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Hopkins AJM, Brace AJ, Bruce JL, Hyde J, Fontaine JB, Walden L, Veber W, Ruthrof KX. Drought legacy interacts with wildfire to alter soil microbial communities in a Mediterranean climate-type forest. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 915:170111. [PMID: 38232837 DOI: 10.1016/j.scitotenv.2024.170111] [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: 06/22/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/19/2024]
Abstract
Mediterranean forest ecosystems will be increasingly affected by hotter drought and more frequent and severe wildfire events in the future. However, little is known about the longer-term responses of these forests to multiple disturbances and the forests' capacity to maintain ecosystem function. This is particularly so for below-ground organisms, which have received less attention than those above-ground, despite their essential contributions to forest function. We investigated rhizosphere microbial communities in a resprouting Eucalyptus marginata forest, southwestern Australia, that had experienced a severe wildfire four years previously, and a hotter drought eight years previously. Our aim was to understand how microbial communities are affected over longer-term trajectories by hotter drought and wildfire, singularly, and in combination. Fungal and bacterial DNA was extracted from soil samples, amplified, and subjected to high throughput sequencing. Richness, diversity, composition, and putative functional groups were then examined. We found a monotonic decrease in fungal, but not bacterial, richness and diversity with increasing disturbance with the greatest changes resulting from the combination of drought and wildfire. Overall fungal and bacterial community composition reflected a stronger effect of fire than drought, but the combination of both produced the greatest number of indicator taxa for fungi, and a significant negative effect on the abundance of several fungal functional groups. Key mycorrhizal fungi, fungal saprotrophs and fungal pathogens were found at lower proportions in sites affected by drought plus wildfire. Wildfire had a positive effect on bacterial hydrogen and bacterial nitrogen recyclers. Fungal community composition was positively correlated with live tree height. These results suggest that microbial communities, in particular key fungal functional groups, are highly responsive to wildfire following drought. Thus, a legacy of past climate conditions such as hotter drought can be important for mediating the responses of soil microbial communities to subsequent disturbance like wildfire.
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Affiliation(s)
- A J M Hopkins
- Molecular Ecology and Evolution Group, School of Science, Edith Cowan University, Joondalup, WA 6027, Australia.
| | - A J Brace
- Molecular Ecology and Evolution Group, School of Science, Edith Cowan University, Joondalup, WA 6027, Australia
| | - J L Bruce
- Molecular Ecology and Evolution Group, School of Science, Edith Cowan University, Joondalup, WA 6027, Australia
| | - J Hyde
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, WA 6151, Australia
| | - J B Fontaine
- School of Environmental and Conservation Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - L Walden
- Soil and Landscape Science, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - W Veber
- School of Environmental and Conservation Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - K X Ruthrof
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, WA 6151, Australia; School of Environmental and Conservation Sciences, Murdoch University, Murdoch, WA 6150, Australia
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Walden L, Fontaine JB, Ruthrof KX, Matusick G, Harper RJ. Drought then wildfire reveals a compound disturbance in a resprouting forest. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2775. [PMID: 36344448 DOI: 10.1002/eap.2775] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 08/18/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
The frequency and intensity of forest disturbances, such as drought and fire, are increasing globally, with an increased likelihood of multiple disturbance events occurring in short succession. Disturbances layered over one another may influence the likelihood or intensity of subsequent events (a linked disturbance) or impact response and recovery trajectories (a compound disturbance), with substantial implications for ecological spatiotemporal vulnerability. This study evaluates evidence for disturbance interactions of drought followed by wildfire in a resprouting eucalypt-dominated forest (the Northern Jarrah Forest) in southwestern Australia. Sites were stratified by drought (high, low), from previous modeling and ground validation, and fire severity (high, moderate, unburnt), via remote sensing using the relative difference normalized burn ratio (RdNBR). Evidence of a linked disturbance was assessed via fine fuel consumption and fire severity. Compound disturbance effects were quantified at stand scale (canopy height, quadratic mean diameter, stem density) and stem scale (mortality). There was no evidence of prior drought influencing fine fuel consumption or fire severity and, hence, no evidence of a linked disturbance. However, compound disturbance effects were evident; stands previously affected by drought experienced smaller shifts in canopy height, quadratic mean diameter, and stem density than stands without prior drought impact. At the stem scale, size and fire severity were the strongest determinants of stem survival. Proportional resprouting height was greater in high drought sites than in low drought sites (p < 0.01), meaning, structurally, the low drought stands decreased in height more than the high drought stands. Thus, a legacy of the drought was evident after the wildfire. Although these resprouting eucalypt forests have been regarded as particularly resilient, this study illustrates how multiple disturbances can overwhelm the larger tree component and promote an abundance of smaller stems. We suggest that this is early evidence of a structural destabilization of these forests under a more fire-prone, hotter, and drier future climate.
