Xylem traits mediate a trade-off between resistance to freeze-thaw-induced embolism and photosynthetic capacity in overwintering evergreens

Brendan Choat, Danielle E. Medek, Stephanie A. Stuart, Jessica Pasquet-Kok, John J G Egerton, Hooman Salari, Lawren Sack, Marilyn C. Ball*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)

Abstract

Hydraulic traits were studied in temperate, woody evergreens in a high-elevation heath community to test for trade-offs between the delivery of water to canopies at rates sufficient to sustain photosynthesis and protection against disruption to vascular transport caused by freeze-thaw-induced embolism. Freeze-thaw-induced loss in hydraulic conductivity was studied in relation to xylem anatomy, leaf- and sapwood-specific hydraulic conductivity and gas exchange characteristics of leaves. We found evidence that a trade-off between xylem transport capacity and safety from freeze-thaw-induced embolism affects photosynthetic activity in overwintering evergreens. The mean hydraulically weighted xylem vessel diameter and sapwood-specific conductivity correlated with susceptibility to freeze-thaw-induced embolism. There was also a strong correlation of hydraulic supply and demand across species; interspecific differences in stomatal conductance and CO 2 assimilation rates were correlated linearly with sapwood- and leaf-specific hydraulic conductivity. Xylem vessel anatomy mediated an apparent trade-off between resistance to freeze-thaw-induced embolism and hydraulic and photosynthetic capacity during the winter. These results point to a new role for xylem functional traits in determining the degree to which species can maintain photosynthetic carbon gain despite freezing events and cold winter temperatures.

Original languageEnglish
Pages (from-to)996-1005
Number of pages10
JournalNew Phytologist
Volume191
Issue number4
DOIs
Publication statusPublished - Sep 2011

Keywords

  • Cavitation
  • Embolism
  • Evergreen
  • Freezing
  • Hydraulic conductivity
  • Photosynthesis
  • Xylem

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