TY - JOUR
T1 - Intensive leaf cooling promotes tree survival during a record heatwave
AU - Posch, Bradley C.
AU - Bush, Susan E.
AU - Koepke, Dan F.
AU - Schuessler, Alexandra
AU - Anderegg, Leander L.D.
AU - Aparecido, Luiza M.T.
AU - Blonder, Benjamin W.
AU - Guo, Jessica S.
AU - Kerr, Kelly L.
AU - Moran, Madeline E.
AU - Cooper, Hillary F.
AU - Doughty, Christopher E.
AU - Gehring, Catherine A.
AU - Whitham, Thomas G.
AU - Allan, Gerard J.
AU - Hultine, Kevin R.
N1 - Publisher Copyright:
Copyright © 2024 the Author(s).
PY - 2024/10/22
Y1 - 2024/10/22
N2 - Increasing heatwaves are threatening forest ecosystems globally. Leaf thermal regulation and tolerance are important for plant survival during heatwaves, though the interaction between these processes and water availability is unclear. Genotypes of the widely distributed foundation tree species Populus fremontii were studied in a controlled common garden during a record summer heatwave—where air temperature exceeded 48 °C. When water was not limiting, all genotypes cooled leaves 2 to 5 °C below air temperatures. Homeothermic cooling was disrupted for weeks following a 72-h reduction in soil water, resulting in leaf temperatures rising 3 °C above air temperature and 1.3 °C above leaf thresholds for physiological damage, despite the water stress having little effect on leaf water potentials. Tradeoffs between leaf thermal safety and hydraulic safety emerged but, regardless of water use strategy, all genotypes experienced significant leaf mortality following water stress. Genotypes from warmer climates showed greater leaf cooling and less leaf mortality after water stress in comparison with genotypes from cooler climates. These results illustrate how brief soil water limitation disrupts leaf thermal regulation and potentially compromises plant survival during extreme heatwaves, thus providing insight into future scenarios in which ecosystems will be challenged with extreme heat and unreliable soil water access.
AB - Increasing heatwaves are threatening forest ecosystems globally. Leaf thermal regulation and tolerance are important for plant survival during heatwaves, though the interaction between these processes and water availability is unclear. Genotypes of the widely distributed foundation tree species Populus fremontii were studied in a controlled common garden during a record summer heatwave—where air temperature exceeded 48 °C. When water was not limiting, all genotypes cooled leaves 2 to 5 °C below air temperatures. Homeothermic cooling was disrupted for weeks following a 72-h reduction in soil water, resulting in leaf temperatures rising 3 °C above air temperature and 1.3 °C above leaf thresholds for physiological damage, despite the water stress having little effect on leaf water potentials. Tradeoffs between leaf thermal safety and hydraulic safety emerged but, regardless of water use strategy, all genotypes experienced significant leaf mortality following water stress. Genotypes from warmer climates showed greater leaf cooling and less leaf mortality after water stress in comparison with genotypes from cooler climates. These results illustrate how brief soil water limitation disrupts leaf thermal regulation and potentially compromises plant survival during extreme heatwaves, thus providing insight into future scenarios in which ecosystems will be challenged with extreme heat and unreliable soil water access.
KW - climate change
KW - heat tolerance
KW - plant hydraulics
KW - stomatal conductance
KW - thermal regulation
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U2 - 10.1073/pnas.2408583121
DO - 10.1073/pnas.2408583121
M3 - Article
C2 - 39401366
AN - SCOPUS:85206274488
SN - 0027-8424
VL - 121
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 43
M1 - e2408583121
ER -