Climate and soils together regulate photosynthetic carbon isotope discrimination within C3 plants worldwide

William K. Cornwell*, Ian J. Wright, Joel Turner, Vincent Maire, Margaret M. Barbour, Lucas A. Cernusak, Todd Dawson, David Ellsworth, Graham D. Farquhar, Howard Griffiths, Claudia Keitel, Alexander Knohl, Peter B. Reich, David G. Williams, Radika Bhaskar, Johannes H.C. Cornelissen, Anna Richards, Susanne Schmidt, Fernando Valladares, Christian KörnerErnst Detlef Schulze, Nina Buchmann, Louis S. Santiago

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review

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    Aim: Within C3 plants, photosynthesis is a balance between CO2 supply from the atmosphere via stomata and demand by enzymes within chloroplasts. This process is dynamic and a complex but crucial aspect of photosynthesis. We sought to understand the spatial pattern in CO2 supply–demand balance on a global scale, via analysis of stable isotopes of carbon within leaves (Δ13C), which provide an integrative record of CO2 drawdown during photosynthesis. Location Global. Time period1951–2011. Major taxa studied Vascular plants. Methods: We assembled a database of leaf carbon isotope ratios containing 3,979 species–site combinations from across the globe, including 3,645 for C3 species. We examined a wide array of potential climate and soil drivers of variation in Δ13C. Results: The strongest drivers of carbon isotope discrimination at the global scale included atmospheric pressure, potential evapotranspiration and soil pH, which explained 44% of the variation in Δ13C. Addition of eight more climate and soil variables (each explaining small but highly significant amounts of variation) increased the explained variation to 60%. On top of this, the largest plant trait effect was leaf nitrogen per area, which explained 11% of Δ13C variation. Main conclusions: By considering variation in Δ13C at a considerably larger scale than previously, we were able to identify and quantify key drivers in CO2 supply–demand balance previously unacknowledged. Of special note is the key role of soil properties, with greater discrimination on low-pH and high-silt soils. Unlike other plant traits, which show typically wide variation within sets of coexisting species, the global pattern in carbon stable isotope ratios is much more conservative; there is relatively narrow variation in time-integrated CO2 concentrations at the site of carboxylation among plants in a given soil and climate.

    Original languageEnglish
    Pages (from-to)1056-1067
    Number of pages12
    JournalGlobal Ecology and Biogeography
    Issue number9
    Publication statusPublished - Sept 2018

    Bibliographical note

    First published [online]: 30 October 2018


    Financial support came from the Australian Research Council, via the ARC‐NZ Research Network for Vegetation Function and from the Netherlands Organization for Scientific Research (NWO) through its Open Competition Program of the section Earth and Life Sciences (ALW) grant no. 820.01.016. Computation was made possible by the Katana High Performance Computing facility in the Faculty of Science at the University of New South Wales.

    FundersFunder number
    Netherlands Organization for Scientific Research
    Natural Environment Research CouncilNE/M001946/1
    Australian Research Council
    Nederlandse Organisatie voor Wetenschappelijk Onderzoek820.01.016


      • carbon isotopes
      • environmental drivers
      • global
      • leaf traits
      • leaves
      • soil


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