Observing how carbon, energy, and water transports fluxes change with the introduction of intensive agriculture in the Amazon.
David
R.
Fitzjarrald, University at Albany, SUNY, fitz@asrc.cestm.albany.edu
(Presenting)
Ricardo
K.
Sakai, University at Albany, SUNY, sakai@asrc.cestm.albany.edu
Otavio
C.
Acevedo, Federal University of Santa Maria, Brazil, acevedo@pesquisador.cnpq.br
Osvaldo
M.M.
Moraes, Federal University of Santa Maria, Brazil, osvaldo.moraes@pesquisador.cnpq.br
Rodrigo
daSilva, LBA Regional Office,, Santarem, rodrigo@lbasantarem.com.br
This study presents direct turbulent flux measurements of carbon, heat, and moisture at an agricultural site near Santarém in the Eastern Brazilian Amazon. Since September 2000, agricultural practices in this region have changed rapidly from cattle grazing, to upland (non-irrigated) rice cultivation, and then to soybean cultivation. The pattern we witnessed in the sampled field is characteristic of the entire region along the BR-163 highway that runs south from the city of Santarém, Pará. At the LBA-ECO km77 site, global radiative fluxes turbulent heat, water vapor and CO2 fluxes, soil heat fluxes and surface layer, state variables are monitored.
We found that the eddy covariance (EC) technique fails to predict the fluxes accurately such is the case at the km77 site on nearly all nights. We estimated respiration fluxes by the boundary layer accumulation approach. during two field campaigns.
Seasonal changes in greenness and reflectivity measured in situ follow the patterns of daytime evaporation and carbon uptake. Lowest values of the Bowen ratio were observed during wet periods, principally during rice plantation. NEE in this field and it is larger than that in the adjacent undisturbed forest. After plowing and tilling there is a small efflux of CO2.
Continuing studies. We seek support to maintain the ongoing measurements. To our knowledge, the km77 agricultural site is unique in the Amazon for having continuous direct flux measurements for a long period of time. Continuing data analysis that is part of our ongoing LBA-ECO phase 3 concentrates on the linking remote sensing measurements (e.g., NDVI from MODIS and microwave band) with in situ measurements such as the radiometric and turbulent fluxes. Clear differences result in the turbulent fluxes (CO2, H2O, and heat,), radiative parameters (albedo and PAR-albedo) due to the landscape changing from pasture to crop field.