Hydraulic redistribution (HR) is the passive movement of water through the roots from wet to dry soil layers when stomata are closed. Then, the soil-plant-atmosphere continuum is broken and a water potential gradient is established between the plant and the soil surrounding the root system. If root water potential is higher than soil water potential then water flows from the root to the soil. HR has been shown in different ecosystems and species and depends on plant physiology and soil properties. Here we determined HR patterns and tested the influence of soil texture on water redistribution in different arid ecosystems. We conducted transpiration suppression experiments during spring 2005 in Chile and spring 2008 in Spain in five shrub species that performed HR, Flourensia thurifera, Senna cumingii and Pleocarphus revolutus (Chile), Retama sphaerocarpa and Artemisia barrelieri (Spain). Shrubs were covered with a black opaque plastic cover for a period of 48-72 h, and soil water potential at three different depths under the shrubs was recorded.

Results/Conclusions

While the shrubs remained covered water potential continuously increased until the cover was removed. Then, soil water potential decreased during daytime and increased at night following typical hydraulic redistribution patterns. Our results indicate that the amount of water redistributed by shrubs during transpiration suppression is independent of the species and highly dependent on soil texture. Shrubs growing in loamy soils released up to 3.6 times more water than shrubs growing in sandy soils. This water redistribution can be of high importance for species to withstand drought by taking up during daytime of water redistributed at night.

This work was supported by FONDECYT (1071012), Compañía Minera del Pacífico (CMP), Chilean Millenium Iniciative (ICM P05-002) and CONICYT (PFB-23) grants in Chile, and the Spanish Ministry of Science and Innovation (grants CGL2004-0355-E and CGL2007-63718) in Spain.