Main content area

The effects of catena positions on greenhouse gas emissions along a seasonal wetland (dambo) transect in tropical Zimbabwe

Nyamadzawo, George, Wuta, Menas, Nyamangara, Justice, Rees, Robert M, Smith, Jeffry L.
Archiv für Acker- und Pflanzenbau und Bodenkunde 2015 v.61 no.2 pp. 203-221
carbon dioxide, greenhouse gas emissions, greenhouse gases, highlands, methane, methane production, nitrous oxide, seasonal wetlands, Zimbabwe
Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern Africa, one of the most extensive wetlands are dambos (seasonal wetlands) which occupy 20–25% of land area. However, there are very little data on GHG methane (CH₄), carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from dambos, and this study presents the first estimates from dambos in Zimbabwe. The objective was to evaluate the effects of catena positions; upland, dambo mid-slope and dambo bottom, on GHG emissions along an undisturbed dambo transect. Methane emissions were −0.3, 29.5 and −1.3 mg m⁻² hr⁻¹, N₂O emission were 40.1, 3.9 and 5.5 µg m² hr⁻¹, while CO₂ emissions were 2648.9, 896.2 and 590.1 mg m⁻² hr⁻¹ for upland, mid-slope and bottom catena, respectively. Our results showed that uplands were important sources of N₂O and CO₂, and a sink for CH₄, while the dambo mid-slope position was a major source of CH₄, but a weak source of CO₂ and N₂O. Dambo bottom catena was weak source GHGs. Overall, dambos were major sources of CH₄ and weak sources of N₂O and CO₂.We concluded that, depending on catenal position, dambos can be major or minor sources of GHGs.