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Affiliation(s)
- Lewis Walden
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
- Soil and Landscape Science, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Joseph B Fontaine
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Katinka X Ruthrof
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, Western Australia, Australia
| | - George Matusick
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Richard J Harper
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
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Hartmann H, Bastos A, Das AJ, Esquivel-Muelbert A, Hammond WM, Martínez-Vilalta J, McDowell NG, Powers JS, Pugh TAM, Ruthrof KX, Allen CD. Climate Change Risks to Global Forest Health: Emergence of Unexpected Events of Elevated Tree Mortality Worldwide. ANNUAL REVIEW OF PLANT BIOLOGY 2022; 73:673-702. [PMID: 35231182 DOI: 10.1146/annurev-arplant-102820-012804] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about climate change risks to global forest health. We currently lack both sufficient data and understanding to identify whether these observations represent a global trend toward increasing tree mortality. Here, we document events of sudden and unexpected elevated tree mortality following heat and drought events in ecosystems that previously were considered tolerant or not at risk of exposure. These events underscore the fact that climate change may affect forests with unexpected force in the future. We use the events as examples to highlight current difficulties and challenges for realistically predicting such tree mortality events and the uncertainties about future forest condition. Advances in remote sensing technology and greater availably of high-resolution data, from both field assessments and satellites, are needed to improve both understanding and prediction of forest responses to future climate change.
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Affiliation(s)
- Henrik Hartmann
- Max Planck Institute for Biogeochemistry, Department of Biogeochemical Processes, Jena, Germany;
| | - Ana Bastos
- Max Planck Institute for Biogeochemistry, Department of Biogeochemical Integration, Jena, Germany
| | - Adrian J Das
- US Geological Survey, Western Ecological Research Center, Three Rivers, Sequoia and Kings Canyon Field Station, California, USA
| | - Adriane Esquivel-Muelbert
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- Birmingham Institute of Forest Research, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - William M Hammond
- Agronomy Department, University of Florida, Gainesville, Florida, USA
| | - Jordi Martínez-Vilalta
- CREAF, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, Richland, Washington, USA
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Jennifer S Powers
- Departments of Ecology, Evolution and Behavior and Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Thomas A M Pugh
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- Birmingham Institute of Forest Research, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
| | - Katinka X Ruthrof
- Department of Biodiversity, Conservation and Attractions, Kensington, Western Australia, Australia
- Murdoch University, Murdoch, Western Australia, Australia
| | - Craig D Allen
- Department of Geography and Environmental Studies, University of New Mexico, Albuquerque, New Mexico, USA
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Muir A, Heyes S, Morgan J, Hoebee S, Enright N, Whelan R, Geschke A, Bennett A, Walsh S, Weatherly W, Milne R. Conservation challenges for Victorian Banksias: Workshop May 2020. ECOLOGICAL MANAGEMENT & RESTORATION 2022. [DOI: 10.1111/emr.12448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dundas SJ, Ruthrof KX, Hardy GES, Fleming PA. Some like it hot: Drought-induced forest die-off influences reptile assemblages. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2021. [DOI: 10.1016/j.actao.2021.103714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Breshears DD, Fontaine JB, Ruthrof KX, Field JP, Feng X, Burger JR, Law DJ, Kala J, Hardy GESJ. Underappreciated plant vulnerabilities to heat waves. THE NEW PHYTOLOGIST 2021; 231:32-39. [PMID: 33728638 DOI: 10.1111/nph.17348] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
With climate change, heat waves are becoming increasingly frequent, intense and broader in spatial extent. However, while the lethal effects of heat waves on humans are well documented, the impacts on flora are less well understood, perhaps except for crops. We summarize recent findings related to heat wave impacts including: sublethal and lethal effects at leaf and plant scales, secondary ecosystem effects, and more complex impacts such as increased heat wave frequency across all seasons, and interactions with other disturbances. We propose generalizable practical trials to quantify the critical bounding conditions of vulnerability to heat waves. Collectively, plant vulnerabilities to heat waves appear to be underappreciated and understudied, particularly with respect to understanding heat wave driven plant die-off and ecosystem tipping points.
