Title: A simple pyrocosm for studying soil microbial response to fire reveals a rapid, massive response by Pyronema species

Abstract

We have designed a pyrocosm to enable fine-scale dissection of post-fire soil microbial communities. Using it we show that the peak soil temperature achieved at a given depth occurs hours after the fire is out, lingers near this peak for a significant time, and is accurately predicted by soil depth and the mass of charcoal burned. Flash fuels that produce no large coals were found to have a negligible soil heating effect. Coupling this system with Illumina MiSeq sequencing of the control and post-fire soil we show that we can stimulate a rapid, massive response by Pyronema, a well-known genus of pyrophilous fungus, within two weeks of a test fire. This specific stimulation occurs in a background of many other fungal taxa that do not change noticeably with the fire, although there is an overall reduction in richness and evenness. We introduce a thermo-chemical gradient model to summarize the way that heat, soil depth and altered soil chemistry interact to create a predictable, depth-structured habitat for microbes in post-fire soils. Coupling this model with the temperature relationships found in the pyrocosms, we predict that the width of a survivable “goldilocks zone”, which achieves temperatures that select for postfire-adapted microbes, willmore » stay relatively constant across a range of fuel loads. In addition we predict that a larger necromass zone, containing labile carbon and nutrients from recently heat-killed organisms, will increase in size rapidly with addition of fuel and then remain nearly constant in size over a broad range of fuel loads. The simplicity of this experimental system, coupled with the availability of a set of sequenced, assembled and annotated genomes of pyrophilous fungi, offers a powerful tool for dissecting the ecology of post-fire microbial communities.« less

Authors:

Bruns, Thomas D. ;

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Chung, Judy A.; Carver, Akiko A.; Glassman, Sydney I.; Suen, ed., Garret

Publication Date:

2020-03-04

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1602906

Alternate Identifier(s):

OSTI ID: 1638367

Grant/Contract Number:  

SC0016365; SC0020351

Resource Type:

Published Article

Journal Name:

PLoS ONE

Additional Journal Information:

Journal Name: PLoS ONE Journal Volume: 15 Journal Issue: 3; Journal ID: ISSN 1932-6203

Publisher:

Public Library of Science

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; fungi; fuels; fungal genomics; wildfires; soil chemistry; fire suppression technologies; thermocouples; plant fungal pathogens