Successional changes in fungal communities occur a few weeks following wildfire in a mixed Douglas-fir-ponderosa pine forest

Abstract

With wildfires reaching unprecedented levels of severity, size and frequency, their impact on soil microbial communities is an important concern. Commencing just weeks following a wildfire in a Douglas-fir-Ponderosa pine forest, we collected surface and mineral soil samples four times over 10 months from four severity levels to better understand the effect of wildfire severity on fungi and their guilds. At medium severity and above, there was a decrease in fungal diversity and a shift in community composition in both layers, while the fungal community from soils burnt by low severity fires remained similar to unburnt soils. Although the richness of putative saprotrophic and pathotrophic fungi in burnt microplots returned to levels comparable to that in the unburnt microplots within weeks of burning, the richness of symbiotrophic, including ectomycorrhizal fungi in burnt plots, did not. The DNA of many putative pyrophilous fungi peaked in estimated abundance within weeks after the fire, even though fruiting was not observed until the following spring.

Index descriptors

pyrophilous fungi; wildfire severity; ITS; metabarcoding; Pseudotsuga menziesii var. glauca; fungal community; disturbance; succession.