Post-fire Soil Erosion Risk in Portugal– Prediction, Validation and Uncertainties of a Nation-wide MMF Application

Wildfires are a recurrent and increasing threat in mainland Portugal, where over 4,5 million hectares of forests and scrublands have burned over the last 38 years. These fire-affected landscapes have suffered an intensification of soil erosion processes, which can negatively affect soil carbon storage, reduce fertility, forest productivity, and become a source of pollutants. The main objective of the present study is to produce a post-fire soil erosion risk map for the forest and scrubland areas in Mainland Portugal and assess its reliability. To this end, the semi-empirical Morgan–Morgan–Finney erosion model was used to assess the potential post-fire soil erosion according to distinct scenarios (burn severity and climate), and the accuracy of the predictions was verified by an uncertainty analysis and validated against independent field datasets. The proposed approach successfully allowed mapping post-fire soil erosion in Portugal and identified the areas with higher post-fire erosion risk for past and future climate extremes. The outcomes of this study comprise a set of tools to help forest managers in their decision-making for post-fire emergency stabilization, ensuring the adequate selection and implementation of mitigation measures to minimize the economic and environmental losses caused by fire-enhanced soil erosion.