Watershed and fire severity are stronger determinants of soil chemistry and microbiomes than within-watershed woody encroachment in a tallgrass prairie system

Fire can impact terrestrial ecosystems by changing abiotic and biotic conditions. Short fire intervals maintain grasslands and communities adapted to frequent, low-severity fires. Shrub encroachment that follows longer fire intervals accumulates fuel and can increase fire severity. This patchily dis...

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Published inFEMS microbiology ecology Vol. 97; no. 12; p. 1
Main Authors Mino, Laura, Kolp, Matthew R, Fox, Sam, Reazin, Chris, Zeglin, Lydia, Jumpponen, Ari
Format Journal Article
LanguageEnglish
Published Oxford University Press 01.12.2021
Subjects
Environmental aspects
Grasses
Microbiological research
Prairies
Soil chemistry
Soil microbiology
Watersheds
Wildfires
United States
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Summary:Fire can impact terrestrial ecosystems by changing abiotic and biotic conditions. Short fire intervals maintain grasslands and communities adapted to frequent, low-severity fires. Shrub encroachment that follows longer fire intervals accumulates fuel and can increase fire severity. This patchily distributed biomass creates mosaics of burn severities in the landscape-pyrodiversity. Afforded by a scheduled burn of a watershed protected from fires for 27 years, we investigated effects of woody encroachment and burn severity on soil chemistry and soil-inhabiting bacteria and fungi. We compared soils before and after fire within the fire-protected, shrub-encroached watershed and soils in an adjacent, annually burned and non-encroached watershed. Organic matter and nutrients accumulated in the fire-protected watershed but responded less to woody encroachment within the encroached watershed. Bioavailable nitrogen and phosphorus and fungal and bacterial communities responded to high-severity burn regardless of encroachment. Low-severity fire effects on soil nutrients differed, increased bacterial but decreased fungal diversity and effects of woody encroachment within the encroached watershed were minimal. High-severity burns in the fire-protected watershed led to a novel soil system state distinct from non-encroached and encroached soil systems. We conclude that severe fires may open grassland restoration opportunities to manipulate soil chemistry and microbial communities in shrub-encroached habitats. Keywords: fire severity and history; woody encroachment; tallgrass prairie ecosystem; soil bacteria and fungi; soil chemistry; alternate ecosystem states
ISSN:0168-6496
1574-6941
DOI:10.1093/femsec/fiabl54