CH4 and N2O fluxes from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China were measured for one year
using closed static chamber technique and gas chromatography method. Three treatments were set in the studied field: (A) litter-free,
(B) with litter, and (C) with litter and seedling. The results showed that the soil in our study was a sink of atmospheric CH4 and
source of atmospheric N2O. The observed mean CH4 fluxes from treatments A, B, and C were –50.0 4.0, –35.9 2.8, –31.6 2.8
gC/(m2 h), respectively, and calculated annual fluxes in 2003 were –4.1, –3.1, and –2.9 kgC/hm2, respectively. The observed mean
N2O fluxes from treatments A, B, and C were 30.9 3.1, 28.2 3.5, 50.2 3.7 gN/(m2 h), respectively, and calculated annual fluxes
in 2003 were 2.8, 2.6, and 3.7 kgN/hm2, respectively. Seasonal variations in CH4 and N2O fluxes were significant among all the three
treatments. The presence of litter decreased CH4 uptake during wet season (P < 0.05), but not during dry season. There was a similar
increase in seedlings-mediated N2O emissions during wet and dry seasons, indicating that seedlings increased N2O emission in both
seasons. A strong positive relationship existed between CH4 fluxes and soil moisture for all the three treatments, and weak relationship
between CH4 fluxes and soil temperature for treatment B and treatment C. The N2O fluxes correlated with soil temperature for all the
three treatments.