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Water potential gradient, root conduit size and root xylem hydraulic conductivity determine the extent of hydraulic redistribution in temperate trees

Citation

Hafner, Benjamin D; Hesse, Benjamin D; Bauerle, Taryn L; Grams, Thorsten EE (2019), Water potential gradient, root conduit size and root xylem hydraulic conductivity determine the extent of hydraulic redistribution in temperate trees, Dryad, Dataset, https://doi.org/10.5061/dryad.tmpg4f4v3

Abstract

1. Hydraulic redistribution (HR) of soil water through plant roots is widely described, however its extent, especially in temperate trees, remains unclear. Here, we quantified redistributed water of five temperate tree species. We hypothesized that both, HR within a plant and into the soil increases with higher water-potential gradients, larger root conduit diameters and root-xylem hydraulic conductivities. 2. Saplings of conifer (Picea abies, Pseudotsuga menziesii), diffuse-porous (Acer pseudoplatanus) and ring-porous species (Castanea sativa, Quercus robur) were planted in split-root systems, where one plant had its roots split between two pots with different water-potential gradients (0.23 to 4.20 MPa). Hydraulic redistribution was quantified via deuterium labeling. 3. On average, species redistributed 0.39 ± 0.14 ml water overnight (0.08 ± 0.01 ml g-1 root mass). Higher pre-dawn water-potential gradients, xylem hydraulic conductivities and larger conduit diameters significantly increased HR. Hydraulic conductivity had the greatest influence on HR, within the plants (0.03 ± 0.01 ml g-1) and into the soil (0.06 ± 0.01 ml g-1). 4. Additional factors as soil-root contact should be considered, especially when calculating water transfer into the soil. Nevertheless, trees maintaining high xylem hydraulic conductivity showed higher HR amounts, potentially making them valuable ‘silvicultural tools’ to improve plant water-status.