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

• Published in: Forest ecology and management Vol. 485; p. 118923
• Main Authors: Pulido-Chavez, M. Fabiola, Alvarado, Ernesto C., DeLuca, Thomas H., Edmonds, Robert L., Glassman, Sydney I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2021
• Subjects: Ectomycorrhizal fungi; High-severity wildfires; Illumina MiSeq; Ponderosa pine; Saprobic fungi; Soil nutrients; Succession; High-severity wildfires; Succession; Illumina MiSeq; Saprobic fungi; Soil nutrients; Ponderosa pine; Ectomycorrhizal fungi
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2021.118923

•EcM species richness was lower in high severity burned sites than unburned sites.•Alterations to EcM richness and EcM and saprobic composition are long-lasting (>11 years).•Organic matter, treatment, total carbon, and total nitrogen predict EcM richness.•Treatment, time since fire, and total carbon predict saprobic richness.•Wilcoxina and Geminibasidium show resilience dominating the burned and unburned sites. Ponderosa pine (Pinus ponderosa) forests are increasingly experiencing high-severity, stand-replacing fires. Whereas alterations to aboveground ecosystems have been extensively studied, little is known about soil fungal responses in fire-adapted ecosystems. We implement a chronosequence of four different fires that varied in time since fire, 2 years (2015) to 11 years (2006) and contained stands of high severity burned P. ponderosa in eastern Washington and compared their soil fungal communities to adjacent unburned plots. Using Illumina Miseq (ITS1), we examined changes in soil nutrients, drivers of species richness for ectomycorrhizal (plant symbionts) and saprobic (decomposers) fungi, community shifts, and post-fire fungal succession in burned and unburned plots. Ectomycorrhizal richness was 43.4% and saprobic richness 12.2% lower in the burned plots, leading to long-term alterations to the fungal communities that did not return to unburned levels, even after 11 years. Differences in the post-fire fungal community were driven by pyrophilous, “fire-loving” fungi, including the ectomycorrhizal Ascomycete genera Pustularia and Wilcoxina, and the saprobic Basidiomycete genus Geminibasidium. Ectomycorrhizal and saprobic fungi were intimately linked to the soil environment: depth of the organic matter, total carbon, total nitrogen, and their interaction with fire predicted ectomycorrhizal richness. Whereas total carbon, time since fire, treatment, and the interaction between time since fire and treatment predicted saprobic richness. We conclude that high-severity wildfires lead to lower ectomycorrhizal richness and significantly altered ectomycorrhizal and saprobic communities in fire-adapted ecosystems, selecting resilient and fire-adapted species, such as W. rehmii and Geminibasidium sp., thus initiating post-fire succession.