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Plant stable isotope composition across habitat gradients in a semi-arid savanna: implications for environmental reconstruction

Authors

  • JACQUELINE CODRON,

    Corresponding author
    1. Department of Archaeology, University of Cape Town, Rondebosch, South Africa
    2. Florisbad Quaternary Research, National Museum, Bloemfontein, South Africa
    • School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa
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  • JULIA A. LEE-THORP,

    1. Research Laboratory for Archaeology, University of Oxford, UK
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  • MATT SPONHEIMER,

    1. Department of Anthropology, University of Colorado at Boulder, USA
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  • DARYL CODRON

    1. School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa
    2. Florisbad Quaternary Research, National Museum, Bloemfontein, South Africa
    3. Department of Anthropology, University of Colorado at Boulder, USA
    4. Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Switzerland
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Correspondence: J. Codron, 3Florisbad Quaternary Research, as above.

E-mail: jacquicodron@gmail.com

ABSTRACT

Field studies of plant stable carbon and nitrogen isotope composition have revealed relationships with temperature and precipitation. These relationships conform to theoretical predictions of how extrinsic factors impact on ecophysiological processes such as photosynthesis and nitrogen cycling. However, examination of many datasets reveals high levels of variation, especially across environments with moderate precipitation (<1000 mm a−1). To test for extrinsic effects on plant isotope composition in such environments, we studied data from plants collected over three years from multiple habitats and seasons in Kruger National Park, South Africa. Our sample is sufficiently large to evaluate not only effects of environmental variables (rainfall up to ∼800 mm a−1, temperature, physical habitat structure) but also taxonomic effects. Species composition of habitats accounted for most of the variation in our data, followed by physical habitat structure (e.g. wooded or riverine compared with open, grassy habitats), while rainfall and temperature had only indirect or negligible effects. The latter finding concurs with subsections of existing datasets and we suggest therefore that such effects usually become visible in datasets that span environmental extremes, implying environmental ranges within which plant isotope variations cannot readily be ascribed to climate. Copyright © 2013 John Wiley & Sons, Ltd.

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