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Affiliation(s)
- David D Breshears
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Joseph B Fontaine
- Environmental and Conservation Sciences, Murdoch University, Murdoch, WA, 6150, Australia
| | - Katinka X Ruthrof
- Environmental and Conservation Sciences, Murdoch University, Murdoch, WA, 6150, Australia
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, WA, 6151, Australia
| | - Jason P Field
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - Xiao Feng
- Department of Geography, Florida State University, Tallahassee, FL, 32306, USA
| | - Joseph R Burger
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Arizona Institutes for Resilience, University of Arizona, Tucson, AZ, 85721, USA
| | - Darin J Law
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - Jatin Kala
- Environmental and Conservation Sciences, Murdoch University, Murdoch, WA, 6150, Australia
- Centre for Climate-Impacted Terrestrial Ecosystems, Harry Butler Institute, Murdoch University, Murdoch, WA, Australia
| | - Giles E St J Hardy
- Environmental and Conservation Sciences, Murdoch University, Murdoch, WA, 6150, Australia
- Centre for Climate-Impacted Terrestrial Ecosystems, Harry Butler Institute, Murdoch University, Murdoch, WA, Australia
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Hoffmann AA, Miller AD, Weeks AR. Genetic mixing for population management: From genetic rescue to provenancing. Evol Appl 2021; 14:634-652. [PMID: 33767740 PMCID: PMC7980264 DOI: 10.1111/eva.13154] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/10/2020] [Accepted: 10/14/2020] [Indexed: 12/21/2022] Open
Abstract
Animal and plant species around the world are being challenged by the deleterious effects of inbreeding, loss of genetic diversity, and maladaptation due to widespread habitat destruction and rapid climate change. In many cases, interventions will likely be needed to safeguard populations and species and to maintain functioning ecosystems. Strategies aimed at initiating, reinstating, or enhancing patterns of gene flow via the deliberate movement of genotypes around the environment are generating growing interest with broad applications in conservation and environmental management. These diverse strategies go by various names ranging from genetic or evolutionary rescue to provenancing and genetic resurrection. Our aim here is to provide some clarification around terminology and to how these strategies are connected and linked to underlying genetic processes. We draw on case studies from the literature and outline mechanisms that underlie how the various strategies aim to increase species fitness and impact the wider community. We argue that understanding mechanisms leading to species decline and community impact is a key to successful implementation of these strategies. We emphasize the need to consider the nature of source and recipient populations, as well as associated risks and trade-offs for the various strategies. This overview highlights where strategies are likely to have potential at population, species, and ecosystem scales, but also where they should probably not be attempted depending on the overall aims of the intervention. We advocate an approach where short- and long-term strategies are integrated into a decision framework that also considers nongenetic aspects of management.
