Monitoring historical (1985-2023) forest disturbances in continental Spain with Landsat dense time series

Forest disturbance dynamics are changing in forests across continents in response to global change. Detailed quantitative data on past disturbance events are necessary to establish baselines against which to assess change. Here, we used dense Landsat time series and a novel forest monitoring algorithm (Continuous Change Detection and Classification - Spectral Mixture Analysis) to monitor forest disturbances in Spain from 1985 to 2023 and adapted the algorithm separately for two biomes (temperate and, for the first time, Mediterranean). We characterised disturbance regimes at the national scale and by the two biomes and forest types (needleleaf, broadleaf and mixed). We found that the total extent of disturbed forest had previously been underestimated by existing products and accounted for 4.5 million ha, and that disturbance size and severity were significantly different (i.e. using the Wilcoxon signed-rank test, p < 0.05) between forest types and biomes, but frequency only for biomes.