Abstract: The role of forest ecosystem under global warming, especially the response of forest soil nitrogen (N) pool to increased atmospheric N deposition, has become one of the hotspots in global change study. Through investigating and systematizing published data, this paper analyzed the distribution patterns of forest soil N2O emission fluxes from 38 in situ observations at global scale in 1984-2009, and assessed the response of forest soil annual cumulative N2O flux to atmospheric N deposition and to the variations in water and heat conditions. In global scale, forest soil N2O flux was averagely 0.47 kg N·hm-2·a-1, and declined gradually from low to high latitude. As a complex ecological process, forest soil cumulative N2O flux was also significantly affected by mean annual temperature, annual precipitation, and soil properties. The temperature sensitivity index of soil N2O flux (Q10 value) in global forest ecosystem was about 1.5. Moreover, forest soil N2O flux increased significantly with increasing atmospheric N deposition. The
atmospheric N deposition could explain 53% of the variations in the forest soil N2O flux across different regions, while the soil pH, mean annual temperature, and atmospheric N deposition could explain 55% of the variations within regions.