Methane and carbon dioxide emissions from different ecosystems at the end of dry period in South Vietnam

The carbon cycle includes important fluxes of methane (CH 4 ) and carbon dioxide (CO 2 ) between the ecosystem and the atmosphere. The fluxes may acquire either positive (release) or negative values (consumption). We calculated these fluxes based on short-campaign in situ chamber measurements from four ecosystems of South Vietnam: intact mountain rain forest, rice field, Melaleuca forest and mangroves (different sites with Avicennia or Rhizophora and a typhoon-disturbed gap). Soil measurements were supplemented by chamber measurements of gas fluxes from the tree stems. Measuring CH 4 and CO 2 together facilitates the assessment of the ratio between these two gases in connection with current conditions and specificity of individual ecosystems. The highest fluxes of CH 4 were recorded in the Melaleuca forest, being within the range from 356.7 to 784.2 mg CH 4 –C m −2 day −1 accompanied by higher fluxes of CH 4 release from Melaleuca tree stems (8.0–262.1 mg CH 4 –C m −2 day −1 ). Significant negative soil fluxes of CH 4 were recorded in the mountain rain forest, within the range from − 0.3 to − 0.8 mg CH 4 –C m −2 day −1 . Fluxes of CO 2 indicate prevailing aerobic activity in the soils of the ecosystems investigated. Quite a large variability of CO 2 fluxes was recorded in the soil of the Avicennia mangroves. The in situ measurements of different ecosystems are fundamental for follow-up measurements at different levels such as aerial and satellite gas fluxes observations.