The dual nature of the hydrogen stable isotopes in tree-rings of the Holocene

The dual nature of tree-ring cellulose hydrogen isotope composition (δ²H) as a hydroclimatic and physiological proxy offers unique opportunities for palaeoclimatic research (Vitali et al. 2022, 2023), yet its application in long-term studies remains limited. Building on recent advances in tree-ring stable isotope research, we analyse the Alpine Holocene Tree-Ring Triple Isotope Record (AHTTRIR, Arosio et al. 2022), a comprehensive dataset spanning 9,000 years of δ²H, δ¹⁸O and δ¹³C measurements from high-altitude Alpine conifer trees. This study focuses on developing novel methodological approaches for δ²H analysis, applying species-specific values to establish the first multi-millennial δ²H chronology, and comparing it with δ¹⁸O chronology from the same dataset, which is known to contain hydroclimatic signals (Arosio et al. 2025). Despite the inherent complexity of δ²H signals and associated methodological challenges, analysis of approximately 7790 δ²H measurements from the AHTTRIR dataset shows that δ²H contains valuable information on both hydroclimatic variability and tree physiological responses. Through comparison with δ¹⁸O data, we show that δ²H provides complementary insights into plant metabolic processes, including storage mobilisation and stress adaptation mechanisms that could occur due to biotic or abiotic events affecting tree vitality, like damage to needles after insect attacks or frost. This dual-isotope approach, incorporating corrections for species- and age-specific effects, allows the separation of climatic signals from physiological responses over millennial timescales. Comparison with independent Alpine paleoclimate proxies and regional records strengthens our understanding of long-term hydroclimatic dynamics and their impact on tree metabolism throughout the Holocene. These results emphasise the importance of preserving long-term trends in isotope data, while highlighting the need for expanded tree-ring isotope research across different species and geographical regions. The establishment of this pioneering δ²H chronology advances our ability to reconstruct past climate variability while providing crucial insights into ecosystem responses to long-term environmental change.

 

Arosio Tito, Malin Ziehmer, Kurt Nicolussi, Christian Schluechter, Andrea Thurner, Andreas Österreicher, Peter Nyfeler, and Markus Christian Leuenberger,. 2022. “Alpine Holocene Triple Tree Ring Isotope Record.” PANGAEA, 2022. https://doi.pangaea.de/10.1594/PANGAEA.941604.

Arosio T, Leuenberger M., Nicolussi K, Esper J, Krusic P, Bebchuk T, Tegel W, Hafner A, Kirdyanov A, Schlüchter C, Reinig F, Muschitiello F and Büntgen U. 2025. “Tree-ring stable isotopes reveal a Holocene-long drying trend for central Europe”. In Revision to Science Advances

Vitali, Valentina, Elisabet Martínez-Sancho, K. Treydte, Laia Andreu-Hayles, Isabel Dorado-Liñán, Emilia Gutierrez, Gerhard Helle, Markus Leuenberger, Neil J. Loader, and Katja T. Rinne-Garmston. 2022. “The Unknown Third–Hydrogen Isotopes in Tree-Ring Cellulose across Europe.” Science of the Total Environment 813:152281.

Vitali, Valentina, Richard L. Peters, Marco M. Lehmann, Markus Leuenberger, Kerstin Treydte, Ulf Büntgen, Philipp Schuler, and Matthias Saurer. 2023. “Tree-Ring Isotopes from the Swiss Alps Reveal Non-Climatic Fingerprints of Cyclic Insect Population Outbreaks over the Past 700 Years.” Tree Physiology 43 (5): 706–21.