioscience 2021. [DOI: 10.1093/biosci/biab102] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Earth is experiencing widespread ecological transformation in terrestrial, freshwater, and marine ecosystems that is attributable to directional environmental changes, especially intensifying climate change. To better steward ecosystems facing unprecedented and lasting change, a new management paradigm is forming, supported by a decision-oriented framework that presents three distinct management choices: resist, accept, or direct the ecological trajectory. To make these choices strategically, managers seek to understand the nature of the transformation that could occur if change is accepted while identifying opportunities to intervene to resist or direct change. In this article, we seek to inspire a research agenda for transformation science that is focused on ecological and social science and based on five central questions that align with the resist–accept–direct (RAD) framework. Development of transformation science is needed to apply the RAD framework and support natural resource management and conservation on our rapidly changing planet.
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Affiliation(s)
- Shelley D Crausbay
- Conservation Science Partners, Fort Collins, Colorado, and is a consortium partner for the US Geological Survey's North Central Climate Adaptation Science Center, Boulder, Colorado, United States
| | - Helen R Sofaer
- US Geological Survey Pacific Island Ecosystems Research Center, Hawaii Volcanoes National Park, Hawai'i, United States
| | - Amanda E Cravens
- US Geological Survey's Social and Economic Analysis Branch, Fort Collins, Colorado, United States
| | | | - Katherine R Clifford
- US Geological Survey's Social and Economic Analysis Branch, Fort Collins, Colorado, United States
| | - John E Gross
- US National Park Service Climate Change Response Program, Fort Collins, Colorado, United States
| | | | - David J Lawrence
- US National Park Service Climate Change Response Program, Fort Collins, Colorado, United States
| | - Dawn R Magness
- US Fish and Wildlife Service, Kenai National Wildlife Refuge, Soldotna, Alaska, United States
| | | | - Gregor W Schuurman
- US National Park Service Climate Change Response Program, in Fort Collins, Colorado, United States
| | - Camille S Stevens-Rumann
- Forest and Rangeland Stewardship Department and assistant director of the Colorado Forest Restoration Institute, at Colorado State University, Fort Collins, Colorado, United States
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14
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Barton AM, Poulos H. Wildfire and topography drive woody plant diversity in a Sky Island mountain range in the Southwest USA. Ecol Evol 2021; 11:14715-14732. [PMID: 34765136 PMCID: PMC8571633 DOI: 10.1002/ece3.8158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/24/2021] [Accepted: 08/31/2021] [Indexed: 11/15/2022] Open
Abstract
AIM Drastic changes in fire regimes are altering plant communities, inspiring ecologists to better understand the relationship between fire and plant species diversity. We examined the impact of a 90,000-ha wildfire on woody plant species diversity in an arid mountain range in southern Arizona, USA. We tested recent fire-diversity hypotheses by addressing the impacts on diversity of fire severity, fire variability, historical fire regimes, and topography. LOCATION Chiricahua National Monument, Chiricahua Mountains, Arizona, USA, part of the Sky Islands of the US-Mexico borderlands. TAXON Woody plant species. METHODS We sampled woody plant diversity in 138 plots before (2002-2003) and after (2017-2018) the 2011 Horseshoe Two Fire in three vegetation types and across fire severity and topographic gradients. We calculated gamma, alpha, and beta diversity and examined changes over time in burned versus unburned plots and the shapes of the relationships of diversity with fire severity and topography. RESULTS Alpha species richness declined, and beta and gamma diversity increased in burned but not unburned plots. Fire-induced enhancement of gamma diversity was confined to low fire severity plots. Alpha diversity did not exhibit a clear continuous relationship with fire severity. Beta diversity was enhanced by variation in fire severity among plots and increased with fire severity up to very high severity, where it declined slightly. MAIN CONCLUSIONS The results reject the intermediate disturbance hypothesis for alpha diversity but weakly support it for gamma diversity. Spatial variation in fire severity promoted variation among plant assemblages, supporting the pyrodiversity hypothesis. Long-term drought probably amplified fire-driven diversity changes. Despite the apparent benign impact of the fire on diversity, the replacement of two large conifer species with a suite of drought-tolerant shrubs signals the potential loss of functional diversity, a pattern that may warrant restoration efforts to retain these important compositional elements.
