Tree-ring δ18O and δ2H stable isotopes reflect the global meteoric water line
Tito Arosio, Ulf Büntgen, Kurt Nicolussi, Gina E. Moseley, Matthias Saurer, Thomas Pichler, M. Paul Smith, Emília Gutiérrez, Laia Andreu‐Hayles, Irka Hajdas, Tatiana Bebchuk, Markus Leuenberger
Abstract
Introduction The Global Meteoric Water Line (GMWL) describes the linear relationship between stable hydrogen ( δ 2 H) and oxygen ( δ 18 O) isotopes in precipitation over large spatial scales and therefore represents a unique reference for water isotopic values. Although trees have the potential to capture the isotopic composition of precipitation, it remains unclear if the GMWL can be reconstructed from tree-ring stable isotopes, since δ 18 O and δ 2 H undergo in vivo physiological fractionation. Methods We analyze the tree rings δ 18 O and δ 2 H values from six regions along a latitudinal gradient from Spain to Greenland. Results The data show that the covariance between δ 18 O and δ 2 H closely follows the GMWL, which reflects the isotopic signature of large-scale precipitation patterns. We show that changes in regional tree-ring δ 18 O and δ 2 H values along wide latitudinal ranges are influenced by the isotopic composition of precipitation with temperature and latitude being the most significant drivers of spatial variation across the studied regions. In contrast, local tree-ring δ 18 O and δ 2 H values are mainly controlled by plant physiological fractionation processes that mask the isotopic signature of precipitation. Conclusion We conclude that covariance in tree-ring δ 18 O and δ 2 H reflects the GMWL at larger spatial scales, but not when evaluating them at individual sites.