Water relations and hydraulic architecture in Cerrado trees: adjustments to seasonal changes in water availability and evaporative demand
| Authors: | Sandra J. Bucci, Fabian G. Scholz, Gullermo Goldstein, Frederick Meinzer, Augusto C. Franco, Yongjiang Zhang, Guang-You Hao |
| Year: | 2008 |
| Type: | Scientific Journal |
| Station: | Pacific Northwest Research Station |
| Source: | Journal of Plant Physiology |
Abstract
We determined adjustments in physiology and morphology that allow Neotropical savanna trees from central Brazil (Cerrado) to avoid water deficits and to maintain a nearly constant internal water balance despite seasonal changes in precipitation and air saturation deficit (D). Precipitation in the study area is highly seasonal with about five nearly rainless months during which D is twofold higher compared to wet season values. As a consequence of the seasonal fluctuations in rainfall and D, soil water potential changes substantially in the upper 100 cm of soil, but remains nearly constant below 2 m depth. These adjustments allow the stems of most Cerrado woody species to operate far from the point of catastrophic dysfunction for cavitation, while leaves operate close to it and experience embolism on a daily basis, especially during the dry season.