Downward flux of water through roots (i.e. inverse hydraulic lift) in dry Kalahari sands

Downward transport of water in roots, in the following termed “inverse hydraulic lift,” has previously been shown with heat flux techniques. But water flow into deeper soil layers was demonstrated in this study for the first time when investigating several perennial grass species of the Kalahari Desert under field conditions. Deuterium labelling was used to show that water acquired by roots from moist sand in the upper profile was transported through the root system to roots deeper in the profile and released into the dry sand at these depths. Inverse hydraulic lift may serve as an important mechanism to facilitate root growth through the dry soil layers underlaying the upper profile where precipitation penetrates. This may allow roots to reach deep sources of moisture in water-limited ecosystems such as the Kalahari Desert.

Authors and Affiliations

1. Max-Planck-Institut for Biogeochemistry, PO Box 100164, D-07401 Jena, Germany, , , , , , DE

   E.-D. Schulze

2. Ecology Center, Utah State University, Logan, UT 84322-5230, USA, , , , , , US

   M. M. Caldwell

3. Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA, , , , , , US

   J. Canadell & H. A. Mooney

4. Department of Botany, University of Texas, Austin, TX 78713, USA, , , , , , US

   R. B. Jackson

5. CSIRO Division of Forest Science and Technology, P Box 395, Pretoria, South Africa, , , , , , ZA

   D. Parson & R. Scholes

6. Department of Ecology, University of Buenos Aires, Av. San Martin 4453, Buenos Aires 1417, Argentina, , , , , , AR

   O. E. Sala

7. Institut für Hydrologie, GSF Neuherberg, Ingolstädter Landstrasse 1, D-81377 München, Germany, , , , , , DE

   P. Trimborn

Received: 1 January 1998 / Accepted: 1 April 1998

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