Soil-Atmosphere Carbon Dioxide Fluxes Measured with Automated Chambers at the Tapajos National Forest
Ruth
Varner, Complex Systems Research Center, University of New Hampshire, ruth.varner@unh.edu
Patrick
Michael
Crill, Department of Geology and Geochemistry, Stockholm University, patrick.crill@unh.edu
(Presenting)
Michael
M.
Keller, International Institute of Tropical Forestry, USDA Forest Service, michael.keller@unh.edu
Raimundo
Cosme de
Oliveira Jr., EMBRAPA, Amazônia Oriental, cosme@cpatu.embrapa.br
Eráclito
Rodrigues de
Sousa Neto, Fundação Floresta Tropical, eraclito@lbaeco.com.br
Jadson
Dizencourt
Dias, Fundação Floresta Tropical, jadson@lbaeco.com.br
Hudson
Silva, Complex Systems Research Center, University of New Hampshire, hsilva@kaos.sr.unh.edu
Kêmeson
Oliveira, Fundação Floresta Tropical, kemeson@lbaeco.com.br
Sérgio
N. da Silva
Albuquerque, Fundação Floresta Tropical, sergio@lbaeco.com.br
Jess
Alexander, Complex Systems Research Center, University of New Hampshire, jessa@kaos.sr.unh.edu
We measured the soil-atmosphere exchange of carbon dioxide (CO2) from 18 chambers randomly deployed over approximately 0.4 ha in the Tapajos National Forest (km 67) undisturbed forest site. Chambers have been automatically controlled and continuously operated since installation in April 2001. CO2 mixing ratio is measured by a Licor infra-red gas analyzer checked with zero and span gases at 5 hour intervals. A set of 8 high frequency chambers were sampled about 5 times daily and the remaining 10 chambers were sampled about once daily. Soil-atmosphere fluxes ranged from less than 0.2 to greater than 10 micro-mol CO2 m-2 s-1. A seasonal signal is apparently related to precipitation, soil moisture dynamics, and temperature. Greater emissions occur during the wet season than during the dry season despite higher temperatures in the dry season. After prolonged dry periods, soil fluxes can increase very quickly following small precipitation events. There is a diel variability in the soil emission of CO2 possibly related to temperature and/or humidity changes. The flux of CO2 from the soil to the atmosphere is is about 10 Mg-C ha-1 y-1.
Submetido por Michael M. Keller em 25-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)