Intensive leaf cooling promotes tree survival during a record heatwave

• 成果类型: Article
• 署名作者: Posch, Bradley C.; Bush, Susan E.; Koepke, Dan F.; Schuessler, Alexandra; Anderegg, Leander L. D.; Aparecido, Luiza M. T.; Blonder, Benjamin W.; Guo, Jessica S.; Kerr, Kelly L.; Moran, Madeline E.; Cooper, Hillary F.; Doughty, Christopher E.; Gehring, Catherine A.; Whitham, Thomas G.; Allan, Gerard J.; Hultine, Kevin R.
• 署名单位: University of California System; University of California Berkeley; University of California System; University of California Santa Barbara; Utah System of Higher Education; University of Utah; University of Arizona; Arizona State University; Arizona State University-Tempe; Northern Arizona University; Northern Arizona University; Northern Arizona University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15111
• DOI: 10.1073/pnas.2408583121
• 发表日期: 2024-10-22
• 关键词: drought tolerance; mortality; populus; vulnerability; cottonwoods; pressure; traits; plants; LIMITS

摘要

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 Populusfremontii were studied in a controlled common garden during a record summer heatwave-where air temperature exceeded 48 degrees C. When water was not limiting, all genotypes cooled leaves 2 to 5 degrees C below air temperatures. Homeothermic cooling was disrupted for weeks following a 72- h reduction in soil water, resulting in leaf temperatures rising 3 degrees C above air temperature and 1.3 degrees 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.