Minimum Leaf Conductance ( g min ) Is Higher in the Treeline of Pinus uncinata Ram. in the Pyrenees: Michaelis' Hypothesis Revisited.

Autor:	Bueno A; Chair of Botany II - Ecophysiology and Vegetation Ecology, Julius von Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany., Alonso-Forn D; Unidad de Recursos Forestales, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain., Peguero-Pina JJ; Unidad de Recursos Forestales, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.; Instituto Agroalimentario de Aragón -IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain., de Souza AX; Chair of Botany II - Ecophysiology and Vegetation Ecology, Julius von Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany., Ferrio JP; Unidad de Recursos Forestales, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.; Aragon Agency for Research and Development (ARAID), Zaragoza, Spain., Sancho-Knapik D; Unidad de Recursos Forestales, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.; Instituto Agroalimentario de Aragón -IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain., Gil-Pelegrín E; Unidad de Recursos Forestales, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.
Jazyk:	angličtina
Zdroj:	Frontiers in plant science [Front Plant Sci] 2022 Jan 24; Vol. 12, pp. 786933. Date of Electronic Publication: 2022 Jan 24 (Print Publication: 2021).
DOI:	10.3389/fpls.2021.786933
Abstrakt:	The search for a universal explanation of the altitudinal limit determined by the alpine treeline has given rise to different hypotheses. In this study, we revisited Michaelis' hypothesis which proposed that an inadequate "ripening" of the cuticle caused a greater transpiration rate during winter in the treeline. However, few studies with different explanations have investigated the role of passive mechanisms of needles for protecting against water loss during winter in conifers at the treeline. To shed light on this, the cuticular transpiration barrier was studied in the transition from subalpine Pinus uncinata forests to alpine tundra at the upper limit of the species in the Pyrenees. This upper limit of P. uncinata was selected here as an example of the ecotones formed by conifers in the temperate mountains of the northern hemisphere. Our study showed that minimum leaf conductance in needles from upper limit specimens was higher than those measured in specimens living in the lower levels of the sub-alpine forest and also displayed lower cuticle thickness values, which should reinforce the seminal hypothesis by Michaelis. Our study showed clear evidence that supports the inadequate development of needle cuticles as one of the factors that lead to increased transpirational water losses during winter and, consequently, a higher risk of suffering frost drought. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Bueno, Alonso-Forn, Peguero-Pina, de Souza, Ferrio, Sancho-Knapik and Gil-Pelegrín.)
Databáze:	MEDLINE
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