Increases in canopy mortality and their impact on the demographic structure of Europe's forests

Pulses of tree mortality have been reported for many ecosystems across the globe recently. Yet, large-scale trends in tree mortality remain poorly quantified. Manually analyzing more than 680,000 satellite image chips at 19,896 plot locations, we here show that forest canopy mortality in Europe has continuously increased since 1985 (+1.5 {+/-} 0.28 % yr-1), with the highest canopy mortality rate of the past 34 years observed in 2018 (1.14 {+/-} 0.16 %). Using simulations, we demonstrate that a continued increase in canopy mortality will strongly alter forest demography, with the median forest age falling below 30 years in more than 50% of Europes countries by 2050. These demographic changes can have substantial cascading effects on forest regeneration, biodiversity, and carbon storage. The current trend of increasing canopy mortality is thus challenging the future of Europes forests, and should be a key priority of forest policy and management.