title: A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies.
abstract: Rising atmospheric [CO2 ], ca , is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca  - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca . To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca  - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain.
authors.affiliation: Department of Forest Ecosystems & Society, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Voelker
authors.affiliation: Western Ecology Division, National Health and Environmental Effects Research Laboratory (NHEERL), U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR, 97333, USA.
authors.forename: J Renée
authors.initials: JR
authors.lastname: Brooks
authors.affiliation: U.S.D.A. Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA.
authors.forename: Frederick C
authors.initials: FC
authors.lastname: Meinzer
authors.affiliation: Jack Baskin Engineering, University of California Santa Cruz, Santa Cruz, CA, 95604, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Anderson
authors.affiliation: New Zealand Forest Research Institute (SCION), Te Papa Tipu Innovation Park, 20 Sala Street, 3046, Rotorua, New Zealand.
authors.forename: Martin K-F
authors.initials: MK
authors.lastname: Bader
authors.affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies (DiSTABiF), Second University of Naples, 81100, Caserta, Italy.|Ecole Pratique des Hautes Etudes, Centre for Bio-Archaeology and Ecology, Institut de Botanique, University of Montpellier 2, Montpellier, F-34090, France.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Battipaglia
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Becklin
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: David
authors.initials: D
authors.lastname: Beerling
authors.affiliation: UMR1202 BIOGECO, INRA, F-33610, Cestas, France.|UMR 1202 BIOGECO, University of Bordeaux, F-33615, Pessac, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Bert
authors.affiliation: National Research Program, Water Mission Area, U.S. Geological Survey, Mail Stop 430, 12201 Sunrise Valley Drive, Reston, VA, 20192, USA.
authors.forename: Julio L
authors.initials: JL
authors.lastname: Betancourt
authors.affiliation: Department of Integrative Biology, University of California Berkeley, 1105 Valley Life Science Bldg #3140, Berkeley, CA, 94720, USA.
authors.forename: Todd E
authors.initials: TE
authors.lastname: Dawson
authors.affiliation: Bordeaux Sciences Agro, UMR ISPA 1391, INRA, 33175, Gradignan, France.|Nicholas School of the Environment, Duke University, Box 90328, Durham, NC, 27708, USA.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Domec
authors.affiliation: Department of Forestry, University of Missouri, 203 ABNR Building, Columbia, MO, 65211, USA.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Guyette
authors.affiliation: Institute of Botany, University of Basel, Schonbeinstrasse 6, CH-4056, Basel, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Körner
authors.affiliation: UMR1391 ISPA, INRA, 33140, Villenave d'Ornon, France.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Leavitt
authors.affiliation: Laboratory for Tree-Ring Research, University of Arizona, 1215 E. Lowell St., Tucson, AZ, 85721-0045, USA.
authors.forename: Sune
authors.initials: S
authors.lastname: Linder
authors.affiliation: Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, PO Box 49, SE-230 53, Alnarp, Sweden.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.
authors.forename: John D
authors.initials: JD
authors.lastname: Marshall
authors.affiliation: Institute of Botany, University of Basel, Schonbeinstrasse 6, CH-4056, Basel, Switzerland.
authors.forename: Manuel
authors.initials: M
authors.lastname: Mildner
authors.affiliation: Bordeaux Sciences Agro, UMR ISPA 1391, INRA, 33175, Gradignan, France.|UMR1391 ISPA, INRA, 33140, Villenave d'Ornon, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Ogée
authors.affiliation: Laboratory for Tree-Ring Research, University of Arizona, 1215 E. Lowell St., Tucson, AZ, 85721-0045, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Panyushkina
authors.affiliation: UMR1391 ISPA, INRA, 33140, Villenave d'Ornon, France.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Plumpton
authors.affiliation: Department of Forest, Rangeland and Fire Sciences, University of Idaho, 875 Perimeter Drive, Moscow, ID, 83844, USA.
authors.forename: Kurt S
authors.initials: KS
authors.lastname: Pregitzer
authors.affiliation: Paul Scherrer Institute, CH-5323, Villigen, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Saurer
authors.affiliation: School of the Environment, Natural Resources and Geography, Bangor University, Gwynedd, LL57 2UW, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Smith
authors.affiliation: Paul Scherrer Institute, CH-5323, Villigen, Switzerland.
authors.forename: Rolf T W
authors.initials: RT
authors.lastname: Siegwolf
authors.affiliation: Department of Forestry, University of Missouri, 203 ABNR Building, Columbia, MO, 65211, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Stambaugh
authors.affiliation: Department of Forest, Rangeland and Fire Sciences, University of Idaho, 875 Perimeter Drive, Moscow, ID, 83844, USA.
authors.forename: Alan F
authors.initials: AF
authors.lastname: Talhelm
authors.affiliation: Centre for Forest Interdisciplinary Research (C-FIR), University of Winnipeg, 515 Avenue Portage, Winnipeg, MB, Canada, R3B 2E9.
authors.forename: Jacques C
authors.initials: JC
authors.lastname: Tardif
authors.affiliation: Department of Earth & Environmental Sciences, California State University, Fresno, 2576 E. San Ramon Ave., Mail Stop ST-24, Fresno, CA, 93740, USA.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Van de Water
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA.
authors.forename: Joy K
authors.initials: JK
authors.lastname: Ward
authors.affiliation: Bordeaux Sciences Agro, UMR ISPA 1391, INRA, 33175, Gradignan, France.|UMR1391 ISPA, INRA, 33140, Villenave d'Ornon, France.
authors.forename: Lisa
authors.initials: L
authors.lastname: Wingate
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D032462:Cycadopsida / Q000378:metabolism; D019684:Magnoliopsida / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D054046:Plant Stomata / Q000378:metabolism; D014197:Trees / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide
keywords: angiosperm; carbon dioxide; free-air CO2 enrichment; gymnosperm; optimal stomatal behavior; photosynthesis; stomatal conductance; water use efficiency