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

Abstract

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. Moreover, 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.