Publication Information
Title:
| Dynamic variation in sapwood specific conductivity in six woody
species |
Author(s): |
Domec, Jean-Christophe; Meinzer, Frederick C.; Lachenbruch, Barbara; Housset, Johann |
Date: |
2008 |
Source: |
Tree Physiology: vol 27 pgs. 1389-1400 |
Description: |
Our goals were to quantify how non-embolism inducing pressure gradients influence trunk sapwood specific conductivity (ks) and to compare the impacts of constant and varying pressure gradients on ks with KCl and H20 as the perfusion solutions. We studied six woody species (three conifers and three angiosperms) which varied in pit membrane structure, pit size and frequency of axial water transport across pits (long versus short conduits). Both stepwise ("steady") and nonlinear continuous ("non-steady") decreases in the pressure gradient led to decreased ks in all species but white oak: (Quercus garryana Dougl. ex Hook), a ring-porous and longvesseled angiosperm. In one diffuse-porous angiosperm (red alder, Alnus rubra Bong.) and two conifers (western red cedar, Thuja plicaia Donn. ex D. Don, and Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco), ks was 10-30% higher under steady pressure gradients than under non-steady pressure gradients, and a decrease in the pressure gradient from 0.15 to 0.01 MPa m-1 caused a 20-42% decrease in ks. In another diffuse~porous angiosperm (maple, Acer macrophyllum Pursh) and in a third coniferous species (western hemlock, Tsuga heterophylla (Raf.) Sarg), there was no difference between kg measured under steady and non~steady pressure gradients. With the exception of western red cedar, a conifer with simple pit membranes, the differences in ks between low and high pressure gradients tended to be lower in the conifers than in the diffuse-porous angiosperms. In Douglas-fir, western red cedar and the diffuse-porous angiosperms, ks was higher when measured with KCI than with H20. In white oak, there were no differences in ks whether measured under steady or non-steady pressure gradients, or when xylem was perfused with KCI or H20. The species differences in the behavior of ks suggest that elasticity of the pit membrane was the main factor causing ks to be disproportionate to the pressure gradient and to the different pressure regimes. The results imply that, if nonlinearities in pressure-flux relationships are ignored when modeling tree water relations in vivo, large errors will result in the predictions of tree water status and its impact on stomatal control of transpiration and photosynthesis. |
![](https://webarchive.library.unt.edu/eot2008/20090305034311im_/http://www.srs.fs.usda.gov/images/pdficonarrow.gif) |
View and Print this Publication () |
Pristine Version: |
An uncaptured or "pristine" version of this publication is available. It has not been subjected to OCR (Optical Character Recognition) and therefore does not have any errors in the text. However it is a larger file size and some people may experience long download times. The "pristine" version of this publication is available here: View and Print the PRISTINE copy of this Publication () |
Publication Notes: |
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some
typographical errors may occur. Please contact the SRS Webmaster, srswebmaster@fs.fed.us if you notice any errors which make this publication unuseable.
|
![[ Get Acrobat ]](https://webarchive.library.unt.edu/eot2008/20090305034311im_/http://www.srs.fs.usda.gov/images/getacro.gif) |
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility |