Mapping fire susceptibility in Portugal

Southern Europe is considered a fire-prone region, and fire events occur here every summer. In this context, large fires have hit Portugal over the last 20 years, due to frequent hot and dry summer conditions, and also to high fuel availability in ecosystems. Moreover, climate change in the Mediterranean basin is expected to increase the severity of fire weather conditions and therefore to increase the occurrence of extreme fire seasons.

Recent catastrophic fire seasons have led to the implementation of a set of policies during the months before the fire-season, aiming at fire prevention and suppression, which can in turn increase the combat efficiency of fires during the fire season. Therefore, this work intends to contribute to fire prevention by identifying regions with a high likelihood to burn.

A Principal Components Analysis (PCA) was applied to several climatological, ecological, and biophysical variables, related to fire weather, fuel availability, and elevation covering the period from 2001 to 2021. Results allowed to assess the areas where large fires were more likely to occur in 2022. The central and southernmost regions of Portugal showed a stronger signal in the PCA, indicating a likely high susceptibility to future fire events. The association of fuel accumulation since the last fire event with elevation and favourable fire weather conditions explains most of the variability of the first six PCs. These results were compared with the fires that occurred in 2022, and a match between larger burned areas and high signals in the PCA was found, highlighting the usefulness of this methodology.

This study was supported by FCT (Fundação para a Ciência e Tecnologia, Portugal) through national funds (PIDDAC) – UIDB/50019/2020, and under the projects FlorestaLimpa (PCIF/MOG/0161/2019).