1
|
Li F, Zhu Q, Yuan K, Huang H, Radeloff VC, Chen M. Exacerbating risk in human-ignited large fires over western United States due to lower flammability thresholds and greenhouse gas emissions. PNAS NEXUS 2025; 4:pgaf012. [PMID: 39935590 PMCID: PMC11812050 DOI: 10.1093/pnasnexus/pgaf012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 12/30/2024] [Indexed: 02/13/2025]
Abstract
Large fires in the western United States become highly probable when dry conditions surpass critical thresholds of vapor pressure deficit (VPDt). VPDt likely differs between human- and lightning-ignited fires, potentially leading to ignition-type varied responses of fire weather risk to natural variability and various anthropogenic forcings, yet a comprehensive quantification remains lacking. Here, through fire observations with ignition types and a machine learning method, we found that human-ignited large fires had consistently lower thresholds (VPDt) across western US ecoregions. Consequently, the annual number of flammable days (when VPD > VPDt) for human-caused large fires was 93% higher on average and increased 21% more rapidly than those caused by lightning during 1979-2020. Through robust statistical detection and attribution of Earth System Models, we found that the anthropogenic greenhouse gas (GHG) emissions predominantly (81%) controlled the human-related flammable day increases, which was 18% greater than the effect of GHGs on the increases in lightning-related flammable days. Such ignition-type varied fire weather risk indicates more large fire-prone conditions for human-regulated fire regimes when GHG emissions are enhancing and ignitions are not limited by fuels.
Collapse
Affiliation(s)
- Fa Li
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Qing Zhu
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Kunxiaojia Yuan
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Huanping Huang
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Geography and Anthropology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Volker C Radeloff
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Min Chen
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| |
Collapse
|
2
|
Clark CM, Coughlin JG, Phelan J, Martin G, Austin K, Salem M, Sabo R, Horn K, Thomas RQ, Dalton R. Winners and Losers From Climate Change: An Analysis of Climate Thresholds for Tree Growth and Survival for Roughly 150 Species Across the Contiguous United States. GLOBAL CHANGE BIOLOGY 2024; 30:e17597. [PMID: 39697146 PMCID: PMC11929975 DOI: 10.1111/gcb.17597] [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: 07/14/2024] [Revised: 09/03/2024] [Accepted: 10/01/2024] [Indexed: 12/20/2024]
Abstract
Changes in temperature and precipitation are already influencing US forests and that will continue in the future even as we mitigate climate change. Using spatiotemporally matched data for mean annual temperature (MAT) and mean annual precipitation (MAP), we used simulated annealing to estimate critical thresholds for changes in the growth and survival of roughly 150 tree species (153 spp. for growth, 159 spp. for survival) across the conterminous United States (CONUS). We found that growth of nearly one-third of tree species assessed (44 spp.) decreased with any increase in MAT (42-49 species), whereas fewer responded negatively to projected regional trends in MAP (< 20 species each in the east and west). Hypothetical increases in temperature (+1°C, +2°C) increased average annual growth in the Central East and Pacific Northwest and decreased growth over large areas of the Rockies and Southeast, while decadal survival generally decreased with temperature. Average annual growth and decadal survival had unfavorable associations with projected precipitation, generally decreasing with wetter conditions (+25%) in the east and decreasing with drier conditions (-25%) in the west. Beyond these averages, there were species that positively and negatively responded nearly everywhere across the CONUS, suggesting changes in forest composition are underway. We identified only eight species out of ~150 assessed that were tolerant to increases in temperature, and 24 species in the east and seven in the west were tolerant to regionally specific trends in precipitation (increases in the east and decreases in the west). We assessed confidence on a 5-point scale (1-5) for five aspects of uncertainty. Average confidence scores were generally high, though some species and metrics had low confidence scores especially for survival. These findings have significant implications for the future national forest carbon sink and for conservation efforts in the face of climate change.
Collapse
Affiliation(s)
- Christopher M. Clark
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC
| | | | | | | | | | | | - Robert Sabo
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC
| | - Kevin Horn
- Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg VA
| | - R. Quinn Thomas
- Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg VA
| | - Rebecca Dalton
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Durham, NC
| |
Collapse
|
3
|
Dye AW, Houtman RM, Gao P, Anderegg WRL, Fettig CJ, Hicke JA, Kim JB, Still CJ, Young K, Riley KL. Carbon, climate, and natural disturbance: a review of mechanisms, challenges, and tools for understanding forest carbon stability in an uncertain future. CARBON BALANCE AND MANAGEMENT 2024; 19:35. [PMID: 39388012 PMCID: PMC11468384 DOI: 10.1186/s13021-024-00282-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 10/01/2024] [Indexed: 10/15/2024]
Abstract
In this review, we discuss current research on forest carbon risk from natural disturbance under climate change for the United States, with emphasis on advancements in analytical mapping and modeling tools that have potential to drive research for managing future long-term stability of forest carbon. As a natural mechanism for carbon storage, forests are a critical component of meeting climate mitigation strategies designed to combat anthropogenic emissions. Forests consist of long-lived organisms (trees) that can store carbon for centuries or more. However, trees have finite lifespans, and disturbances such as wildfire, insect and disease outbreaks, and drought can hasten tree mortality or reduce tree growth, thereby slowing carbon sequestration, driving carbon emissions, and reducing forest carbon storage in stable pools, particularly the live and standing dead portions that are counted in many carbon offset programs. Many forests have natural disturbance regimes, but climate change and human activities disrupt the frequency and severity of disturbances in ways that are likely to have consequences for the long-term stability of forest carbon. To minimize negative effects and maximize resilience of forest carbon, disturbance risks must be accounted for in carbon offset protocols, carbon management practices, and carbon mapping and modeling techniques. This requires detailed mapping and modeling of the quantities and distribution of forest carbon across the United States and hopefully one day globally; the frequency, severity, and timing of disturbances; the mechanisms by which disturbances affect carbon storage; and how climate change may alter each of these elements. Several tools (e.g. fire spread models, imputed forest inventory models, and forest growth simulators) exist to address one or more of the aforementioned items and can help inform management strategies that reduce forest carbon risk, maintain long-term stability of forest carbon, and further explore challenges, uncertainties, and opportunities for evaluating the continued potential of, and threats to, forests as viable mechanisms for forest carbon storage, including carbon offsets. A growing collective body of research and technological improvements have advanced the science, but we highlight and discuss key limitations, uncertainties, and gaps that remain.
