Skip to Main Content
Disentangling the role of photosynthesis and stomatal conductance on rising forest water-use efficiencyAuthor(s): Rossella Guerrieri; Soumaya Belmecheri; Scott V Ollinger; Heidi Asbjornsen; Katie Jennings; Jingfeng Xiao; Benjamin D. Stocker; Mary Martin; David Y. Hollinger; Rosvel Bracho-Garrillo; Kenneth Clark; Sabina Dore; Thomas Kolb; J. William Munger; Kimberly Novick; Andrew D. Richardson
Source: Proceedings of the National Academy of Sciences
Publication Series: Scientific Journal (JRNL)
Station: Northern Research Station
Download Publication (2.0 MB)
DescriptionMultiple lines of evidence suggest that plant water-use efficiency (WUE)—the ratio of carbon assimilation to water loss—has increased in recent decades. Although rising atmospheric CO2 has been proposed as the principal cause, the underlying physiological mechanisms are still being debated, and implications for the global water cycle remain uncertain. Here, we addressed this gap using 30-y tree ring records of carbon and oxygen isotope measurements and basal area increment from 12 species in 8 North American mature temperate forests. Our goal was to separate the contributions of enhanced photosynthesis and reduced stomatal conductance to WUE trends and to assess consistency between multiple commonly used methods for estimating WUE. Our results show that tree ring-derived estimates of increases in WUE are consistent with estimates from atmospheric measurements and predictions based on an optimal balancing of carbon gains and water costs, but are lower than those based on ecosystem-scale flux observations. Although both physiological mechanisms contributed to rising WUE, enhanced photosynthesis was widespread, while reductions in stomatal conductance were modest and restricted to species that experienced moisture limitations. This finding challenges the hypothesis that rising WUE in forests is primarily the result of widespread, CO2-induced reductions in stomatal conductance.
- Check the Northern Research Station web site to request a printed copy of this publication.
- Our on-line publications are scanned and captured using Adobe Acrobat.
- During the capture process some typographical errors may occur.
- Please contact Sharon Hobrla, firstname.lastname@example.org if you notice any errors which make this publication unusable.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationGuerrieri, Rossella; Belmecheri, Soumaya; Ollinger, Scott V.; Asbjornsen, Heidi; Jennings, Katie; Xiao, Jingfeng; Stocker, Benjamin D.; Martin, Mary; Hollinger, David Y.; Bracho-Garrillo, Rosvel; Clark, Kenneth; Dore, Sabina; Kolb, Thomas; Munger, J. William; Novick, Kimberly; Richardson, Andrew D. 2019. Disentangling the role of photosynthesis and stomatal conductance on rising forest water-use efficiency. Proceedings of the National Academy of Sciences. 116(34): 16909-16914. https://doi.org/10.1073/pnas.1905912116.
Keywordstree rings, stable isotopes, water-use efficiency, AmeriFlux, CO2 fertilization
- Stomatal uptake of O3 in aspen and aspen-birch forests under free-air CO2 and O3 enrichment
- Increase in forest water-use efficiency as atmospheric carbon dioxide concentrations rise
- Impact of simulated herbivory on water relations of aspen (Populus tremuloides) seedlings: the role of new tissue in the hydraulic conductivity recovery cycle
XML: View XML