Daily courses isotopic analysis of plant tissues and water vapor at Seca Floresta experiment, Santarem, PA.
Haroldo
Jackson
Silva, Universidade Federal do Par�, haroldo@lbaeco.com.br
(Presenting)
Jean
Ometto, CENA/USP, jpometto@cena.usp.br
James
Ehleringer, University of Utah, ehleringer@biology.utah.edu
Luiz
Antonio
Martinelli, CENA/USP, martinelli@cena.usp.br
Joe
Berry, university of Stanford, joeberry@stanford.edu
Francoise
Yoko
Ishida, ESALQ/CENA/USP, fyishida@cena.usp.br
Tomas
Ferreira
Domingues, University of Utah, domingues@biology.utah.edu
Edmar
Mazzi, CENA/USP, eamazzi@cena.usp.br
Sebastiao
Lopes, Universidade Federal do Par�, seblopes@yahoo.com.br
Several studies have shown a good tolerance of the Amazon forest to severe droughts, although a long deficit in the soil water content can induce significant stress and loss of productivity to the primary forests vegetation. Therefore, understanding the physiological responses to drought conditions is a challenge to pursue in tropical forests ecosystems. In this context, leaves and stems tissues were collected in the canopy profile in both drought and control plot of the Seca Floresta experiment. The oxygen isotopic composition (d18O) of the leaf water reflects the intensity of evaporation and stomata conductance to water when compared to the source water. The d18O of the source water can be identified through analysis of stem water, since no evaporation, and consequently isotopic fractionation, occurs during water uptake in plants. The expected results shall reflect different stomatal control on water loss among plants located in the dry and control experimental plots. In addition to that a seasonal variation on this response may occur. Preliminary results from the 2003 wet season showed just a slight difference between plots. Results from the dry season are being analyzed and more significant differences are expected to be found
Submetido por Francoise Ishida em 22-MAR-2004
Tema Cient�fico do LBA: CD (Armazenamento e Trocas de Carbono)