Centennial-scale atmospheric CO2 rise increased photosynthetic efficiency in a tropical tree species
Zwartsenberg, Sophie A., Sterck, Frank J., Haddad, Lenny, Schleucher, Jürgen, Anten, Niels P.R., Morales, Alejandro, Cernusak, Lucas A., Medina-Vega, José A., Rahman, Mizanur, Vlam, Mart, Heinrich, Ingo, and Zuidema, Pieter A. (2025) Centennial-scale atmospheric CO2 rise increased photosynthetic efficiency in a tropical tree species. New Phytologist, 246 (1). pp. 131-143.
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Abstract
Tropical forests substantially influence the terrestrial carbon sink. Their contributions to the forest carbon sink may increase due to the stimulation of photosynthesis by rising atmospheric CO2 (Ca); however, the magnitude of this effect is poorly quantified for tropical canopy trees.
We measured the ratio of two deuterium isotopomers of glucose derived from tree rings to estimate how photosynthetic efficiency (photorespiration-to-photosynthesis ratio) has responded to Ca rise at a centennial scale. Wood samples were obtained from Toona ciliata trees from three climatically distinct forests in Asia and Australia. We applied Bayesian mixed effect models to test how the isotopomer ratio changes with Ca, tree diameter (as a proxy for crown exposure), temperature, and precipitation.
Across all sites, long-term Ca rise increased photosynthetic efficiency, likely due to increased photosynthesis and the concurrent suppression of photorespiration. Increasing tree size reduced photosynthetic efficiency, likely due to reduced leaf internal CO2 at higher irradiance and stronger hydraulic limitation. Associations of photosynthetic efficiency with temperature and precipitation were inconclusive.
Our study reveals a centennial-scale association between photosynthetic efficiency and increasing Ca in canopy trees and provides a new and independent line of evidence for Ca-induced stimulation of photosynthetic efficiency in tropical forests.
| Item ID: | 88192 |
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| Item Type: | Article (Research - C1) |
| ISSN: | 1469-8137 |
| Keywords: | atmospheric CO2, canopy tree, photorespiration, photosynthesis, photosynthetic efficiency, Toona ciliata, tree-ring, tropical forest |
| Copyright Information: | © 2025 The Author(s). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Date Deposited: | 25 Mar 2026 23:17 |
| FoR Codes: | 41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50% 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310802 Plant biochemistry @ 50% |
| SEO Codes: | 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 50% 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180699 Terrestrial systems and management not elsewhere classified @ 50% |
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