title: The redistribution of soil water by tree root systems.
abstract: Plant roots transfer water between soil layers of different water potential thereby significantly affecting the distribution and availability of water in the soil profile. We used a modification of the heat pulse method to measure sap flow in roots of Grevillea robusta and Eucalyptus camaldulensis and demonstrated a redistribution of soil water from deeper in the profile to dry surface horizons by the root system. This phenomenon, termed "hydraulic lift" has been reported previously. However, we also demonstrated that after the surface soils were rewetted at the break of season, water was transported by roots from the surface to deeper soil horizons - the reverse of the "hydraulic lift" behaviour described for other woody species. We suggest that "hydraulic redistribution" of water in tree roots is significant in maintaining root viability, facilitating root growth in dry soils and modifying resource availability.
authors.affiliation: Department of Botany, University of Western Australia, Nedlands, WA 6907, Australia e-mail: sburgess@cyllene.uwa.edu.au; fax: +61-8-9380-1001, , , , , , AU.
authors.forename: Stephen S O
authors.initials: SS
authors.lastname: Burgess
authors.affiliation: Department of Botany, University of Western Australia, Nedlands, WA 6907, Australia e-mail: sburgess@cyllene.uwa.edu.au; fax: +61-8-9380-1001, , , , , , AU.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Adams
authors.affiliation: CSIRO Plant Industry, Private Bag, P.O., Wembley, WA 6014, Australia, , , , , , AU.
authors.forename: Neil C
authors.initials: NC
authors.lastname: Turner
authors.affiliation: International Centre for Research in Agroforestry (ICRAF), P.O. Box 30677, Nairobi, Kenya, , , , , , KE.
authors.forename: Chin K
authors.initials: CK
authors.lastname: Ong
keywords: Hydraulic lift; Key words Plant roots; Sap flow; Water use