Assessing Post-Fire Rock Weathering and Slope Instabilities in Fire-Prone Landscapes: Spanish Case Studies

Wildfires constitute one of the main agents of change in fire-prone landscapes. Beyond the immediate loss of vegetation and biodiversity, as well as the well-documented impacts on air and water quality, burned watersheds and hillslopes may trigger cascading geo-hydrological hazards in the weeks to years following a fire. Moreover, climate change is increasing the extent and intensity of wildfires, extending their impacts to territories with diverse geological and geomorphological characteristics, including high-altitude ecosystems with a greater extent of exposed rocky areas.

Despite extensive research on fire effects on vegetation and soils, knowledge gaps remain regarding the impact of wildfires on exposed rock outcrops and boulders directly affected by flames. In particular, little is known about how fire-induced thermal stress and accelerated rock weathering influence post-fire geo-hydrological processes. Much of the current understanding is based on qualitative observations rather than quantitative measurements, highlighting the need for systematic field-based studies to assess the effects of fire on rock materials.

This study presents field-based data collection and analysis from two case studies conducted over different post-fire periods. The first examines a short-term post-fire scenario following the 2025 Yeres wildfire affecting the Las Médulas Cultural Heritage Site (León, Spain), focusing on the assessment, sampling, and quantification of fire effects on rock materials using a hybrid methodological approach that integrates ecological sampling with non-destructive techniques (NDTs). The second case addresses mid-term fire effects after the 2023 Arafo wildfire (Tenerife, Spain) through a comprehensive inventory of slope instabilities and erosion processes triggered by the fire. Together, these complementary case studies provide an integrated framework for understanding both the direct and indirect impacts of wildfire processes operating at different temporal scales.

This work was developed within the framework of the CSIC Scientific Technical Advisory Group for Emergency Crises (GADE CSIC, Spain) and the project DINCAN (ref. 20125), funded under the 2024 Call for the Promotion of Scientific, Technological, and Innovation Culture (I+P) by the Spanish Foundation for Science and Technology (FECYT).