Sulfur regulation on microbial biodiversity in a montane peatland

Peatlands occur globally, and peat's microbial biodiversity is dominated by nutrient cycling. Peat soils derive acidity through carbon cycling, and the role of sulfur-utilising bacteria is less understood. A montane peatland within the Greater Blue Mountains World Heritage Area in New South Wales, Australia, was investigated to understand microbial controls on sulfide acidity. Peat soils were mildly acidic, with sulfides present in the transition and reduced zones. Sulfur-reducing bacteria, including from the Desulfobaccaceae and Syntrophobacteraceae families, were present in the transition and reduced zones of the soil profile. The key drivers of the microbial biodiversity were acid extractable sulfate in the oxidised zone (0-20 cm) and chromium reducible sulfur potential acidity in the transition to reduced (60-150 cm) zones. This peatland is unique as it reflects a montane, freshwater landscape with sulfides at depth, which exert a distinct control on soil microbial biodiversity. The formation and presence of sulfides place the site at risk for acidity generation, where landscape dehydration may occur.