Resilience dynamics of European forests under consecutive drought events

The increasing frequency and persistence of drought and compound hot and dry extreme events have raised growing concerns about the future of forest ecosystems, given the strong link between climatic stress, tree mortality, and declining biomass carbon stocks. European forests are particularly vulnerable, as the continent is among the regions most affected by compound hot and dry extremes in terms of both spatial extent and duration. Assessing how forests respond to repeated drought events is therefore important in understanding ecosystem vulnerability under ongoing climate change and to pinpoint adaptation strategies.

In the presented study, we investigate the dynamics of the resilience of stable European forests where repeated drought events occur. Using a 2003-2022 time series of Normalized Difference Vegetation Index (NDVI) anomalies at an 8-day temporal resolution from MODIS satellites, we quantify ecosystem resilience via the lag-1 temporal autocorrelation (AC1). Drought events are retrieved from the Dheed global database of dry and hot extreme events based on ERA5 (Weynants et al., 2025). 

Trends in AC1 in between the events are then assessed to identify dynamics in forest resilience across Europe and to explore their correlation with drought frequency and a set of drought metrics. The link between forest resilience and drought events is also explored at the biogeographical scale. This approach assesses the potential cumulative impact of repeated extreme events on forest resilience beyond a single-event recovery analysis. By understanding if and how repeated droughts shape European forests' response to extreme events we aim to eventually identify preconditions, such as ecosystem heterogeneity, that positively influence their resilience.