Soil moisture–atmosphere feedback dominates land N2O nitrification emissions and denitrification reduction

摘要

Abstract Soil moisture (SM) is essential to microbial nitrogen (N)‐cycling networks in terrestrial ecosystems. Studies have found that SM–atmosphere feedbacks dominate the changes in land carbon fluxes. However, the influence of SM–atmosphere feedbacks on the N fluxes changes, and the underlying mechanisms remain highly unsure, leading to uncertainties in climate projections. To fill this gap, we used in situ observation coupled with gridded and remote sensing data to analyze N2O fluxes emissions globally. Here, we investigated the synergistic effects of temperature, hydroclimate on global N2O fluxes, as the result of SM–atmosphere feedback impact on N fluxes. We found that SM–temperature feedback dominates land N2O emissions by controlling the balance between nitrifier and denitrifier genes. The mechanism is that atmospheric water demand increases with temperature and thereby reduces SM, which increases the dominant N2O production nitrifier (containing amoA AOB gene) and decreases the N2O consumption denitrifier (containing the nosZ gene), consequently will potential increasing N2O emissions. However, we find that the spatial variations of soil–water availability as a result of the nonlinear response of SM to vapor pressure deficit caused by temperature are some of the greatest challenges in predicting future N2O emissions. Our data‐driven assessment deepens the understanding of the impact of SM–atmosphere interactions on the soil N cycle, which remains uncertain in earth system models. We suggest that the model needs to account for feedback between SM and atmospheric temperature when estimating the response of the N2O emissions to climatic change globally, as well as when conducting field‐scale investigations of the response of the ecosystem to warming.