HR: 1340h
AN: B53A-0929    [Abstracts]
TI: A First Estimate of African Tropical Dambo Wetland Spatial Extent, Saturation Seasonality and Duration, and Methane Emissions
AU: * Nyamadzawo, G
EM: gnyama@yahoo.com
AF: Washington State University, PO Box 646420, Pullman, WA 99164-6420, United States
AU: Brown, D J
EM: david_brown@wsu.edu
AF: Washington State University, PO Box 646420, Pullman, WA 99164-6420, United States
AU: Dennison, P E
EM: dennison@geog.utah.edu
AF: University of Utah, Department of Geography 260 S. Central Campus Dr. Rm. 270, Salt Lake City, UT 84112-9155, United States
AU: Matthews, E E
EM: Elaine.E.Matthews@nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AB: Dambos constitute the largest geographic extent of seasonal wetlands in Central and Southern Africa, with potentially 2.3 million km² of dambo wetlands throughout the African continent (United Nations Food and Agriculture Organization (FAO) estimate based upon the FAO soil map of the world). These indigenous African landscape features are seasonally saturated, grassy, channelless, gently sloping valley floors that occupy up to 20% of the gently undulating land surface on the elevated plateaus of Central and Southern Africa and can also be found scattered across the West African Sahel. With widespread occurrence, saturation and inundation for months during rainy seasons, an equatorial climate, and abundant soil organic matter, dambos likely play an important role in global atmospheric methane (CH₄) dynamics. However, though a single unpublished measurement of dambo methane emissions has been reported, reliably estimating potential CH₄ emissions for this type of wetland (amount, seasonality, and potential response to climate change) is difficult given a lack of reliable continent-wide data on dambo extent and annual duration of saturated conditions. Even where dambos have been well mapped (as in Zimbabwe), their methane-relevant components (margins, floors and bottoms) have not been distinguished. Moreover, static maps of dambo extent do not address significant variations in the annual duration of dambo saturation even within individual countries. To remedy this data gap, we report on a compilation of existing dambo data from the African continent. Using existing reports, unpublished data, paper maps, and available digital spatial datasets, we estimate: (1) the geographic extent of dambo-occupied landscapes, dambos, and dambo components (with a focus on the wettest dambo bottoms); (2) the duration of dambo saturation for different climatic regions; and (3) total month x km² of annual dambo saturation. Applying the limited CH₄ measurements available, we derive a first estimate of dambo CH₄ annual emissions for the African continent.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0486 Soils/pedology (1865)
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting