Title: Evapotranspiration and energy balance of Brazilian savannas with contrasting tree density
Author: Giambelluca, Thomas W.; Scholz, Fabian G.; Bucci, Sandra J.; Meinzer, Frederick C.; Goldstein, Guillermo; Hoffmann, William A.; Franco, Augusto C.; Buchert, Martin P.;
Source: Agricultural and Forest Meteorology
Publication Series: Scientific Journal (JRNL)
Tropical savannas including those of central Brazil (Cerrado) serve as an important regulator of energy and mass exchange with the atmosphere. However, the effects of interactions between grasses and deeply rooted trees and shrubs on energy and water fluxes of savannas are not well understood. In this study, eddy-covariance measurements were used to observe and compare the energy balance and evapotranspiration at two adjacent Cerrado sites differing in woody plant density. At both sites, ET reached a minimum at near the end of the dry season, indicating that reduced water availability constrained dry season ET at both sites. The Bowen ratio at both sites increased as soil moisture decreased, but with a stronger dependency at the Campo Cerrado site, presumably due to the dominance of shallow-rooted plants and the larger contribution of soil evaporation there. Energy partitioning, as indicated by the Bowen ratio, was also strongly influenced by variations in leaf area index (LAI). The strong similarity in the Bowen ratio-LAI relationship for the two sites suggests that LAI can be used to explain much of the observed temporal and spatial ET variability across seasons and variations in woody plant density in the Cerrado.
Keywords: tropical savannas, land-atmosphere interaction, leaf area index, soil moisture
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Giambelluca, Thomas W.; Scholz, Fabian G.; Bucci, Sandra J.; Meinzer, Frederick C.; Goldstein, Guillermo; Hoffmann, William A.; Franco, Augusto C.; Buchert, Martin P. 2009. Evapotranspiration and energy balance of Brazilian savannas with contrasting tree density. Agricultural and Forest Meteorology. 149:1365-1376.
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