Tree ring chronologies – study the past to predict the future

Tree rings are one of the most powerful natural footprints of past ecological conditions. Their formation and characteristics are directly influenced by the environment in which the tree has grown. The width of tree rings provides valuable information about how site conditions and competition among trees affect their growth and health. As a result, longer records of tree-ring widths enable scientists to explore the past more thoroughly, helping them understand how trees respond to environmental change.

The backbone of studying the tree-environment dynamics, i.e., various dendrochronological investigations, is the concept of cross-dating. It is the process of matching patterns of wide and narrow rings between trees from the same region to assign exact calendar years to each ring. This common population signal is recorded in their rings as a synchronised pattern, in which all trees have a
narrow ring in a drought year and a wide ring in ideal growing conditions. Such a unique pattern of tree-ring width oscillation acts as a fingerprint of environmental conditions.

In order to accurately detect and measure tree-ring widths, it is essential to meticulously prepare the sample cores’ surfaces. Properly polishing or cutting perpendicular to the tree-ring borders enhances visibility, enabling the succeeding digitalisation of the sample. Measurement of tree-ring width on high-resolution pictures enables more reliable results and the establishment of a digital archive. The next important step in data handling is to check out measurement quality by filtering out common signals from noise in tree-ring chronologies. This process, known as synchronisation, involves both visual and statistical evaluations to identify common patterns in tree growth.

To successfully fulfil the aims of the SmartTogether research initiative, all the outlined procedures were carried out in the Laboratory for Tree-Ring Research and Biomonitoring at the University of Belgrade, Faculty of Forestry. As a result of WP3 activities, we have prepared the database containing tree-ring chronologies for pedunculate oak and white ash at established pilot plots. As the project team collaborates closely produce a comprehensive database to underlie research, here we integrated tree-ring chronologies with information on the most important environmental predictors collected in WP2. These research outputs are publicly available at Zenodo under the CC BY 4.0 licence.