Norway spruce: Steady value
Several million Norway spruce seedlings have been
planted in private forests in Quebec over the past 30 years.
This species has been highly successful on account
of its ability to adapt to conditions in Quebec, its rapid growth
rate and its high productivity. However, the popularity of Norway
spruce underwent a sharp decline when woodlot owners and forest
managers discovered white pine weevil damage in plantations.
Studies done by researchers working at the Laurentian
Forestry Centre of the Canadian Forest Service, in collaboration
with the ministère des Ressources naturelles, de la Faune
et des Parcs du Québec, have nonetheless shown that the white
pine weevil has a relatively minor impact on the overall productivity
and quality of Norway spruce (see box). This species has the ability
to overcome deformities resulting from weevil attack and its impressive
annual increment reduces the negative effects associated with this
insect pest.
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Experimental Norway spruce plantation infested
by the white pine weevil and used to study lumber yield.
Photo: Daniel Plourde |
To harness the natural advantages offered by Norway
spruce and to reduce the proportion of deformities caused by the
weevil, control measures need to be carried out every year in plantations
between 3 and 12 years old1. Pruning the
affected leaders eliminates the entire annual weevil generation2.
In weevil-infested plantations, a selective thinning
regime can be applied in order to maximize log quality over the
long term. Thinning offers several key advantages:
- increases in diameter and volume growth
(per tree);
- increases in the growth of the best stems (selective
thinning);
- removal of the most damaged stems at a young age;
- slight increase in productivity (per hectare);
- improvement in the stability of plantations;
- increase in the economic value of plantations.
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Trees resulting from thinning carried out in
the experimental plantation and used to study lumber yield.
Photo: Daniel Plourde |
However, thinning must be carried out at a given competition
threshold, which can be expressed with reference to the basal area
of the plantation, for example, rather than at a specific age. The
best timing for this operation depends on site quality, reforestation
density, survival rate and production objectives.It should be kept
in mind that less fertile or poorly drained sites may be more vulnerable
to weevil attack and that trees growing on such sites are likely
to sustain more extensive damage. This points to the importance
of planting Norway spruce on suitable sites.
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Lumber yield of Norway
spruce
In a detailed study (2002) aimed at assessing
the lumber yield of Norway spruce compared with white spruce,
150 trees, including 40 white spruce, were cut down, measured
and classified based on the extent of major weevil-caused
defects.
The average results for all classes of Norway
spruce taken together are as follows:
- the volume of wood delivered to the mill
was 13% higher;
- the lumber volume was 19% higher;
- the lumber value3
was 27% higher;
- the usable wood volume was 21% higher.
Despite its susceptibility to the weevil, Norway
spruce is able to overcome many of the deformities caused
by repeated attacks. Given its low level of tapering4,
this species also has excellent potential to produce high-quality
wood. |
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Overview of lumber products obtained.
Photo: Daniel Plourde |
Testing, Experimentation and Technology Transfer in Forestry
Program (TETTF)
www.cfl.scf.rncan.gc.ca/CFL-LFC/nos_realisations/eettf_e.html
Network of demonstration plantations for showing growth
and quality gains in forest tree species achieved through breeding
programs (TETTF Program)
www.cfl.scf.rncan.gc.ca/CFL-LFC/nos_realisations/eettf/ficheprojets_eettf_e.asp?id=9001
Web site of the Genetic Gains Demonstration Network
http://demonstration.cfl.scf.rncan.gc.ca/accueil_e.html
For further information,
please contact:
Gaëtan Daoust
Natural Resources Canada, Canadian Forest Service
Laurentian Forestry Centre
1055 du P.E.P.S., P.O. Box 3800, Sainte-Foy, Quebec G1V 4C7
Phone: (418) 648-5830 • Fax: (418) 648-5849
E-mail:
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1 Not all plantations are affected and the degree of
infestation can vary considerably among those that are.
2 This technique is explained and illustrated on the colour poster,
“Simple steps for controlling the white pine weevil”
available from the Laurentian Forestry Centre.
3 According to market prices in 2001.
4 Tapering: a more or less progressive decrease in the thickness of
a tree stem or log from the base upwards.
© Her Majesty the Queen in Right of Canada 2004
Catalogue Number Fo29-54/9-2003E
ISBN 0-662-34050-7
ISSN 1705-5784
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