Forest management affecting the impact of natural disturbances on the mitigation potential of European forests

Natural disturbances are increasingly exerting pressure on European forests, compromising the forest ecosystems dynamics and significantly impacting their functioning, as well as the provision of ecosystem services, including the potential for climate change mitigation. The disturbance regimes are even expected to be exacerbated by climate change in the near future. Nevertheless, there is growing evidence indicating that forest management practices can play a pivotal role in influencing the impacts of natural disturbances on forests. Currently, in most European countries, forest harvest is below the increment, resulting in a projected increase in growing stock - that is however reaching saturation. This means that a higher amount of carbon is retained in the forest growing stock, making it more susceptible to disturbances and tree mortality that reduce the carbon residence time in living biomass and soils thus compromising the carbon storage potential of forests. According to a recently published database, during the past decades (1990-2019) more than 2.3 billion m3 of living biomass were lost in European forests due to different causes of disturbance: wind, fire, spruce bark beetle, other biotic agents (i.e., fungi, nematodes, other insects, pathogens, and animals damaging trees) and other abiotic disturbance (i.e., drought, snow, ice, hail, and rime).  In this study we assessed the potential amount of carbon that would have been saved from the forest disturbances losses in the period 1990-2019, considering the application of a different historical forest management involving higher wood harvesting intensity across Europe. We derived data and information from different existing databases and literature sources to define for each European country the unutilized woody biomass as a portion of the net annual increment that could potentially have been harvested but was instead lost due to natural disturbances, as recorded in the EFI database. Results show that with a hypothetical full utilization of the net increment in European forests, up to 75 MtCO2 emissions could have been avoided during the period from 1990 to 2019 (i.e. about 2.5 MtCO2 every year, on average) and instead stored in Harvested Wood Products, serving as a long-term carbon stock, or utilized as substitute for energy-intensive materials or fossil fuel.