Limits of thermal and hydrological tolerance in a foundation tree species (Populus fremontii) in the desert southwestern United States.

Autor:	Moran ME; School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA., Aparecido LMT; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA., Koepke DF; Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA., Cooper HF; Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA., Doughty CE; School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, 86011, USA., Gehring CA; Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA., Throop HL; School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA.; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA., Whitham TG; Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA., Allan GJ; Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA., Hultine KR; Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA.
Jazyk:	angličtina
Zdroj:	The New phytologist [New Phytol] 2023 Dec; Vol. 240 (6), pp. 2298-2311. Date of Electronic Publication: 2023 Sep 07.
DOI:	10.1111/nph.19247
Abstrakt:	Populus fremontii is among the most dominant, and ecologically important riparian tree species in the western United States and can thrive in hyper-arid riparian corridors. Yet, P. fremontii forests have rapidly declined over the last decade, particularly in places where temperatures sometimes exceed 50°C. We evaluated high temperature tolerance of leaf metabolism, leaf thermoregulation, and leaf hydraulic function in eight P. fremontii populations spanning a 5.3°C mean annual temperature gradient in a well-watered common garden, and at source locations throughout the lower Colorado River Basin. Two major results emerged. First, despite having an exceptionally high T crit (the temperature at which Photosystem II is disrupted) relative to other tree taxa, recent heat waves exceeded T crit , requiring evaporative leaf cooling to maintain leaf-to-air thermal safety margins. Second, in midsummer, genotypes from the warmest locations maintained lower midday leaf temperatures, a higher midday stomatal conductance, and maintained turgor pressure at lower water potentials than genotypes from more temperate locations. Taken together, results suggest that under well-watered conditions, P. fremontii can regulate leaf temperature below T crit along the warm edge of its distribution. Nevertheless, reduced Colorado River flows threaten to lower water tables below levels needed for evaporative cooling during episodic heat waves. (© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation.)
Databáze:	MEDLINE
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