Fire as a driver of fungal diversity — A synthesis of current knowledge

Abstract

Fires occur in most terrestrial ecosystems where they drive changes in the traits, composition, and diversity of fungal communities. Fires range from rare, stand-replacing wildfires to frequent, prescribed fires used to mimic natural fire regimes. Fire regime factors, including burn severity, fire intensity, and timing vary widely and likely determine how fungi respond to fires. Despite the importance of fungi to post-fire plant communities and ecosystem functioning, attempts to identify common fungal responses and their major drivers are lacking. This synthesis addresses this knowledge gap, and ranges from fire adaptations of specific fungi to succession and assembly fungal communities as they respond to spatially heterogenous burning within the landscape. Fires impact fungi directly and indirectly through their effects on fungal survival, substrate and habitat modifications, changes in environmental conditions, and/or physiological responses of the hosts with which fungi interact. Some specific pyrophilous, or "fire-loving", fungi often appear after fire. Our synthesis explores whether such taxa can be considered cosmopolitan, and whether they are truly fire-adapted, or simply opportunists adapted to rapidly occupy substrates and habitats made available by fires. We also discuss the possible inoculum sources of post-fire fungi and explore existing conceptual models and ecological frameworks that may be useful to generalize fungal fire responses. We conclude with identifying research gaps and areas that may best transform the current knowledge and understanding of fungal responses to fire.

Diversity of genomic adaptations to the post‐fire environment in Pezizales fungi points to crosstalk between charcoal tolerance and sexual development

“…The soil colonization after fire events happens in succession – not all of the species grow simultaneously (Bruns et al ., 2020; Hughes et al ., 2020). We considered pyrotolerant fungi opportunists that occupy, at a later stage than pyrophilous fungi, substrates and habitats made available by fires (Fox et al ., 2022). This colonization process is represented in Fig.…”

“…The colonization is then followed by other pyrophilous species (Bruns et al, 2020). Also, the drastic environmental changes triggered by the fireheat, pH, and chemical compositionmight induce spore germination and the appearance of fruiting bodies (El-Abyad & Webster, 1968;Petersen, 1970;Fox et al, 2022). One would expect the early colonizers of the necromass zone to be 'r-selected', benefitting from the open niche and undergoing rapid growth, initially with little competition.…”

“…www.newphytologist.com This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Pressler et al, 2019;Fox et al, 2022). Most soil microorganisms are killed in the temperature range of 70-80°C, and the disruption of cellular components, including membrane lipids, nucleic acids, and proteins, occurs just above 100°C (Cerda, 2009).…”

Prescribed fire selects for a pyrophilous soil subcommunity in a northern California mixed conifer forest

“…It’s notable that most taxa that we identify as pyrophilous fell below the neutral partition in our burned plots (Figure 5B), indicating that they were found at high abundance with relatively low frequency. Such a patchy distribution may be explained by the fact that the effects of fire across a landscape result in a spatially heterogeneous mosaic [74, 75]. For example, individual soil patches experience varied levels of perturbation from irregular heating, as well as non-uniform deposition of PyOM and changes in pH.…”

Rapid bacterial and fungal successional dynamics in first year after Chaparral wildfire

“…Although it is clear that pyrophilous fungi exist and are widespread, we lacked an understanding of how soon these pyrophilous fungi appear, their turnover rates, and if they trade off in abundance over time (Fox et al, 2022). Here, we show that surviving ectomycorrhizal Basidiomycetes Cortinarius, Inocybe, and Tomentella, previously found in burned temperate pine forests (Owen et al, 2019; Pulido-Chavez et al, 2021) and pine-dominated Mediterranean systems (Gassibe et al, 2011; Hernández-Rodríguez et al, 2013) also dominate early chaparral fungal succession.…”