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Continuous stem water potential measurements of a diffuse-porous tree species offer new insights into tree water relations
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  • Simon Haberstroh,
  • Fabio Scarpa,
  • Stefan Seeger,
  • Andreas Christen,
  • Christiane Werner
Simon Haberstroh
Albert-Ludwigs-Universitat Freiburg Fakultat fur Umwelt und Naturliche Ressourcen

Corresponding Author:[email protected]

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Fabio Scarpa
Albert-Ludwigs-Universitat Freiburg Fakultat fur Umwelt und Naturliche Ressourcen
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Stefan Seeger
Georg-August-Universitat Gottingen Department fur Nutzpflanzenwissenschaften
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Andreas Christen
Albert-Ludwigs-Universitat Freiburg Fakultat fur Umwelt und Naturliche Ressourcen
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Christiane Werner
Albert-Ludwigs-Universitat Freiburg Fakultat fur Umwelt und Naturliche Ressourcen
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Abstract

Water potential is a crucial parameter for assessing tree water status and hydraulic strategies. However, methods for measuring water potential, such as the Scholander pressure chamber, are destructive and discontinuous, and difficult to perform in tall forests. Consequently, important dynamics in water potentials, particularly during short-term drought, are difficult to capture. Recent advancements have introduced low-maintenance sensors capable of measuring continuous, high-resolution stem water potentials. If applicable to forest trees, such sensors hold the potential to significantly enhance our understanding of tree water relations. We evaluated these sensors in a temperate, diffuse-porous tree species ( Carpinus betulus) over a growing season marked by dry-down periods and heat. Concurrent measurements of branch water potential, sap flow, and environmental factors (air temperature, vapor pressure deficit, and soil water content) were conducted. Midday stem water potentials of C. betulus reached minimum values of -3.39 ± 0.10 MPa and exhibited pronounced seasonal fluctuations, mirroring changes in environmental conditions and sap flow. Comparison of stem water potentials with Scholander-type measurements revealed a very good correlation with predawn (R 2 = 0.98) and a general agreement with midday measurements (R 2 = 0.71). Diurnal variations in stem water potentials and sap flow exhibited a hysteresis, consistent with other plant parameters. In this first assessment, the agreement with Scholander-type measurements, sap flow, and environmental parameters suggests the tested water potential sensors yield reliable data. If applicable to other tree species, including conifers, these sensors could significantly advance our understanding of tree water relations and their role in forest drought responses.
25 Jul 2024Submitted to Ecohydrology
26 Jul 2024Submission Checks Completed
26 Jul 2024Assigned to Editor
05 Aug 2024Review(s) Completed, Editorial Evaluation Pending
05 Aug 2024Reviewer(s) Assigned
31 Oct 2024Editorial Decision: Revise Major