EGU22-1111
https://doi.org/10.5194/egusphere-egu22-1111
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Investigating C3/C4 plants competition using carbon isotopes and optimality principles

Aliénor Lavergne1,2, Sandy P. Harrison1, and Iain Colin Prentice3
Aliénor Lavergne et al.
  • 1Department of Geography and Environmental Science, University of Reading, Reading, United Kingdom of Great Britain – England, Scotland, Wales (alienor.lavergne@gmail.com)
  • 2Department of Physics, Imperial College London, South Kensington campus, London, United Kingdom of Great Britain – England, Scotland, Wales
  • 3Department of Life Sciences, Imperial College London, Silwood Park, Ascot, United Kingdom of Great Britain – England, Scotland, Wales

Understanding the mechanisms underlying changes in carbon isotope discrimination (Δ13C) in C3 and C4 plants is critical for predicting the C3/C4 fraction in mixed ecosystems. Variations in Δ13C are closely related to changes in the stomatal limitation of photosynthesis (i.e. the ratio of leaf internal to ambient partial pressure of CO2, ci/ca), which are in turn determined by environmental variables, but also depend on the pathway of carbon assimilation. For instance, isotopic fractionation during the diffusion of CO2 through the stomata primarily influences Δ13C in C4 plants, while fractionation during Rubisco carboxylation has a stronger imprint on Δ13C in C3 plants. As a result, C3 plants are depleted in 13C compared to C4 plants. Isotopic measurements can thus be used as tracers of physiological processes in plants.

Here we implement Δ13C formulations for C3 and C4 plants in the optimal P model to investigate the abundance of C3 and C4 plants at different locations across the globe. We first test model predictions of Δ13C (and hence ci/ca) for the two carbon pathways against a large network of isotopic measurements from leaves. We then predict the expected mean Δ13C in soil organic materials after plants decomposition using maps of C3/C4 plants distribution and assess model predictions with real isotopic measurements. Based on our results, we propose a model to predict the competition of C3/C4 plants as a response to environmental variations in different ecosystems.

How to cite: Lavergne, A., Harrison, S. P., and Prentice, I. C.: Investigating C3/C4 plants competition using carbon isotopes and optimality principles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1111, https://doi.org/10.5194/egusphere-egu22-1111, 2022.