Collapse
Affiliation(s)
- Alex W Dye
- Department of Forest Ecosystems & Society, Oregon State University, Corvallis, OR, USA.
| | - Rachel M Houtman
- USDA Forest Service Rocky Mountain Research Station, Missoula Fire Sciences Lab, Missoula, MT, USA
| | - Peng Gao
- Department of Earth & Ocean Sciences, University of North Carolina at Wilmington, Wilmington, NC, USA
| | - William R L Anderegg
- Wilkes Center for Climate Science and Policy, University of Utah, Salt Lake City, UT, USA
| | | | - Jeffrey A Hicke
- Department of Earth & Spatial Sciences, University of Idaho, Moscow, ID, USA
| | - John B Kim
- USDA Forest Service Western Wildland Environmental Threat Assessment Center, Corvallis, OR, USA
| | - Christopher J Still
- Department of Forest Ecosystems & Society, Oregon State University, Corvallis, OR, USA
| | - Kevin Young
- University of North Carolina at Wilmington, Wilmington, NC, USA
| | - Karin L Riley
- USDA Forest Service Rocky Mountain Research Station, Missoula Fire Sciences Lab, Missoula, MT, USA
| |
Collapse
|
4
|
Reese A, Clark CM, Phelan J, Buckley J, Cajka J, Sabo RD, Van Houtven G. Geographic variation in projected US forest aboveground carbon responses to climate change and atmospheric deposition. ENVIRONMENTAL RESEARCH LETTERS : ERL [WEB SITE] 2024; 19:1-12. [PMID: 38752201 PMCID: PMC11091792 DOI: 10.1088/1748-9326/ad2739] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Forest composition and ecosystem services are sensitive to anthropogenic pressures like climate change and atmospheric deposition of nitrogen (N) and sulfur (S). Here we extend recent forest projections for the current cohort of trees in the contiguous US, characterizing potential changes in aboveground tree carbon at the county level in response to varying mean annual temperature, precipitation, and N and S deposition. We found that relative to a scenario with N and S deposition reduction and no climate change, greater climate change led generally to decreasing aboveground carbon (mean -7.5% under RCP4.5, -16% under RCP8.5). Keeping climate constant, reduced N deposition tended to lessen aboveground carbon (mean -7%), whereas reduced S deposition tended to increase aboveground carbon (+3%) by 2100. Through mid-century (2050), deposition was more important for predicting carbon responses except under the extreme climate scenarios (RCP8.5); but, by 2100, climate drivers generally outweighed deposition. While more than 70% of counties showed reductions in aboveground carbon relative to the reference scenario, these were not evenly distributed across the US. Counties in the Northwest and Northern Great Plains, and the northern parts of New England and the Midwest, primarily showed positive responses, while counties in the Southeast showed negative responses. Counties with greater initial biomass showed less negative responses to climate change while those which exhibited the greatest change in composition (>15%) had a 95% chance of losing carbon relative to a no-climate change scenario. This analysis highlights that declines in forest growth and survival due to increases in mean temperature and reductions in atmospheric N deposition are likely to outweigh positive impacts of reduced S deposition and potential increases in precipitation. These effects vary at the regional and county level, however, so forest managers must consider local rather than national dynamics to maximize forest carbon sinks in the future.
