Global variations and drivers of nitrous oxide emissions from forests and grasslands

Nitrous oxide (N$_2$O) emissions are highly variable due to the complex interaction of climatic and ecological factors. Here, we obtained in-situ annual N$_2$O emission flux data from almost 180 peer-papers to evaluate the dominant drivers of N$_2$O emissions from forests and unfertilized grasslands at a global scale. The average value of N$_2$O emission fluxes from forest (1.389 kg Nha$^{-1}$yr$^{-1}$) is almost twice as large as that from grassland (0.675 kg Nha$^{-1}$yr$^{-1}$). Soil texture and climate are the primary drivers of global forest and grassland annual N$_2$O emissions. However, the best predictors varied according to land use and region. Soil clay content was the best predictor for N$_2$O emissions from forest soils, especially in moist or wet regions, while soil sand content predicted N$_2$O emissions from dry or moist grasslands in temperate and tropical regions best. Air temperature was important for N$_2$O emission from forest, while precipitation was more efficient in grassland. This study provides an overall understanding of the relationship between natural N$_2$O emissions and climatic and environmental variables. ... mehrMoreover, the identification of principle factors for different regions will reduce the uncertainty range of N$_2$O flux estimates, and help to identify region specific climate change mitigation and adaptation strategies.