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Affiliation(s)
- Andrew M. Barton
- Department of BiologyUniversity of Maine at FarmingtonFarmingtonMEUSA
| | - Helen Poulos
- College of the EnvironmentWesleyan UniversityMiddletownCTUSA
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15
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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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16
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Merrick MJ, Morandini M, Greer VL, Koprowski JL. Endemic Population Response to Increasingly Severe Fire: A Cascade of Endangerment for the Mt. Graham Red Squirrel. Bioscience 2021. [DOI: 10.1093/biosci/biaa153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Abstract
Drought, past fire suppression, insect invasion, and high-severity fire represent a disturbance cascade characteristic of forests in the western United States. The result is altered forest ecosystems diminished in their function and capacity to support biodiversity. Small habitat specialists are particularly vulnerable to the impacts of disturbances because of their limited movement capacity and high site fidelity. Research suggests that small mammals suffer limited direct mortality from fire but are increasingly vulnerable to local extirpation because of secondary impacts that include habitat loss and reduced food availability, survival, and reproduction. We examine the direct and secondary impacts of increasingly severe fire events on the endangered Mt. Graham red squirrel—a model system to demonstrate how disturbances can threaten the persistence of range-limited species. We document survival, space use, and displacement prior to and following fires and discuss implications for conservation. We suggest that management plans address future threats, including disturbance-related habitat loss.
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Affiliation(s)
| | | | | | - John L Koprowski
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States
- JK is also a dean, professor, and the Wyoming Excellence Chair of at the Haub School of Environment and Natural Resources, University of Wyoming
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17
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A climatic dipole drives short- and long-term patterns of postfire forest recovery in the western United States. Proc Natl Acad Sci U S A 2020; 117:29730-29737. [PMID: 33168732 DOI: 10.1073/pnas.2007434117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Researchers are increasingly examining patterns and drivers of postfire forest recovery amid growing concern that climate change and intensifying fires will trigger ecosystem transformations. Diminished seed availability and postfire drought have emerged as key constraints on conifer recruitment. However, the spatial and temporal extent to which recurring modes of climatic variability shape patterns of postfire recovery remain largely unexplored. Here, we identify a north-south dipole in annual climatic moisture deficit anomalies across the Interior West of the US and characterize its influence on forest recovery from fire. We use annually resolved establishment models from dendrochronological records to correlate this climatic dipole with short-term postfire juvenile recruitment. We also examine longer-term recovery trajectories using Forest Inventory and Analysis data from 989 burned plots. We show that annual postfire ponderosa pine recruitment probabilities in the northern Rocky Mountains (NR) and the southwestern US (SW) track the strength of the dipole, while declining overall due to increasing aridity. This indicates that divergent recovery trajectories may be triggered concurrently across large spatial scales: favorable conditions in the SW can correspond to drought in the NR that inhibits ponderosa pine establishment, and vice versa. The imprint of this climatic dipole is manifest for years postfire, as evidenced by dampened long-term likelihoods of juvenile ponderosa pine presence in areas that experienced postfire drought. These findings underscore the importance of climatic variability at multiple spatiotemporal scales in driving cross-regional patterns of forest recovery and have implications for understanding ecosystem transformations and species range dynamics under global change.
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18
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Urza AK, Weisberg PJ, Dilts T. Evidence of widespread topoclimatic limitation for lower treelines of the Intermountain West, United States. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02158. [PMID: 32365241 DOI: 10.1002/eap.2158] [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: 12/04/2019] [Revised: 03/24/2020] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
Many forests in dry mountain regions are characterized by a lower elevational treeline. Understanding the controls on the position of lower treeline is important for predicting future forest distributional shifts in response to global environmental change. Lower treelines currently at their climate limit are expected to be more sensitive to changing climate, whereas lower treelines constrained by non-climatic factors are less likely to respond directly to climate change but may be sensitive to other global change agents. In this study, we used existing vegetation classifications to map lower treelines for our 1.7 million km2 study region in the U. S. Intermountain West. We modeled topoclimatic drivers of lower treeline position for each of three dominant forest types to identify topoclimatically limited treelines. We then used spatial data of edaphic properties, recent fire, and land use to identify lower treelines potentially constrained above their ecophysiological limits by non-climatic processes. We found that the lower treeline ecotone of pinyon-juniper woodlands is largely limited by topoclimate and is likely to be sensitive to increasing temperatures and associated droughts, though these effects may be heterogeneously distributed across the landscape. In contrast, dry mixed-conifer lower treelines in the northern portion of the study area rarely reached their modeled topoclimatic limit, suggesting that non-climatic processes, including fire and land use, constrain the lower treeline above its ecophysiological limits in this forest type. Our results suggest that much of the lower treeline in the Intermountain West is currently climate limited and will thus be sensitive to ongoing climate changes. Lower treelines in other arid or semi-arid mountainous regions around the globe may also be strongly sensitive to climate, though treeline response to climate change will be mediated at the local scale by soil properties, biotic interactions, and natural or anthropogenic disturbances. Our regional study of lower treeline provides a framework for identifying the drivers of lower treeline formation and allows for more robust projections of future treeline dynamics, which are needed to anticipate shifting global distributions of the forest biome.