Collapse
Affiliation(s)
- Aspen Reese
- American Association for the Advancement of Science (AAAS) Science and Technology Policy Fellow, at the US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC, United States of America
| | - Christopher M Clark
- US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC, United States of America
| | - Jennifer Phelan
- RTI International, Research Triangle Park, NC, United States of America
| | - John Buckley
- RTI International, Research Triangle Park, NC, United States of America
| | - James Cajka
- RTI International, Research Triangle Park, NC, United States of America
| | - Robert D Sabo
- US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC, United States of America
| | | |
Collapse
|
5
|
Boonman CCF, Serra-Diaz JM, Hoeks S, Guo WY, Enquist BJ, Maitner B, Malhi Y, Merow C, Buitenwerf R, Svenning JC. More than 17,000 tree species are at risk from rapid global change. Nat Commun 2024; 15:166. [PMID: 38167693 PMCID: PMC10761716 DOI: 10.1038/s41467-023-44321-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Trees are pivotal to global biodiversity and nature's contributions to people, yet accelerating global changes threaten global tree diversity, making accurate species extinction risk assessments necessary. To identify species that require expert-based re-evaluation, we assess exposure to change in six anthropogenic threats over the last two decades for 32,090 tree species. We estimated that over half (54.2%) of the assessed species have been exposed to increasing threats. Only 8.7% of these species are considered threatened by the IUCN Red List, whereas they include more than half of the Data Deficient species (57.8%). These findings suggest a substantial underestimation of threats and associated extinction risk for tree species in current assessments. We also map hotspots of tree species exposed to rapidly changing threats around the world. Our data-driven approach can strengthen the efforts going into expert-based IUCN Red List assessments by facilitating prioritization among species for re-evaluation, allowing for more efficient conservation efforts.
Collapse
Affiliation(s)
- Coline C F Boonman
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus, Denmark.
| | - Josep M Serra-Diaz
- Department of Ecology and Evolution and Eversource Energy Center, University of Connecticut, Storrs, CT, USA
- Université de Lorraine, AgroParisTech, INRAE, Silva, Nancy, France
| | - Selwyn Hoeks
- Department of Environmental Science, Radboud Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, The Netherlands
| | - Wen-Yong Guo
- Research Center for Global Change and Complex Ecosystems, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, People's Republic of China
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, People's Republic of China
| | - Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Brian Maitner
- Department of Geography, University at Buffalo, Buffalo, NY, USA
| | - Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, South Parks Road, Oxford, OX1 3QY, England, UK
- Leverhulme Centre for Nature Recovery, University of Oxford, Oxford, UK
| | - Cory Merow
- Department of Ecology and Evolution and Eversource Energy Center, University of Connecticut, Storrs, CT, USA
| | - Robert Buitenwerf
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus, Denmark
| | - Jens-Christian Svenning
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus, Denmark
| |
Collapse
|
6
|
Kovalenko V, Doser JW, Bate LJ, Six DL. Paired acoustic recordings and point count surveys reveal Clark's nutcracker and whitebark pine associations across Glacier National Park. Ecol Evol 2024; 14:e10867. [PMID: 38274862 PMCID: PMC10808773 DOI: 10.1002/ece3.10867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 12/28/2023] [Accepted: 01/05/2024] [Indexed: 01/27/2024] Open
Abstract
Global declines in tree populations have led to dramatic shifts in forest ecosystem composition, biodiversity, and functioning. These changes have consequences for both forest plant and wildlife communities, particularly when declining species are involved in coevolved mutualisms. Whitebark pine (Pinus albicaulis) is a declining keystone species in western North American high-elevation ecosystems and an obligate mutualist of Clark's nutcracker (Nucifraga columbiana), an avian seed predator and disperser. By leveraging traditional point count surveys and passive acoustic monitoring, we investigated how stand characteristics of whitebark pine in a protected area (Glacier National Park, Montana, USA) influenced occupancy and vocal activity patterns in Clark's nutcracker. Using Bayesian spatial occupancy models and generalized linear mixed models, we found that habitat use of Clark's nutcracker was primarily supported by greater cone density and increasing diameter of live whitebark pine. Additionally, we demonstrated the value of performing parallel analyses with traditional point count surveys and passive acoustic monitoring to provide multiple lines of evidence for relationships between Clark's nutcracker and whitebark pine forest characteristics. Our findings allow managers to gauge the whitebark pine conditions important for retaining high nutcracker visitation and prioritize management efforts in whitebark pine ecosystems with low nutcracker visitation.
Collapse
Affiliation(s)
- Vladimir Kovalenko
- Department of Ecosystem and Conservation SciencesUniversity of MontanaMissoulaMontanaUSA
- Science CenterGlacier National ParkWest GlacierMontanaUSA
| | - Jeffrey W. Doser
- Department of Integrative Biology, Ecology, Evolution and Behavior ProgramMichigan State UniversityEast LansingMichiganUSA
| | - Lisa J. Bate
- Science CenterGlacier National ParkWest GlacierMontanaUSA
| | - Diana L. Six
- Department of Ecosystem and Conservation SciencesUniversity of MontanaMissoulaMontanaUSA
| |
Collapse
|
7
|
Harris GM, Sesnie SE, Stewart DR. Climate change and ecosystem shifts in the southwestern United States. Sci Rep 2023; 13:19964. [PMID: 37968297 PMCID: PMC10651835 DOI: 10.1038/s41598-023-46371-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 10/31/2023] [Indexed: 11/17/2023] Open
Abstract
Climate change shifts ecosystems, altering their compositions and instigating transitions, making climate change the predominant driver of ecosystem instability. Land management agencies experience these climatic effects on ecosystems they administer yet lack applied information to inform mitigation. We address this gap, explaining ecosystem shifts by building relationships between the historical locations of 22 ecosystems (c. 2000) and abiotic data (1970-2000; bioclimate, terrain) within the southwestern United States using 'ensemble' machine learning models. These relationships identify the conditions required for establishing and maintaining southwestern ecosystems (i.e., ecosystem suitability). We projected these historical relationships to mid (2041-2060) and end-of-century (2081-2100) periods using CMIP6 generation BCC-CSM2-MR and GFDL-ESM4 climate models with SSP3-7.0 and SSP5-8.5 emission scenarios. This procedure reveals how ecosystems shift, as suitability typically increases in area (~ 50% (~ 40% SD)), elevation (12-15%) and northing (4-6%) by mid-century. We illustrate where and when ecosystems shift, by mapping suitability predictions temporally and within 52,565 properties (e.g., Federal, State, Tribal). All properties had ≥ 50% changes in suitability for ≥ 1 ecosystem within them, irrespective of size (≥ 16.7 km2). We integrated 9 climate models to quantify predictive uncertainty and exemplify its relevance. Agencies must manage ecosystem shifts transcending jurisdictions. Effective mitigation requires collective action heretofore rarely instituted. Our procedure supplies the climatic context to inform their decisions.
