© 2005 Heron Publishing—Victoria, Canada
Stem water transport of Lithocarpus edulis, an evergreen oak with radial-porous wood
Shigeki Hirose (1), Atsushi Kume (2, 3), Shinichi Takeuchi (4), Yasuhiro Utsumi (1), Kyoichi Otsuki (1) and Shigeru Ogawa (1)
1. Department of Forest and Forest Products Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 811-2415, Japan / 2. Department of Environmental Biology and Chemistry, Faculty of Science, Toyama University, Toyama 930-8555, Japan / 3. Corresponding author (akume@attglobal.net) / 4. Department of Regional Environment Engineering, Faculty of Engineering, Kyushu-kyouritsu University, Kita-kyushu 807-8585,
Japan / Received December 30, 2003; accepted June 30, 2004; published online December 1, 2004
Summary
The stem water conducting system of an evergreen broad-leaved oak, Lithocarpus edulis (Mak.) Nakai, was investigated. Evergreen broad-leaved oaks (Lithocarpus, Castanopsis, Cyclobalanopsis, Quercus) belonging to the Quercoideae are a major component of Asian monsoon forests, and are characterized by the possession of
radial-porous wood. A characteristic of radial-porous wood is the development of aggregate rays between radially oriented
files of vessels. We measured the distribution of vessel lumen diameters in a stem cross section and calculated the theoretical
water conductivity of the wood. The radial profile of the heat pulse velocity (HPV) was measured for an intact whole tree
under field conditions and compared with the theoretical distribution of water conductivity. Soft X-ray photographs of frozen
stem sections indicated that most of the vessel lumina were filled with water, including those of vessels more than 20 years
old. Even when vessels were relatively wide (lumen diameters > 100 μm), cavitation was negligible. The rate of water uptake
from the cut stem base correlated closely with HPV (r = 0.96), and HPV closely reflected the mean volume flow per stem sectional area (SFVS) around the sensor probes. However, the ray tissue sharply inhibited heat transfer, and the positioning of the probes strongly
affected the absolute value of HPV. It was also found that HPV more closely reflected the mean sap flow velocity in the vessels
than did SFVS.
Keywords:
cavitation, heat pulse, sap flow, tree cutting.
