Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 9, 587-606, 2016
https://doi.org/10.5194/gmd-9-587-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Model description paper
12 Feb 2016
A global scale mechanistic model of photosynthetic capacity (LUNA V1.0)
A. A. Ali1,2, C. Xu1, A. Rogers3, R. A. Fisher4, S. D. Wullschleger5, E. C. Massoud2, J. A. Vrugt2,6, J. D. Muss1, N. G. McDowell1, J. B. Fisher7, P. B. Reich8,9, and C. J. Wilson1 1Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
2Department of Civil and Environmental Engineering, University of California Irvine, Irvine, California, USA
3Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York, USA
4Climate and Global Dynamics, National Center for Atmospheric Research, Boulder, Colorado, USA
5Climate Change Science Institute, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
6Department of Earth System Science, University of California Irvine, Irvine, California, USA
7Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
8Department of Forest Resources, University of Minnesota, St. Paul, Minnesota, USA
9Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, New South Wales, Australia
Abstract. Although plant photosynthetic capacity as determined by the maximum carboxylation rate (i.e., Vc, max25) and the maximum electron transport rate (i.e., Jmax25) at a reference temperature (generally 25 °C) is known to vary considerably in space and time in response to environmental conditions, it is typically parameterized in Earth system models (ESMs) with tabulated values associated with plant functional types. In this study, we have developed a mechanistic model of leaf utilization of nitrogen for assimilation (LUNA) to predict photosynthetic capacity at the global scale under different environmental conditions. We adopt an optimality hypothesis to nitrogen allocation among light capture, electron transport, carboxylation and respiration. The LUNA model is able to reasonably capture the measured spatial and temporal patterns of photosynthetic capacity as it explains  ∼  55 % of the global variation in observed values of Vc, max25 and  ∼  65 % of the variation in the observed values of Jmax25. Model simulations with LUNA under current and future climate conditions demonstrate that modeled values of Vc, max25 are most affected in high-latitude regions under future climates. ESMs that relate the values of Vc, max25 or Jmax25 to plant functional types only are likely to substantially overestimate future global photosynthesis.

Citation: Ali, A. A., Xu, C., Rogers, A., Fisher, R. A., Wullschleger, S. D., Massoud, E. C., Vrugt, J. A., Muss, J. D., McDowell, N. G., Fisher, J. B., Reich, P. B., and Wilson, C. J.: A global scale mechanistic model of photosynthetic capacity (LUNA V1.0), Geosci. Model Dev., 9, 587-606, https://doi.org/10.5194/gmd-9-587-2016, 2016.
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We have developed a mechanistic model of leaf utilization of nitrogen for assimilation (LUNA V1.0) to predict the photosynthetic capacities at the global scale based on the optimization of key leaf-level metabolic processes. LUNA model predicts that future climatic changes would mostly affect plant photosynthetic capabilities in high-latitude regions and that Earth system models using fixed photosynthetic capabilities are likely to substantially overestimate future global photosynthesis.
We have developed a mechanistic model of leaf utilization of nitrogen for assimilation (LUNA...
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