HR: 1340h
AN: B13B-1194    [Abstracts]
TI: Physiological, anatomical and leaf hydraulic effects on leaf water δ18O enrichment in different plant species
AU: * Kahmen, A
EM: akahmen@berkeley.edu
AF: Center for Stable Isotope Biogeochemistry, University of California, Berkeley Valley Life Sciences Building 3140, Berkeley, CA 94720, United States
AU: Arndt, S K
EM: sarndt@unimelb.edu.au
AF: School of Forest and Ecosystem Science, University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
AU: Dawson, T E
EM: tdawson@berkeley.edu
AF: Center for Stable Isotope Biogeochemistry, University of California, Berkeley Valley Life Sciences Building 3140, Berkeley, CA 94720, United States
AB: Stable oxygen isotope ratios (δ18O) of plant and source waters are valuable tools in the analysis of water and carbon fluxes at leaf, plant, and ecosystem scales. Recent improvements in mechanistic models have significantly advanced the understanding of isotopic leaf water enrichment, which is an important source of δ18O variability in plants and ecosystems. However, the marked variability in leaf water δ18O values that have been reported for different plant species hampers efforts to interpret and then apply data on leaf water δ18O values for studies conducted at the ecosystem scale. To improve the understanding and application of δ18O values in leaf water, we tested the interplay of physiological, morphological, anatomical and leaf hydraulic properties as drivers of leaf water δ18O values across 17 Eucalyptus species growing in a common garden. We observed large differences in leaf water δ18O across the 17 species. These differences were only partly driven by physiological and leaf morphological differences across species. A sensitivity analysis using state-of-the-art leaf water enrichment models showed that the parameter ‘effective path length’ (L) is of critical importance for the variability of leaf water δ18O across different species. The data show that L can be related to a suite of leaf properties that include physiology, anatomy and hydraulics. Consequently, consideration of leaf properties will significantly improve the interpretation of δ18O values in leaf water across different plant species and will therefore help in the application of δ18O values in carbon and water cycle assessments at both the plant and the ecosystem scale.
DE: 0410 Biodiversity
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting