Forestry Insights

Almost all New Zealand forest products come from commercial, sustainably managed plantation forests.

More than 97% of the plantation forests are 'softwood'. Radiata pine is the dominant species with 1.6 million ha.

Dominant Species
	Hectares (thousands)	% of Total
Radiata pine	1626	89.2
Douglas fir	112	6.2
Other exotic softwoods	33	1.8
All exotic hardwoods	51	2.8
Total	1822	100

Radiata pine (Pinus radiata) is a versatile species and grows on a wide range of sites throughout New Zealand.

Special features:

• Will grow on soils from sand to clay and withstand frost and mild salt spray.
• Needs only 600 millimetres of rainfall per annum.
• Is fast growing, maturing in about 30 years.
• Responds quickly to thinning and heals quickly after pruning.
• Produces timber that is easy to dry, machine and treat with preservative.
• Has good nailing, gluing and painting properties.
• Suitable for a wide range of uses including: roundwood and the manufacture of wood-based panels, pulp and paper products.

Generally, radiata pine height growth (site index) in New Zealand decreases from north to south, but diameter (basal area) growth tends to increase from north to south. It can be broadly described as a medium-density, even-textured softwood. Wood properties vary widely, however, depending on the site, silviculture and the region from which the trees are sourced.

Douglas Fir

Douglas fir (Pseudotsuga menziesii) is a good alternative to radiata pine on higher altitude and snow-prone sites throughout New Zealand. It is unsuitable in the Auckland and Northland regions due to the warmer temperatures. Douglas fir is the most common species after radiata pine, but still only represents 5% of the planted forest area.

Douglas fir growth rates on favourable sites can exceed the fastest North American stands by as much as 50%. The species is used mainly as a construction timber and large volumes are exported. New Zealand-grown Douglas fir has similar wood qualities and export value to North American second growth timber.

Special features:

• One of the world's best known timber trees and commands premium sawlog prices.
• Can be used internally without preservative treatment.
• Requires less intensive management than radiata pine.
• Can shed snow.
• Has root grafting ability that provides better soil protection than radiata pine in some situations.
• Is aesthetically attractive.

Douglas fir also has some disadvantages in comparison with radiata pine:

• Less versatile on lowland sites.
• Slower initial growth makes it less desirable on weedy sites.
• Slower overall growth requires a longer rotation.
• Not easily treated with preservatives for external or ground contact use.
• Not as versatile.

Other Softwoods

Macrocarpa (Cupressus macrocarpa) and Lusitanica (Cupressus lusitanica) are the most promising alternatives to radiata pine on fertile, sheltered sites below 400 metres altitude. Lusitanica has distinct advantages over Macrocarpa in terms of tree form and Cypress canker resistance, and tends to be planted more widely in the warmer parts of the country. Lusitanica does not perform as well as Macrocarpa on coastal, cold or drier sites. Macrocarpa is more widely planted in the South Island.

Lusitanica and Macrocarpa can be classified as low to medium-density softwoods, with yellow-brown heartwood, fine, even texture and pronounced growth rings. The timber of both species looks like kauri and has good machining properties. Cypress wood in New Zealand has been widely used for furniture.

Some older forests in the colder parts of the country grow Corsican pine (Pinus nigra). It fell from favour in the 1950s when a fungal disease (Dothistroma) appeared in New Zealand and it became obvious that radiata pine could outperform Corsican pine on all but the very hardest sites. Corsican pine has a significant role in parts of the country with harsher climates, such as the Canterbury high country and Central Otago.

Hardwoods

Eucalypts are the main hardwoods grown in New Zealand. But no one species will thrive on the range of sites where radiata pine will grow. Consequently, eucalypt species must not only be suitable for the required end use, but should also be matched to the site's climate and topography.

Eucalypts can grow faster than radiata pine, as long as adequate attention is given to their special requirements of site, nutrients and silvicultural treatment.

Some advantages are:

• Aesthetics.
• Natural pruning of some species.
• Excellent furniture/veneer properties of some species.
• Desirable pulping properties.

The potential disadvantages of eucalypts are:

• Site sensitivity.
• Sensitivity to weed competition.
• Tendency to develop "growth stresses", causing distortion during sawing.
• Drying difficulties.

Australian Blackwood (Acacia melanoxylon) is a hardwood whose timber is highly valued for its attractive appearance. It can be grown on sheltered, warm, fertile sites throughout New Zealand.