Collapse
Affiliation(s)
- Grant M Harris
- United States Fish and Wildlife Service, Albuquerque, NM, USA.
| | - Steven E Sesnie
- United States Fish and Wildlife Service, Albuquerque, NM, USA
| | - David R Stewart
- United States Fish and Wildlife Service, Albuquerque, NM, USA
| |
Collapse
|
8
|
Clark CM, Phelan J, Ash J, Buckley J, Cajka J, Horn K, Thomas RQ, Sabo RD. Future climate change effects on US forest composition may offset benefits of reduced atmospheric deposition of N and S. GLOBAL CHANGE BIOLOGY 2023; 29:4793-4810. [PMID: 37417247 PMCID: PMC11166206 DOI: 10.1111/gcb.16817] [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: 12/09/2022] [Accepted: 04/26/2023] [Indexed: 07/08/2023]
Abstract
Climate change and atmospheric deposition of nitrogen (N) and sulfur (S) are important drivers of forest demography. Here we apply previously derived growth and survival responses for 94 tree species, representing >90% of the contiguous US forest basal area, to project how changes in mean annual temperature, precipitation, and N and S deposition from 20 different future scenarios may affect forest composition to 2100. We find that under the low climate change scenario (RCP 4.5), reductions in aboveground tree biomass from higher temperatures are roughly offset by increases in aboveground tree biomass from reductions in N and S deposition. However, under the higher climate change scenario (RCP 8.5) the decreases from climate change overwhelm increases from reductions in N and S deposition. These broad trends underlie wide variation among species. We found averaged across temperature scenarios the relative abundance of 60 species were projected to decrease more than 5% and 20 species were projected to increase more than 5%; and reductions of N and S deposition led to a decrease for 13 species and an increase for 40 species. This suggests large shifts in the composition of US forests in the future. Negative climate effects were mostly from elevated temperature and were not offset by scenarios with wetter conditions. We found that by 2100 an estimated 1 billion trees under the RCP 4.5 scenario and 20 billion trees under the RCP 8.5 scenario may be pushed outside the temperature record upon which these relationships were derived. These results may not fully capture future changes in forest composition as several other factors were not included. Overall efforts to reduce atmospheric deposition of N and S will likely be insufficient to overcome climate change impacts on forest demography across much of the United States unless we adhere to the low climate change scenario.
Collapse
Affiliation(s)
- Christopher M. Clark
- US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington DC
| | | | - Jeremy Ash
- US Department of Agriculture, US Forest Service, Region 8, Ashville, NC
| | | | - James Cajka
- RTI International, Research Triangle Park, NC
| | - Kevin Horn
- Virginia Polytechnical University, Department of Forest Resources and Environmental Conservation, Blacksburg, VA
| | - R. Quinn Thomas
- Virginia Polytechnical University, Department of Forest Resources and Environmental Conservation, Blacksburg, VA
| | - Robert D. Sabo
- US Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Washington DC
| |
Collapse
|
9
|
Zhao ZY, Tong YP, Jiang W, Zang Y, Xiong J, Li J, Hu JF. Structurally Diverse Triterpene-26-oic Acids as Potential Dual ACL and ACC1 Inhibitors from the Vulnerable Conifer Keteleeria fortunei. JOURNAL OF NATURAL PRODUCTS 2023; 86:1487-1499. [PMID: 37291059 DOI: 10.1021/acs.jnatprod.3c00181] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A preliminary phytochemical investigation on the 90% MeOH extract from the twigs and needles of the vulnerable conifer Keteleeria fortunei led to the isolation and characterization of 17 structurally diverse triterpen-26-oic acids, including nine previously undescribed ones (fortunefuroic acids A-I, 1-9) featuring a rare furoic acid moiety in the lateral chain. Among them, 1-5 are uncommon 9βH-lanostane-type triterpenoic acids. Friedo-rearranged triterpenoids 6 and 7 feature a unique 17,14-friedo-lanostane skeleton, whereas 9 possesses a rare 17,13-friedo-cycloartane-type framework. Their structures and absolute configurations were elucidated by extensive spectroscopic (e.g., detailed 2D NMR) and computational (NMR/ECD) calculations and the modified Mosher's method. In addition, the absolute structure of compound 1 was ascertained by single-crystal X-ray diffraction analyses. Fortunefuroic acids B (2), G (7), and I (9), along with isomangiferolic acid (12) and 3α,27-dihydroxycycloart-24E-en-26-oic acid (14), exhibited dual inhibitory effects against the adenosine triphosphate (ATP)-citrate lyase (ACL, IC50s: 5.7-11.4 μM) and acetyl-CoA carboxylase 1 (ACC1, IC50s: 7.5-10.5 μM), both of which are key enzymes for glycolipid metabolism. The interactions of the bioactive triterpenoids with both enzymes were examined by molecular docking studies. The above findings reveal the important role of protecting plant species diversity in support of chemical diversity and potential sources of new therapeutics for ACL-/ACC1-associated diseases.
