Unraveling interactions of climate and N dynamics in European forest ecosystems (UNICAN)

The project contributes to the general aims of the WG 2 and 3 of the COST Action CLEANFOREST of investigating Nitrogen (N) deposition and climate effects on forests by

1. evaluate dynamics of experimentally added 15N-labelled nitrogen,
2. evaluate climate signals with natural abundance of stable C, N and O isotopes in tree rings, soil or leaves
3. upscale to plots with intensive monitored of nutrient fluxes.

The project UNICAN tries to investigate the residence time of nitrogen, oxigen, hydrogen and carbon based on isotopic composition. The aim is to improve the interpretation of observations regarding the process that are relevant for future effects of nitrogen deposition and climate extremes.

The impact of N deposition and climate extreme of the health and functioning of forest ecosystems have mainly be investigated separately from each other in the past. However, since we face an increase of N deposition since 1950 and a beginning re-decrease since 1990, as well as rapid climatic changes during the same time which complicate to draw conclusions from observation data to future development. The main aim of UnICaN is therefore to investigate the interactions of N deposition and climatic impacts on European forest ecosystems over the course of the last 30 years. Therefore, the project will make use of the scientific network of the COST Action CLEANFOREST, providing an excellent opportunity platform to use synergies between researchers and jointly evaluate unique experimental and long-term monitoring data regarding this question. In several work packages (WP), the project will investigate N dynamics in a unique 30-year N addition experiment based on ¹⁵N-tracer and process-based models (WP1), determine the interaction of N deposition and climate on tree physiology through multi-stable isotope applications on chronosequences of soil, foliar and tree-ring material across several forest sites (WP2), and use the knowledge of WP1 and WP2 in order to constrain the statistical analysis and aggregate meaningful main drivers on forest ecosystems in Europe a-priori (WP3), including N deposition and climatic effects, through making use of long-term and large-scale data set of the European forest monitoring network (ICP Forests). This will allow to improve models used for scenario analyses and derive recommendations for adapted forest management.

The COST Action 'Joint effects of CLimate Extremes and Atmospheric depositioN on European FORESTs (CLEANFOREST)'.