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Forcada J, Hoffman JI, Gimenez O, Staniland IJ, Bucktrout P, Wood AG. Ninety years of change, from commercial extinction to recovery, range expansion and decline for Antarctic fur seals at South Georgia. Glob Chang Biol 2023; 29:6867-6887. [PMID: 37839801 DOI: 10.1111/gcb.16947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 10/17/2023]
Abstract
With environmental change, understanding how species recover from overharvesting and maintain viable populations is central to ecosystem restoration. Here, we reconstruct 90 years of recovery trajectory of the Antarctic fur seal at South Georgia (S.W. Atlantic), a key indicator species in the krill-based food webs of the Southern Ocean. After being harvested to commercial extinction by 1907, this population rebounded and now constitutes the most abundant otariid in the World. However, its status remains uncertain due to insufficient and conflicting data, and anthropogenic pressures affecting Antarctic krill, an essential staple for millions of fur seals and other predators. Using integrated population models, we estimated simultaneously the long-term abundance for Bird Island, northwest South Georgia, epicentre of recovery of the species after sealing, and population adjustments for survey counts with spatiotemporal applicability. Applied to the latest comprehensive survey data, we estimated the population at South Georgia in 2007-2009 as 3,510,283 fur seals [95% CI: 3,140,548-3,919,604] (ca. 98% of global population), after 40 years of maximum growth and range expansion owing to an abundant krill supply. At Bird Island, after 50 years of exponential growth followed by 25 years of slow stable growth, the population collapsed in 2009 and has thereafter declined by -7.2% [-5.2, -9.1] per annum, to levels of the 1970s. For the instrumental record, this trajectory correlates with a time-varying relationship between coupled climate and sea surface temperature cycles associated with low regional krill availability, although the effects of increasing krill extraction by commercial fishing and natural competitors remain uncertain. Since 2015, fur seal longevity and recruitment have dropped, sexual maturation has retarded, and population growth is expected to remain mostly negative and highly variable. Our analysis documents the rise and fall of a key Southern Ocean predator over a century of profound environmental and ecosystem change.
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Affiliation(s)
- Jaume Forcada
- British Antarctic Survey, Natural Environment Research Council, UKRI, Cambridge, UK
| | - Joseph I Hoffman
- British Antarctic Survey, Natural Environment Research Council, UKRI, Cambridge, UK
- Department of Animal Behavior, University of Bielefeld, Bielefeld, Germany
| | - Olivier Gimenez
- CEFE, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France
| | | | - Pete Bucktrout
- British Antarctic Survey, Natural Environment Research Council, UKRI, Cambridge, UK
| | - Andrew G Wood
- British Antarctic Survey, Natural Environment Research Council, UKRI, Cambridge, UK
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Magnabosco Marra D, Trumbore SE, Higuchi N, Ribeiro GHPM, Negrón-Juárez RI, Holzwarth F, Rifai SW, Dos Santos J, Lima AJN, Kinupp VF, Chambers JQ, Wirth C. Windthrows control biomass patterns and functional composition of Amazon forests. Glob Chang Biol 2018; 24:5867-5881. [PMID: 30256494 DOI: 10.1111/gcb.14457] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 09/08/2018] [Accepted: 09/10/2018] [Indexed: 06/08/2023]
Abstract
Amazon forests account for ~25% of global land biomass and tropical tree species. In these forests, windthrows (i.e., snapped and uprooted trees) are a major natural disturbance, but the rates and mechanisms of recovery are not known. To provide a predictive framework for understanding the effects of windthrows on forest structure and functional composition (DBH ≥10 cm), we quantified biomass recovery as a function of windthrow severity (i.e., fraction of windthrow tree mortality on Landsat pixels, ranging from 0%-70%) and time since disturbance for terra-firme forests in the Central Amazon. Forest monitoring allowed insights into the processes and mechanisms driving the net biomass change (i.e., increment minus loss) and shifts in functional composition. Windthrown areas recovering for between 4-27 years had biomass stocks as low as 65.2-91.7 Mg/ha or 23%-38% of those in nearby undisturbed forests (~255.6 Mg/ha, all sites). Even low windthrow severities (4%-20% tree mortality) caused decadal changes in biomass stocks and structure. While rates of biomass increment in recovering vegetation were nearly double (6.3 ± 1.4 Mg ha-1 year-1 ) those of undisturbed forests (~3.7 Mg ha-1 year-1 ), biomass loss due to post-windthrow mortality was high (up to -7.5 ± 8.7 Mg ha-1 year-1 , 8.5 years since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40 years. Resprouting trees contributed little to biomass recovery. Instead, light-demanding, low-density genera (e.g., Cecropia, Inga, Miconia, Pourouma, Tachigali, and Tapirira) were favored, resulting in substantial post-windthrow species turnover. Shifts in functional composition demonstrate that windthrows affect the resilience of live tree biomass by favoring soft-wooded species with shorter life spans that are more vulnerable to future disturbances. As the time required for forests to recover biomass is likely similar to the recurrence interval of windthrows triggering succession, windthrows have the potential to control landscape biomass/carbon dynamics and functional composition in Amazon forests.
