Short-term responses of soil microbial communities to wildfire in a seasonally dry forest

Filippini E.R.; Gallinger M.; García G.; Torres R.C.; Fernández G.; Argibay D.S.; Vila J.A.; Barbero F.; Meriles J.; Roldán D.; Brito D.; Iturri A.; Mlewski E.C. · Applied Soil Ecology (2026) · DOI: 10.1016/j.apsoil.2026.107361

Resumen

Fire is a key ecological driver that shapes ecosystems by altering vegetation, soil properties, and biodiversity. We examined the short-term effects of low-to-moderate severity fire on soil microbiota in Argentina's Chaco Serrano forest using integrated molecular, biogeochemical, and remote-sensing approaches. Burned soils showed marked compositional shifts, with Actinobacteria (e.g., Paenarthrobacter , Crossiella ) increasing and Proteobacteria and Bacteroidota declining, consistent with heat-resistant traits such as spore formation. Although alpha diversity remained largely stable, forest soils displayed reduced richness. Fire also modified soil properties, raising pH and reducing organic carbon, reflecting surface biomass combustion. Vegetation type strongly modulated microbial responses: forest patches exhibited the greatest divergence, whereas shrubland and grassland were less affected. Fire severity (dNBR) further explained variation in beta diversity. Several taxa showed vegetation-dependent responses, including Sphingomonas , which increased in burned forest and shrubland but declined in grassland. No strong correlations were detected between microbial composition and soil chemistry, indicating that additional environmental factors or microbial resilience mechanisms influence post-fire dynamics. Overall, our findings show that even low-severity fires can restructure soil microbial communities, with vegetation patch identity playing a central role. These compositional changes, particularly the rise of Actinobacteria, may alter early nutrient cycling pathways. These findings improve our understanding of fire ecology in understudied South American ecosystems and highlight the need for long-term monitoring of functional impacts. This study underscores the need to interpret short-term microbial shifts within broader recovery trajectories, and highlights the importance of minimizing early disturbance, retaining surface cover, and considering vegetation patch structure to improve post-fire assessments and ecosystem recovery predictions in fire-prone South American landscapes.

Instituciones: Universidad Privada San Juan Bautista