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!

New Instructional Video Module on Biogeography and Isotope Fractionation in C3 & C4 plants with Christopher Still! Check out all of the videos at the bottom of the 'Summer Courses' tab!


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


New Blog Post - Former SPATIAL student Katie Wedemeyer-Strombel discusses her experience as a SPATIAL student last summer! (Check it out here!)


Awards - Former ITCE post-doc Jennifer Cotton has received an NSF Macrosystems Biology Grant. Congratulations, Jen! (Check out the NEON press release here!)

New Publications - Former SPATIAL student Chabi Djagoun's work on carbon isotope niches in herbivores in a west African savannah is now available in Mammalian Biology - Free download until Nov 7th! (Check it out here)


New Publications - Former SPATIAL student Giovanny Mosquera in two new publications involving high elevation tropical ecosystems (Hydrological Processes and Hydrology and Earth System Sciences)


Awards - Congratulations to Jim Ehleringer for receiving the prestigious Rosenblatt Prize for Excellenc! (Read more here.)


Presentations - Several SPATIAL & IsoCamp instructors and past students represented at the 10th annual (ISOECOL meeting in Tokyo!) last week.

Archived ITCE News


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!