Hydraulic lift in three shrub species from the Chilean coastal desert

Abstract

Hydraulic lift is defined as the passive movement of water through roots from wetter, deeper soil layers into drier shallower layers along a gradient in soil water potential. This process is generally found in plant species with dimorphic root systems, which use water from both shallow and deep layers. We assessed the ability of three shrub species of the Chilean coastal desert, Porlieria chilensis, Adesmia bedwellii and Proustia cuneifolia, to act as hydraulic lifters. Our results showed evidences that the three species are hydraulic lifters with larger fluctuations of soil water potentials in summer 2004 and smaller fluctuations in winter 2004 and summer 2005. The soil water potential was higher beneath P. chilensis than beneath P. cuneifolia and A. bedwellii. Soils were significantly wetter at 60 cm than at 30 cm depth. The movement of water from wetter and deeper soil layers to drier and shallower soil layers through hydraulic lift may allow these shrubs to extend their metabolic activity into the lengthy drought period that characterizes the Chilean desert ecosystems.