Lehmann et al. (2025) Soil and tree stem xylem water isotope data from two pan-European sampling campaigns

Identification

• Journal: Earth system science data
• Year: 2025
• Date: 2025-11-14
• Authors: Marco M. Lehmann, Josie Geris, Ilja van Meerveld, Daniele Penna, Youri Rothfuss, Matteo Verdone, Pertti Ala‐aho, Mátyás Árvai, Alise Babre, Philippe Balandier, Fabian Bernhard, Lukrecija Butorac, Simon Carrière, Natalie Ceperley, Zuosinan Chen, Alicia Correa, Haoyu Diao, David Dubbert, Maren Dubbert, Fabio Ercoli, Marius G. Floriancic, Alligin Ghazoul, Teresa E. Gimeno, Damien Gounelle, Frank Hagedorn, Christophe Hissler, Frédéric Huneau, Alberto Iraheta, Tamara Jakovljević, Nerantzis Kazakis, Zoltán Kern, Laura Kinzinger, Karl Knaebel, Johannes Kobler, Jiří Kocum, Charlotte Koeber, Gerbrand Koren, Angelika Kübert, Dawid Kupka, Samuel Le Gall, Aleksi Lehtonen, Thomas Leydier, Philippe Malagoli, Francesca Sofia Manca di Villahermosa, Chiara Marchina, Núria Martínez‐Carreras, Nicolas Martin‐StPaul, Hannu Marttila, Aline Meyer Oliveira, Gaël Monvoisin, Natalie Orlowski, Kadi Palmik‐Das, Aurel Perşoiu, Andreï Popa, Egor Prikaziuk, Cécile Quantin, Katja T. Rinne‐Garmston, Clara Rohde, Martin Šanda, Matthias Saurer, Daniel Schulz, Michael Stockinger, Christine Stumpp, Jean‐Stéphane Venisse, Lukáš Vlček, Stylianos Voudouris, Björn Weeser, Mark E. Wilkinson, Giulia Zuecco, Katrin Meusburger
• DOI: 10.5194/essd-17-6129-2025

Research Groups

A large consortium of researchers from numerous European universities and research institutes, coordinated by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Short Summary

This paper presents a pan-European dataset of stable hydrogen (δ2H) and oxygen (δ18O) isotope ratios in soil and tree stem xylem water from 40 forest sites, collected during spring and summer 2023, revealing spatial and seasonal variations in isotopic signatures and species-specific differences in water uptake.

Objective

• To provide the first systematic, large-scale isotope dataset for soil and stem xylem water across Europe to enhance understanding of tree water uptake, facilitate ecohydrological model testing, and support isotope mapping.

Study Configuration

• Spatial Scale: 40 forest sites (beech, spruce, or mixed) across 18 European countries, covering a range of temperate and cold climates and elevations from 14 to 1870 m above sea level.
• Temporal Scale: Two sampling campaigns in 2023: spring (25 May to 16 June) and summer (17 August to 18 September).

Methodology and Data

• Models used: None directly used for data generation or analysis in this paper; the dataset is intended for ecohydrological model testing and isotope mapping.
• Data sources:
  • Field sampling: 381 soil samples (up to 5 depths, 0-90 cm) and 311 stem xylem samples (from 3 trees per site) collected from 40 sites in 18 European countries following a standardized protocol.
  • Laboratory analysis: Water extracted using cryogenic vacuum distillation. Isotopic composition (δ2H and δ18O) measured using a laser cavity ring-down spectrometer (L2140-i, Picarro Inc.) with a micro-combustion module. A subset of samples also analyzed with an isotope ratio mass spectrometer (IRMS, DeltaPlus XP, Finnigan MAT).
  • Metadata: Comprehensive site-specific (geographic, climate, slope, stand type), soil-specific (type, texture, maximum depth), and tree-specific (species, height, diameter at breast height, canopy cover) metadata.

Main Results

• The dataset comprises 381 soil and 311 stem xylem samples from 40 sites in 18 European countries.
• Data quality checks revealed a high mean total extraction efficiency of 100.6 % and a mean extracted water amount greater than 1 mL.
• Isotopic signatures (δ2H and δ18O) varied significantly with geographic origin (latitude, longitude, and elevation) and seasonally from spring to summer across all sites.
• Soil water isotope ratios were generally closer to the Global Meteoric Water Line (GMWL) than stem xylem water.
• Stem xylem water was systematically enriched in δ2H compared to soil water, leading to a deviation from the GMWL.
• Isotopic enrichment of stem xylem water at mixed forest sites was larger for spruce trees than for beech trees.
• Mean δ18O values were higher in summer than in spring for stem xylem water of both species and for shallower soil water (0–30 cm). Deeper soil water (30–90 cm) showed no significant seasonal difference.
• The isotopic composition of stem xylem water overlapped with soil water at more beech sites (68 % in spring, 84 % in summer) than spruce sites (41 % in spring, 48 % in summer).
• Mean species difference (spruce-beech) in δ2H and δ18O values was 5.5 ‰ and 0.8 ‰ in spring, and 9.5 ‰ and 1.1 ‰ in summer, respectively, indicating spruce xylem water tended to be isotopically enriched.
• Cryogenic water extraction biases were observed, with a small positive offset for δ2H (mean 0.7 ‰) and δ18O (mean 0.3 ‰) between laser spectrometer and IRMS measurements, and species-dependent offsets for stem xylem.

