| Autor: |
Gondwe MJ; Okavango Research Institute, University of Botswana, P/Bag 285, Maun, Botswana., Helfter C; UK Centre for Ecology and Hydrology, Atmospheric Chemistry and Effects, Bush Estate, Penicuik EH26 0QB, UK., Murray-Hudson M; Okavango Research Institute, University of Botswana, P/Bag 285, Maun, Botswana., Levy PE; UK Centre for Ecology and Hydrology, Atmospheric Chemistry and Effects, Bush Estate, Penicuik EH26 0QB, UK., Mosimanyana E; Okavango Research Institute, University of Botswana, P/Bag 285, Maun, Botswana., Makati A; Okavango Research Institute, University of Botswana, P/Bag 285, Maun, Botswana., Mfundisi KB; Okavango Research Institute, University of Botswana, P/Bag 285, Maun, Botswana., Skiba UM; UK Centre for Ecology and Hydrology, Atmospheric Chemistry and Effects, Bush Estate, Penicuik EH26 0QB, UK. |
| Abstrakt: |
Data-poor tropical wetlands constitute an important source of atmospheric CH 4 in the world. We studied CH 4 fluxes using closed chambers along a soil moisture gradient in a tropical seasonal swamp in the Okavango Delta, Botswana, the sixth largest tropical wetland in the world. The objective of the study was to assess net CH 4 fluxes and controlling environmental factors in the Delta's seasonal floodplains. Net CH 4 emissions from seasonal floodplains in the wetland were estimated at 0.072 ± 0.016 Tg a -1 . Microbial CH 4 oxidation of approximately 2.817 × 10 -3 ± 0.307 × 10 -3 Tg a -1 in adjacent dry soils of the occasional floodplains accounted for the sink of 4% of the total soil CH 4 emissions from seasonal floodplains. The observed microbial CH 4 sink in the Delta's dry soils is, therefore, comparable to the global average sink of 4-6%. Soil water content (SWC) and soil organic matter were the main environmental factors controlling CH 4 fluxes in both the seasonal and occasional floodplains. The optimum SWC for soil CH 4 emissions and oxidation in the Delta were estimated at 50% and 15%, respectively. Electrical conductivity and pH were poorly correlated ( r 2 ≤ 0.11, p < 0.05) with CH 4 fluxes in the seasonal floodplain at Nxaraga. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part1)'. |
