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Kübert A, Dubbert M, Bamberger I, Kühnhammer K, Beyer M, van Haren J, Bailey K, Hu J, Meredith LK, Nemiah Ladd S, Werner C. Tracing plant source water dynamics during drought by continuous transpiration measurements: An in-situ stable isotope approach. PLANT, CELL & ENVIRONMENT 2023; 46:133-149. [PMID: 36305510 DOI: 10.1111/pce.14475] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/21/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The isotopic composition of xylem water (δX ) is of considerable interest for plant source water studies. In-situ monitored isotopic composition of transpired water (δT ) could provide a nondestructive proxy for δX -values. Using flow-through leaf chambers, we monitored 2-hourly δT -dynamics in two tropical plant species, one canopy-forming tree and one understory herbaceous species. In an enclosed rainforest (Biosphere 2), we observed δT -dynamics in response to an experimental severe drought, followed by a 2 H deep-water pulse applied belowground before starting regular rain. We also sampled branches to obtain δX -values from cryogenic vacuum extraction (CVE). Daily flux-weighted δ18 OT -values were a good proxy for δ18 OX -values under well-watered and drought conditions that matched the rainforest's water source. Transpiration-derived δ18 OX -values were mostly lower than CVE-derived values. Transpiration-derived δ2 HX -values were relatively high compared to source water and consistently higher than CVE-derived values during drought. Tracing the 2 H deep-water pulse in real-time showed distinct water uptake and transport responses: a fast and strong contribution of deep water to canopy tree transpiration contrasting with a slow and limited contribution to understory species transpiration. Thus, the in-situ transpiration method is a promising tool to capture rapid dynamics in plant water uptake and use by both woody and nonwoody species.
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Affiliation(s)
- Angelika Kübert
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland
| | - Maren Dubbert
- Isotope Biogeochemistry and Gas Fluxes, Landscape Functioning, ZALF, Müncheberg, Germany
| | - Ines Bamberger
- Atmospheric Chemistry Group, University of Bayreuth, Bayreuth, Germany
| | - Kathrin Kühnhammer
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Institute for Geoecology, Technical University of Braunschweig, Braunschweig, Germany
| | - Matthias Beyer
- Institute for Geoecology, Technical University of Braunschweig, Braunschweig, Germany
| | - Joost van Haren
- Biosphere 2, University of Arizona, Tucson, Arizona, USA
- Honors College, University of Arizona, Tucson, Arizona, USA
| | - Kinzie Bailey
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Jia Hu
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Laura K Meredith
- Biosphere 2, University of Arizona, Tucson, Arizona, USA
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - S Nemiah Ladd
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Biogeochemistry Group, Department of Environmental Sciences, University of Basel, Basel, Switzerland
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Abstract
The availability and quality of freshwater currently represent one of the great issues for mankind [...]
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