Some wood characteristics of New Zealand grown western red cedar ( Thuja plicata D. Don )

Authors: D.J. Cown, S.R. Bigwood
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1979, Issue N.Z.J.For. 24(1) 1979, pp 125-132, May 1979
Publisher: New Zealand Institute of Forestry

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Abstract: Wood samples of western red cedar (Thuja plicata D. Don) from four New Zealand State forests (Whakarewarewa, Waiotapu, Mahinapua, and Conical Hill) were examined for wood density, moisture content, shrinkage characteristics, and extractives content. On the basis of these data and of other observations on locally grown red cedar, a comparison is made with North American material.
The local product is of comparable or slightly superior wood density to that of western red cedar in its native habitat (published mean basic density 310 kg/m3). The two- North Island sites averaged 330 to 340 kg/m3, and the South Island sites 310 to 320 kg/m3. The New Zealand timber is characterised by saturated heartwood (average moisture content >200%) and needs to be dried carefully to avoid checking and collapse. Shrinkage tends to be greater and dimensional stability poorer than North American western red cedar. The average extractives content is also lower, and so natural durability might be expected to be less.
Western red cedar is an attractive and useful timber for both interior and exterior use, but as a forest tree has proved disappointing in many parts of New Zealand. It could be a useful minor species on moist sheltered sites and, given appropriate silvicultural treatment, could produce a valuable specialty timber.

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