Frequent fire reorganizes fungal communities and slows decomposition across a heterogeneous pine savanna landscape

Abstract

Summary 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.

Agricultural land‐use history and restoration impact soil microbial biodiversity

“…The frequency of prescribed surface fire did vary among the 26 blocks since the initiation of the experiment; however, all plots, and thus all four treatment combinations, within a block were always burned together. Although fire could be an important factor shaping soil microbes within longleaf pine savannas (Semenova‐Nelsen, Platt, Patterson, Huffman, & Sikes, ) looking at this is beyond the scope of this study.…”

Disruption of Traditional Grazing and Fire Regimes Shape the Fungal Endophyte Assemblages of the Tall-Grass Brachypodium rupestre

“…Regarding microbial soil communities, even low-intensity fires may depress soil microbial biomass (Múgica et al, 2018), with complex consequences on the C and N cycles (Soong and Cotrufo, 2015;Shaw et al, 2016;Pellegrini et al, 2020). The composition of soil fungal communities has been documented to be disrupted by fires as well (Artz et al, 2009;Egidi et al, 2016;Semenova-Nelsen et al, 2019). Few studies have addressed the effects of fire on plant fungal assemblages (Bellgard et al, 1994;Eom et al, 1999;Mataix-Solera et al, 2002), although changes in species richness have been detected in foliar endophytes of burned trees (Huang et al, 2016), and specific plant-fungal mutualisms and pyrophilous fungal species have been described (Baynes et al, 2012;Raudabaugh et al, 2020).…”

Contrasting fungal responses to wildfire across different ecosystem types

“…Indeed, some evidence indicates that pyrogenic ecosystems might host, alongside their fire‐adapted plant communities, distinct soil fungal communities that resist fire‐related change (Hansen et al, 2019; Oliver et al, 2015). However, others have also observed significant short‐term rearrangement of fungal community structure after fire even within these ecosystem types (Semenova‐Nelsen et al, 2019).…”