Minimum Leaf Conductance (gmin) Is Higher in the Treeline of Pinus uncinata Ram. in the Pyrenees: Michaelis Hypothesis Revisited
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Date
2022
Authors
Bueno, A.Alonso Forn, David
Peguero Pina, José Javier
de Souza, Aline Xavier
Ferrio Díaz, Juan Pedro
Sancho Knapik, Domingo
Gil Pelegrín, Eustaquio
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Abstract
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.
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Bibliographic citation
Domínguez, E., Heredia, A., Molina, I., & Bueno, A. (2023). Plant Cuticle: From Biosynthesis To Ecological Functions. Frontiers Media Sa., 2023, 228-234
AGROVOC subjects
Pinus uncinataBosques
Transpiración
Sequía
Sponsorship
The work of DA-F was supported by an FPI-INIA contract BES2017-081208. AS was a recipient of a doctoral fellowship from
the Brazilian National Council for Scientific and Technological
Development (CNPq). DA-F, JF, JP-P, DS-K, and EG-P
acknowledge the financial contribution by Reference Group
H09_20R (Gobierno de Aragón, Spain)