Structure and function of the soil microbiome underlying N₂O emissions from global wetlands

Wetland soils are the greatest source of nitrous oxide (N₂O), a critical greenhouse gas and ozone depleter released by microbes. Yet, microbial players and processes underlying the N₂O emissions from wetland soils are poorly understood. Using in situ N₂O measurements and by determining the structure and potential functional of microbial communities in 645 wetland soil samples globally, we examined the potential role of archaea, bacteria, and fungi in nitrogen (N) cycling and N₂O emissions. We show that N₂O emissions are higher in drained and warm wetland soils, and are correlated with functional diversity of microbes. We further provide evidence that despite their much lower abundance compared to bacteria, nitrifying archaeal abundance is a key factor explaining N₂O emissions from wetland soils globally. Our data suggest that ongoing global warming and intensifying environmental change may boost archaeal nitrifiers, collectively transforming wetland soils to a greater source of N₂O.

Mohammad Bahram, Mikk Espenberg, Jaan Pärn, Laura Lehtovirta-Morley, Sten Anslan, Kuno Kasak, Urmas Kõljalg, Jaan Liira, Martin Maddison, Mari Moora, Ülo Niinemets, Maarja Öpik, Meelis Pärtel, Kaido Soosaar, Martin Zobel, Falk Hildebrand, Leho Tedersoo, Ülo Mander