Farm Forestry New ZealandRadiata pine is the primary plantation forest species grown in Northland and throughout New Zealand. Northland has a reputation for growing some of the strongest and densest radiata timber in New Zealand. The well-established industry provides a ready market for logs, high-quality genetically improved planting stock and well established management regimes with good data on productivity and expected yields. Radiata pine is a versatile timber used for a wide range of products, with reasonable strength and stiffness properties suitable for most structural applications. The key to its historical success as a timber in New Zealand is that it is easy to treat with preservatives, especially Chrome Copper Arsenic (CCA) formulations. Being very permeable, radiata is the only species authorised for treatment to hazard classes H3.2 and above in the building code, with proven durability performance in a range of exterior applications. However, because radiata heartwood is so permeable this can be seen as a double-edged sword because this property makes radiata both treatable but also perishable. It holds very low natural durability so industry depends on being able to treat it with preservatives. Radiata pine also has reasonably low stiffness values so applications are limited by this, in particular longer structural spans.
Health: Subject to foliar diseases, including cyclaneusma needle cast and red needle cast. Red needle cast is worse in high-elevation Northland sites. Dothistroma doesn't appear to be prevalent in Northland. Incidences of flagging seem to be on the increase. Subject to root disease where drainage is poor.
Timber: Low durability, fairly soft, moderately strong and stiff. Radiata timber processes well into a range of structural products because it is easy to machine and glues well. Perhaps its greatest claim to fame is the ease with which radiata and other pines take chemical treatment, the heartwood can be easily pressure-treated with water-borne preservatives such as CCA.
| Species | Density, dry (kg/m3) | Bending strength, MoR (MPa) | Stiffness, MoE (GPa) | Hardness, Janka (kN) |
|---|---|---|---|---|
| Pinus radiata | 500 | 85.8 | 8.2 | 3.6 |
Siting: Radiata pine is hardy to strong wind and poor fertility soils, but has some siting limitations. Trees are prone to toppling and root disease where soil drainage is poor so the species is best planted on free draining soils. Radiata will grow on slip faces, skeletal soils devoid of topsoil and soils with a low nutrient status, but growth rates will be reduced on these sites. It is recommended that phosphate be applied if the soil is especially poor. Radiata will grow reasonably well on exposed ridgetops but poorer form and slower growth will result compared with less-exposed sites.
Steep slopes: Because radiata roots decay rapidly after harvest, clearfell radiata regimes pose concerns regarding risk of post-harvest erosion. The higher costs involved with harvesting under a continuous canopy regime limit economic viability because of higher harvesting costs. The log price threshold that justifies greater harvesting costs is the subject of research.
Species characteristics: Hardy and "bulletproof", with fast growth rates and a short rotation length.
Recommended regime: Plant at 600-1200 stems per hectare. For clearwood production prune to 6-8m in 3-4 lifts and thin down to 200-400 stems per hectare. For unpruned framing regimes final crop stocking can be as high as 600 stems per hectare.
Key message: The conservative option, tried and true.
NZFFA on facebook