Structure and function of the soil microbiome underlying N 2 O emissions from global wetlands.

Wetland soils are the greatest source of nitrous oxide (N 2 O), a critical greenhouse gas and ozone depleter released by microbes. Yet, microbial players and processes underlying the N 2 O emissions from wetland soils are poorly understood. Using in situ N 2 O 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 N 2 O emissions. We show that N 2 O 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 N 2 O 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 N 2 O.