Abstract:Human activities such as combustion of fossil fuels, intensive agriculture and stockbreeding, have significantly altered the global nitrogen cycling in the last several decades, resulting in increasing concentrations of nitrogenous compounds in the atmosphere and increasing N deposition several fold. Nitrogen deposition can lead to changes in N-status of forest soils, species composition, and possible decline in the function and primary productivity of forest. In addition, nitrogen deposition can alter the rates of microbial N- and C- turnover, and thus, can affect the fluxes of greenhouse gases (e.g. CO2, CH4, and N2O) from forest soils. The effects of N deposition on the fluxes of greenhouse gases from forest soils are reviewed in this paper. The effects of N deposition on greenhouse gas fluxes from forest soils range from positive to negative depending on forest type, N-status of the soil, and the rate of N deposition. In forest ecosystems where biological processes are limited by N supply, N additions either stimulate soil respiration or have no significant effect, whereas in “N saturated” forest ecosystems, N additions decrease CO2 emission, reduce CH4 oxidation, and elevate N2O flux from the soil. The mechanisms and research methods about the effects of N deposition on greenhouse gas fluxes from forest soils are also reviewed in this paper. Finally, the present and future research needs about the effects of N deposition on the fluxes of greenhouse gases from forest soils are discussed.