During the ISOBOREAL project, we conducted extensive fieldwork over two growing seasons in Eurasian boreal forests and a controlled drought experiment to understand how stable carbon and oxygen isotope composition (δ13C and δ18O, respectively) in tree rings respond to environmental and physiological factors. This research aimed to provide a deeper understanding of tree physiology and climate interactions, offering insights into forest adaptation to climate change.
Our approach included collecting a wide array of samples, such as tree tissues, soil, atmospheric CO2, and water. By integrating isotopic data with observations of tree and ecosystem gas exchange, we developed a comprehensive view of forest dynamics. This combination of direct field observations and process-based modelling helped us to understand how forests respond to and interact with their environment.
A significant part of our research focused on isotope analysis of individual sugars (i.e. compound-specific isotope analysis, CSIA) in leaves and other tree components. This technique allowed us to trace the metabolic processes affecting isotopic signals from photosynthesis to their incorporation into tree rings. For example, our findings indicated that the environmental signals captured in leaf sugars are consistently reflected in the tree-ring data, suggesting the value of δ13C and d18O records for studying forest responses to climate change.
Within the project, we established a laboratory for high-resolution isotope analysis of tree rings using laser ablation-isotope ratio mass spectrometry (LA-IRMS). This method enabled us to examine seasonal climate signals in tree rings and contributed to our ability to interpret tree ring chronologies. We also introduced a new technique for δ18O analysis in tree rings, enhancing our capacity to produce detailed climate data.
Moreover, ISOBOREAL introduced a novel method for analysing tree ring cellulose, aiming to clarify the mixed climate signals in δ18O values. This development and its ongoing refinement promise to advance our ability to interpret environmental and physiological signals in tree rings.
Overall, the ISOBOREAL project has significantly advanced our understanding of boreal forests and their responses to climate change. The project's findings and new analytical methods have been disseminated through scientific publications and collaborations, contributing to the broader scientific community's efforts in forest management, carbon cycling, and climate adaptation strategies. The establishment of a stable isotope laboratory and the development of advanced analytical techniques ensure that the knowledge and capabilities gained will continue to support research in this field.
