Vapour pressure deficit modulates hydraulic function and structure of tropical rainforests under nonlimiting soil water supply

Binks, Oliver, Cernusak, Lucas A., Liddell, Michael, Bradford, Matt, Coughlin, Ingrid, Bryant, Callum, Palma, Ana C., Hoffmann, Luke, Alam, Iftakharul, Carle, Hannah J., Rowland, Lucy, Oliveira, Rafael S., Laurance, Susan G.W., Mencuccini, Maurizio, and Meir, Patrick (2023) Vapour pressure deficit modulates hydraulic function and structure of tropical rainforests under nonlimiting soil water supply. New Phytologist. (In Press)

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Atmospheric conditions are expected to become warmer and drier in the future, but little is known about how evaporative demand influences forest structure and function independently from soil moisture availability, and how fast-response variables (such as canopy water potential and stomatal conductance) may mediate longer-term changes in forest structure and function in response to climate change. We used two tropical rainforest sites with different temperatures and vapour pressure deficits (VPD), but nonlimiting soil water supply, to assess the impact of evaporative demand on ecophysiological function and forest structure. Common species between sites allowed us to test the extent to which species composition, relative abundance and intraspecific variability contributed to site-level differences. The highest VPD site had lower midday canopy water potentials, canopy conductance (gc), annual transpiration, forest stature, and biomass, while the transpiration rate was less sensitive to changes in VPD; it also had different height–diameter allometry (accounting for 51% of the difference in biomass between sites) and higher plot-level wood density. Our findings suggest that increases in VPD, even in the absence of soil water limitation, influence fast-response variables, such as canopy water potentials and gc, potentially leading to longer-term changes in forest stature resulting in reductions in biomass.

Item ID: 80534
Item Type: Article (Research - C1)
ISSN: 1469-8137
Keywords: allometry, canopy conductance, canopy-atmosphere coupling, drought stress, hydraulic vulnerability, rainforest hydraulics, tree height, vapour pressure deficit
Copyright Information: © 2023 The Authors. New Phytologist © 2023 New Phytologist Foundation. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC grant DP17010409
Date Deposited: 26 Sep 2023 01:24
FoR Codes: 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 50%
31 BIOLOGICAL SCIENCES > 3103 Ecology > 310303 Ecological physiology @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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