Methane emission from flooded forest in central Africa

Abstract

In this report we give results of methane flux measurement in the flooded forest zone of the Congo River basin in central Africa. Methane fluxes are measured by the static chamber method above three types of soils characterized by various water contents. High methane emission is recorded on flooded soils (4.59 × 10 12 molecules/cm 2 /s) while methane uptake occurs in dry soil (−8.38 × 10 10 molecules/cm 2 /s). Methane flux is also derived from variations of surface concentrations of methane related to the variations of air stability and from vertical profiles in the lower troposphere. The four methods used to determine the average methane emission from this wetland type yield compatible values. The average yearly flux is estimated at 2 to 4 × 10 12 molecules/cm 2 /s or 45 to 90 mg/m 2 /d The total wetland area being about 10 5 km 2 , global methane emission from the flooded forest zone of the Congo River basin would represent 1.6 to 3.2 Tg (CH 4 ) per year.