In this project, we want to explore a stable isotope tree-ring approach for retrospectively analyzing physiological drought responses of trees. Deuterium isotope ratios have been rarely applied in this context, but could be an indicator of reserve use versus use of fresh assimilates and help resolve the importance of carbon limitation for tree decline. We will compare surviving and dying Scots pine individuals in dry stand in the inner-Alpine valley and analyse a tree-ring network across Europe with a focus on severe drought periods. We will conduct a controlled drought-experiment with tree saplings, including physiological measurements and application of compound-specific isotope analysis, for deciphering drought-related isotope fractionations. The results are expected to provide a novel diagnostic tool for retrospectively analyzing causes of tree decline, which will also be helpful for assessing future drought adaption potential of forests.
2018 - 2021