焼けた土に菌やバクテリアが牙をむく(Fungi and bacteria are binging on burned soil)

メガファイアの死角を微生物が蘇らせる? Can microbes revive megafire dead zones?

2023-02-07 カリフォルニア大学リバーサイド校(UCR)

<関連情報>

• https://news.ucr.edu/articles/2023/02/07/fungi-and-bacteria-are-binging-burned-soil
• https://onlinelibrary.wiley.com/doi/10.1111/mec.16835

森林火災後の初年度の細菌および菌類による急速な後継者育成の動き Rapid bacterial and fungal successional dynamics in first year after chaparral wildfire

M. Fabiola Pulido-Chavez, James W. J. Randolph, Cassandra Zalman, Loralee Larios, Peter M. Homyak, Sydney I. Glassman
Molecular Ecology  Published: 29 December 2022
DOI:https://doi.org/10.1111/mec.16835

Abstract

The rise in wildfire frequency and severity across the globe has increased interest in secondary succession. However, despite the role of soil microbial communities in controlling biogeochemical cycling and their role in the regeneration of post-fire vegetation, the lack of measurements immediately post-fire and at high temporal resolution has limited understanding of microbial secondary succession. To fill this knowledge gap, we sampled soils at 17, 25, 34, 67, 95, 131, 187, 286, and 376 days after a southern California wildfire in fire-adapted chaparral shrublands. We assessed bacterial and fungal biomass with qPCR of 16S and 18S and richness and composition with Illumina MiSeq sequencing of 16S and ITS2 amplicons. Fire severely reduced bacterial biomass by 47%, bacterial richness by 46%, fungal biomass by 86%, and fungal richness by 68%. The burned bacterial and fungal communities experienced rapid succession, with 5–6 compositional turnover periods. Analogous to plants, turnover was driven by “fire-loving” pyrophilous microbes, many of which have been previously found in forests worldwide and changed markedly in abundance over time. Fungal secondary succession was initiated by the Basidiomycete yeast Geminibasidium, which traded off against the filamentous Ascomycetes Pyronema, Aspergillus, and Penicillium. For bacteria, the Proteobacteria Massilia dominated all year, but the Firmicute Bacillus and Proteobacteria Noviherbaspirillum increased in abundance over time. Our high-resolution temporal sampling allowed us to capture post-fire microbial secondary successional dynamics and suggest that putative tradeoffs in thermotolerance, colonization, and competition among dominant pyrophilous microbes control microbial succession with possible implications for ecosystem function.