Long‐term drought effects on the thermal sensitivity of Amazon forest trees

The continued functioning of tropical forests under climate change depends on their resilience to drought and heat. However, there is little understanding of how tropical forests will respond to combinations of these stresses, and no field studies to date have explicitly evaluated whether sustained...

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Bibliographic Details
Published in:	Plant, cell and environment Vol. 46; no. 1; pp. 185 - 198
Main Authors:	Docherty, Emma M., Gloor, Emanuel, Sponchiado, Daniela, Gilpin, Martin, Pinto, Carlos A. D., Junior, Haroldo M., Coughlin, Ingrid, Ferreira, Leandro, Junior, João A. S., Costa, Antonio C. L., Meir, Patrick, Galbraith, David
Format:	Journal Article
Language:	English
Published:	United States Wiley Subscription Services, Inc 01-01-2023 John Wiley and Sons Inc
Subjects:	Air temperature Amazon rainforest chlorophyll a fluorescence Climate change Climate models Damage tolerance Drought drought and heat stress interactions Forests Original Photosynthesis Photosystem II Photosystem II Protein Complex Plant species Quantum efficiency Respiration thermal traits thermotolerance throughfall exclusion Trees tropical evergreen trees Tropical forests chlorophyll a fluorescence drought and heat stress interactions thermotolerance Amazon rainforest photosynthesis throughfall exclusion tropical evergreen trees thermal traits respiration
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Summary:	The continued functioning of tropical forests under climate change depends on their resilience to drought and heat. However, there is little understanding of how tropical forests will respond to combinations of these stresses, and no field studies to date have explicitly evaluated whether sustained drought alters sensitivity to temperature. We measured the temperature response of net photosynthesis, foliar respiration and the maximum quantum efficiency of photosystem II (Fv/Fm) of eight hyper‐dominant Amazonian tree species at the world's longest‐running tropical forest drought experiment, to investigate the effect of drought on forest thermal sensitivity. Despite a 0.6°C–2°C increase in canopy air temperatures following long‐term drought, no change in overall thermal sensitivity of net photosynthesis or respiration was observed. However, photosystem II tolerance to extreme‐heat damage (T50) was reduced from 50.0 ± 0.3°C to 48.5 ± 0.3°C under drought. Our results suggest that long‐term reductions in precipitation, as projected across much of Amazonia by climate models, are unlikely to greatly alter the response of tropical forests to rising mean temperatures but may increase the risk of leaf thermal damage during heatwaves.
ISSN:	0140-7791 1365-3040
DOI:	10.1111/pce.14465