Growing and harvesting productive Douglas-fir
Issue
- Douglas-fir is the forest owners’ species of choice in snow-prone areas of both the North & South Islands. It produces structural timber from areas that radiata pine cannot.
- There are big opportunities to improve the productivity and quality of Douglas-fir through genetic improvement.
- There are few management support tools available to assist decision making by forest owners compared to those available for radiata pine.
Potential benefits
An increase in productivity of Douglas-fir forests on some sites by at least 30%. The predicted NPV of this gain is conservatively estimated at $3,000/ha, an annual value gain of $2.25m on a new planting and restocking programme of 750 ha.
Investors and land owners have profitable forestry options for sites less suited to radiate pine.
Research
New selections for growth and quality traits have been grafted into clonal seed orchards.
Nation-wide growth trends have been developed and sawing studies to assess timber quality have been completed.
Wood density and wood stiffness have been studied to understand the influence of the environment on these traits.
Outcomes
Improved Douglas-fir seed with at least a 30% increase in growth is now available from Proseed and Ernslaw One seed orchards.
On better sites, the productivity of NZ grown Douglas-fir is as good as the highest in the world.
The Douglas-fir 500-Index Growth Model and Douglas-fir calculator have been upgraded. The 500-Index has been incorporated into the Forecaster modelling framework used by a number of companies.
Conclusion
Improved genetics have enhanced the profitability of growing Douglas-fir for structural timber on sites where radiata pine is limited.
Douglas-fir management decisions and forest valuations can now be undertaken with greater confidence.
