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Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns.

Publication ,  Journal Article
Ewers, BE; Oren, R; Kim, H-S; Bohrer, G; Lai, C-T
Published in: Plant, cell & environment
April 2007

In a Pinus taeda L. (loblolly pine) plantation, we investigated whether the response to vapour pressure deficit (D) of canopy average stomatal conductance (G(S)) calculated from sap flux measured in upper and lower branches and main stems follows a hydraulically modelled response based on homeostasis of minimum leaf water potential (Psi(L)). We tested our approach over a twofold range of leaf area index (L; 2-4 m(2) m(-2)) created by irrigation, fertilization, and a combination of irrigation and fertilization relative to untreated control. We found that G(S) scaled well from leaf-level porometery [porometry-based stomatal conductance (g(s))] to branch-estimated and main stem-estimated G(S). The scaling from branch- to main stem-estimated G(S) required using a 45 min moving average window to extract the diurnal signal from the large high-frequency variation, and utilized a light attenuation model to weigh the contribution of upper and lower branch-estimated G(S). Our analysis further indicated that, regardless of L, lower branch-estimated G(S) represented most of the main stem-estimated G(S) in this stand. We quantified the variability in both upper and lower branch-estimated G(S) by calculating the SD of the residuals from a moving average smoothed diurnal. A light model, which incorporated penumbral effects on vertical distribution of direct light, was employed to estimate the variability in light intensity at each canopy level in order to explain the increasing SD of both upper and lower branch-estimated G(S) with light. The results from the light model showed that the upper limit of the variability in individual branch-estimated G(S) could be attributed to incoming light, but not the variation below that upper limit. A porous medium model of water flow in trees produced a pattern of variation below the upper limit that was consistent with the observed variability in branch-estimated G(S). Our results indicated that stems acted to buffer leaf- and branch-level variation and might transmit a less-variable water potential signal to the roots.

Duke Scholars

Published In

Plant, cell & environment

DOI

EISSN

1365-3040

ISSN

0140-7791

Publication Date

April 2007

Volume

30

Issue

4

Start / End Page

483 / 496

Related Subject Headings

  • Water
  • Trees
  • Plant Leaves
  • Plant Biology & Botany
  • Pinus taeda
  • Models, Biological
  • Light
  • Homeostasis
  • Biomass
  • 3108 Plant biology
 

Citation

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Ewers, B. E., Oren, R., Kim, H.-S., Bohrer, G., & Lai, C.-T. (2007). Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns. Plant, Cell & Environment, 30(4), 483–496. https://doi.org/10.1111/j.1365-3040.2007.01636.x
Ewers, B. E., R. Oren, H. -. S. Kim, G. Bohrer, and C. -. T. Lai. “Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns.Plant, Cell & Environment 30, no. 4 (April 2007): 483–96. https://doi.org/10.1111/j.1365-3040.2007.01636.x.
Ewers BE, Oren R, Kim H-S, Bohrer G, Lai C-T. Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns. Plant, cell & environment. 2007 Apr;30(4):483–96.
Ewers, B. E., et al. “Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns.Plant, Cell & Environment, vol. 30, no. 4, Apr. 2007, pp. 483–96. Epmc, doi:10.1111/j.1365-3040.2007.01636.x.
Ewers BE, Oren R, Kim H-S, Bohrer G, Lai C-T. Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns. Plant, cell & environment. 2007 Apr;30(4):483–496.
Journal cover image

Published In

Plant, cell & environment

DOI

EISSN

1365-3040

ISSN

0140-7791

Publication Date

April 2007

Volume

30

Issue

4

Start / End Page

483 / 496

Related Subject Headings

  • Water
  • Trees
  • Plant Leaves
  • Plant Biology & Botany
  • Pinus taeda
  • Models, Biological
  • Light
  • Homeostasis
  • Biomass
  • 3108 Plant biology