Combining satellite-derived standing deadwood estimates and vegetation modelling to predict climate change impacts on Norway spruce forests in Germany

Recent summer droughts (2018–2020) caused unprecedented Norway spruce ( Picea abies ) mortality in Central Europe, resulting in large amounts of standing deadwood in forests. Using an existing spatially continuous, multi-year Germany-wide satellite-derived deadwood dataset, we developed an empirical model of Norway spruce tree mortality based exclusively on weather-related predictors. We integrated this model into the European forestry version of the dynamic global vegetation model LPJ-GUESS as a species-specific, drought-related mortality component to simulate Norway spruce forest dynamics across Germany. Without the new drought-related mortality component, LPJ-GUESS strongly underestimates the effects of droughts. Including the component improves the representation of observed temporal patterns of annual drought-related Norway spruce mortality (NRMSE = 1.07%, MAE = 1.92%) and associated biomass declines across Germany from 2010 to 2020. Using large-scale satellite data substantially improved the model’s explanatory power (R 2 dev = 0.43), outperforming previous approaches based on ground-based mortality observations. Summer solar radiation anomalies emerged as a key predictor, reflecting links to drought stress, canopy heat stress and increased bark beetle activity. Future simulations (2021–2070) under RCP2.6 and RCP8.5 scenarios project recurring drought-related Norway spruce mortality comparable to post-2018 events, leading to substantial reductions in carbon stocks (-20% on average) and increases in calamity timber (46% under RCP2.6, 52% under RCP8.5), while harvests of target-diameter timber decline in subsequent years. Our results highlight significant risks for carbon storage in Norway spruce forests with recurring droughts in Germany, which also challenge Germany’s climate goals. To avoid those negative consequences, we strongly recommend a rapid transition to diverse mixed forests across Germany.