Similar patterns of leaf temperatures and thermal acclimation to warming in temperate and tropical tree canopies

Crous, K.Y., Cheesman, A.W., Middleby, K., Rogers, E.I.E, Wujeska-Klause, A., Bouet, A.Y.M., Ellsworth, D.S., Liddell, M.J., Cernusak, L.A., and Barton, C.V.M. (2023) Similar patterns of leaf temperatures and thermal acclimation to warming in temperate and tropical tree canopies. Tree Physiology, 43. pp. 1383-1399.

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Abstract

As the global climate warms, a key question is how increased leaf temperatures will affect tree physiology and the coupling between leaf and air temperatures in forests. To explore the impact of increasing temperatures on plant performance in open air, we warmed leaves in the canopy of two mature evergreen forests, a temperate Eucalyptus woodland and a tropical rainforest. The leaf heaters consistently maintained leaves at a target of 4 °C above ambient leaf temperatures. Ambient leaf temperatures (Tleaf) were mostly coupled to air temperatures (Tair), but at times, leaves could be 8–10 °C warmer than ambient air temperatures, especially in full sun. At both sites, Tleaf was warmer at higher air temperatures (Tair > 25 °C), but was cooler at lower Tair, contrary to the ‘leaf homeothermy hypothesis’. Warmed leaves showed significantly lower stomatal conductance (−0.05 mol m−2 s−1 or −43% across species) and net photosynthesis (−3.91 μmol m−2 s−1 or −39%), with similar rates in leaf respiration rates at a common temperature (no acclimation). Increased canopy leaf temperatures due to future warming could reduce carbon assimilation via reduced photosynthesis in these forests, potentially weakening the land carbon sink in tropical and temperate forests.

Item ID: 80135
Item Type: Article (Research - C1)
ISSN: 1758-4469
Copyright Information: © The Author(s) 2023. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DE160101484
Date Deposited: 29 Aug 2023 00:57
FoR Codes: 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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