Douglas Fir (Pseudotsuga menzeii) was first introduced into New Zealand in the mid 1800's with token plantings. Used for amenity and ornamental plantings from 1870, it was first tried in state forests in Rotorua and Tapanui from the late 1890's and on a wider scale from 1901. Planted at a steady rate averaging 1500ha per year for the last 30 years they are the second most important species of forestry tree after radiata pine in the Nelson Marlborough region, accounting for 11% of the planted production forest.
According to MAF, as of April 1999 planted production forest covered 172,490 hectares of Nelson Marlborough land (7.6 %), with a standing volume of 31,381,000 m3. Dominated by almost 90% with radiata pine, the benefits of Douglas fir appear neglected. Large areas of Douglas fir in the Golden Downs forest have shown good growth rates, and in some areas it is more productive than radiata pine.
Douglas fir timber is mainly used for building construction and framing, mostly heartwood it does not require treatment for internal use and is rarely attacked by the common house borer in New Zealand. Recent export log prices for unpruned Douglas fir are similar to those paid for pruned radiata, and in Asian markets logs have obtained around twice the price of equivalent grades of radiata pine.
Better able to withstand extreme climatic conditions, especially heavy snow and strong wind storms, Douglas fir is more site demanding needing good free-draining soils and moist conditions, preferring sheltered south facing sites with excess of 1200 millimetres of rain annually. It can also be planted in erosion prone areas where its longer rotation length of 45-55 years, provides soil stabilisation for longer periods between clearfelling.
Silviculture practices prior to 1970 involved initial stockings of 2,500-3,000 stems/ha that resulted in high quality timber with small branches but which involved high establishment costs and longer rotations (60-80 years) if thinning was delayed. Initial stockings now range from 1200-2000 stems/ha, thinning out to a final stocking of between 250 to 500 stems/ha.
Swiss needle cast fungus (Phaeocryptopus gaumannii) was first found on Douglas fir in New Zealand in 1959 and was first found in the South Island near Nelson in 1969, reaching Southland in 1977. There are now few areas where P. gaeumannii cannot be found but older infected stands in the northern South Island do not appear to have suffered a growth loss comparable to that observed in North Island stands and the fungus has not yet had any commercially significant impact.
NZ Forest Research Institute Ltd, Rotorua reported that a 61 year old Nelson stand had 1500m3/ha on a stocking of 560 stems/ha, with a mean annual increment of 30m3 /ha/year. Robert Appleton from Appletons Tree Nursery Ltd cited another example, City Forests stand of Douglas fir at the Maori Hill reservoir in Dunedin. Recently measured at 1,800m3/ha at a stocking of 260 stem/ha and with an average height of 52m this stand was valued 3 months ago at approximately $400,000 per hectare standing. Demonstrating that on favourable sites, New Zealand grown Douglas fir can be one of the most productive plantation species in the world.
Robert also noted the importance of site selection. "It is important that in Nelson and Marlborough that the site be ideally a south facing, cooler site. This is an ideal species for Rai Valley, Murchison, St Arnaud, North Bank and high altitude Marlborough."
