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Determining soil and ground water use of vegetation from heat pulse, water potential and stable isotope data


Cook, PG and O'Grady, AP, Determining soil and ground water use of vegetation from heat pulse, water potential and stable isotope data, Oecologia, 148, (1) pp. 97-107. ISSN 0029-8549 (2006) [Refereed Article]

DOI: doi:10.1007/s00442-005-0353-4


A simple model of water uptake by vegetation is used to aid the discrimination of plant water sources determined with isotope data. In the model, water extracted from different soil depths depends on the leaf-soil potential difference, a root distribution function and a lumped hydraulic conductance parameter. Measurements of plant transpiration rate, and soil and leaf water potentials are used to estimate the value of the conductance parameter. Isotopic ratios in soil water and xylem are then used to constrain the root distribution. The model is applied to field measurements of transpiration, leaf water potential and 18O composition of xylem water on Corymbia clarksoniana, Lophostemon suaveolens, Eucalpylus platyphylla and Melaleuca viridiflora, and soil water potential and 18O composition of soil water to 8.5 m depth, in an open woodland community, Pioneer Valley, North Queensland. Estimates of the water uptake from various depths below the surface are determined for each species. At the time of sampling, the proportion of groundwater extracted by the trees ranged from 100% for C. clarksoniana to < 15% for L. suaveolens and E. platyphylla. The advantages of the model over the traditional approach to determining sources of water used by plants using isotope methods are that it: (1) permits more quantitative assessments of the proportion of water sourced from different depths, (2) can deal with gradational soil water isotope profiles (rather than requiring distinct values for end-members), and (3) incorporates additional data on plant water potentials and is based on simple plant physiological processes. © Springer-Verlag 2006.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Forestry
Objective Field:Native forests
UTAS Author:O'Grady, AP (Dr Anthony O'Grady)
ID Code:42652
Year Published:2006
Web of Science® Times Cited:27
Deposited By:Plant Science
Deposited On:2006-08-01
Last Modified:2007-05-03

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