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Journal article
Bark water affects the isotopic composition of xylem water in tropical rainforest trees
Frontiers in Forests and Global Change, Vol.7, pp.1-16
2025
Abstract
The movement of water between xylem and inner bark (phloem and associated tissues), mostly driven by water potential differences, forms a key part of the diel transpiration cycle. It is not known how the use of water stored in bark at the diel transpiration cycle may influence the isotopic composition of xylem water. Understanding these possible effects is a major challenge for the identification of tree water sources and the interpretation of water use patterns using isotopes. Here, we examined the variation in the isotopic composition of water in inner bark and xylem at the diel scale and assessed how this varied in relation to traits and water use strategies on nine tree species in a tropical rainforest at the end of the dry season. We measured δ 2 H and δ 18 O in bark and xylem at two shallow depths: 'outer xylem' and 'inner xylem' (up to ~0.5 cm and ~1 cm from inner bark, respectively) collected at predawn, morning and midday. Considering all species together, the average isotopic composition of water in bark and outer xylem was similar at predawn and midday, suggesting water exchange between these tissues was reflected at these times, but differed significantly in the morning during increased transpiration. Results suggest that bark-xylem water exchange throughout the diel transpiration cycle affects the isotopic composition of xylem water in tropical rainforest trees. Furthermore, variations in δ 2 H and δ 18 O between xylem and bark were more pronounced in a deep-rooted, more isohydric species with dense wood than in a shallow-rooted, more anisohydric species with low wood density. This may suggest differences related to traits and hydraulic strategies in the reliance of bark-stored water across the diel cycle to buffer changes in xylem water potential. We discuss implications for interpreting tropical tree water sources in relation to water use strategies.
Details
- Title
- Bark water affects the isotopic composition of xylem water in tropical rainforest trees
- Authors
- Adriana Vega Grau (Corresponding Author) - University of the Sunshine Coast, Queensland, Tropical Forests and People Research CentreJohn Herbohn - University of the Sunshine Coast, Queensland, Australian Centre for Pacific Islands ResearchSusanne Schmidt - The University of QueenslandJeffrey J McDonnell - University of Saskatchewan
- Publication details
- Frontiers in Forests and Global Change, Vol.7, pp.1-16
- Publisher
- Frontiers Research Foundation
- Date published
- 2025
- DOI
- 10.3389/ffgc.2024.1457522
- ISSN
- 2624-893X
- Copyright note
- © 2024 Vega Grau, Herbohn, Schmidt and McDonnell. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
- Data Availability
- The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
- Grant note
- This work was supported by an Australian Government Research Training Program Scholarship Stipend, an Australian Government Research Training Program Tuition Fee Offset Scholarship, the Wet Tropics Management Authority, the Skyrail Rainforest Foundation and the Tropical Forests and People Research Centre.
- Organisation Unit
- Australian Centre for Pacific Islands Research; Tropical Forests and People Research Centre; Forest Research Institute
- Language
- English
- Record Identifier
- 991095746102621
- Output Type
- Journal article
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