Isotopic steady state or non-steady state transpiration? Insights from whole-tree chambers
Journal Publication ResearchOnline@JCUAbstract
Unravelling the complexities of transpiration can be assisted by understanding the oxygen isotope composition of transpired water vapour (δE). It is often assumed that δE is at steady state, thereby mirroring the oxygen isotope composition of source water (δsource), but this assumption has never been tested at the whole-tree scale. This study utilized the unique infrastructure of 12 whole-tree chambers enclosing Eucalyptus parramattensis E.C.Hall trees to measure δE along with concurrent temperature and gas exchange data. Six chambers tracked ambient air temperature and six were exposed to an ambient +3 °C warming treatment. Day time means for δE were within 1.2‰ of δsource (−3.3‰) but varied considerably throughout the day. Our observations show that E. parramattensis trees are seldom transpiring at isotopic steady state over a diel period, but transpiration approaches source water isotopic composition over longer time periods.
Journal
Tree Physiology
Publication Name
Tree Physiology
Volume
44
ISBN/ISSN
1758-4469
Edition
N/A
Issue
11
Pages Count
13
Location
N/A
Publisher
Oxford University Press
Publisher Url
N/A
Publisher Location
N/A
Publish Date
N/A
Url
N/A
Date
N/A
EISSN
N/A
DOI
10.1093/treephys/tpae125