Pyrogenic savannas with a tree-grassland 'matrix' experience frequent fires (i.e. every 1-3 yr). Aboveground responses to frequent fires have been well studied, but responses of fungal litter decomposers, which directly affect fuels, remain poorly known. We hypothesized that each fire reorganizes belowground communities and slows litter decomposition, thereby influencing savanna fuel dynamics. In a pine savanna, we established patches near and away from pines that were either burned or unburned in that year. Within patches, we assessed fungal communities and microbial decomposition of newly deposited litter. Soil variables and plant communities were also assessed as proximate drivers of fungal communities. Fungal communities, but not soil variables or vegetation, differed substantially between burned and unburned patches. Saprotrophic fungi dominated in unburned patches but decreased in richness and relative abundance after fire. Differences in fungal communities with fire were greater in litter than in soils, but unaffected by pine proximity. Litter decomposed more slowly in burned than in unburned patches. Fires drive shifts between fire-adapted and sensitive fungal taxa in pine savannas. Slower fuel decomposition in accordance with saprotroph declines should enhance fuel accumulation and could impact future fire characteristics. Thus, fire reorganization of fungal communities may enhance persistence of these fire-adapted ecosystems.
Keywords: fine fuels; frequent fire; fungal diversity; metabarcoding; pyrogenic ecosystems; recurrent fire.
© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.