Between light and dark, source and sink: N₂O dynamics in a subarctic, nutrient-poor permafrost peatland

Global warming and permafrost thaw in the Arctic raise concerns about increased greenhouse gas emissions. Nitrous oxide(N ₂ O) is a potent greenhouse gas produced in soils, but its fluxes from nutrient-poor Arctic peatlands remain poorly quantified. Here, we present 1,487 chamber flux observations across three snow-free seasons in a nutrient-poor thawing permafrost peatland. Our results reveal this ecosystem acts as a continuous, albeit small N ₂ O sink during the snow-free season—unreported in prior in-situ studies. We also identify a persistent N ₂ O hot spot, indicating substantial localised production potential. Complex interactions between photosynthetically active radiation (PAR), CO ₂ fluxes, and other environmental factors drive N ₂ O fluxes, with PAR being important but not exclusive. Differences in drivers and response shapes were evident between light and dark conditions. These findings highlight non-negligible N ₂ O fluxes in nutrient-poor Arctic soils and the significance of hot spots for landscape-scale budgets. The critical role of soil-plant-atmosphere interactions and light as a driver has implications for global greenhouse gas budgets and climate mitigation, underscoring the need for further research.