Douglas fir – Southern gold
Phil De La Mare and Matt Hitchings
New Zealand Tree
Grower August 2007
Ernslaw One has a planted forest area of 85,000 hectares, of which
13,000 hectares are planted in Douglas fir in Otago and Southland.
There has always been a history of growing and milling Douglas
fir – New Zealand Oregon – in southern areas. Until the 1980s the
pattern of usage for all species was –
- Radiata pine for appearance grade, framing and industrial
grade
- Corsican pine for poles, roundwood and framing
- Douglas-fir, larch and spruce for framing grade
- Ponderosa pine for industrial grade
In the late 1980s the Forest Service management changed to include just
two species, radiata pine and Douglas fir. When Ernslaw One
commenced in 1990, the pattern of replanting was 50:50. In the 1990s
this was complemented with a significant expansion of new planting of
Douglas fir which continued through until 2000.
Crisis for Douglas fir
After World War II, the usage of Douglas Fir started to steadily
increase as native timber availability declined and the use of pine
framing took time to adopt. However, this familiarity of usage by the
building industry was shattered in 2004 when Douglas fir got relegated
into a much lower category with all the fall-out from legislative
reaction to the leaky homes saga. Sales plummeted as the requirement to
use treated timber for even low risk areas in timber framing meant that
radiata provided the only option for pressure treatment. This crisis in
the Douglas fir industry spawned the establishment of the Douglas-fir
Association to lobby for legislative change, and promote the use of the
timber.
For some time, the Douglas-fir Association tried to regain acceptance
of untreated framing. The difficulty was that as Douglas fir is a
refractory species, it repels moisture which made it difficult to
treat. Ironically, this same characteristic also assists with
maintaining board straightness and durability, contributing to Douglas
fir being the preferred framing species in the south. Fortunately new
treatment systems arrived which ensured that the old boron standards
could be implemented again, breaking the stalemate with the
regulators.
Use of boron
To comply with NZS3604, the H1.2 treatment standard requires 0.4 BAE
boron to be contained within the boards. Some sawmills are achieving
this by forcing active ingredients into the wood using various wet
pressure treatment systems. Ernslaw One Ltd’s sawmill has preferred to
use Kop-Coat’s patented dry Tru-core system. This process achieves the
required boron loadings by using a chemical mixture which allows the
boron to quickly penetrate to the core of each board. Health and
safety, environmental and commercial benefits are making this product
highly sought after.
Treatment was still a bitter pill to swallow, since the real solution
to leaky homes was with design and workmanship, not in treating the
symptoms. However, commercial survival was more important. The battle
had been lost but not the war, so 2006 saw some recovery of the market
share which had been lost in the years before.
Radiata a poor second
The next change to the industry was a positive one. With the imminent
change to machine stress grading requirements in April 2007, the
industry had to prepare itself. The resource was sampled and tested,
the results of which showed that most logs would produce timber
achieving MSG 8 with much of the volume achieving MSG 10 or better.
Radiata in comparison came a very poor second in Otago, Southland and
Canterbury, with only Nelson showing any comparative stiffness
properties close to Douglas fir.
For many in the industry these results did not come as a surprise,
rather it validated what was already known. Douglas fir is an excellent
framing timber, it is strong, stiff, stays straight and is good to work
with.
An easy decision
For Ernslaw One, the differences between the species in terms of
economics resulted in changing to all Douglas-fir and dropping radiata
from our South Island forests. For us the changes were painful and
commercially damaging. Three years loss of revenue for Blue Mountain
Lumber which could never be made up, and the loss of Naseby Lumber
which was too small to install a treatment plant. However, since April
2007, we have exceeded previous sales levels and are able to supply a
grade of timber in very strong demand by the domestic building
industry. Log supply now constrains production. Timber demand means
buying and transporting additional logs from as far away as Canterbury.
This is a complete turn round from three years ago.
Stiffness testing has also reinforced the use of conservative
silvicultural regimes. Lighter thinnings and higher residual stockings,
combined with sheltered locations all combine to provide for higher
stiffness. It has brought about the re-introduction of radiata
shelterbelts for exposed Douglas fir stands, a practice European
foresters introduced to West Otago 100 years ago. No doubt this was to
improve stem form, but until recently was not fully appreciated.
As a company and an industry, we have survived a severe blow, but we
have all come out the other side wishing we had a greater resource of
this wonderful species.
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