History of Radiata Pine in New Zealand
New Zealand has had planted production forests, of mainly softwood species, since the early 20th century.
Currently over 1.5 million hectares of planted production forests have been established of which the
dominant species is Pinus radiata (Radiata Pine). This species accounts for about 90 percent of the total planted resource. Radiata Pine is originally a native species from California and was introduced to New Zealand in the 1860's as part of a reforestation programme. It performed well and was able to withstand the variety of climatic conditions and soil structures, typical of the New Zealand countryside whilst maturing to a fully grown tree within 20-30 years.
Properties of Radiata Pine
Radiata Pine is one to the world's most versatile softwoods. It has a medium density with light colouration, uniform texture and relatively straight grain. It also shows little variation in density between spring wood and summer wood within a growth ring. Extensive trials with other competing softwood species have shown that Radiata Pine has excellent treatment, drying, machine, finishing, staining, gluing and laminating properties. The finishing and woodworking properties of the wood mean that it is ideally suited to a widerange of high value end uses.
There is a consistent pattern of density outwards from the pith with a tendency to level off as wood reaches 15 to 20 years of age. The density of the younger wood is between 350 kg/m³ to 400 kg/m³ that stabilises as the wood reaches maturity to a density of 450 kg/m³ to 610 kg/m³. The corewood, which is usually confined to the innermost five rings, has a very low density, shorter fibers and higher longitudinal shrinkage than the outer wood. This wood is used mainly for pulp. The density of the outer wood varies considerably between trees and is closely related to the mean annual temperature of the site.
The timber from the trees grown in northern parts of the country and at low altitudes generally has a higher density and consequently higher clearwood strength. The inner heartwood rings show a relatively high resin content in comparison to outer wood. Resin pockets in Radiata Pine are typically lens-shaped. Although they occur in trees in all parts of the country they are the most prevalent in some areas, particularly Canterbury.
Other than the defects associated with the weaker corewood zone, such as pith and spiral grain, the main defect found in the sawn timber is that of knots and to a lesser degree resin pockets. Other tree species with similar density patterns are the European Spruce and other European Pine species.
Radiata Pine is easy to season and can be kiln-dried rapidly from green. Material from near the pith is prone to twist, but twisting can be minimised by good stacking and restraint.
Tests show that Radiata Pine has machining properties (cross-cutting, turning, planing, moulding, boring and sanding) equal to or superior to many of the internationally traded softwoods. The fast growth does not adversely affect its working properties and good results can be obtained from working with both hand and machine tools.
(1) D.J. Cown, 1992 New Zealand Radiata Pine and Douglas Fir, Suitability for Processing, Ministry of Forestry, Forest Research Institute, New Zealand. FIR bulletin 168.
(2) P.M. Heilig, 1981 Houtvademecum, Publikatie Centrum Hout/HI TNO, Kluwer Technische Boeken U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.
(3) Forest Products Laboratory. 1999. Wood handbook-Wood as an engineering material. Gen. Tech. Rep. FPL-GTR-113. Madison, WI:
(4) H. Bier revised by R.A.J. Britton, 1999 Strength Properties of Small Clear Specimens of New Zealand- Grown Timbers, New Zealand Forest Research Institute Limited, Rotorua, New Zealand, FRI bulletin 41.
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