Optimal balancing of xylem efficiency and safety explains plant vulnerability to drought

Abstract

In vast areas of the world, forests and vegetation are water limited and plant survival depends on the ability to avoid catastrophic hydraulic failure. Therefore, it is remarkable that plants take hydraulic risks by operating at water potentials (psi) that induce partial failure of the water conduits (xylem). Here we present an eco-evolutionary optimality principle for xylem conduit design that explains this phenomenon based on the hypothesis that conductive efficiency and safety are optimally co-adapted to the environment. The model explains the relationship between the tolerance to negative water potential (psi(50)) and the environmentally dependent minimum psi (psi(min)) across a large number of species, and along the xylem pathway within individuals of two species studied. The wider hydraulic safety margin in gymnosperms compared to angiosperms can be explained as an adaptation to a higher susceptibility to accumulation of embolism. The model provides a novel optimality-based perspective on the relationship between xylem safety and efficiency.

Keywords

conductivity; embolism; functional traits; optimality; tracheids; trees; vessels; vulnerability; xylem

Published in

Ecology Letters
2023, volume: 26, number: 9, pages: 1485-1496
Publisher: WILEY

SLU Authors

• Franklin, Oskar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • International Institute for Applied Systems Analysis (IIASA)

• Fransson, Peter

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • University of Heidelberg

Associated SLU-program

SLU Forest Damage Center

UKÄ Subject classification

Ecology

Publication identifier

• DOI: https://doi.org/10.1111/ele.14270

Permanent link to this page (URI)

https://res.slu.se/id/publ/122787