Skip to main content
Journal cover image

Age- and position-related changes in hydraulic versus mechanical dysfunction of xylem: inferring the design criteria for Douglas-fir wood structure.

Publication ,  Journal Article
Domec, JC; Gartner, BL
Published in: Tree physiology
February 2002

We do not know why trees exhibit changes in wood characteristics as a function of cambial age. In part, the answer may lie in the existence of a tradeoff between hydraulic properties and mechanical support. In conifers, longitudinal tracheids represent 92% of the cells comprising the wood and are involved in both water transport and mechanical support. We used three hydraulic parameters to estimate hydraulic safety factors at several vertical and radial locations in the trunk and branches: vulnerability to cavitation; variation in xylem water potential (psi); and xylem relative water content. The hydraulic safety factors for 12 and 88 percent loss of conductivity (S(H12) and S(H88), representing the hydraulic safety factors for the air entry point and full embolism point, respectively) were determined. We also estimated the mechanical safety factor for maximum tree height and for buckling. We estimated the dimensionless hydraulic and mechanical safety factors for six seedlings (4 years old), six saplings (10 years old) and six mature trees (> 110 years old) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Over the natural range of psi, S(H12) decreased linearly from treetop to a minimum of 0.95 at the tree base. Young and mature trees had S(H12) values 1.4 and 1.3 times higher, respectively, at their tips (juvenile wood) than at their bases (mature wood). Modeling analyses indicated that if trees were made entirely of mature wood, S(H12) at the stem base would be only 0.7. The mechanical safety factor was 1.2 times higher for the base of the tree than for the rest of the tree. The minimum mechanical safety factor-1.6 for the critical buckling height and 2.2 for the critical buckling load-occurred at the base of the live crown. Modeling analysis indicated that if trees were made only of mature wood, these values would increase to 1.7 and 2.3, respectively. Hydraulic safety factors had values that were less than half those for mechanical safety factors, suggesting that wood structure in Douglas-fir has evolved primarily as a result of selection for hydraulic safety rather than mechanical safety. The results suggest that forest managers must consider the role of juvenile wood in tree physiology to avoid producing plantations vulnerable to drought.

Duke Scholars

Published In

Tree physiology

DOI

EISSN

1758-4469

ISSN

0829-318X

Publication Date

February 2002

Volume

22

Issue

2-3

Start / End Page

91 / 104

Related Subject Headings

  • Wood
  • Water
  • Pseudotsuga
  • Plant Stems
  • Plant Leaves
  • Plant Biology & Botany
  • Oregon
  • 4101 Climate change impacts and adaptation
  • 3108 Plant biology
  • 3103 Ecology
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Domec, J. C., & Gartner, B. L. (2002). Age- and position-related changes in hydraulic versus mechanical dysfunction of xylem: inferring the design criteria for Douglas-fir wood structure. Tree Physiology, 22(2–3), 91–104. https://doi.org/10.1093/treephys/22.2-3.91
Domec, J. C., and B. L. Gartner. “Age- and position-related changes in hydraulic versus mechanical dysfunction of xylem: inferring the design criteria for Douglas-fir wood structure.Tree Physiology 22, no. 2–3 (February 2002): 91–104. https://doi.org/10.1093/treephys/22.2-3.91.
Domec, J. C., and B. L. Gartner. “Age- and position-related changes in hydraulic versus mechanical dysfunction of xylem: inferring the design criteria for Douglas-fir wood structure.Tree Physiology, vol. 22, no. 2–3, Feb. 2002, pp. 91–104. Epmc, doi:10.1093/treephys/22.2-3.91.
Journal cover image

Published In

Tree physiology

DOI

EISSN

1758-4469

ISSN

0829-318X

Publication Date

February 2002

Volume

22

Issue

2-3

Start / End Page

91 / 104

Related Subject Headings

  • Wood
  • Water
  • Pseudotsuga
  • Plant Stems
  • Plant Leaves
  • Plant Biology & Botany
  • Oregon
  • 4101 Climate change impacts and adaptation
  • 3108 Plant biology
  • 3103 Ecology