CO2 [carbon dioxide] and CH4 [methane] fluxes were monitored over 4 years in a range of taiga forests along the Tanana River in interior Alaska. Floodplain alder and white spruce sites and upland birch/aspen and white spruce sites were examined. Each site had control, fertilized, and sawdust amended plots; flux measurements began during the second treatment year. CO2 emissions decreased with successional age across the sites (alder, birch/aspen, and white spruce, in order of succession) regardless of landscape position. Although CO2 fluxes showed an exponential relationship with soil temperature, the response of CO2 production to moisture fit an asymptotic model. Of the manipulations, only N fertilization had an effect on CO2 flux, [...]