Why are Europe’s forests losing more biomass since 2018?

Researchers analyzed 216 million hectares of European forests using satellite data to estimate biomass losses from high-severity natural disturbances and stand-replacing harvesting between 1985 and 2023. They found that forests lost an estimated 6.5 ± 0.8 petagrams of aboveground biomass over the period. Harvesting accounted for 82% of the loss, while natural disturbances caused 18%.

The pace of biomass loss increased sharply after 2018. Across Europe, annual losses from harvest and natural disturbances were 30.8% higher in 2018-2023 than in 1985-2017. Losses from natural disturbances alone rose by 45.5%. In temperate forests, natural disturbance-related biomass losses increased by 47.6%.

The strongest increase was recorded in temperate forests of Central Europe, where large-scale bark beetle outbreaks affected Germany, Czechia and Poland. The researchers found that biomass loss increased disproportionately compared with the area of forest disturbed. In other words, even relatively small increases in disturbance can cause substantial biomass losses when they occur in forests with large carbon stocks.

The study links this pattern partly to drought. The 2018-2022 drought period intensified bark beetle disturbances in temperate forests, while high-biomass forests were particularly vulnerable. The researchers said increasing drought under climate change could further increase bark beetle disturbances, putting forests dominated by susceptible trees such as Norway spruce at greater risk.

The findings also highlight differences between European forest regions. Fires are expected to increase, but Mediterranean forests generally have lower biomass stocks, meaning fires there tend to produce smaller biomass losses than disturbances in high-biomass temperate forests. In boreal forests, meanwhile, rising biomass losses were primarily associated with expanding harvest areas rather than increasing sensitivity to natural disturbances.

Earlier, Qazinform News Agency reported that since the start of this year, wildfires destroyed a record 4,350 square kilometers of forest across EU member states.