Pragmatic Hydraulic Theory Predicts Stomatal Responses to Climatic Water Deficits

Model validated particularly well against multiple empirical datasets.

The Science

This study introduces a new approach to modeling stomatal function based on trait-based hydraulics.

The Impact

This model will radically simplify, yet improve, Earth system models, once incorporated.


Earth system models do not simulate stomatal conductance, and hence photosynthesis, correctly. Here, a team from the Next-Generation Ecosystem Experiments (NGEE)–Tropics project introduce a modeling approach that is simple yet mechanistically accurate. The model validated particularly well against multiple empirical datasets.  Furthermore, the researchers propose ways this model can be incorporated into Earth system models, thus greatly improving their realism and accuracy.

Principal Investigator(s)

Nate McDowell
Pacific Northwest National Laboratory


Funding was provided by the Next-Generation Ecosystem Experiments (NGEE)–Tropics project of the Office of Biological and Environmental Research, within the U.S. Department of Energy (DOE) Office of Science, and by the National Science Foundation (NSF).


Sperry, J.S., Wang, Y., Wolfe, B.T., Mackay, D.S., Anderegg, W.R., McDowell, N.G. and Pockman, W.T. “Pragmatic hydraulic theory predicts stomatal responses to climatic water deficits.” New Phytologist 212(3), 577–589 (2016). [DOI:10.1111/nph.14059]