Wildfires leave soil fungi altered for decades, study finds

A study of pine forests in northwestern Estonia found that the time since a wildfire strongly influenced which fungi lived in the soil. The findings were reported by ERR and written by Estonian University of Life Sciences researchers Ahto Agan, Argo Orumaa and Marek Metslaid.

Fungal communities differed between forests burned at different times, even many years after the fires. Overall fungal diversity could be similar across sites despite major differences in the species present.

Researchers studied seven pine forest areas in the Vihterpalu and Nõva regions, where the last fires had occurred 1, 14, 25, 40, 71, 82 or 185 years before samples were collected. They analysed soil samples from three locations at each site and used fungal DNA to identify more than 800 taxa. They also measured soil acidity and nutrient levels.

Soil fungi perform different roles in forests. Saprotrophic fungi break down dead organic matter, while ectomycorrhizal fungi live in symbiosis with tree roots, helping trees absorb water and nutrients in exchange for carbon compounds produced through photosynthesis.

Overall fungal diversity was lowest at the site burned one year before sampling and notably higher at the site burned 14 years earlier. However, species richness did not recover uniformly across the older burned areas.