Ecophysiological processes in Brazilian savannas: A multiscale analysis

SCHOLZ, F.G., BUCCI, S.J., GOLDSTEIN, G., MEINZER, F.C., MIRALLES WILHELM, F., FRANCO, A.C.

Kumming China

Simposio; ATBC Conference; 2006

Physiological mechanisms and processes that regulate water transport along the soil-plant-atmosphere continuum were studied in central savannas of Brazil (Cerrado). The magnitude and the possible consequences of hydraulic redistribution (HR), its relationships and/or tradeoffs with nocturnal water use, root hydraulic conductivity, as well as the role of the internal water storages on the water economy of Cerrado trees, were assessed using different approaches and scales. Consequently it was necessary to utilize several methods and techniques, including a mathematical model that was used to extrapolate to the ecosystem level studies done at a lower level of organization. Results from this study demonstrated that the water transport in the soil-plant continuum in trees of Neotropical savannas is influenced by the magnitudes and variations of hydraulic resistances and driving forces for water transport (gradient in water potentials) and also by processes and mechanisms such as HR, nocturnal transpiration and internal capacitance of plants which helped to buffer the effects of diurnal and seasonal water deficits in the extreme seasonal environment of the tropical Brazilian savannas. Hydraulic redistribution was also related to species-specific patterns of leaf dynamics: deciduous and brevideciduous tree species with dimorphic root systems tended to perform HR, during the dry season, more frequently than evergreen tree species did.