34 research outputs found

    Evidence of prehistoric human activity in the Falkland Islands

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    Funding Information: This material is based on work supported by the NSF Graduate Research Fellowship under grant no.1840992 to K.M.H., an Explorer's Club Student Research Grant, a Rolex/Explorer's Club grant, the Dan and Betty Churchill Exploration Fund, and >200 crowdfunders on experiment.com. J.L.G. was supported by NSF CAREER grant EAR-1753186.Peer reviewedPublisher PD

    A practical solution: the Anthropocene is a geological event, not a formal epoch

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    The Anthropocene has yet to be defined in a way that is functional both to the international geological community and to the broader fields of environmental and social sciences. Formally defining the Anthropocene as a chronostratigraphical series and geochronological epoch with a precise global start date would drastically reduce the Anthropocene’s utility across disciplines. Instead, we propose the Anthropocene be defined as a geological event, thereby facilitating a robust geological definition linked with a scholarly framework more useful to and congruent with the many disciplines engaging with human-environment interactions. Unlike formal epochal definitions, geological events can recognize the spatial and temporal heterogeneity and diverse social and environmental processes that interact to produce anthropogenic global environmental changes. Consequently, an Anthropocene Event would incorporate a far broader range of transformative human cultural practices and would be more readily applicable across academic fields than an Anthropocene Epoch, while still enabling a robust stratigraphic characterization

    Using photogrammetry to create virtual permanent plots in rare and threatened plant communities

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    Abstract Premise Many plant communities across the world are undergoing changes due to climate change, human disturbance, and other threats. These community‐level changes are often tracked with the use of permanent vegetative plots, but this approach is not always feasible. As an alternative, we propose using photogrammetry, specifically photograph‐based digital surface models (DSMs) developed using structure‐from‐motion, to establish virtual permanent plots in plant communities where the use of permanent structures may not be possible. Methods In 2021 and 2022, we took iPhone photographs to record species presence in 1‐m2 plots distributed across alpine communities in the northeastern United States. We then compared field estimates of percent coverage with coverage estimated using DSMs. Results Digital surface models can provide effective, minimally invasive, and permanent records of plant species presence and percent coverage, while also allowing managers to mark survey locations virtually for long‐term monitoring. We found that percent coverage estimated from DSMs did not differ from field estimates for most species and substrates. Discussion In order to continue surveying efforts in areas where permanent structures or other surveying methods are not feasible, photogrammetry and structure‐from‐motion methods can provide a low‐cost approach that allows agencies to accurately survey and record sensitive plant communities through time

    Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation

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    Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions
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