| Grant number: | 03/13172-2 |
| Support Opportunities: | Research Projects - Thematic Grants |
| Start date: | October 01, 2004 |
| End date: | January 31, 2009 |
| Field of knowledge: | Biological Sciences - Ecology - Ecosystems Ecology |
| Principal Investigator: | Reynaldo Luiz Victória |
| Grantee: | Reynaldo Luiz Victória |
| Host Institution: | Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil |
| Pesquisadores principais: | Alex Vladimir Krusche ; ANTONIO ROBERTO PEREIRA ; Maria Victoria Ramos Ballester |
| Associated research grant(s): | 06/52251-3 - Linda Anne Deegan | The Ecosystems Center - MBL - United States,
AV.EXT 06/52242-4 - Christopher Neill | The Ecosystems Center - MBL - Estados Unidos, AV.EXT |
| Associated scholarship(s): | 05/56386-8 - Isotopic discrimination of sources of methane in tropical forests of Amazonia, BP.DR |
Abstract
The humid tropics play an important but ambiguous role in the global carbon cycle. While deforestation has been estimated to release about 1.6 Gt C y-¹ (HOUGHTON, 2000), mature Amazon rainforests appear to sequester carbon (act as a sink), but of an uncertain magnitude. Current estimates of sequestration have wide variation between different types of measurements, ~1,3 Mg C.ha-¹ yr-¹ based on the accumulation of biomass and soils (PHILLIPS et aI., 1998; CHAMBERS et aI., 2001; TRUMBORE, 2000) to 1.0 to > 5.9 Mg C ha-¹ y-¹ based on eddy covariance measurements (FAN et al. 1990; GRACE et al. 1995; MALHI et al. 1998). However, recent calculations from global atmospheric inverse modeling imply that the net carbon exchange of the tropics with the atmosphere is about zero (SCHIMEL et al.; 2001). Discrepancies between these estimates of carbon sequestration rates may be due in part to methodological issues and integration times of methods. However, it is also possible that at least part of the carbon fixed in the upland could be "exported in fluxes not yet quantified. In fact, preliminary results (RICHEY et al., 2002) show that evasive fluxes of C02 from aquatic systems of the Amazon can account for as much as the lower estimate of carbon sequestration by "terra firme" forests in the central part of the basin. In this project we hypothesize that "CO2 evasion returns as much carbon to the atmosphere as is sequestered in upland forests on an interannual basis and the export of organic material from upland forests to fluvial environments is the primary source of carbon that is eventually respired in rivers and evaded as CO2. To test it, we intend to: 1) conduct fieldwork in characteristic sub basins to obtain an extensive suite of pC02 distribution measurements over the hydrologic regime; 2) use proven geochemical techniques (gas flux measurements, isotopic tracers, demineralization rates) to quantify the rates of the lateral transfer and cycling of water and bioactive organic matter from the land, through riparian environments and to the river system and; 3) use a terrestrial source/river transport and reaction model to synthesize and extrapolate the site-specific C02 evasion rate measurements to a basin-wide estimate of C02 evasion rate. This project consolidates and extends the scientific and educational activities of this group in fluvial systems of the Amazon, started 20 years ago with a successful cooperation between Centro de Energia Nuclear na Agricultura, Instituto Nacional de Pesquisas da Amazônia and University of Washington, Seattle, USA, and which was followed by the thematic project "Changes in organic matter dynamics in micro and meso-scale rivers of Rondônia, as a function of changes in land cover" Its feasibility is also assured by various cooperation within LBA (NASA), with the University of Washington and the Marine Biological Laboratory (Woods Hole, MA, USA) and within the Millennium Institute (CNPq), with several research institutions in the Amazon. (AU)
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