Approach:
The degree to which primary production, soil carbon, and trace gas fluxes in tropical forests of
the Amazon are limited by moisture availability and other environmental factors has been examined
using an ecosystem modeling application for the country of Brazil. A regional geographic
information system (GIS) serves as the data source of climate drivers, satellite "greenness"
images, land cover, and soil properties for input to the NASA-CASA model over a 8-km grid
resolution.
Major findings:
- Simulation results imply that net primary production (NPP) is limited by
cloud interception of solar radiation over the humid northwestern portion of
the region, with peak annual rates for NPP of nearly 1.4 kg C m-2 yr-1
localized in the seasonally dry eastern Amazon in areas that we assume are
primarily deep-rooted evergreen forest cover.
- Regional effects of Amazon forest conversion to pasture on NPP and soil
carbon content are indicated in the model results, especially in seasonally
dry areas.
- Comparison of model flux predictions along selected eco-climatic transects reveal moisture,
soil, and land use controls on gradients of ecosystem production and soil trace gas emissions
(CO2, N2O, and NO).
Net primary production estimated at 8-km cell resolution by the NASA-CASA model for Brazil,
circa 1990.
To view monthly animation of net primary production click here.
Net Primary Production
References:
Potter, C. S., E. A. Davidson, S. A. Klooster, D. C. Nepstad, G. H. de
Negreiros, and V. Brooks. 1998. Regional application of an ecosystem
production model for studies of biogeochemistry in Brazilian Amazonia.
Global Change Biology. 4(3):315-334.
Produced in collaboration with D. Nepstad and E. Davidson (Woods Hole
Research Center), with grant support from the National Science Foundation
Support for computing resources provided by the High Performance Computing
and Communications (HPPC) Program by granting access to their testbed
computers at the Numerical Aerodynamic Simulation (NAS) facility at NASA-Ames.
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