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Camarero JJ, Colangelo M, Rodríguez-Gonzalez PM. Historical disconnection from floodplain alters riparian forest composition, tree growth and deadwood amount. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 896:165266. [PMID: 37406690 DOI: 10.1016/j.scitotenv.2023.165266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/30/2023] [Accepted: 06/30/2023] [Indexed: 07/07/2023]
Abstract
Riparian forests are among the most dynamic but threatened terrestrial ecosystems. Their dynamism and conservation depend on historical changes in river geomorphology, which can be evaluated through changes in channel sinuosity. However, we lack long-term assessments on sinuosity and how they impact riparian forest composition, tree growth and deadwood amount. To fill this research gap, we reconstructed river sinuosity in 14 sites across the middle Ebro basin, north-eastern Spain, using historical aerial photographs taken in 1927, 1956, 1998-2003 and 2014-2015. Relationships between sinuosity, stand composition and deadwood amount and decay degree were calculated. We also reconstructed radial growth of the major tree species (Populus alba, Populus nigra, Fraxinus angustifolia, Salix alba and Ulmus minor) in two sites to evaluate how coupled it was with changes in river flow after dam building. From 1927 to 2015, sinuosity decreased passing from 1.39 to 1.20. The river dynamics were altered in the 1950s and 1960s after dam and dyke building. Sites with high sinuosity values in 1956 corresponded to mature stands with large P. nigra individuals. Sinuosity was negatively related to F. angustifolia (rs = -0.83, p < 0.001) and P. alba (rs = -0.64, p = 0.02) abundance, whereas sites dominated by P. alba and U. minor presented abundant decayed deadwood. A loss of sinuosity and a contraction of the riverbank gradient increased disconnection of active channel from floodplain, with a mixing of more (e.g., P. nigra) and less phreatophytic species (e.g., U. minor). River flow diversion reduced growth and increased the tree-to-tree P. alba growth coherence. Hydrological droughts contributed to growth decline and dieback of U. minor, which is sensitive to spring river flow. Conservation and restoration of riparian forests must consider historical changes in river geomorphology related to human activities.
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Affiliation(s)
- J Julio Camarero
- Pyrenean Institute of Ecology (IPE-CSIC), Avda. Montañana 1005, 50192 Zaragoza, Spain.
| | - Michele Colangelo
- Pyrenean Institute of Ecology (IPE-CSIC), Avda. Montañana 1005, 50192 Zaragoza, Spain; School of Agricultural, Forestry, Food and Environmental Sciences, University of Basilicata, Viale dell'Ateneo Lucano 10, 85100 Potenza, Italy.
| | - Patricia M Rodríguez-Gonzalez
- Forest Research Centre and Associate Laboratory TERRA, School of Agriculture, University of Lisbon, Lisbon 1349-017, Portugal.
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Robinson W, Kerhoulas LP, Sherriff RL, Roletti G, van Mantgem PJ. Drought survival strategies differ between coastal and montane conifers in northern California. Ecosphere 2023. [DOI: 10.1002/ecs2.4480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
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Havrdová A, Douda J, Doudová J. Threats, biodiversity drivers and restoration in temperate floodplain forests related to spatial scales. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158743. [PMID: 36108840 DOI: 10.1016/j.scitotenv.2022.158743] [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: 05/04/2022] [Revised: 08/19/2022] [Accepted: 09/09/2022] [Indexed: 06/15/2023]
Abstract
Floodplain forests offer a diversity of habitats and resources for a very wide range of plant and animal species. They also offer many benefits to humankind and are considered essential to the mitigation of the effects of climate change. Nevertheless, throughout the world they are suffering the most intense of anthropogenic pressures so are, of all ecosystems, among the most endangered. Here, we bring together and synthesise existing ecological understanding of the mechanisms underlying the high heterogeneity and diversity of temperate floodplain forests and of the pressures threatening their high biological value due to habitat homogenisation. Floodplain forests depend on the periodic disturbances under which they evolved, including fluvial dynamics, traditional management practices and the activities of herbivores. However, they have been heavily degraded by climate change, invasion of exotic species, river-flow regulation, landscape fragmentation, eutrophication and the cessation of traditional management. We can now observe two general trends in temperate floodplain forests: (1) Due to intensive landscape exploitation, they are now more open and thus prone to the spread of competitive species, including of invasive exotics and (2) Due to the cessation of traditional management, along with modified hydrological conditions, they are composed of species in the later successional stages (i.e., more shade-tolerant and mesic) while light-demanding species are quickly vanishing. Restoration practices have brought about contrasting results when restoration of floodplains to their natural states has been problematic. This is likely because of interplay between various natural and artificial processes not previously taken into proper consideration. We would like to draw attention to the fact that restoration projects or the preservation of existing floodplain forest ecosystems should combine the restoration of watercourses with the mitigation of other important threats acting at different scales of the landscape (spread of invasive species, eutrophication of watersheds and inappropriate forest management).
