In spite of advances in greenhouse gas research, the spatiotemporal CH.sub.4 and N.sub.2 O dynamics of boreal landscapes remain challenging, e.g., we need clarification of whether forest-mire transitions are occasional hotspots of landscape CH.sub.4 and N.sub.2 O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH.sub.4 and N.sub.2 O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest-mire ecotone. Soils changed from Podzols to Histosols and ground water rose downslope from a depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from -51 to 586 μg m.sup.-2 h.sup.-1 for CH.sub.4 and from 0 to 6 μg m.sup.-2 h.sup.-1 for N.sub.2 O between forest and mire types throughout the entire wet-dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest-mire transitions, there were no large peak emissions in CH.sub.4 and N.sub.2 O fluxes and the flux rates changed minimally between years. Methane uptake was significantly lower in poorly drained transitions than in the well-drained uplands. Water-saturated mires showed large CH.sub.4 emissions, which were reduced entirely during the exceptional summer drought period. Near-zero N.sub.2 O fluxes did not differ significantly between the forest and mire types probably due to their low nitrification potential. When upscaling boreal landscapes, pristine forest-mire transitions should be regarded as CH.sub.4 sinks and minor N.sub.2 O sources instead of CH.sub.4 and N.sub.2 O emission hotspots.