Soil‐atmosphere exchange of N 2 O, CH 4 , and CO 2 and controlling environmental factors for tropical rain forest sites in western Kenya

N 2 O, CH 4 and CO 2 soil‐atmosphere exchange and controlling environmental factors were studied for a 3‐month period (dry‐wet season transition) at the Kakamega Rain forest, Kenya, Africa, using an automated measurement system. The mean N 2 O emission was 42.9 ± 0.7 μ g N m −2 h −1 (range: 1.1–324.8 μ g N m −2 h −1 ). Considering the duration of dry and wet season the annual N 2 O emission was estimated at 2.6 ± 1.2 kg N ha −1 yr −1 . Large pulse emissions of N 2 O were observed after the first rainfall events of the wet season, and the magnitude of N 2 O emissions steadily declined thereafter. A comparable trend in soil CO 2 emissions (mean: 71.8 ± 0.3 mg C m −2 h −1 ) indicates that the rapid mineralization of litter accumulated during the dry period produced the high N 2 O emissions at the start of the wet season. Manual N 2 O emission measurements at four additional rain forest sites were comparable to those measured at the main site, whereas N 2 O emissions measured at a regrowth site were significantly lower. Spatial differences in N 2 O emissions could be explained by differences in soil texture and topsoil C:N‐ratio (CO 2 : subsoil C and N concentrations), whereas the temporal variability of N 2 O and CO 2 emissions was primarily driven by soil moisture. Soils predominantly acted as sinks for CH 4 (−56.4 ± 0.8 μ g C m −2 h −1 ). For some chamber positions, episodes of net CH 4 release were observed, which could be due to high WFPS and/or termite activity. CH 4 fluxes were weakly correlated with soil moisture levels but showed no relation to temperature, texture, pH, carbon or nitrogen contents.