In:
New Phytologist, Wiley, Vol. 240, No. 1 ( 2023-10), p. 127-137
Abstract:
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 crit ), temperature and photosynthetic optima ( T opt and A opt ), and canopy temperature ( T can ) to stay below damaging thresholds. However, we lack an understanding of how soil droughts affect photosynthetic thermal plasticity and T can regulation. In this study, we measured the effect of soil moisture on the seasonal and diurnal dynamics of net photosynthesis ( A ), stomatal conductance ( g s ), and T can , as well as the thermal plasticity of photosynthesis ( T crit , T opt , and A opt ), 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 s , T opt , and A opt compared with naturally drought‐exposed trees. No daily or seasonal differences in T can were observed between treatments. Trees operated below their thermal thresholds ( T crit ), independently of soil moisture content. Despite strong T can and T air coupling, we provide evidence that drought reduces trees' temperature optimum due to a substantial reduction of g s 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 .
Type of Medium:
Online Resource
ISSN:
0028-646X
,
1469-8137
Language:
English
Publisher:
Wiley
Publication Date:
2023
detail.hit.zdb_id:
208885-X
detail.hit.zdb_id:
1472194-6
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