Ecosystem heterogeneity is key to limiting the increasing climate-driven risks to European forests

The rise in forest disturbances due to climate change poses a serious threat to key forest ecosystem services, yet impact and adaptation assessments are scarce at European scale. Here we estimate the forest biomass loss in Europe due to fires, windthrows and insect outbreaks over 1979-2018 and evaluate potential adaptation benefits by integrating machine learning with disturbance data and satellite products. Results show an average overall annual biomass loss of 41.6±5.3 Mt at European level subject to a significant rise of 2.3±0.3 Mt year^-1, largely influenced by climate change (72-98%). The contribution of insect outbreaks appears prominent (79%) compared to windthrows (20%) and fires (1%) and linked to their upsurge after year 2000. However, impacts vary greatly across Europe depending on local environmental conditions. We estimate that enhancing ecosystem heterogeneity could reduce biomass loss by about 18% and such action should therefore be fostered in forest adaptation policies.