Rafael
S
Oliveira, University of California - Berkeley, rafaels@socrates.berkeley.edu
(Presenting)
Todd
E
Dawson, UC Berkeley, tdawson@socrates.berkeley.edu
Stephen
O
Burgess, University of Western Australia, ssb@cyllene.uwa.edu.au
Scott
R.
Saleska, Harvard University, saleska@fas.harvard.edu
Steven
C.
Wofsy, Harvard University, scw@io.harvard.edu
Daniel
Curtis
Nepstad, Woods Hole Research center, dnepstad@whrc.org
It is regularly assumed that plants do not transpire during the night. Here, we show that this assumption is incorrect and provide evidence that nighttime transpiration can constitute a significant part of daily water loss for trees inhabiting the Tapajos National Forest, Amazonia. To quantify nighttime water fluxes at the tree and ecosystem scales we used heat ratio sapflow on trees and eddy covariance methods during 2 years in the “km 67” site of the Tapajos forest. We found that tree crowns do loose water at night and that nighttime transpiration can constitutes 5-14% of the total daily forest water use. These findings have implications for investigations of tree physiology (nighttime transpiration contributes to predawn water potential disequilibrium) and are relevant for constructing whole ecosystem water balance. To our knowledge this is the first documented case of nighttime water loss for Amazonian trees and forest stands.
Submetido por Rafael Silva Oliveira em 17-MAR-2004