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Thermal acclimation of leaf photosynthetic traits in an evergreen woodland, consistent with the coordination hypothesis

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Title: Thermal acclimation of leaf photosynthetic traits in an evergreen woodland, consistent with the coordination hypothesis
Authors: Togashi, HF
Prentice, IC
Atkin, OK
Macfarlane, C
Prober, SM
Bloomfield, KJ
Evans, BJ
Item Type: Journal Article
Abstract: Ecosystem models commonly assume that key photosynthetic traits, such as carboxylation capacity measured at a standard temperature, are constant in time. The temperature responses of modelled photosynthetic or respiratory rates then depend entirely on enzyme kinetics. Optimality considerations, however, suggest this assumption may be incorrect. The "coordination hypothesis" (that Rubisco- and electron-transport-limited rates of photosynthesis are co-limiting under typical daytime conditions) predicts, instead, that carboxylation (Vcmax) capacity should acclimate so that it increases somewhat with growth temperature but less steeply than its instantaneous response, implying that Vcmax when normalized to a standard temperature (e.g. 25 °C) should decline with growth temperature. With additional assumptions, similar predictions can be made for electron-transport capacity (Jmax) and mitochondrial respiration in the dark (Rdark). To explore these hypotheses, photosynthetic measurements were carried out on woody species during the warm and the cool seasons in the semi-arid Great Western Woodlands, Australia, under broadly similar light environments. A consistent proportionality between Vcmax and Jmax was found across species. Vcmax, Jmax and Rdark increased with temperature in most species, but their values standardized to 25 °C declined. The ci : ca ratio increased slightly with temperature. The leaf N  :  P ratio was lower in the warm season. The slopes of the relationships between log-transformed Vcmax and Jmax and temperature were close to values predicted by the coordination hypothesis but shallower than those predicted by enzyme kinetics.
Issue Date: 11-Jun-2018
Date of Acceptance: 22-May-2018
URI: http://hdl.handle.net/10044/1/61089
DOI: https://dx.doi.org/10.5194/bg-15-3461-2018
ISSN: 1726-4170
Publisher: Copernicus Publications
Start Page: 3461
End Page: 3474
Journal / Book Title: Biogeosciences
Volume: 15
Issue: 11
Copyright Statement: © 2018 The Author(s). This work is distributed under the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/).
Sponsor/Funder: AXA Research Fund
Funder's Grant Number: AXA Chair Programme in Biosphere and Climate Impacts
Keywords: Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Ecology
Geosciences, Multidisciplinary
Environmental Sciences & Ecology
Geology
TEMPERATURE RESPONSE FUNCTIONS
BIOCHEMICALLY BASED MODEL
LIMITED PHOTOSYNTHESIS
DECIDUOUS FOREST
RESPIRATION
NITROGEN
LEAVES
C-3
PARAMETERS
CO2
04 Earth Sciences
05 Environmental Sciences
06 Biological Sciences
Meteorology & Atmospheric Sciences
Publication Status: Published
Open Access location: https://www.biogeosciences.net/15/3461/2018/
Online Publication Date: 2018-06-11
Appears in Collections:Department of Life Sciences