Tracing water uptake by jarrah (Eucalyptus marginata) trees using natural abundances of deuterium |
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Authors: | P Farrington J V Turner V Gailitis |
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Institution: | (1) CSIRO Division of Water Resources, Private Bag, Wembley, W. A. 6014, Australia, AU |
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Abstract: | Seasonal change in the δ2H content of water from twig sap, soil, rainfall and groundwater were measured to determine the water sources accessed by
jarrah (Eucalyptus marginata) trees at three sites in Western Australia with differing soils and depths to water table. During winter and spring the main
contributor to the water uptake of the trees was stored water in the surface layers of the soil replenished by predominantly
winter rainfall. With the onset of summer drought jarrah became more reliant on water from deeper down the profile. There
was no clear evidence that jarrah could tap water from groundwater more than 14 m deep in deep sands. Defining the source
of water for trees in deep lateritic soils using stable isotopes is hampered by the uniform deuterium profiles down most of
the unsaturated zone and into the groundwater. There was a limited response in the δ2H values of sapwater in twigs to changes in the δ2H of the upper layers of the deep sand following input of rainfall in autumn. The damped response was related to the small
variation in the δ2H composition of rainfall in most events during the year and the mixing in the tree of water extracted from different locations
in the soil profile.
Received: 21 August 1995 / Accepted: 3 December 1995 |
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Keywords: | Deuterium Stable water isotopes Water sources Eucalyptus marginata |
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