Contributions

• Creation of the first systematic, large-scale (pan-European) dataset of soil and stem xylem water isotopes for two common tree species (Fagus sylvatica and Picea abies).
• Implementation of a standardized sampling protocol across 40 sites in 18 countries, coupled with centralized laboratory and analytical work to minimize inter-laboratory biases.
• Provision of comprehensive site-, soil-, and tree-specific metadata alongside isotope data, enhancing the utility of the dataset.
• The dataset serves as a valuable baseline for future ecohydrological studies, enabling large-scale research on plant water use, ecohydrological model testing, and isotope mapping across Europe.
• Facilitates investigation of seasonal differences in root water uptake, infiltration, evaporative enrichment, and methodological biases in isotope analysis.

Funding

• COST Action: “WATSON” CA19120
• Swiss National Science Foundation: “TreeWater” (grant no. 205492), “InsightForest” (grant no. 213367)
• WSL: “Innovative project Oxygen17”
• German Academic Exchange Service (DAAD) / Federal Ministry for Economic Cooperation (BMZ): SDGnexus Network (grant no. 57526248)
• UEFISCDI Romania: grant nos. PN-III-P2-2.1-PED-2019-4102 and PN-III-P4-ID-PCE-2020-2723
• Deutsche Forschungsgemeinschaft (DFG): grant no. 501530203
• Leibniz collaborative excellent grant: grant no. K444/2022
• Academy of Finland: grant no. 343059
• Research Council of Finland: grant nos. 347348 and 356043
• Marie Skłodowska-Curie Postdoctoral Fellowship: grant no. 101111527
• Czech Science Foundation: grant no. 22-12837S
• Czech Academy of Sciences: RVO grant no. 67985874
• Faculty of Science, Charles University in Prague: SVV grant no. 244-260694

Citation

@article{Lehmann2025Soil,
  author = {Lehmann, Marco M. and Geris, Josie and Meerveld, Ilja van and Penna, Daniele and Rothfuss, Youri and Verdone, Matteo and Ala‐aho, Pertti and Árvai, Mátyás and Babre, Alise and Balandier, Philippe and Bernhard, Fabian and Butorac, Lukrecija and Carrière, Simon and Ceperley, Natalie and Chen, Zuosinan and Correa, Alicia and Diao, Haoyu and Dubbert, David and Dubbert, Maren and Ercoli, Fabio and Floriancic, Marius G. and Ghazoul, Alligin and Gimeno, Teresa E. and Gounelle, Damien and Hagedorn, Frank and Hissler, Christophe and Huneau, Frédéric and Iraheta, Alberto and Jakovljević, Tamara and Kazakis, Nerantzis and Kern, Zoltán and Kinzinger, Laura and Knaebel, Karl and Kobler, Johannes and Kocum, Jiří and Koeber, Charlotte and Koren, Gerbrand and Kübert, Angelika and Kupka, Dawid and Gall, Samuel Le and Lehtonen, Aleksi and Leydier, Thomas and Malagoli, Philippe and Villahermosa, Francesca Sofia Manca di and Marchina, Chiara and Martínez‐Carreras, Núria and Martin‐StPaul, Nicolas and Marttila, Hannu and Oliveira, Aline Meyer and Monvoisin, Gaël and Orlowski, Natalie and Palmik‐Das, Kadi and Perşoiu, Aurel and Popa, Andreï and Prikaziuk, Egor and Quantin, Cécile and Rinne‐Garmston, Katja T. and Rohde, Clara and Šanda, Martin and Saurer, Matthias and Schulz, Daniel and Stockinger, Michael and Stumpp, Christine and Venisse, Jean‐Stéphane and Vlček, Lukáš and Voudouris, Stylianos and Weeser, Björn and Wilkinson, Mark E. and Zuecco, Giulia and Meusburger, Katrin},
  title = {Soil and tree stem xylem water isotope data from two pan-European sampling campaigns},
  journal = {Earth system science data},
  year = {2025},
  doi = {10.5194/essd-17-6129-2025},
  url = {https://doi.org/10.5194/essd-17-6129-2025}
}