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Affiliation(s)
- Alena Havrdová
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Praha-Suchdol 165 00, Czech Republic.
| | - Jan Douda
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Praha-Suchdol 165 00, Czech Republic
| | - Jana Doudová
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Praha-Suchdol 165 00, Czech Republic
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Williams J, Stella JC, Voelker SL, Lambert AM, Pelletier LM, Drake JE, Friedman JM, Roberts DA, Singer MB. Local groundwater decline exacerbates response of dryland riparian woodlands to climatic drought. GLOBAL CHANGE BIOLOGY 2022; 28:6771-6788. [PMID: 36045489 PMCID: PMC9804274 DOI: 10.1111/gcb.16376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
Dryland riparian woodlands are considered to be locally buffered from droughts by shallow and stable groundwater levels. However, climate change is causing more frequent and severe drought events, accompanied by warmer temperatures, collectively threatening the persistence of these groundwater dependent ecosystems through a combination of increasing evaporative demand and decreasing groundwater supply. We conducted a dendro-isotopic analysis of radial growth and seasonal (semi-annual) carbon isotope discrimination (Δ13 C) to investigate the response of riparian cottonwood stands to the unprecedented California-wide drought from 2012 to 2019, along the largest remaining free-flowing river in Southern California. Our goals were to identify principal drivers and indicators of drought stress for dryland riparian woodlands, determine their thresholds of tolerance to hydroclimatic stressors, and ultimately assess their vulnerability to climate change. Riparian trees were highly responsive to drought conditions along the river, exhibiting suppressed growth and strong stomatal closure (inferred from reduced Δ13 C) during peak drought years. However, patterns of radial growth and Δ13 C were quite variable among sites that differed in climatic conditions and rate of groundwater decline. We show that the rate of groundwater decline, as opposed to climate factors, was the primary driver of site differences in drought stress, and trees showed greater sensitivity to temperature at sites subjected to faster groundwater decline. Across sites, higher correlation between radial growth and Δ13 C for individual trees, and higher inter-correlation of Δ13 C among trees were indicative of greater drought stress. Trees showed a threshold of tolerance to groundwater decline at 0.5 m year-1 beyond which drought stress became increasingly evident and severe. For sites that exceeded this threshold, peak physiological stress occurred when total groundwater recession exceeded ~3 m. These findings indicate that drought-induced groundwater decline associated with more extreme droughts is a primary threat to dryland riparian woodlands and increases their susceptibility to projected warmer temperatures.