Collapse
Affiliation(s)
- Ze-Yu Zhao
- Department of Natural Medicine, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
- Institute of Natural Medicine and Health Products, School of Pharmaceutical Sciences, Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000, People's Republic of China
| | - Ying-Peng Tong
- Institute of Natural Medicine and Health Products, School of Pharmaceutical Sciences, Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000, People's Republic of China
| | - Wei Jiang
- Department of Natural Medicine, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
- School of Life Science and Technology, Wuhan Polytechnic University, Hubei 430023, People's Republic of China
| | - Yi Zang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai 201203, People's Republic of China
| | - Juan Xiong
- Department of Natural Medicine, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
| | - Jia Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai 201203, People's Republic of China
| | - Jin-Feng Hu
- Department of Natural Medicine, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China
- Institute of Natural Medicine and Health Products, School of Pharmaceutical Sciences, Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000, People's Republic of China
| |
Collapse
|
10
|
Lindroth RL, Wooley SC, Donaldson JR, Rubert-Nason KF, Morrow CJ, Mock KE. Phenotypic Variation in Phytochemical Defense of Trembling Aspen in Western North America: Genetics, Development, and Geography. J Chem Ecol 2023; 49:235-250. [PMID: 36765024 DOI: 10.1007/s10886-023-01409-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/12/2023]
Abstract
Trembling aspen (Populus tremuloides) is arguably the most important deciduous tree species in the Intermountain West of North America. There, as elsewhere in its range, aspen exhibits remarkable genetic variation in observable traits such as morphology and phenology. In contrast to Great Lakes populations, however, relatively little is known about phytochemical variation in western aspen. This survey of phytochemistry in western aspen was undertaken to assess how chemical expression varies among genotypes, cytotypes (diploid vs. triploid), and populations, and in response to development and mammalian browsing. We measured levels of foliar nitrogen, salicinoid phenolic glycosides (SPGs) and condensed tannins (CTs), as those constituents influence organismal interactions and ecosystem processes. Results revealed striking genotypic variation and considerable population variation, but minimal cytotype variation, in phytochemistry of western aspen. Levels of SPGs and nitrogen declined, whereas levels of CTs increased, with tree age. Browsed ramets had much higher levels of SPGs, and lower levels of CTs, than unbrowsed ramets of the same genotype. We then evaluated how composite chemical profiles of western aspen differ from those of Great Lakes aspen (assessed in earlier research). Interestingly, mature western aspen trees maintain much higher levels of SPGs, and lower levels of CTs, than Great Lakes aspen. Phenotypic variation in chemical composition of aspen - a foundation species - in the Intermountain West likely has important consequences for organismal interactions and forest ecosystem dynamics. Moreover, those consequences likely play out over spatial and temporal scales somewhat differently than have been documented for Great Lakes aspen.
Collapse
Affiliation(s)
- Richard L Lindroth
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Stuart C Wooley
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Biological Sciences, California State University-Stanislaus, Turlock, CA, 95382, USA
| | - Jack R Donaldson
- Department of Zoology, University of Wisconsin-Madison, Madison, WI, 53706, USA
- , Orem, UT, USA
| | - Kennedy F Rubert-Nason
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Division of Natural Sciences, University of Maine at Fort Kent, Fort Kent, ME, 04743, USA
| | - Clay J Morrow
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Karen E Mock
- Department of Wildland Resources and Ecology Center, Utah State University, Logan, UT, 84322, USA
| |
Collapse
|
11
|
Asaro C, Koch FH, Potter KM. Denser forests across the USA experience more damage from insects and pathogens. Sci Rep 2023; 13:3666. [PMID: 36871063 PMCID: PMC9985637 DOI: 10.1038/s41598-023-30675-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Forests across much of the United States are becoming denser. Trees growing in denser stands experience more competition for essential resources, which can make them more vulnerable to disturbances. Forest density can be expressed in terms of basal area, a metric that has been used to assess vulnerability of some forests to damage by certain insects or pathogens. A raster map of total tree basal area (TBA) for the conterminous United States was compared with annual (2000-2019) survey maps of forest damage due to insects and pathogens. Across each of four regions, median TBA was significantly higher within forest areas defoliated or killed by insects or pathogens than in areas without recorded damage. Therefore, TBA may serve as a regional-scale indicator of forest health and a first filter for identifying areas that merit finer-scale analysis of forest conditions.
