Fire in the beech forest (Fagus sylvatica)

August 2025 recorded both the largest burned area and the most extreme fire‑weather conditions in the Iberian Peninsula (Spain and Portugal) in the historical record (1985–2025 [1]). The fire affected not only typical Mediterranean fire‑prone ecosystems but also some ecosystems that rarely burn. This was the case for the beech (Fagus sylvatica) forest in the Picos de Europa, northern Spain.

Beech forests may sometimes experience very low‑intensity and low‑severity surface fires (litter fires) in winter or spring, when the trees are leafless and have low biological activity. These occur during some dry winters, are often human-ignited, and typically kill very few trees. During the heatwave of August 2025, however, the Barniedo fire (León, Spain; source: lightning) burned approximately 19,100 ha and affected a significant proportion of the beech forest. Although it was a surface fire, when it crossed the beech forest, it killed many beech trees, a clear case of a surface high‑severity fire.

References

[1] Sánchez-Hernández G, Turco M, Repeto-Deudero I, Royé D, Baudena M, Montávez JP, Pietroiusti R, Provenzale A, Santin C, Torres-Vázquez MA, Pausas JG. 2025. Record-breaking 2025 European wildfires season concentrated in the western Iberian Peninsula. Global Change Biology 31:e70649 [doi | pdf]