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Affiliation(s)
- Jared Williams
- Graduate Program in Environmental ScienceCollege of Environmental Science and Forestry, State University of New YorkSyracuseNew YorkUSA
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | - John C. Stella
- Graduate Program in Environmental ScienceCollege of Environmental Science and Forestry, State University of New YorkSyracuseNew YorkUSA
- Department of Sustainable Resources ManagementState University of New York College of Environmental Science and ForestrySyracuseNew YorkUSA
| | - Steven L. Voelker
- College of Forest Resources and Environmental ScienceMichigan Technological UniversityHoughtonMichiganUSA
| | - Adam M. Lambert
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- Cheadle Center for Biodiversity and Ecological RestorationUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | - Lissa M. Pelletier
- Graduate Program in Environmental ScienceCollege of Environmental Science and Forestry, State University of New YorkSyracuseNew YorkUSA
| | - John E. Drake
- Department of Sustainable Resources ManagementState University of New York College of Environmental Science and ForestrySyracuseNew YorkUSA
| | | | - Dar A. Roberts
- Department of GeographyUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- Earth Research InstituteUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | - Michael Bliss Singer
- Earth Research InstituteUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- School of Earth and Environmental SciencesCardiff UniversityCardiffUK
- Water Research InstituteCardiff UniversityCardiffUK
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Snyder KA, Robinson SA, Schmidt S, Hultine KR. Stable isotope approaches and opportunities for improving plant conservation. CONSERVATION PHYSIOLOGY 2022; 10:coac056. [PMID: 35966756 PMCID: PMC9367551 DOI: 10.1093/conphys/coac056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 04/15/2021] [Accepted: 08/01/2022] [Indexed: 06/01/2023]
Abstract
Successful conservation of threatened species and ecosystems in a rapidly changing world requires scientifically sound decision-making tools that are readily accessible to conservation practitioners. Physiological applications that examine how plants and animals interact with their environment are now widely used when planning, implementing and monitoring conservation. Among these tools, stable-isotope physiology is a potentially powerful, yet under-utilized cornerstone of current and future conservation efforts of threatened and endangered plants. We review the underlying concepts and theory of stable-isotope physiology and describe how stable-isotope applications can support plant conservation. We focus on stable isotopes of carbon, hydrogen, oxygen and nitrogen to address plant ecophysiological responses to changing environmental conditions across temporal scales from hours to centuries. We review examples from a broad range of plant taxa, life forms and habitats and provide specific examples where stable-isotope analysis can directly improve conservation, in part by helping identify resilient, locally adapted genotypes or populations. Our review aims to provide a guide for practitioners to easily access and evaluate the information that can be derived from stable-isotope signatures, their limitations and how stable isotopes can improve conservation efforts.
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Affiliation(s)
- Keirith A Snyder
- Corresponding author: USDA Agricultural Research Service, Great Basin Rangelands Research Unit, Reno,
920 Valley Road, NV 89512, USA.
| | - Sharon A Robinson
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Securing Antarctica’s Environmental Future, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, Building 62, Brisbane Queensland 4075, Australia
| | - Kevin R Hultine
- Department of Research, Conservation and Collections, Desert Botanical Garden, 1201 Galvin Parkway, Phoenix, AZ 85008, USA
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Keen RM, Voelker SL, Wang SYS, Bentz BJ, Goulden ML, Dangerfield CR, Reed CC, Hood SM, Csank AZ, Dawson TE, Merschel AG, Still CJ. Changes in tree drought sensitivity provided early warning signals to the California drought and forest mortality event. GLOBAL CHANGE BIOLOGY 2022; 28:1119-1132. [PMID: 34735729 DOI: 10.1111/gcb.15973] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
Climate warming in recent decades has negatively impacted forest health in the western United States. Here, we report on potential early warning signals (EWS) for drought-related mortality derived from measurements of tree-ring growth (ring width index; RWI) and carbon isotope discrimination (∆13 C), primarily focused on ponderosa pine (Pinus ponderosa). Sampling was conducted in the southern Sierra Nevada Mountains, near the epicenter of drought severity and mortality associated with the 2012-2015 California drought and concurrent outbreak of western pine beetle (Dendroctonus brevicomis). At this site, we found that widespread mortality was presaged by five decades of increasing sensitivity (i.e., increased explained variation) of both tree growth and ∆13 C to Palmer Drought Severity Index (PDSI). We hypothesized that increasing sensitivity of tree growth and ∆13 C to hydroclimate constitute EWS that indicate an increased likelihood of widespread forest mortality caused by direct and indirect effects of drought. We then tested these EWS in additional ponderosa pine-dominated forests that experienced varying mortality rates associated with the same California drought event. In general, drier sites showed increasing sensitivity of RWI to PDSI over the last century, as well as higher mortality following the California drought event compared to wetter sites. Two sites displayed evidence that thinning or fire events that reduced stand basal area effectively reversed the trend of increasing hydroclimate sensitivity. These comparisons indicate that reducing competition for soil water and/or decreasing bark beetle host tree density via forest management-particularly in drier regions-may buffer these forests against drought stress and associated mortality risk. EWS such as these could provide land managers more time to mitigate the extent or severity of forest mortality in advance of droughts. Substantial efforts at deploying additional dendrochronological research in concert with remote sensing and forest modeling will aid in forecasting of forest responses to continued climate warming.
