The project Caleidoscope is a three years international cooperation project jointly funded by the Province of Bolzano and the Swiss National Science Foundation (January 2023 – December 2025). The overall aim of Caleidoscope is to assess impacts of droughts on forests and specifically to improve our understanding of how Earth Observation based drought impacts are linked to forest productivity and functioning. We address this by calibrating EO forest canopies observations to a unique time-series of tree water use and carbon fixation. By comparing the differences in sensitivity, dynamics, and delays of EO and ground-based observations of the last decade and around two recent major drought events (2015 and 2018), we expect to provide a benchmark for an EO-based quantification of drought impacts on forest productivity and water use. In particular, this study builds upon unique multi-year and daily-resolved tree water use and stem carbon sink observations of differently drought-exposed conifer sites along elevation gradients in the Alps and exploits a new generation of high-resolution multispectral EO sensors to model evapotranspiration. This information together with other spectral indices and EO-derived physiological measures will be used to assess and quantify drought impacts on forest productivity and water use over the heterogeneous Alpine region. Cutting-edge approaches for timing and synchronizing the dynamics across drought intensity and by differently stressed trees will serve as the back-bone to time and quantify environment explicit tree responses (WP1) for comparison and calibration with various spatially distributed EO datasets at different spatial scales (WP2). The pattern of spatial and temporal matches and mismatches between ground-based and EO drought impacts will be quantified, explained, and accounted for to upscale tree level drought impacts for the studied species at the regional scale by using climate and EO data (WP3).

Contact: claudia.notarnicola@eurac.edu