Disentangling the role of photosynthesis and stomatal conductance on rising forest water-use efficiency
Guerrieri, Rossella (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Belmecheri, Soumaya (University of Arizona. Laboratory of Tree-Ring Research (USA))
Ollinger, Scott V. (University of New Hampshire. Earth Systems Research Center (USA))
Asbjornsen, Heidi (University of New Hampshire. Earth Systems Research Center (USA))
Jennings, Katie (University of New Hampshire. Earth Systems Research Center (USA))
Xiao, Jingfeng (University of New Hampshire. Earth Systems Research Center (USA))
Stocker, Benjamin D. (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Martin, Mary (University of New Hampshire. Earth Systems Research Center (USA))
Hollinger, David Y. (Northern Research Station. Department of Agriculture Forest Service (USA))
Bracho-Garrillo, Rosvel (University of Florida. School of Forest Resources and Conservation (USA))
Clark, Kenneth (Northern Research Station. Department of Agriculture Forest Service. Silas Little Experimental Forest (USA))
Dore, Sabina (Northern Arizona University. School of Forestry (USA))
Kolb, Thomas (Northern Arizona University. School of Forestry (USA))
Munger, J. William (Harvard University. School of Engineering and Applied Sciences)
Novick, Kimberly (Indiana University. School of Public and Environmental Affair (USA))
Richardson, Andrew D. (Northern Arizona University, School of Informatics, Computing and Cyber Systems (USA))

Date:	2019
Abstract:	Multiple 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 ecosystemscale 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.
Grants:	European Commission 705432 European Commission 701329
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Tree rings ; Stable isotopes ; Water-use efficiency ; AmeriFlux ; CO2 fertilization
Published in:	Proceedings of the National Academy of Sciences of the United States of America, Vol. 116, Issue 34 (August 2019) , p. 16909-16914, ISSN 1091-6490

DOI: 10.1073/pnas.1905912116
PMID: 31383758

6 p, 2.3 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Research articles
Articles > Published articles