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Abstract Detail


Ecophysiology

Barnard, David  [1], Lachenbruch, Barbara [2], Meinzer, Frederick [3].

Radial water transport and sapwood use efficiency of two conifers from contrasting climate regimes in the Pacific Northwest.

As part of a larger project investigating ecophysiology and anatomical differences of conifers in different climate types, we looked at xylem characteristics related to water transport. We hypothesized that trees with greater radial hydraulic conductivity (conductivity in the radial direction, within and between growth rings) will have greater sapwood area and be able to use their sapwood more efficiently than trees with lower radial conductivity under similar transpirational demands. High axial tension gradients in trees can cause embolism and may result in hydraulic dysfunction; by spreading water transport over a greater area (through increased radial transport) the tension gradient could effectively be reduced. In our pilot studies our proxy measurement for radial conductivity was ray tracheid proportion (ray tracheid lumen area as a function of total area). Trees of Pinus contorta and Pseudotsuga menziesii were sampled from sites on the east and west sides of the Cascade mountain range, which differ greatly in temperature (mild on the west side and hotter summers and colder winters on the east side) and precipitation (higher on the west side). All trees sampled were 50-100 years old. Results so far suggest that west side varieties have fewer rings of sapwood and lower ray tracheid proportion than the east side trees, and that P. contorta has more rings of sapwood and higher ray tracheid proportion than P. menziesii, regardless of site conditions. Further research will include leaf area/sapwood area, directional measurement of radial water transport and measurements of vulnerability in these two species at four sites for each species.


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1 - Oregon State University, Forest Ecosystems and Society, 301E Richardson Hall, Corvallis, OR, 97331, United States
2 - Dept. of Wood Science and Engineering, Oregon State University, Corvallis, OR, 97331, USA
3 - USDA Forest Service, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, USA

Keywords:
ray tracheid
water transport
tree
hydraulic architecture
hydraulic conductivity
functional plant anatomy.

Presentation Type: Oral Paper:Papers for Topics
Session: 8
Location: Cottonwood A/Snowbird Center
Date: Monday, July 27th, 2009
Time: 9:00 AM
Number: 8005
Abstract ID:925


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