Collapse
Affiliation(s)
- Christopher Asaro
- USDA Forest Service, State and Private Forestry, Forest Health Protection, Atlanta, GA, 30309, USA
| | - Frank H Koch
- USDA Forest Service, Southern Research Station, Research Triangle Park, NC, 27709, USA.
| | - Kevin M Potter
- Department of Forestry and Environmental Resources, North Carolina State University, Research Triangle Park, NC, 27709, USA.,USDA Forest Service, Southern Research Station, Research Triangle Park, NC, 27709, USA
| |
Collapse
|
12
|
Eisenring M, Lindroth RL, Flansburg A, Giezendanner N, Mock KE, Kruger EL. Genotypic variation rather than ploidy level determines functional trait expression in a foundation tree species in the presence and absence of environmental stress. ANNALS OF BOTANY 2023; 131:229-242. [PMID: 35641114 PMCID: PMC9904343 DOI: 10.1093/aob/mcac071] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/28/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS At the population level, genetic diversity is a key determinant of a tree species' capacity to cope with stress. However, little is known about the relative importance of the different components of genetic diversity for tree stress responses. We compared how two sources of genetic diversity, genotype and cytotype (i.e. differences in ploidy levels), influence growth, phytochemical and physiological traits of Populus tremuloides in the presence and absence of environmental stress. METHODS In a series of field studies, we first assessed variation in traits across diploid and triploid aspen genotypes from Utah and Wisconsin under non-stressed conditions. In two follow-up experiments, we exposed diploid and triploid aspen genotypes from Wisconsin to individual and interactive drought stress and defoliation treatments and quantified trait variations under stress. KEY RESULTS We found that (1) tree growth and associated traits did not differ significantly between ploidy levels under non-stressed conditions. Instead, variation in tree growth and most other traits was driven by genotypic and population differences. (2) Genotypic differences were critical for explaining variation of most functional traits and their responses to stress. (3) Ploidy level played a subtle role in shaping traits and trait stress responses, as its influence was typically obscured by genotypic differences. (4) As an exception to the third conclusion, we showed that triploid trees expressed 17 % higher foliar defence (tremulacin) levels, 11 % higher photosynthesis levels and 23 % higher rubisco activity under well-watered conditions. Moreover, triploid trees displayed greater drought resilience than diploids as they produced 35 % more new tissue than diploids when recovering from drought stress. CONCLUSION Although ploidy level can strongly influence the ecology of tree species, those effects may be relatively small in contrast to the effects of genotypic variation in highly diverse species.
Collapse
Affiliation(s)
| | - Richard L Lindroth
- Department of Entomology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WI, USA
| | - Amy Flansburg
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WIUSA
| | - Noreen Giezendanner
- Department of Entomology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WI, USA
| | - Karen E Mock
- Department of Wildland Resources and Ecology Center, 5230 Old Main Hill, Utah State University, Logan, UT, USA
| | - Eric L Kruger
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WIUSA
| |
Collapse
|
13
|
Williams JN, Safford HD, Enstice N, Steel ZL, Paulson AK. High‐severity burned area and proportion exceed historic conditions in Sierra Nevada, California, and adjacent ranges. Ecosphere 2023. [DOI: 10.1002/ecs2.4397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- J. N. Williams
- Department of Environmental Science and Policy University of California Davis California USA
| | - H. D. Safford
- Department of Environmental Science and Policy University of California Davis California USA
- Vibrant Planet Incline Village Nevada USA
| | - N. Enstice
- California Department of Conservation Sacramento California USA
- California Sierra Nevada Conservancy Auburn California USA
| | - Z. L. Steel
- USDA Forest Service Rocky Mountain Research Station Fort Collins Colorado USA
| | - A. K. Paulson
- USDA Forest Service, Humboldt‐Toiyabe National Forest Sparks Nevada USA
| |
Collapse
|
14
|
Peltier DMP, Anderegg WRL, Guo JS, Ogle K. Contemporary tree growth shows altered climate memory. Ecol Lett 2022; 25:2663-2674. [PMID: 36257775 DOI: 10.1111/ele.14130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 11/25/2022]
Abstract
Trees are long-lived organisms, exhibiting temporally complex growth arising from strong climatic "memory." But conditions are becoming increasingly arid in the western USA. Using a century-long tree-ring network, we find altered climate memory across the entire range of a widespread western US conifer: growth is supported by precipitation falling further into the past (+15 months), while increasingly impacted by more recent temperature conditions (-8 months). Tree-ring datasets can be biased, so we confirm altered climate memory in a second, ecologically-sampled tree-ring network. Predicted drought responses show trees may have also become more sensitive to repeat drought. Finally, plots near sites with relatively longer precipitation memory and shorter temperature memory had significantly lower recent mortality rates (R2 = 0.61). We argue that increased drought frequency has altered climate memory, demonstrate how non-stationarity may arise from failure to account for memory, and suggest memory length may be predictive of future tree mortality.
Collapse
Affiliation(s)
- Drew M P Peltier
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | | | - Jessica S Guo
- Arizona Experiment Station, College of Agriculture and Life Sciences, University of Arizona, Tucson, Arizona, USA
| | - Kiona Ogle
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA.,School of Informatics, Computing, and Cyber-Systems, Northern Arizona University, Flagstaff, Arizona, USA
| |
Collapse
|
15
|
Busby PE, Newcombe G, Neat AS, Averill C. Facilitating Reforestation Through the Plant Microbiome: Perspectives from the Phyllosphere. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:337-356. [PMID: 35584884 DOI: 10.1146/annurev-phyto-021320-010717] [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] [Indexed: 06/15/2023]
Abstract
Tree planting and natural regeneration contribute to the ongoing effort to restore Earth's forests. Our review addresses how the plant microbiome can enhance the survival of planted and naturally regenerating seedlings and serve in long-term forest carbon capture and the conservation of biodiversity. We focus on fungal leaf endophytes, ubiquitous defensive symbionts that protect against pathogens. We first show that fungal and oomycetous pathogen richness varies greatly for tree species native to the United States (n = 0-876 known pathogens per US tree species), with nearly half of tree species either without pathogens in these major groups or with unknown pathogens. Endophytes are insurance against the poorly known and changing threat of tree pathogens. Next, we review studies of plant phyllosphere feedback, but knowledge gaps prevent us from evaluating whether adding conspecific leaf litter to planted seedlings promotes defensive symbiosis, analogous to adding soil to promote positive feedback. Finally, we discuss research priorities for integrating the plant microbiome into efforts to expand Earth's forests.
Collapse
Affiliation(s)
- Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - George Newcombe
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, Idaho, USA
| | - Abigail S Neat
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - Colin Averill
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| |
Collapse
|
16
|
Yang X, Angert AL, Zuidema PA, He F, Huang S, Li S, Li SL, Chardon NI, Zhang J. The role of demographic compensation in stabilising marginal tree populations in North America. Ecol Lett 2022; 25:1676-1689. [PMID: 35598109 DOI: 10.1111/ele.14028] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/22/2022] [Accepted: 04/25/2022] [Indexed: 12/21/2022]
Abstract
Demographic compensation-the opposing responses of vital rates along environmental gradients-potentially delays anticipated species' range contraction under climate change, but no consensus exists on its actual contribution. We calculated population growth rate (λ) and demographic compensation across the distributional ranges of 81 North American tree species and examined their responses to simulated warming and tree competition. We found that 43% of species showed stable population size at both northern and southern edges. Demographic compensation was detected in 25 species, yet 15 of them still showed a potential retraction from southern edges, indicating that compensation alone cannot maintain range stability. Simulated climatic warming caused larger decreases in λ for most species and weakened the effectiveness of demographic compensation in stabilising ranges. These findings suggest that climate stress may surpass the limited capacity of demographic compensation and pose a threat to the viability of North American tree populations.
Collapse
Affiliation(s)
- Xianyu Yang
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Research Center of Global Change and Complex Ecosystems, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, P. R. China.,Shanghai Institute of Pollution Control and Ecological Security, Shanghai, P.R. China.,Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, Canada
| | - Amy L Angert
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, Canada
| | - Pieter A Zuidema
- Forest Ecology and Forest Management Group, Wageningen University, Wageningen, the Netherlands
| | - Fangliang He
- Department of Renewable Resources, University of Alberta, Edmonton, Canada
| | - Shongming Huang
- Government of Alberta, Department of Agriculture, Forestry and Rural Economic Development, Edmonton, Canada
| | - Shouzhong Li
- Key Laboratory for Subtropical Mountain Ecology, Ministry of Science and Technology and Fujian Province Funded, School of Geographical Sciences, Fujian Normal University, Fuzhou, P. R. China
| | - Shou-Li Li
- State Key Laboratory of Grassland Agro-ecosystems, and College of Pastoral, Agriculture Science and Technology, Lanzhou University, Lanzhou, P. R. China
| | - Nathalie I Chardon
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, Canada
| | - Jian Zhang
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Research Center of Global Change and Complex Ecosystems, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, P. R. China.,Shanghai Institute of Pollution Control and Ecological Security, Shanghai, P.R. China
| |
Collapse
|
17
|
Anderegg WRL, Chegwidden OS, Badgley G, Trugman AT, Cullenward D, Abatzoglou JT, Hicke JA, Freeman J, Hamman JJ. Future climate risks from stress, insects and fire across US forests. Ecol Lett 2022; 25:1510-1520. [PMID: 35546256 PMCID: PMC9321543 DOI: 10.1111/ele.14018] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/28/2022] [Accepted: 04/09/2022] [Indexed: 12/04/2022]
Abstract
Forests are currently a substantial carbon sink globally. Many climate change mitigation strategies leverage forest preservation and expansion, but rely on forests storing carbon for decades to centuries. Yet climate‐driven disturbances pose critical risks to the long‐term stability of forest carbon. We quantify the climate drivers that influence wildfire and climate stress‐driven tree mortality, including a separate insect‐driven tree mortality, for the contiguous United States for current (1984–2018) and project these future disturbance risks over the 21st century. We find that current risks are widespread and projected to increase across different emissions scenarios by a factor of >4 for fire and >1.3 for climate‐stress mortality. These forest disturbance risks highlight pervasive climate‐sensitive disturbance impacts on US forests and raise questions about the risk management approach taken by forest carbon offset policies. Our results provide US‐wide risk maps of key climate‐sensitive disturbances for improving carbon cycle modeling, conservation and climate policy.
