High-severity wildfire reduces richness and alters composition of ectomycorrhizal fungi in low-severity adapted ponderosa pine forests

Mega-fire in Redwood Tanoak Forest Reduces Bacterial and Fungal Richness and Selects for Pyrophilous Taxa and Traits that are Phylogenetically Conserved

“…Moreover, when reported, it is based on plant mortality measured at coarse levels (30km 2 in the case of the Soberanes Fire) (Potter, 2016) that do not correspond well to the scale of the soil core and can lead to wide disparities in the presence or absence of live plants, duff, or ash in soil cores all taken in high severity defined fire zones. We also found that EMF richness declined following fire, which makes sense given large host mortality, and is in accordance with other high severity fires in pine forests (Glassman et al, 2016; Pulido-Chavez et al, 2021; Reazin et al, 2016). This large-scale reduction in the microbial richness can have far reaching impacts on the surrounding ecosystem from radically altered nutrient cycling (Crowther et al, 2019) to the inability to reestablish critical plant species (Van der Heijden et al, 2008).…”

“…Perhaps the visual similarity to Ascomycetes is representative of convergent evolution with other ascomycetes, which are more often associated with fire (Cairney & Bastias, 2007). Only one other wildfire study has found Basidioascus to increase post-fire (Pulido-Chavez et al, 2021) though not with the level of dominance in our study. A couple recent studies have found an increase in dominance of the sister genus Geminibasidium , including a study of a Pinus ponderosa forest in the American Pacific Northwest (Pulido-Chavez et al, 2021) and a study of Larix and Betula dominated forests in northeastern China (Yang et al, 2020).…”

“…Only one other wildfire study has found Basidioascus to increase post-fire (Pulido-Chavez et al, 2021) though not with the level of dominance in our study. A couple recent studies have found an increase in dominance of the sister genus Geminibasidium , including a study of a Pinus ponderosa forest in the American Pacific Northwest (Pulido-Chavez et al, 2021) and a study of Larix and Betula dominated forests in northeastern China (Yang et al, 2020). Geminibasidium was also present at 0.05% sequence abundance, the same amount as our pre-fire soil, in an unburned giant sequoia forest (Carey et al, 2019).…”

“…In contrast, a meta-analysis of fungal response to fire found an average richness reduction of 28% (Dove & Hart, 2017). However, the range for both fungal (12-80%) (Brown et al, 2019;Pulido-Chavez et al, 2021) and bacterial (20-58% ) (Brown et al, 2013;Pérez-Valera et al, 2018) richness reduction can be quite large. This is likely due to differences in fire severity, which is often not measured or consistently reported in post-fire microbial surveys, despite that more severe fires have been shown to have greater impacts on the soil community (Whitman et al, 2019).…”

“…In contrast, a meta-analysis of fungal response to fire found an average richness reduction of 28% (Dove & Hart, 2017). However, the range for both fungal (12-80%) (Brown et al, 2019; Pulido-Chavez et al, 2021) and bacterial (20-58%) (Brown et al, 2013; Pérez-Valera et al, 2018) richness reduction can be quite large.…”