Intensive leaf cooling promotes tree survival during a record heatwave

Bradley C. Posch, Susan E. Bush, Dan F. Koepke, Alexandra Schuessler, Leander L.D. Anderegg, Luiza M.T. Aparecido, Benjamin W. Blonder, Jessica S. Guo, Kelly L. Kerr, Madeline E. Moran, Hillary F. Cooper, Christopher E. Doughty, Catherine A. Gehring, Thomas G. Whitham, Gerard J. Allan, Kevin R. Hultine

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article numbere2408583121
JournalProceedings of the National Academy of Sciences of the United States of America
Volume121
Issue number43
DOIs
StatePublished - Oct 22 2024

Keywords

  • climate change
  • heat tolerance
  • plant hydraulics
  • stomatal conductance
  • thermal regulation

ASJC Scopus subject areas

  • General

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