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Affiliation(s)
- Daniel Magnabosco Marra
- Biogeochemical Processes Department, Max-Planck-Institute for Biogeochemistry, Jena, Germany
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
- AG Spezielle Botanik und Funktionelle Biodiversität, Universität Leipzig, Leipzig, Germany
| | - Susan E Trumbore
- Biogeochemical Processes Department, Max-Planck-Institute for Biogeochemistry, Jena, Germany
| | - Niro Higuchi
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
| | - Gabriel H P M Ribeiro
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
| | - Robinson I Negrón-Juárez
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - Frederic Holzwarth
- AG Spezielle Botanik und Funktionelle Biodiversität, Universität Leipzig, Leipzig, Germany
| | - Sami W Rifai
- Environmental Change Institute, University of Oxford, Oxford, UK
| | - Joaquim Dos Santos
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
| | - Adriano J N Lima
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
| | - Valdely F Kinupp
- Ciência e Tecnologia do Amazonas, Campus Manaus-Zona Leste, Herbário EAFM, Instituto Federal de Educação, Manaus, Brazil
| | - Jeffrey Q Chambers
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
- Geography Department, University of California, Berkeley, California
| | - Christian Wirth
- AG Spezielle Botanik und Funktionelle Biodiversität, Universität Leipzig, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Functional Biogeography Fellow Group, Max-Planck-Institute for Biogeochemistry, Jena, Germany
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Schauer S, Meier T, Reinhard M, Röhrig M, Schneider M, Heilig M, Kolew A, Worgull M, Hölscher H. Tunable Diffractive Optical Elements Based on Shape-Memory Polymers Fabricated via Hot Embossing. ACS Appl Mater Interfaces 2016; 8:9423-9430. [PMID: 26998646 DOI: 10.1021/acsami.6b00679] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We introduce actively tunable diffractive optical elements fabricated from shape-memory polymers (SMPs). By utilizing the shape-memory effect of the polymer, at least one crucial attribute of the diffractive optical element (DOE) is tunable and adjustable subsequent to the completed fabrication process. A thermoplastic, transparent, thermoresponsive polyurethane SMP was structured with diverse diffractive microstructures via hot embossing. The tunability was enabled by programming a second, temporary shape into the diffractive optical element by mechanical deformation, either by stretching or a second embossing cycle at low temperatures. Upon exposure to the stimulus heat, the structures change continuously and controllable in a predefined way. We establish the novel concept of shape-memory diffractive optical elements by illustrating their capabilities, with regard to tunability, by displaying the morphing diffractive pattern of a height tunable and a period tunable structure, respectively. A sample where an arbitrary structure is transformed to a second, disparate one is illustrated as well. To prove the applicability of our tunable shape-memory diffractive optical elements, we verified their long-term stability and demonstrated the precise adjustability with a detailed analysis of the recovery dynamics, in terms of temperature dependence and spatially resolved, time-dependent recovery.
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Affiliation(s)
- Senta Schauer
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Tobias Meier
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Maximilian Reinhard
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Michael Röhrig
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Marc Schneider
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Markus Heilig
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Alexander Kolew
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Matthias Worgull
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Hendrik Hölscher
- Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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