Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (Vc,max.25 and Jmax.25, respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We then measured photosynthetic CO2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska. The activation energies associated with the temperature response functions of Vc,max and Jmax were 17% lower than commonly used values. When scaled to 25°C, Vc,max.25 and Jmax.25 were two- to five-fold higher than the values used to parameterize current TBMs. This high photosynthetic capacity was attributable to a high leaf N content and the high fraction of N invested in Rubisco. Leaf-level modeling demonstrated that current parameterization of TBMs resulted in a two-fold underestimation of the capacity for leaf-level CO2 assimilation in Arctic vegetation. Our study highlights the poor representation of Arctic photosynthesis in TBMs, and provides the critical data necessary to improve our ability to project the response of the Arctic to global environmental change.
Rogers, Alistair, et al. "Terrestrial biosphere models underestimate photosynthetic capacity and CO <sub>2</sub> assimilation in the Arctic." New Phytologist, vol. 216, no. 4, Sep. 2017. https://doi.org/10.1111/nph.14740
Rogers, Alistair, Serbin, Shawn P., Ely, Kim S., Sloan, Victoria L., & Wullschleger, Stan D. (2017). Terrestrial biosphere models underestimate photosynthetic capacity and CO <sub>2</sub> assimilation in the Arctic. New Phytologist, 216(4). https://doi.org/10.1111/nph.14740
Rogers, Alistair, Serbin, Shawn P., Ely, Kim S., et al., "Terrestrial biosphere models underestimate photosynthetic capacity and CO <sub>2</sub> assimilation in the Arctic," New Phytologist 216, no. 4 (2017), https://doi.org/10.1111/nph.14740
@article{osti_1392220,
author = {Rogers, Alistair and Serbin, Shawn P. and Ely, Kim S. and Sloan, Victoria L. and Wullschleger, Stan D.},
title = {Terrestrial biosphere models underestimate photosynthetic capacity and CO <sub>2</sub> assimilation in the Arctic},
annote = {Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (Vc,max.25 and Jmax.25, respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We then measured photosynthetic CO2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska. The activation energies associated with the temperature response functions of Vc,max and Jmax were 17% lower than commonly used values. When scaled to 25°C, Vc,max.25 and Jmax.25 were two- to five-fold higher than the values used to parameterize current TBMs. This high photosynthetic capacity was attributable to a high leaf N content and the high fraction of N invested in Rubisco. Leaf-level modeling demonstrated that current parameterization of TBMs resulted in a two-fold underestimation of the capacity for leaf-level CO2 assimilation in Arctic vegetation. Our study highlights the poor representation of Arctic photosynthesis in TBMs, and provides the critical data necessary to improve our ability to project the response of the Arctic to global environmental change.},
doi = {10.1111/nph.14740},
url = {https://www.osti.gov/biblio/1392220},
journal = {New Phytologist},
issn = {ISSN 0028-646X},
number = {4},
volume = {216},
place = {United States},
publisher = {Wiley},
year = {2017},
month = {09}}
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 373, Issue 2054https://doi.org/10.1098/rsta.2014.0423
Next Generation Ecosystems Experiment - Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (US); NGEE Arctic, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)https://doi.org/10.5440/1336809