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<Emphasis Type="BoldItalic">Key message</Emphasis> <p><b>Low-altitude trees allocate a greater proportion of assimilated carbon to growth, whereas treeline trees preferentially allocate carbon to storage to cope with environmental constraints.</b></p> Abstract <p>Stomatal conductance contributes decisively to regulate water and carbon fluxes and constitutes a fundamental mechanism to guarantee water conservation and leaf survival in water-limited environments. There is controversy with respect to the role of stomatal traits in the determination of stomatal conductance values and their variations through time. We analyzed the stomatal traits, leaf phenology, leaf water potentials and the maximum (g<sub>max</sub>) and minimum (g<sub>min</sub>) stomatal conductance in two Mediterranean <i>Quercus</i> species (<i>Quercus faginea</i> Lam. and <i>Q. pyrenaica</i> Willd.) and their hybrids, as well as their changes across a climatic gradient. Our purpose was to study whether the stomatal traits determine the possible differences in conductance between genetic groups and between sites. <i>Q. faginea</i> exhibited more drought-adapted traits (larger stomatal density, but lower stomatal index and g<sub>max</sub>) than <i>Q. pyrenaica</i>. Hybrids possessed intermediate stomatal traits between the two parent species but maintained g<sub>max</sub> values similar to those of <i>Q. pyrenaica.</i> Mean leaf longevity was shorter for <i>Q. pyrenaica</i> and the hybrids with respect to <i>Q. faginea</i>, mainly because of delayed leaf emergence. This suggests that the higher g<sub>max</sub> of <i>Q. pyrenaica</i> and hybrids may be due to the need to increase CO<sub>2</sub> assimilation during the shorter time available to compensate investments in leaf production. Within a single genetic group, there were no changes in stomatal traits across the climatic gradient. However, g<sub>max</sub> was significantly larger and g<sub>min</sub> lower for all groups at the warmest site, which indicates that operational stomatal conductance would vary independently of stomatal traits.</p>

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Differences in stomatal conductance between two mediterranean oaks and their hybrids across a climatic gradient: what do they respond to?

  • 期刊论文

  • 发表日期：

    2026年2月10日

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  • S. González-Carrera,
  • A. Escudero,
  • I. Martín,
  • C. Talma,
  • M. Martínez-Ortega,
  • S. Mediavilla

摘要

Key message

Low-altitude trees allocate a greater proportion of assimilated carbon to growth, whereas treeline trees preferentially allocate carbon to storage to cope with environmental constraints.

Abstract

Stomatal conductance contributes decisively to regulate water and carbon fluxes and constitutes a fundamental mechanism to guarantee water conservation and leaf survival in water-limited environments. There is controversy with respect to the role of stomatal traits in the determination of stomatal conductance values and their variations through time. We analyzed the stomatal traits, leaf phenology, leaf water potentials and the maximum (gmax) and minimum (gmin) stomatal conductance in two Mediterranean Quercus species (Quercus faginea Lam. and Q. pyrenaica Willd.) and their hybrids, as well as their changes across a climatic gradient. Our purpose was to study whether the stomatal traits determine the possible differences in conductance between genetic groups and between sites. Q. faginea exhibited more drought-adapted traits (larger stomatal density, but lower stomatal index and gmax) than Q. pyrenaica. Hybrids possessed intermediate stomatal traits between the two parent species but maintained gmax values similar to those of Q. pyrenaica. Mean leaf longevity was shorter for Q. pyrenaica and the hybrids with respect to Q. faginea, mainly because of delayed leaf emergence. This suggests that the higher gmax of Q. pyrenaica and hybrids may be due to the need to increase CO2 assimilation during the shorter time available to compensate investments in leaf production. Within a single genetic group, there were no changes in stomatal traits across the climatic gradient. However, gmax was significantly larger and gmin lower for all groups at the warmest site, which indicates that operational stomatal conductance would vary independently of stomatal traits.