Tracing plant source water dynamics during drought by continuous transpiration measurements: An in-situ stable isotope approach

Angelika Kübert, Maren Dubbert, Ines Bamberger, Kathrin Kühnhammer, Matthias Beyer, Joost van Haren, Kinzie Bailey, Jia Hu, Laura K. Meredith, S. Nemiah Ladd, Christiane Werner

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

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 2H 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 δ18OT-values were a good proxy for δ18OX-values under well-watered and drought conditions that matched the rainforest's water source. Transpiration-derived δ18OX-values were mostly lower than CVE-derived values. Transpiration-derived δ2HX-values were relatively high compared to source water and consistently higher than CVE-derived values during drought. Tracing the 2H 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.

Original languageEnglish (US)
Pages (from-to)133-149
Number of pages17
JournalPlant Cell and Environment
Volume46
Issue number1
DOIs
StatePublished - Jan 2023

Keywords

  • CRDS
  • cryogenic vacuum extraction
  • herbaceous species
  • laser spectrometry
  • method comparison
  • nonwoody
  • woody
  • xylem water

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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