Empirical evidence for resilience of tropical forest photosynthesis in a warmer world.

Smith, MN; Taylor, TC; van Haren, J; Rosolem, R; Restrepo-Coupe, N; Adams, J; Wu, J; de Oliveira, RC; da Silva, R; de Araujo, AC; de Camargo, PB; Huxman, TE; Saleska, SR

Empirical evidence for resilience of tropical forest photosynthesis in a warmer world.

Smith, MN Taylor, TC van Haren, J Rosolem, R Restrepo-Coupe, N

Adams, J Wu, J de Oliveira, RC da Silva, R de Araujo, AC de Camargo, PB Huxman, TE Saleska, SR

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Publisher:: NATURE RESEARCH
Publication Type:: Journal Article
Citation:: Nature plants, 2020, 6, (10), pp. 1225-1230
Issue Date:: 2020-10-12

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Field	Value	Language
dc.contributor.author	Smith, MN
dc.contributor.author	Taylor, TC
dc.contributor.author	van Haren, J
dc.contributor.author	Rosolem, R
dc.contributor.author	Restrepo-Coupe, N https://orcid.org/0000-0003-3921-1772
dc.contributor.author	Adams, J
dc.contributor.author	Wu, J
dc.contributor.author	de Oliveira, RC
dc.contributor.author	da Silva, R
dc.contributor.author	de Araujo, AC
dc.contributor.author	de Camargo, PB
dc.contributor.author	Huxman, TE
dc.contributor.author	Saleska, SR
dc.date.accessioned	2021-02-08T04:46:39Z
dc.date.available	2020-09-03
dc.date.available	2021-02-08T04:46:39Z
dc.date.issued	2020-10-12
dc.identifier.citation	Nature plants, 2020, 6, (10), pp. 1225-1230
dc.identifier.issn	2055-0278
dc.identifier.issn	2055-0278
dc.identifier.uri	http://hdl.handle.net/10453/145941
dc.description.abstract	Tropical forests may be vulnerable to climate change<sup>1-3</sup> if photosynthetic carbon uptake currently operates near a high temperature limit<sup>4-6</sup>. Predicting tropical forest function requires understanding the relative contributions of two mechanisms of high-temperature photosynthetic declines: stomatal limitation (H1), an indirect response due to temperature-associated changes in atmospheric vapour pressure deficit (VPD)<sup>7</sup>, and biochemical restrictions (H2), a direct temperature response<sup>8,9</sup>. Their relative control predicts different outcomes-H1 is expected to diminish with stomatal responses to future co-occurring elevated atmospheric [CO<sub>2</sub>], whereas H2 portends declining photosynthesis with increasing temperatures. Distinguishing the two mechanisms at high temperatures is therefore critical, but difficult because VPD is highly correlated with temperature in natural settings. We used a forest mesocosm to quantify the sensitivity of tropical gross ecosystem productivity (GEP) to future temperature regimes while constraining VPD by controlling humidity. We then analytically decoupled temperature and VPD effects under current climate with flux-tower-derived GEP trends in situ from four tropical forest sites. Both approaches showed consistent, negative sensitivity of GEP to VPD but little direct response to temperature. Importantly, in the mesocosm at low VPD, GEP persisted up to 38 °C, a temperature exceeding projections for tropical forests in 2100 (ref. <sup>10</sup>). If elevated [CO<sub>2</sub>] mitigates VPD-induced stomatal limitation through enhanced water-use efficiency as hypothesized<sup>9,11</sup>, tropical forest photosynthesis may have a margin of resilience to future warming.
dc.format	Print-Electronic
dc.language	eng
dc.publisher	NATURE RESEARCH
dc.relation	Office of the Director0730305
dc.relation.ispartof	Nature plants
dc.relation.isbasedon	10.1038/s41477-020-00780-2
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject	0607 Plant Biology, 0703 Crop and Pasture Production
dc.title	Empirical evidence for resilience of tropical forest photosynthesis in a warmer world.
dc.type	Journal Article
utslib.citation.volume	6
utslib.location.activity	England
utslib.for	0607 Plant Biology
utslib.for	0703 Crop and Pasture Production
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney
utslib.copyright.status	closed_access	*
dc.date.updated	2021-02-08T04:46:11Z
pubs.issue	10
pubs.publication-status	Published
pubs.volume	6
utslib.citation.issue	10

Abstract:

Tropical forests may be vulnerable to climate change^1-3 if photosynthetic carbon uptake currently operates near a high temperature limit^4-6. Predicting tropical forest function requires understanding the relative contributions of two mechanisms of high-temperature photosynthetic declines: stomatal limitation (H1), an indirect response due to temperature-associated changes in atmospheric vapour pressure deficit (VPD)⁷, and biochemical restrictions (H2), a direct temperature response^8,9. Their relative control predicts different outcomes-H1 is expected to diminish with stomatal responses to future co-occurring elevated atmospheric [CO₂], whereas H2 portends declining photosynthesis with increasing temperatures. Distinguishing the two mechanisms at high temperatures is therefore critical, but difficult because VPD is highly correlated with temperature in natural settings. We used a forest mesocosm to quantify the sensitivity of tropical gross ecosystem productivity (GEP) to future temperature regimes while constraining VPD by controlling humidity. We then analytically decoupled temperature and VPD effects under current climate with flux-tower-derived GEP trends in situ from four tropical forest sites. Both approaches showed consistent, negative sensitivity of GEP to VPD but little direct response to temperature. Importantly, in the mesocosm at low VPD, GEP persisted up to 38 °C, a temperature exceeding projections for tropical forests in 2100 (ref. ¹⁰). If elevated [CO₂] mitigates VPD-induced stomatal limitation through enhanced water-use efficiency as hypothesized^9,11, tropical forest photosynthesis may have a margin of resilience to future warming.

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http://hdl.handle.net/10453/145941