Forest composition effect on wildfire pattern and run-off regime in a Mediterranean watershed

Fire may alter land cover throughout the landscape and affect run-off responses to rainfall events in a burnt watershed. Therefore, the challenge is to understand the interactions between forest composition and fire patterns in a karstic, Mediterranean watershed that affects the run-off regime. The aim of this research is to improve the understanding of the interactive effects of wildfire and land-cover change on the rainfall-run-off relationship in a first-order watershed. To achieve this goal, satellite imagery, official spatial data, and hydrological modelling were used to study forest composition in relation to extreme fire and to simulate run-off response for 2 rainfall events. The results show that an extreme wildfire had a greater impact on planted forest, composed mostly of pines, than on native species. Additionally, it was found that the land-cover alternation due to fire affected the run-off regime and contributed to an increase in maximum discharge and run-off volume for the 2 rainfall events by similar to 39-47%. During the regeneration period, the run-off response for the 2 rainfall events decreased by similar to 7.7-9%. Wildfires may impact the run-off response more profoundly as the plantation of pine trees increases. A greater increase in run-off response may endanger infrastructure in terms of flooding and affect the population well-being. Watershed management in areas where afforestation is considered should focus on planting native species that are less flammable rather than introducing combustible pines, thus reducing the hydrologic impacts of land-cover alteration due to wildfire, especially when climate warms and wildfires become more frequent and intense.