Collapse
Affiliation(s)
| | | | - Grayson Badgley
- Blackrock Forest, Cornwall, New York, USA.,Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
| | - Anna T Trugman
- Department of Geography, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Danny Cullenward
- CarbonPlan, San Francisco, California, USA.,Institute for Carbon Removal Law and Policy, American University, Washington, DC, USA
| | - John T Abatzoglou
- Management of Complex Systems Department, University of California, Merced, Merced, California, USA
| | - Jeffrey A Hicke
- Department of Geography, University of Idaho, Moscow, Idaho, USA
| | | | - Joseph J Hamman
- CarbonPlan, San Francisco, California, USA.,National Center for Atmospheric Research, Boulder, Colorado, USA
| |
Collapse
|
18
|
Iglesias V, Balch JK, Travis WR. U.S. fires became larger, more frequent, and more widespread in the 2000s. SCIENCE ADVANCES 2022; 8:eabc0020. [PMID: 35294238 PMCID: PMC8926334 DOI: 10.1126/sciadv.abc0020] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Recent fires have fueled concerns that regional and global warming trends are leading to more extreme burning. We found compelling evidence that average fire events in regions of the United States are up to four times the size, triple the frequency, and more widespread in the 2000s than in the previous two decades. Moreover, the most extreme fires are also larger, more common, and more likely to co-occur with other extreme fires. This documented shift in burning patterns across most of the country aligns with the palpable change in fire dynamics noted by the media, public, and fire-fighting officials.
Collapse
Affiliation(s)
- Virginia Iglesias
- Earth Lab, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Boulder, CO 80309, USA
- Corresponding author.
| | - Jennifer K. Balch
- Earth Lab, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Boulder, CO 80309, USA
- Department of Geography, University of Colorado, Boulder, Boulder, CO 80309, USA
| | - William R. Travis
- Earth Lab, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Boulder, CO 80309, USA
- Department of Geography, University of Colorado, Boulder, Boulder, CO 80309, USA
| |
Collapse
|
19
|
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.
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
Relative density of United States forests has shifted to higher levels over last two decades with important implications for future dynamics. Sci Rep 2021; 11:18848. [PMID: 34552151 PMCID: PMC8458300 DOI: 10.1038/s41598-021-98244-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 09/06/2021] [Indexed: 11/08/2022] Open
Abstract
Tree size-density dynamics can inform key trends in forest productivity along with opportunities to increase ecosystem resiliency. Here, we employ a novel approach to estimate the relative density (RD, range 0–1) of any given forest based on its current size-density relationship compared to a hypothetical maximum using the coterminous US national forest inventory between 1999 and 2020. The analysis suggests a static forest land area in the US with less tree abundance but greatly increased timber volume and tree biomass. Coupled with these resource trends, an increase in RD was identified with 90% of US forest land now reaching a biologically-relevant threshold of canopy closure and/or self-thinning induced mortality (RD > 0.3), particularly in areas prone to future drought conditions (e.g., West Coast). Notably, the area of high RD stands (RD > 0.6) has quintupled over the past 20 years while the least stocked stands (RD < 0.3) have decreased 3%. The evidence from the coterminous US forest RD distribution suggest opportunities to increase live tree stocking in understocked stands, while using density management to address tree mortality and resilience to disturbances in increasingly dense forests.
Collapse
|
22
|
Zhirnova DF, Belokopytova LV, Meko DM, Babushkina EA, Vaganov EA. Climate change and tree growth in the Khakass-Minusinsk Depression (South Siberia) impacted by large water reservoirs. Sci Rep 2021; 11:14266. [PMID: 34253791 PMCID: PMC8275609 DOI: 10.1038/s41598-021-93745-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/30/2021] [Indexed: 11/23/2022] Open
Abstract
Regional and local climate change depends on continentality, orography, and human activities. In particular, local climate modification by water reservoirs can reach far from shore and downstream. Among the possible ecological consequences are shifts in plant performance. Tree-ring width of affected trees can potentially be used as proxies for reservoir impact. Correlation analysis and t-tests were applied to climatic data and tree-ring chronologies of Pinus sylvestris L. and Larix sibirica Ledeb. from moisture-deficit habitats in the intermontane Khakass-Minusinsk Depression, to assess modification of climate and tree growth by the Krasnoyarsk and Sayano-Shushenskoe Reservoirs on the Yenisei River. Abrupt significant cooling in May–August and warming in September-March occurred after the launch of the turbines in dams, more pronounced near the Sayano-Shushenskoe dam (up to – 0.5 °C in summer and to + 3.5 °C in winter) than near the Krasnoyarsk Reservoir headwaters (– 0.3 °C and + 1.4 °C). Significant lengthening of the warm season was also found for temperature thresholds 0–8 °C. Shifts of seasonality and intensity occurred in climatic responses of all tree-ring chronologies after development of water reservoirs. Patterns of these shifts, however, depended on species-specific sensitivity to climatic modification, distance from reservoirs, and physiographic regions. Mitigation of climate continentality and extremes by reservoirs appears to have offset possible negative effects of warming on tree growth.
Collapse
Affiliation(s)
- D F Zhirnova
- Khakass Technical Institute, Siberian Federal University, Abakan, Russia
| | - L V Belokopytova
- Khakass Technical Institute, Siberian Federal University, Abakan, Russia.
| | - D M Meko
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, USA
| | - E A Babushkina
- Khakass Technical Institute, Siberian Federal University, Abakan, Russia
| | - E A Vaganov
- Siberian Federal University, Krasnoyarsk, Russia.,Sukachev Institute of Forest SB RAS, Krasnoyarsk, Russia
| |
Collapse
|