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High variation in hydraulic efficiency but not xylem safety between roots and branches in four temperate broad-leaved tree species

Citation

Lübbe, Torben et al. (2022), High variation in hydraulic efficiency but not xylem safety between roots and branches in four temperate broad-leaved tree species, Dryad, Dataset, https://doi.org/10.5061/dryad.nzs7h44sz

Abstract

Xylem hydraulic safety and efficiency are key traits determining tree fitness in a warmer and drier world. While numerous plant hydraulic studies have focused on branches, our understanding of root hydraulic functioning remains limited, although roots control water uptake, influence stomatal regulation and have commonly been considered as the most vulnerable organ along the hydraulic pathway. We investigated 11 traits related to xylem safety and efficiency along the hydraulic pathway in four temperate broad-leaved tree species. Continuous vessel tapering from coarse roots to stems and branches caused considerable reduction in hydraulic efficiency. Wood density was always lowest in roots, but did not decline linearly along the flow path. In contrast, xylem embolism resistance (P50) did not differ significantly between roots and branches, except for one species. The limited variation in xylem safety between organs did not adequately reflect the corresponding reductions in vessel diameter (by ~70%) and hydraulic efficiency (by ~85%). Although we did not observe any trade-off between xylem safety and specific conductivity, vessel diameter, vessel lumen fraction and wood density were related to embolism resistance, both across and partly within organs. We conclude that coarse roots are not highly vulnerable to xylem embolism as commonly believed, indicating that hydraulic failure during soil drying might be restricted to fine roots.

Methods

For methodological details, please refer to the material and methods chpater of the following publication:

Journal: Functional Ecology

Title: High variation in hydraulic efficiency but not xylem safety between roots and branches in four temperate broad-leaved tree species

Acceptance date: 13.11.2021

Funding

Deutsche Forschungsgemeinschaft, Award: DFG GRK 1086

Exzellenzclusters Entzündungsforschung, Award: NAR-10-LABX_45

European Research Council, Award: FP7-339728

Investments for the Future, Award: ANR-10-EQPX-16