Stable isotope analyses provide evidence of drought stress impacting plant function at the Seca Floresta
James
R
Ehleringer, University of Utah, ehleringer@biology.utah.edu
(Presenting)
Jean
P
Ometto, CENA-USP, ometto@biology.utah.edu
Francoise
Y
Ishida, CENA-USP, fyishida@cena.usp.br
Luiz
Antonio
Martinelli, CENA-USP, zebu@cena.usp.br
Joseph
A
Berry, Carnegie Institution of Washington, joeberry@stanford.edu
Tomas
Domingues, University of Utah, domingues@biology.utah.edu
Haroldo
Jackson
Silva, CENA-USP, haroldo@lbaeco.com.br
Edmar
Mazzi, CENA-USP, eamazzi@cena.usp.br
Daniel
Curtis
Nepstad, Woods Hole, dnepstad@whrc.org
Carbon isotope ratios have been measured to examine the impacts of a drought treatment at the Seca Floresta. We measured the carbon isotope ratio values of leaf organic matter and on the carbon dioxide effluxing from soil and litter components in droughted and non-droughted plots. In addition, we quantified soil carbon dioxide efflux rates in order to partition this flux into its soil and litter components. The observations suggest that a reduction in soil moisture availability results in both increased carbon isotope ratio values of the leaf organic matter and increased carbon isotope ratio values of the soil carbon dioxide efflux. Further examination of the data suggest that the carbon isotope ratio values of the soil carbon dioxide efflux can be partitioned into two components: a litter component that changed modestly its carbon isotope ratio value seasonally and a soil component that showed larger interseasonal fluctuations in carbon isotope ratio values. The seasonal fluctuations in both the leaf organic matter and the carbon dioxide efflux of the soil component were consistent with a photosynthetic carbon supply reflecting reduced stomatal closure.
Submetido por James Ehleringer em 17-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)