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Affiliation(s)
- Ary A. Hoffmann
- School of BioSciencesBio21 InstituteThe University of MelbourneParkvilleVic.Australia
| | - Adam D. Miller
- School of Life and Environmental SciencesCentre for Integrative EcologyDeakin UniversityWarrnamboolVic.Australia
- Deakin Genomics CentreDeakin UniversityGeelongVic.Australia
| | - Andrew R. Weeks
- School of BioSciencesBio21 InstituteThe University of MelbourneParkvilleVic.Australia
- cesar Pty LtdParkvilleVic.Australia
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Miller AD, Nitschke C, Weeks AR, Weatherly WL, Heyes SD, Sinclair SJ, Holland OJ, Stevenson A, Broadhurst L, Hoebee SE, Sherman CDH, Morgan JW. Genetic data and climate niche suitability models highlight the vulnerability of a functionally important plant species from south-eastern Australia. Evol Appl 2020; 13:2014-2029. [PMID: 32908601 PMCID: PMC7463319 DOI: 10.1111/eva.12958] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/23/2020] [Accepted: 03/02/2020] [Indexed: 11/28/2022] Open
Abstract
Habitat fragmentation imperils the persistence of many functionally important species, with climate change a new threat to local persistence due to climate niche mismatching. Predicting the evolutionary trajectory of species essential to ecosystem function under future climates is challenging but necessary for prioritizing conservation investments. We use a combination of population genetics and niche suitability models to assess the trajectory of a functionally important, but highly fragmented, plant species from south-eastern Australia (Banksia marginata, Proteaceae). We demonstrate significant genetic structuring among, and high level of relatedness within, fragmented remnant populations, highlighting imminent risks of inbreeding. Population simulations, controlling for effective population size (N e), suggest that many remnant populations will suffer rapid declines in genetic diversity due to drift in the absence of intervention. Simulations were used to demonstrate how inbreeding and drift processes might be suppressed by assisted migration and population mixing approaches that enhance the size and connectivity of remnant populations. These analyses were complemented by niche suitability models that predicted substantial reductions of suitable habitat by 2080; ~30% of the current distribution of the species climate niche overlaps with the projected distribution of the species climate niche in the geographic region by the 2080s. Our study highlights the importance of conserving remnant populations and establishing new populations in areas likely to support B. marginata in the future, and adopting seed sourcing strategies that can help populations overcome the risks of inbreeding and maladaptation. We also argue that ecological replacement of B. marginata using climatically suited plant species might be needed in the future to maintain ecosystem processes where B. marginata cannot persist. We recommend the need for progressive revegetation policies and practices to prevent further deterioration of species such as B. marginata and the ecosystems they support.
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Affiliation(s)
- Adam D. Miller
- Centre for Integrative EcologySchool of Life and Environmental SciencesDeakin UniversityGeelongVicAustralia
- Deakin Genomics CentreDeakin UniversityGeelongVicAustralia
| | - Craig Nitschke
- School of Ecosystem and Forest SciencesThe University of MelbourneRichmondVicAustralia
| | - Andrew R. Weeks
- School of BioSciencesThe University of MelbourneParkvilleVicAustralia
| | | | - Simon D. Heyes
- Department of Ecology, Environment and EvolutionLa Trobe UniversityBundooraVicAustralia
| | - Steve J. Sinclair
- Department of Environment, Land, Water and PlanningArthur Rylah InstituteHeidelbergVicAustralia
| | - Owen J. Holland
- Centre for Integrative EcologySchool of Life and Environmental SciencesDeakin UniversityGeelongVicAustralia
- Deakin Genomics CentreDeakin UniversityGeelongVicAustralia
| | - Aggie Stevenson
- Glenelg Hopkins Catchment Management AuthorityHamiltonVicAustralia
| | - Linda Broadhurst
- Centre for Australian National Biodiversity ResearchCSIRO National Research CollectionsCanberraACTAustralia
| | - Susan E. Hoebee
- Department of Ecology, Environment and EvolutionLa Trobe UniversityBundooraVicAustralia
| | - Craig D. H. Sherman
- Centre for Integrative EcologySchool of Life and Environmental SciencesDeakin UniversityGeelongVicAustralia
- Deakin Genomics CentreDeakin UniversityGeelongVicAustralia
| | - John W. Morgan
- Department of Ecology, Environment and EvolutionLa Trobe UniversityBundooraVicAustralia
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