The Effect of Catena Position on Greenhouse Gas Emissions from Dambo Located Termite ( Odontotermes transvaalensis) Mounds from Central Zimbabwe

Abstract

Methane (CH 4), carbon dioxide (CO 2) and nitrous oxide (N 2 O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emissions from upland termites and no study has reported GHG emissions from seasonal wetlands (dambo) located termite mounds. The objective of this study was to evaluate the effect of dambo catena position on termite mound distribution and GHG emissions. It was hypothesized that mound density and GHG emissions from Odontotermes transvaalensis mounds, vary with catena position. The evaluated catena positions were margin, mid-slope, lower slope and bottom. Mound density was significantly lower in the bottom when compared to the other catena positions. The mean GHG fluxes were 88 µg·m 2 ·hr-1 , 0.78 mg m-2 ·hr-1 and 1361 mg·m-2 ·hr-1 for N 2 O, CH 4 and CO 2 respectively. Fluxes varied with catena position and were 0.48, 0.72, 1.35 and 0.79 mg·m-2 ·hr-1 for CH 4 , and 1173.7, 1440.7, 1798.7 and 922.8 mg·m-2 ·hr-1 for CO 2 in the margin, mid-slope, lower slope and the bottom catena position respectively. For N 2 O, there were no significant differences between catena positions. It was concluded that dambo located Odontotermes trans-vaalensis termite mounds are an important source of GHGs, and emissions varied with catena position for CO 2 and CH 4 .