Absence of canopy temperature variation despite stomatal adjustment in Pinus sylvestris under multidecadal soil moisture manipulation

Global warming and droughts push forests closer to their thermal limits, altering tree carbon uptake and growth. To prevent critical overheating, trees can adjust their thermotolerance (T ), temperature and photosynthetic optima (T and A ), and canopy temperature (T ) to stay below damaging threshol...

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Bibliographic Details
Published in:The New phytologist 2023-10, Vol.240 (1), p.127-137
Main Authors: Gauthey, Alice, Bachofen, Christoph, Deluigi, Janisse, Didion-Gency, Margaux, D'Odorico, Petra, Gisler, Jonas, Mas, Eugénie, Schaub, Marcus, Schuler, Philipp, Still, Christopher J, Tunas, Alex, Grossiord, Charlotte
Format: Article
Language:English
Subjects:
Canopies
Canopy
Climate change
Drought
Global warming
Irrigation
Moisture content
Moisture effects
Overheating
Photosynthesis
Pine needles
Pine trees
Pinus sylvestris
Plant cover
Plastic properties
Plasticity
Seasonal variations
Soil
Soil dynamics
Soil moisture
Soil temperature
Stomata
Stomatal conductance
Temperature
Temperature tolerance
Thermal stress
Thresholds
Trees
Uptake
Water content
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Summary:Global warming and droughts push forests closer to their thermal limits, altering tree carbon uptake and growth. To prevent critical overheating, trees can adjust their thermotolerance (T ), temperature and photosynthetic optima (T and A ), and canopy temperature (T ) to stay below damaging thresholds. However, we lack an understanding of how soil droughts affect photosynthetic thermal plasticity and T regulation. In this study, we measured the effect of soil moisture on the seasonal and diurnal dynamics of net photosynthesis (A), stomatal conductance (g ), and T , as well as the thermal plasticity of photosynthesis (T , T , and A ), over the course of 1 yr using a long-term irrigation experiment in a drought-prone Pinus sylvestris forest in Switzerland. Irrigation resulted in higher needle-level A, g , T , and A compared with naturally drought-exposed trees. No daily or seasonal differences in T were observed between treatments. Trees operated below their thermal thresholds (T ), independently of soil moisture content. Despite strong T and T coupling, we provide evidence that drought reduces trees' temperature optimum due to a substantial reduction of g during warm and dry periods of the year. These findings provide important insights regarding the effects of soil drought on the thermal tolerance of P. sylvestris.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.19136