Identifying Climate Analogues and Selecting Resilient Tree Species for Future Austrian Forests

Climate change poses substantial challenges to forest ecosystems, with increasing temperatures and prolonged droughts driving tree mortality and pest outbreaks across Europe. In Austria, such events threaten the productivity, the forest carbon sink capacity and other forest ecosystem services, necessitating evidence-based strategies to enhance forest resilience. This study addresses this challenge by identifying climate-analogous regions and selecting suitable tree species for Austrian forest ecoregions under changing climatic conditions.

We utilize the CHELSA V2.1 climate data set to identify target regions across the Northern hemisphere where current climatic conditions mirror those projected for the Austrian forest ecoregions by 2100 using three different climate scenarios (SSP1.26, SSP3.70 and SSP5.85). This specifically involves the analysis of a comprehensive set of climate indicators reflecting drivers causing heat stress and drought events, to ensure a precise match with expected conditions. Having tested different metrics, we employ Euclidian distance as measure for climatic similarity. The resulting climate analogues serve as reference areas for identifying tree species that thrive under comparable environmental conditions

The selection of putative tree species from across the northern hemisphere is based on species distribution maps from in total 832 tree species, from which about 15–25 tree species are being selected for each of the nine forest ecoregions. The climatic analysis of putative origins of future tree species or seed provenances is accompanied by a literature analysis of wood characteristics, ecological risks (i.e. invasive potential) and legal constraints for the utilization of the candidate tree species.

By focusing on both the ecological and practical dimensions of species selection, the study provides actionable insights for forest managers. The findings will be integrated into tools such as the "tree species traffic light (https://www.klimafitterwald.at/baumarten/)" facilitating the implementation of forest adaptation strategies with climate-resilient trees in Austrian forests. This research offers a transferable methodology for regions globally, addressing the critical intersection of climate change adaptation and sustainable forest management.