| Summary: | Introduction: The Global Meteoric Water Line (GMWL) describes the linear relationship between stable hydrogen (δ 2H) and oxygen (δ 18O) 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 18O and δ 2H undergo in vivo physiological fractionation. Methods: We analyze the tree rings δ 18O and δ 2H values from six regions along a latitudinal gradient from Spain to Greenland. Results: The data show that the covariance between δ 18O and δ 2H closely follows the GMWL, which reflects the isotopic signature of large-scale precipitation patterns. We show that changes in regional tree-ring δ 18O and δ 2H 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 18O and δ 2H 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 18O and δ 2H reflects the GMWL at larger spatial scales, but not when evaluating them at individual sites.
|
|---|