Mining Impacts on a Threatened and Burnt Swamp Ecosystem: Responses of the Microbial Soil Community.

Peatlands are globally important carbon reservoirs that mitigate global warming while regulating biogeochemical cycles. However, these ecosystems are highly vulnerable to environmental disturbances, such as fire and mining. Despite the key ecological roles of soil microbes, descriptions of microbial assemblages in many peatland systems, and how they may shift under the dual disturbances of fire and mining, remain poorly addressed. Here, we assessed the composition and diversity of soil microbial communities in three mined and three unmined swamps in southeastern Australia, all affected by the unprecedented summer bushfires during 2019-2020. Bacterial and eukaryotic communities were analysed alongside soil chemical properties across a moisture gradient within each swamp. Our results revealed significant differences in communities due to mining activities, with the most pronounced differences observed within swamp communities rather than other sites along the moisture gradient. The eukaryotic community was significantly influenced by the combined effects of mining activity and fire history. The bacterial community was significantly correlated with pH. Our findings suggest that mining was associated with changes in eukaryotic diversity and bacterial community structure and functionality, with fire history potentially contributing to the observed patterns. This study underscores the critical, detrimental impacts that mining can have on peatland microbial composition.