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Affiliation(s)
- Rachel M Keen
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Steven L Voelker
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, USA
| | - S-Y Simon Wang
- Department of Plants, Soils and Climate, Utah State University, Logan, Utah, USA
| | - Barbara J Bentz
- USDA Forest Service, Rocky Mountain Research Station, Logan, Utah, USA
| | - Michael L Goulden
- Department of Earth System Science, University of California, Irvine, California, USA
| | - Cody R Dangerfield
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
| | - Charlotte C Reed
- Fire Sciences Laboratory, USDA Forest Service, Rocky Mountain Research Station, Missoula, Montana, USA
| | - Sharon M Hood
- Fire Sciences Laboratory, USDA Forest Service, Rocky Mountain Research Station, Missoula, Montana, USA
| | - Adam Z Csank
- Department of Geography, University of Nevada, Reno, Nevada, USA
| | - Todd E Dawson
- Department of Environmental Science, Policy & Management, University of California, Berkeley, California, USA
| | - Andrew G Merschel
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, Oregon, USA
| | - Christopher J Still
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, Oregon, USA
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Binda G, Di Iorio A, Monticelli D. The what, how, why, and when of dendrochemistry: (paleo)environmental information from the chemical analysis of tree rings. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 758:143672. [PMID: 33277003 DOI: 10.1016/j.scitotenv.2020.143672] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 10/13/2020] [Accepted: 11/02/2020] [Indexed: 05/21/2023]
Abstract
The chemical analysis of tree rings has attracted the interest of researchers in the past five decades in view of the possibility of exploiting this biological indicator as a widely available, high-resolution environmental archive. Information regarding the surrounding environment can be derived either by directly measuring environmental variables (nutrient availability, presence of pollutants, etc.) or by exploiting proxies (e.g. paleoclimatic and paleoenvironmental reconstructions). This review systematically covers the topic and provides a critical view on the reliability of dendrochemical information. First, we introduce the determinable chemical species, such as major elements, trace metals, isotopic ratios, and organic compounds, together with a brief description of their uptake mechanisms and functions in trees. Subsequently, we present the possibilities offered by analytical techniques in the field of tree ring analysis, focusing on direct methods and recent developments. The latter strongly improved the details of the accessible information, enabling the investigation of complex phenomena associated with plant life and encouraging the direct analysis of new analytes, particularly minor organic compounds. With regard to their applications, dendrochemical proxies have been used to trace several processes, such as environmental contamination, paleoclimate reconstruction, global environmental changes, tree physiology, extreme events, ecological trends, and dendroprovenance. Several case studies are discussed for each proposed application, with special emphasis on the reliability of tracing each process. Starting from the reviewed literature data, the second part of the paper is devoted to the critical assessment of the reliability of tree ring proxies. We provide an overview of the current knowledge, discuss the limitations of the inferences that may be drawn from the dendrochemical data, and provide recommendations for the best practices to be used for their validation. Finally, we present the future perspectives related to the advancements in analytical instrumentation and further extension of application fields.
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Affiliation(s)
- Gilberto Binda
- Department of Science and High Technology, Università degli Studi dell'Insubria, Via Valleggio, 12, 22100 Como, Italy
| | - Antonino Di Iorio
- Department of Biotechnology and Life Sciences, Università degli Studi dell'Insubria, Via Jean Henry Dunant, 3, 21100 Varese, Italy
| | - Damiano Monticelli
- Department of Science and High Technology, Università degli Studi dell'Insubria, Via Valleggio, 12, 22100 Como, Italy.
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