Abstract We investigated soil carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) exchanges in an age‐sequence (4, 17, 32, 67 years old) of eastern white pine ( Pinus strobus L.) forests in southern Ontario, Canada, for the period of mid‐April to mid‐December in 2006 and 2007. For both CH 4 and N 2 O, we observed uptake and emission ranging from −160 to 245 μg CH 4 m −2 h −1 and −52 to 21 μg N 2 O m −2 h −1 , respectively (negative values indicate uptake). Mean fluxes from mid‐April to mid‐December across the 4, 17, 32, 67 years old stands were similar for CO 2 fluxes (259, 246, 220, and 250 mg CO 2 m −2 h −1 , respectively), without pattern for N 2 O fluxes (−3.7, 1.5, −2.2, and −7.6 μg N 2 O m −2 h −1 , respectively), whereas the uptake rates of CH 4 increased with stand age (6.4, −7.9, −10.8, and −23.3 μg CH 4 m −2 h −1 , respectively). For the same period, the combined contribution of CH 4 and N 2 O exchanges to the global warming potential (GWP) calculated from net ecosystem exchange of CO 2 and aggregated soil exchanges of CH 4 and N 2 O was on average 4%, <1%, <1%, and 2% for the 4, 17, 32, 67 years old stand, respectively. Soil CO 2 fluxes correlated positively with soil temperature but had no relationship with soil moisture. We found no control of soil temperature or soil moisture on CH 4 and N 2 O fluxes, but CH 4 emission was observed following summer rainfall events. LFH layer removal reduced CO 2 emissions by 43%, increased CH 4 uptake during dry and warm soil conditions by more than twofold, but did not affect N 2 O flux. We suggest that significant alternating sink and source potentials for both CH 4 and N 2 O may occur in N‐ and soil water‐limited forest ecosystems, which constitute a large portion of forest cover in temperate areas.