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

Henrique Fürstenau Togashi*, Iain Colin Prentice, Owen K. Atkin, Craig Macfarlane, Suzanne M. Prober, Keith J. Bloomfield, Bradley John Evans

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
54 Downloads (Pure)

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 V ca ratio increased slightly with temperature. The leaf NV 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.

Original languageEnglish
Pages (from-to)3461-3474
Number of pages14
JournalBiogeosciences
Volume15
Issue number11
DOIs
Publication statusPublished - 11 Jun 2018

Bibliographical note

Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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