Deciphering the role of fungi in post-fire succession in Canada's Great Lakes–St. Lawrence forest region

Abstract

Fungi are important drivers of forest health, as well as culturally important for many Indigenous communities. In Canada, increasingly intense and frequent wildfires affect fungal substrates and habitats, environmental conditions, and physiological responses of hosts with which fungi may interact. In Ontario, aggressive fire suppression raises the question of how fungal regeneration, and taxonomic compositions, may be affected when fires do appear on the landscape. This study investigates the fungal regrowth post-fire above and below-ground and the role fungal species play in post fire ecological succession in Southeastern Ontario. The study sites are two black oak savannas in restoration, previously prescribed a burn (Northumberland County, 2022 and 2023), and a recent wildfire burned mixed deciduous forest (Centennial Lake, 2023). We collected fruiting body and soil samples for fungal identification via observational and DNA methods. Above ground vegetation assays were made at 9 burned plots within these three sites and another 8 adjacent unburned (control) plots. We extracted soil DNA and will amplify fungal ITS2 amplicons by PCR. Then, we will sequence the amplified DNA using MiSeq to compare burned and unburned soil fungi. Lastly, we will use statistical methods to differentiate effects from fire and soil texture and type in burned and control plots. Thus far, we found that Pyropyxis rubra, a pyrophilous ascomycete fungus, is extremely abundant just weeks after the lightning-induced fire at Centennial Lake. Our combined observational and quantitative descriptions of above-and below ground soil fungi provide a deeper understanding of how fire affects species composition, fungal reproduction, and population dynamics in Ontario. This research may help inform other successional processes, and fungal harvesting of culturally important species.