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Affiliation(s)
- Alexandra K Urza
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, Nevada, 89512, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
| | - Peter J Weisberg
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
| | - Thomas Dilts
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
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19
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Harris LB, Taylor AH. Rain‐shadow forest margins resilient to low‐severity fire and climate change but not high‐severity fire. Ecosphere 2020. [DOI: 10.1002/ecs2.3258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Lucas B. Harris
- Department of Geography The Pennsylvania State University 302 Walker Building University Park Pennsylvania16802USA
| | - Alan H. Taylor
- Department of Geography Earth and Environmental Systems Institute The Pennsylvania State University 302 Walker Building University Park Pennsylvania16802USA
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20
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Povak NA, Churchill DJ, Cansler CA, Hessburg PF, Kane VR, Kane JT, Lutz JA, Larson AJ. Wildfire severity and postfire salvage harvest effects on long‐term forest regeneration. Ecosphere 2020. [DOI: 10.1002/ecs2.3199] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Nicholas A. Povak
- USDA‐Forest Service Pacific Northwest Research Station 1133 N Western Avenue Wenatchee Washington98801‐1229USA
- Oak Ridge Institute for Science and Education (ORISE) Oak Ridge Tennessee37830USA
| | - Derek J. Churchill
- Washington State Department of Natural Resources Forest Health and Resiliency Division Olympia Washington98504USA
| | - C. Alina Cansler
- School of Environmental and Forest Sciences University of Washington Box 352100 Seattle Washington98195USA
| | - Paul F. Hessburg
- USDA‐Forest Service Pacific Northwest Research Station 1133 N Western Avenue Wenatchee Washington98801‐1229USA
- School of Environmental and Forest Sciences University of Washington Box 352100 Seattle Washington98195USA
| | - Van R. Kane
- School of Environmental and Forest Sciences University of Washington Box 352100 Seattle Washington98195USA
| | - Jonathan T. Kane
- School of Environmental and Forest Sciences University of Washington Box 352100 Seattle Washington98195USA
| | - James A. Lutz
- Quinney College of Natural Resources & Ecology Center Utah State University Logan Utah84322USA
| | - Andrew J. Larson
- W.A. Franke College of Forestry & Conservation University of Montana Missoula Montana59812USA
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21
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Coop JD, Parks SA, Stevens-Rumann CS, Crausbay SD, Higuera PE, Hurteau MD, Tepley A, Whitman E, Assal T, Collins BM, Davis KT, Dobrowski S, Falk DA, Fornwalt PJ, Fulé PZ, Harvey BJ, Kane VR, Littlefield CE, Margolis EQ, North M, Parisien MA, Prichard S, Rodman KC. Wildfire-Driven Forest Conversion in Western North American Landscapes. Bioscience 2020; 70:659-673. [PMID: 32821066 PMCID: PMC7429175 DOI: 10.1093/biosci/biaa061] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high-severity fire, forest recovery may be compromised by lack of tree seed sources, warmer and drier postfire climate, or short-interval reburning. A potential outcome of the loss of resilience is the conversion of the prefire forest to a different forest type or nonforest vegetation. Conversion implies major, extensive, and enduring changes in dominant species, life forms, or functions, with impacts on ecosystem services. In the present article, we synthesize a growing body of evidence of fire-driven conversion and our understanding of its causes across western North America. We assess our capacity to predict conversion and highlight important uncertainties. Increasing forest vulnerability to changing fire activity and climate compels shifts in management approaches, and we propose key themes for applied research coproduced by scientists and managers to support decision-making in an era when the prefire forest may not return.
