Protected and non-protected areas burned at a similar fire severity within the 2025 megafires in Spain

Abstract Background Extreme wildfires are becoming increasingly common worldwide, raising concerns about the ability of protected areas to maintain their ecological role under a changing climate. Protected areas are often assumed to burn at higher fire severity due to greater fuel continuity, steeper terrain, and lower land-use intensity, among others. However, broad-scale comparisons between protected and non-protected areas frequently fail to control for vegetation composition, fire-relevant site characteristics, or fire size. In addition, protected and non-protected sectors within the same wildfire share identical fire conditions and therefore cannot be treated as statistically independent. Results The 2025 extreme wildfire event in northern Spain offered a natural experiment involving multiple large fires to address these issues. During this episode, the Fire Weather Index and short-term drought conditions were extreme, while long-term drought remained near normal. A total of 336,000 ha burned, 72.5% of which was consumed by megafires (>10,000 ha), setting a new national record. We intersected wildfire perimeters with land cover layer, protected areas network, and regional maps of threatened (endangered and vulnerable) species in Castilla y León. Fire severity was quantified using satellite-derived perimeters and the Relativized Burn Ratio. Natura 2000 sites accounted for 44% of the burned area, and habitats belonging to 14 endangered and 51 vulnerable species were affected. Paired comparisons between protected and non-protected areas within each fire revealed no consistent prefire differences in vegetation or terrain, except steeper slopes in protected areas. Fire severity was uniformly high to very high across all categories, irrespective of protection or conservation status. Generalized additive models further showed that mean fire severity increased with fire size and varied significantly among land use-land cover types, whereas neither protection nor conservation status had a significant effect. These findings indicate that under extreme wildfire conditions, protection status may not affect fire-severity patterns.