Evapotranspiration regulates leaf temperature and respiration in dryland vegetation

Kibler, Christopher L., Trugman, Anna T., Roberts, Dar A., Still, Christopher J., Scott, Russell L., Caylor, Kelly K., Stella, John C. and Singer, Michael Bliss ORCID: https://orcid.org/0000-0002-6899-2224 2023. Evapotranspiration regulates leaf temperature and respiration in dryland vegetation. Agricultural and Forest Meteorology 339 , 109560. 10.1016/j.agrformet.2023.109560

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Abstract

Evapotranspiration regulates energy flux partitioning at the leaf surface, which in turn regulates leaf temperature. However, the mechanistic relationship between evapotranspiration and leaf temperature remains poorly constrained. In this study, we present a novel mechanistic model to predict leaf temperature as a linearized function of the evaporative fraction. The model is validated using measurements from infrared radiometers mounted on two flux towers in Arizona, USA, which measure canopies of Prosopis velutina with contrasting water availability. Both the observations and model predictions reveal that leaf temperature equilibrates with air temperature when latent heat flux consumes all of the energy incident on the leaf surface. Leaf temperature exceeds air temperature when there is a net input of energy into the leaf tissue. The flux tower observations revealed that evaporative cooling reduced canopy leaf temperature by ca. 1–5 °C, depending on water availability. Evaporative cooling also enhanced net carbon uptake by reducing leaf respiration by ca. 15% in the middle of the growing season. The regulation of leaf temperature by evapotranspiration and the resulting impact on net carbon uptake represents an important link between plant water and carbon cycles that has received little attention in literature. The model presented here provides a mechanistic framework to quantify leaf evaporative cooling and examine its impacts on plant physiological function.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Earth and Environmental Sciences
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Start Date: 2023-06-08
Publisher:	Elsevier
ISSN:	0168-1923
Date of First Compliant Deposit:	26 June 2023
Date of Acceptance:	6 June 2023
Last Modified:	30 Jun 2023 05:53
URI:	https://orca.cardiff.ac.uk/id/eprint/160588

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