Field studies of methane emission from termite nests into the atmosphere and measurements of methane uptake by tropical soils

The flux of CH4 and CO2 from termite nests into the atmosphere has been measured in a broad-leafed-type savannah in South Africa. Measurements were carried out on nests of species of six genera, i.e., Hodotermes, Macrotermes, Odontotermes, Trinervitermes, Cubitermes, and Amitermes. The flux rates of CH4 relative to the flux rate of CO2 in terms of carbon obtained for the individual species showed ratios of 2.9 x 10 E-3, 7.0 x 10 E-4, 6.7 x 10 E-5; 8.7 x 10 E-3, 2.0 x 10 E-3 and 4.2 x 10 E-3, respectively. Using data published on the assimilation efficiencies of termites, the flux of carbon as CH4 accounts for 6.0 x 10 E-5 to 2.6 x 10 E-3 of the carbon ingested which results in a global CH4 emission by termites of 2 to 5 x 10 E12 g/yr. Methane is decomposed in the soil with average decomposition rates of 52 myg/square meter/h. The annual CH4 consumption in the tropics and subtropics is estimated to be 21 x 10 E12 g which exceeds the CH4 emission rate by termites. (IFU)