Abiotic Stress/Whole Plant Bio

Abstract

CS-14-4 - The effects of warming on the performance of tropical trees

Monday, July 16
2:03 PM - 2:23 PM

Global warming may severely impact lowland tropical forests by bringing tropical trees closer to their physiological thresholds. Given the importance of tropical forests in the regulation of the earth’s climate it is important to understand how rising temperatures affect the capacity of tropical trees to take up and store carbon. We measured photosynthesis and dark respiration at different temperatures for >40 tree and liana species in the upper-canopy of two tropical forests in Panama to identify species and functional group differences in short-term temperature sensitivity. In addition, we determined the capacity for thermal acclimation of photosynthesis and respiration for seedlings of three tree species in a growth chamber experiment. While rates of photosynthesis and respiration differed enormously, the key temperature-response parameters—the optimum temperature for photosynthesis (TOpt), and the slope of the increase in respiration with rising temperature—were consistent across species. Photosynthesis peaked around 30–31°C; the decrease above TOpt was largely driven by reduced stomatal conductance, not by biochemical limitations. Respiration more than doubled for every 10°C increase in temperature (Q10≈2.3). Both photosynthesis and respiration acclimated to warming, but high growth temperatures were nonetheless supra-optimal for photosynthesis. The observed convergence of short-term temperature response traits among ecologically diverse species should facilitate scaling temperature-dependent carbon uptake in species rich tropical forests. In the long term, thermal acclimation reduces the direct negative impact of moderate warming of tropical trees. Indirect effects of warming, through rising atmospheric drought, are likely to govern the response of tropical forests to global warming.


 

Co-Authors

Klaus Winter – Smithsonian Tropical Research Institute

Martijn Slot, PhD

Postdoctoral fellow
Smithsonian Tropical Research Institute

Presentation(s):

Send Email for Martijn Slot


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CS-14-4 - The effects of warming on the performance of tropical trees



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