Increasing canopy mortality affects the future demographic structure of Europe's forests

Increasing tree mortality can have pervasive impacts on forest dynamics. Yet, large-scale trends in tree mortality and their effects on forest demography remain poorly quantified despite the important role of forest demography for forest carbon pools and biodiversity. Analyzing satellite data at 19,896 plots, we here show that canopy mortality in 35 European countries increased from 1985 to 2018 (+1.5% ± 0.28% yr⁻¹). Using simulations, we demonstrate that recent levels of canopy mortality will halt the aging trend of Europe's forests and that a further increase in canopy mortality has the potential to strongly alter Europe's forest demography toward younger forests. These demographic changes will have cascading negative effects on forest biodiversity and carbon storage. Developing strategies to address the increasing canopy mortality should thus be a key priority of forest policy and management in Europe.