C3 and C4 photosynthesis


Carbon isotope values of plants reflect photosynthetic pathways, allowing for a clear distinction between C3 and C4 plants. Mechanistic models to predict the distributions of C3 and C4 plants provided one foundation for photosynthetic ecology at continental scales. Existing spatial models provide a foundation to predict equilibrium C3-C4 geographical distributions, based on photorespiration and quantum efficiency concepts. Equilibrium models already are in place to produce raster-based precitions at global scale, incorporating additional precipitation constraints.

Several initial projects are anticipated:

  • First, when the biochemistry and spatial concepts are intergrated, the models can be used to explore equilibrium C3-C4 distributions under historically low and anticipated high atmospheric [CO2], allowing extension to different time periods in the Earth's past and future. Together, these theories constitute a foundation for scaling biochemical and physiological processes relevant to photosynthetic pathway distributions to regional and continental scales.
  • Second, isotopically, animals are what they eat , and knowing the carbon isotope values of animals we can reconstruct their dietary histories. Interpretation of such data as in source of information on dietary ecology requires understanding of the isotopic composition of the spatially and temporally varying dietary environment for animals. Conversely, the models might have applications to predicting animal distributions in the future, given a changing photosynthetic landscape.

The project will support a postdoc to integrate available C3-C4 plant, vegetation, and soil isotope data, ancillary climate and land use data, and animal carbon isotope data. These integrated data sets will be used to test and improve the continental-scale, biochemistry-based predictions of photosynthetic pathway distributions.

These syntheses and modeling efforts will provide a framework for interpreting the very large number of carbon isotope data that will emerge on both insets and vegetation at NEON sites across the US.

Affiliated faculty

Bowling, Cerling, Ehleringer, Pendall, Still, Wofsy

ITCE News!

2018 course application window is now closed - admission decisions by end February

New Publication – SPATIAL and IsoCamp alum Cat Jarman develops ITCE research-in-residence project and reports paleogenomic analysis of skeletal samples in determining the origins of inhabitants of Rapa Nui. Read the paper published in Current Biology (here)

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Open PhD position - The research group of Prof. Kahmen at the University of Basel just published an open ERC-funded PhD position in stable isotope physiology. Read it (here).


New Publication - Marine isoscape paper from ITCE research-in-residence team including SPATIAL alum Sarah Magozzi, SPATIAL instructors Clive Trueman and Michael Wunder, and former ITCE post-doc Hannah Vander Zanden! Read it (here)!

New Publication - Marine Biology paper by SPATIAL alum Julia Adams (2015). Link to full-text article (here)!


New Publications - Two new papers by SPATIAL alum Sean Brennan involving salmon migration (here) and using dendritic network models to improve Strontium isoscapes (here)!


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IsoMAP: WebGIS for Isotopes

IsoMAP is a dynamic, online workspace for spatial analysis, modeling and prediction of stable isotope ratio variation in the natural environment. The initial realease of the IsoMAP gateway is now live and supports precipitation isotope ratio modeling. Visit IsoMAP to learn more or to start making isoscapes today!