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Detailed in-situ leaf energy budget permits the assessment of leaf aerodynamic resistance as a key to enhance non-evaporative cooling under drought
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  • Jonathan Muller,
  • Eyal Rotenberg,
  • Fedor Tatarinov,
  • Itay Oz,
  • Dan Yakir
Jonathan Muller
Weizmann Institute of Science

Corresponding Author:[email protected]

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Eyal Rotenberg
Weizmann Institute of Science
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Fedor Tatarinov
Weizmann Institute of Science
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Itay Oz
Weizmann Institute of Science
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Dan Yakir
Weizmann Institute of Science
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Abstract

The modulation of the leaf energy budget components to maintain optimal leaf temperature are fundamental aspects of plant functioning and survival. Better understanding these aspects becomes increasingly important under a drying and warming climate when cooling through evapotranspiration (ET) is suppressed. Combining novel measurements and theoretical estimates, we obtained unusually comprehensive twig-scale leaf energy budgets under extreme field conditions in droughted (suppressed ET) and non-droughted (enhanced ET) plots of a semi-arid pine forest. Under the same high mid-summer radiative load, leaf cooling shifted from relying on nearly equal contributions of sensible ( H) and latent ( LE) energy fluxes in non-droughted trees to relying almost exclusively on H in droughted ones, with no change in leaf temperature. Relying on our detailed leaf energy budget, we could demonstrate that this is due to a 2× reduction in leaf aerodynamic resistance. This capability for LE-to-H shift in leaves of mature Aleppo pine trees under droughted field conditions without increasing leaf temperature is likely a critical factor in the resilience and relatively high productivity of this important Mediterranean tree species under drying conditions.