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Affiliation(s)
- Jonathan D Coop
- School of Environment and Sustainability, Western Colorado University, Gunnison
| | - Sean A Parks
- Research ecologist with the Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, US Forest Service, Missoula, Montana
| | | | - Shelley D Crausbay
- Senior scientist with Conservation Science Partners, Fort Collins, Colorado
| | - Philip E Higuera
- Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, Montana
| | | | - Alan Tepley
- Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta, Canada
| | - Ellen Whitman
- Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta, Canada
| | - Timothy Assal
- Department of Geography, Kent State University, Kent, Ohio
| | - Brandon M Collins
- Fire Research and Outreach, University of California, Berkeley, Berkeley, California, and with the Pacific Southwest Research Station, US Forest Service, in Davis, California
| | - Kimberley T Davis
- Department of Ecosystem and Conservation Sciences, University of Montana, Missoula
| | | | - Donald A Falk
- Natural Resources and the Environment, University of Arizona, Tucson
| | - Paula J Fornwalt
- Rocky Mountain Research Station, US Forest Service, Fort Collins, Colorado
| | - Peter Z Fulé
- School of Forestry, Northern Arizona University, Flagstaff
| | - Brian J Harvey
- School of Environmental and Forest Sciences, University of Washington, Seattle
| | - Van R Kane
- School of Environmental and Forest Sciences, University of Washington, Seattle
| | - Caitlin E Littlefield
- Caitlin Littlefield is a postdoctoral research associate, Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington
| | - Ellis Q Margolis
- US Geological Survey, New Mexico Landscapes Field Station, Santa Fe
| | - Malcolm North
- US Forest Service, Pacific Southwest Research Station, Mammoth Lakes, California
| | - Marc-André Parisien
- Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta, Canada
| | - Susan Prichard
- School of Environmental and Forest Sciences, University of Washington, Seattle
| | - Kyle C Rodman
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison
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22
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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: 17] [Impact Index Per Article: 3.4] [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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23
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Rodman KC, Veblen TT, Chapman TB, Rother MT, Wion AP, Redmond MD. Limitations to recovery following wildfire in dry forests of southern Colorado and northern New Mexico, USA. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02001. [PMID: 31518473 DOI: 10.1002/eap.2001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 06/26/2019] [Accepted: 08/07/2019] [Indexed: 06/10/2023]
Abstract
Climate warming is contributing to increases in wildfire activity throughout the western United States, leading to potentially long-lasting shifts in vegetation. The response of forest ecosystems to wildfire is thus a crucial indicator of future vegetation trajectories, and these responses are contingent upon factors such as seed availability, interannual climate variability, average climate, and other components of the physical environment. To better understand variation in resilience to wildfire across vulnerable dry forests, we surveyed conifer seedling densities in 15 recent (1988-2010) wildfires and characterized temporal variation in seed cone production and seedling establishment. We then predicted postfire seedling densities at a 30-m resolution within each fire perimeter using downscaled climate data, monthly water balance models, and maps of surviving forest cover. Widespread ponderosa pine (Pinus ponderosa) seed cone production occurred at least twice following each fire surveyed, and pulses of conifer seedling establishment coincided with years of above-average moisture availability. Ponderosa pine and Douglas-fir (Pseudotsuga menziesii) seedling densities were higher on more mesic sites and adjacent to surviving trees, though there were also important interspecific differences, likely attributable to drought and shade tolerance. We estimated that postfire seedling densities in 42% (for ponderosa pine) and 69% (for Douglas-fir) of the total burned area were below the lowest reported historical tree densities in these forests. Spatial models demonstrated that an absence of mature conifers (particularly in the interior of large, high-severity patches) limited seedling densities in many areas, but 30-yr average actual evapotranspiration and climatic water deficit limited densities on marginal sites. A better understanding of the limitations to postfire forest recovery will refine models of vegetation dynamics and will help to improve strategies of adaptation to a warming climate and shifting fire activity.
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Affiliation(s)
- Kyle C Rodman
- Department of Geography, University of Colorado, Boulder, Colorado, 80309, USA
| | - Thomas T Veblen
- Department of Geography, University of Colorado, Boulder, Colorado, 80309, USA
| | - Teresa B Chapman
- Department of Geography, University of Colorado, Boulder, Colorado, 80309, USA
- The Nature Conservancy, Boulder, Colorado, 80302, USA
| | - Monica T Rother
- Department of Environmental Studies, University of North Carolina, Wilmington, North Carolina, 28403, USA
| | - Andreas P Wion
- Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado, 80524, USA
| | - Miranda D Redmond
- Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado, 80524, USA
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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: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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25
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Holsinger L, Parks SA, Parisien M, Miller C, Batllori E, Moritz MA. Climate change likely to reshape vegetation in North America's largest protected areas. CONSERVATION SCIENCE AND PRACTICE 2019. [DOI: 10.1111/csp2.50] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Lisa Holsinger
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research StationUSDA Forest Service Missoula Montana
| | - Sean A. Parks
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research StationUSDA Forest Service Missoula Montana
| | - Marc‐André Parisien
- Northern Forestry Centre, Canadian Forest ServiceNatural Resources Canada Edmonton Alberta Canada
| | - Carol Miller
- Aldo Leopold Wilderness Research Institute, Rocky Mountain Research StationUSDA Forest Service Missoula Montana
| | | | - Max A. Moritz
- University of California Cooperative Extension and Bren School of Environmental Science and ManagementUniversity of California at Santa Barbara Santa Barbara California
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