Climate change mitigation strategies have increased the demand for wood products, resulting in an urgent needto increase wood production. One approach is to fertilize forest land, but this can influence greenhouse gas (GHG) fluxes within the ecosystem. The aim of this study was to examine the effects of forest N fertilization onsoil CH4 and N2O fluxes in young Norway spruce (Picea abies (L.) Karst.) stands in southern Sweden. The gasfluxes were measured using flow-through non-steady-state dark chambers. In the first, long-term, experiment,half of the stand was fertilized twice (once in 2014 and once in 2016) with 150 kg ha-1 of N, and gas fluxmeasurements were taken throughout 2014–2017. In the second, dose, experiment, 0, 150, 300, or 450 kg ha-1 of N was added to the stand in April 2016, and gas flux measurements were taken during April-December 2016.The dose experiment showed that the sink strength of CH4 decreased with increasing amounts of N; the long-termexperiment indicated that repeated fertilization decreased the CH4 sink strength over time. Additionally, thelong-term experiment indicated that, while significantly higher N2O emissions were recorded in the fertilizationyears, this was not detected in subsequent years, suggesting the effect to be short-lived. In the dose experiment,fertilization tended to increase the N2O emissions relative to the amount of fertilizer. However, despite thesignificant effects of fertilization on these GHGs, the summed fluxes were a fraction of the net uptake of C at thesites, as recorded in another study. These findings suggest that fertilizing forest land with commercial NP or NPKfertilizers corresponding to 150 kg ha-1 of N, the level used in operational forestry in Sweden today, can beconducted without changing CH4 and N2O fluxes to any great extent.