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The role of aquatic macrophytes in the carbon dynamics of Amazon floodplains

John Michael Melack, Univ. of California, Santa Barbara, (Presenting)
Thiago Sanna Freire Silva, Univ. of Victoria,
Diana Engle, Univ. of California, Santa Barbara,
Maycira Costa, Univ. of Victoria,

The high productivity and rapid turnover of biomass by floating aquatic macrophytes indicates that these plants are likely to be an important source of organic carbon fueling the production of carbon dioxide and methane that evades from floodplains and rivers of the Amazon basin. Remote sensing with radar and optical sensors combined with field measurements permit regional estimates of the role of floating aquatic macrophytes in the carbon dynamics of Amazon floodplains. Floating aquatic macrophytes cover approximately 1,400,000 ha at high water in the floodplain of the mainstem Solimoes/Amazon in Brazil. Monthly radar data from the Santarem area indicate considerable seasonal variability in area and biomass. Three years of data from L. Calado, a floodplain lake west of Manaus, did not show a consistent seasonal pattern in biomass, but the mixed Paspalum - Echinochlora stands had high net productivity productivity (0.6 Mg dry weight per ha per day) and monthly biomass turnover of about 50%. If these rates are extrapolated to the central Amazon floodplain, macrophyte-derived organic carbon can account for the majority of the annual flux of carbon dioxide to the atmosphere.

Science Theme:  CD (Carbon Dynamics)

Session:  3A: Carbon, Rivers, and Wetlands

Presentation Type:  Oral

Abstract ID: 94

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