Soil fungal communities respond compositionally to recurring frequent prescribed burning in a managed southeastern US forest ecosystem

• Prescribed fire management over twenty years minimally affects soil fungal community diversity.
• In contrast to lacking diversity responses, short (two to three years) fire intervals alter community composition.
• In a six-year interval burn management, fungal communities are only marginally distinguishable from unburned controls.
• Fire adapted and fire sensitive taxa include fungi across a range of fungal functional guilds.
• Frequent prescribed burning selects fire adapted soil fungal communities.

Prescribed fire is an important management tool to reduce fuel loads, to remove non-fire adapted species and to sustain fire-adapted taxa in many forested ecosystems of the southeastern USA. Yet, the long-term effects of recurring prescribed fires on soil fungi and their communities in these ecosystems remain unclear. We Illumina MiSeq sequenced and analyzed fungal Internal Transcribed Spacer (ITS2) amplicons from a long-term prescribed burn experiment that has implemented different regimes for nearly a quarter century to evaluate the effects of differing prescribed fire intervals and the season of their implementation on soil-inhabiting fungal communities. Unburned plots were used as a reference to represent the compositional state resulting from fire suppression. Our data show that while the recurring burning or the season of the prescribed burning do not affect richness and diversity of the fungal communities, the frequent (two and three year interval) fires maintain a fire-adapted community that is distinct from those in unburned reference plots. Subsequent indicator taxon analyses identified a total of 37 Operational Taxonomic Units (OTUs) that were more frequent in the frequently implemented burns and 26 OTUs that were more frequent in the fire suppressed treatment. We conclude that frequent prescribed burning maintains fire selected soil fungal communities that may support plant communities that are composed of desired fire adapted or fire tolerant species that dominate the frequently burned areas.