HR: 1340h
AN: B43A-0137    [Abstracts]
TI: Soil-Atmosphere Carbon Dioxide and Methane Fluxes in Undisturbed Tropical Forest
AU: * Crill, P M
EM: patrick.crill@geo.su.se
AF: Inst Geologi och Geockemi, Stockholm Univ, Stockholm, 106 91 Sweden
AU: * Crill, P M
EM: patrick.crill@geo.su.se
AF: Complex Systems Res Cen, Univ of New Hampshire, Durham, NH 03824 United States
AU: Varner, R K
AF: Complex Systems Res Cen, Univ of New Hampshire, Durham, NH 03824 United States
AU: Keller, M M
AF: Complex Systems Res Cen, Univ of New Hampshire, Durham, NH 03824 United States
AU: Keller, M M
AF: Int Inst Tropical Forestry, USDA Forest Service, Rio Piedras, PR 00926 United States
AU: Silva, H
AF: Complex Systems Res Cen, Univ of New Hampshire, Durham, NH 03824 United States
AU: Dias, J D
AF: Esc Sup de Agricultura, CENA,Univ Sao Paulo, Piracicaba, SP 13416000 Brazil
AU: Neto, E S
AF: Fundacao Floresta Tropical, Rua 24 de Outubro, Santarem, PA 68040 Brazil
AU: de Oliveira, R C
AF: EMBRAPA Amazonia Oriental, Rua Capanema, Belem, PA 66620 Brazil
AB: Measured carbon dioxide (CO$_{2}$) fluxes at soil surfaces are are the result of many biological below ground and surface processes that remineralize organic matter. Methane fluxes are the result of the balance between production and oxidation and transport. Soil temperature and moisture exert strong controls on the soil-atmosphere trace gas fluxes. We measured the soil-atmosphere flux of CO$_{2}$ and CH$_{4}$ with an automated chamber system that was installed in April 2001 in the Tapajos National Forest, Para, Brazil. This is a mature forest on a clay Oxisol. The mean annual temperature is 25$\deg$C with diurnal range often exceeding the variability in the annual daily means. The mean annual precipitation is ca. 2000 mm per year with a distinct dry season from July to December. Eighteen aluminum chambers were installed in a 0.5 ha area close to the flux tower at the km 67 LBA site. Eight of these chambers are sampled about 5 times per day (closed 7$%$ daily) and the other 10 chambers are sampled individually approximately once per day (closed 1.5$%$ daily). For the 8 frequently sampled chambers, dry season fluxes over the 3 year period averaged 2.4 $\mu$mol CO$_{2}$ m$^{-2}$ s$^{-1}$ and the wet season averages were 3.0 $\mu$mol CO$_{2}$ m$^{-2}$ s$^{-1}$ . As expected, the drained upland soils were most often a weak CH4 sink but during wet periods erratic positive fluxes of greater than 20 mg CH$_{4}$ m$^{-2}$ d$^{-1}$ were measured. The soil effluxes do not appear to be consistent with nocturnal accumulations of CH4. Soil CO$_{2}$ flux is positively correlated with both soil temperature and soil moisture content. In tropical forests, soil temperature and soil moisture are often negatively correlated with one another, thereby complicating their combined effect on soil efflux.
DE: 1890 Wetlands
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting