© 2005 Heron Publishing—Victoria, Canada
Modeling the dynamics of pressure propagation and diameter variation in tree sapwood
Martti Perämäki (1, 2), Timo Vesala (3) and Eero Nikinmaa (1)
1. Department of Forest Ecology, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland / 2. Corresponding author (martti.peramaki@helsinki.fi) / 3. Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland / Received October 12, 2004; accepted January 21, 2005; published online July 4, 2005
Summary
A non-steady-state model of water tension propagation in tree stems was developed. The model is based on the cohesion theory
and the assumption that fluctuating water tension driven by transpiration together with the elasticity of wood cause variations
in the diameter of a tree stem. The change in xylem diameter can be linked to water tension in accordance with Hooke’s law.
The model was tested against field measurements of the diurnal change in xylem diameter at different heights in a 180-year-old
Scots pine tree at Hyytiälä, southern Finland. Model predictions agreed well with measurements. The effect of tree dimensions
on pressure propagation was examined with the model. The model outcomes were also consistent with results of several field
measurements presented in the literature.
Keywords:
cohesion theory, Hooke’s law, transpiration, xylem water transport, water tension propagation.
