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Larix occidentalis |
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Family: Pinaceae |
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Western Larch |
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The genus Larix contains about ten
species, native to North America [3] and Eurasia [7]. Larix is the classical
name of Larix
decidua
Mill., or European larch. The word occidentalis means western.
Other Common
Names:
Alerce americano occidental, British Columbia tamarack, hackmatack, larice
americano occidentale, larice occidentale, meleze occidental, Montana larch,
mountain larch, Oregon larch, red American larch, roughbarked larch, tamarack,
vastamerikansk lark, Westamerikaanse lariks, Westamerikaanse lork, Westamerikanische
larche, western larch, western tamarack.
Distribution
Western larch
is native to the high mountains of the upper Columbia River Basin in
southeastern British Columbia, northwestern Montana, northern and central
Idaho, Washington and northern and northeastern Oregon..
The Tree
Western larch
trees reach heights of 180 feet, with diameters of 4 feet at an age of 400
years. Older trees, of 700 years, may reach heights of 200 feet, with diameters
of 8 feet. About two-thirds of the lumber of this species is produced in Idaho
and Montana and one- third in Oregon and Washington.
General Wood
Characteristics:
The heartwood of western larch is yellowish brown and the sapwood yellowish
white. The sapwood is generally not more than 1 inch thick. The wood is stiff,
moderately strong and hard, moderately high in shock resistance, and moderately
heavy. It has moderately large shrinkage. The wood is usually straight grained,
splits easily, and is subject to ring shake. Knots are common but generally
small and tight. The properties of western larch are similar to those of
Douglas-fir and sometimes they are sold mixed.
??
Mechanical
Properties (2-inch standard)
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Compression |
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Specific gravity |
MOE x106 lbf/in2 |
MOR lbf/in2 |
Parallel lbf/in2 |
Perpendicular lbf/in2 |
WMLa in-lbf/in3 |
Hardness lbf |
Shear lbf/in2 |
Green |
0. 48 |
1.46 |
7700 |
3760 |
400 |
10.3 |
510 |
870 |
Dry |
0.59 |
1.87 |
13000 |
7620 |
930 |
12.6 |
830 |
1360 |
aWML = Work to maximum load.
Reference (56) |
Drying and
Shrinkage
Type of shrinkage |
Percentage of
shrinkage |
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0% MC |
6% MC |
20% MC |
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Tangential |
9.1 |
6.3 |
2.6 |
Radial |
4.5 |
3.4 |
1.4 |
Volumetric |
14.0 |
9.5 |
4.0 |
References: 0% (185) |
Kiln Drying
Schedulesa
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Conventional
temperature/moisture content-controlled schedulesa |
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4/4,
5/4 |
6/4
stock |
8/4 |
10/4 |
12/4 |
British
schedule |
Lower grades |
T7-C5 |
NA |
T7-C5 |
NA |
NA |
NA |
Upper grades |
T9-B4 |
T7-C4 |
T7-C3 |
T7-A3 |
T7-A2 |
K |
aReference
(28, 185). Reference (74) |
Conventional
temperature/time-controlled schedulesa |
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Lower
grades |
Upper
grades |
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4/4,
5/4 stock |
6/4
stock |
8/4
stock |
4/4,
5/4 stock |
6/4
stock |
8/4
stock |
12/4,
16/4 stock |
Standard |
291 |
291 |
291 |
294 |
294 |
294 |
288 |
aReferences
(28, 185). |
High temperaturea |
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4/4,
5/4 stock |
6/4
stock |
8/4
stock |
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Standard |
400 |
400 |
400/
414 |
NA |
aReferences
(28, 186) |
Working
Properties: The wood is stiff, moderately strong and hard, moderately high in
shock resistance, and moderately heavy. It has moderately large shrinkage. The
wood is usually straight grained, splits easily, and is subject to ring shake.
Knots are common but generally small and tight.
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Durability: : Western
larch is rated as moderately resistant to heartwood decay (12).
Preservation:
It is rated as resistant to preservative treatment (4).
Uses: Western
larch is used mainly in building construction for rough dimension, small
timbers, planks and boards, and for railroad crossties and mine timbers. It is
used also for piles, poles, and posts. Some high-grade material is manufactured
into interior finish, flooring, sash, and doors.
Toxicity: No
information available at this time.
Additional
Reading and References Cited (in parentheses)
1. Boone, R.
S.; Kozlik, C. J.; Bois, P. J., and Wengert, E. M. Dry kiln schedules for
commercial woods - temperate and tropical. Madison, WI: USDA Forest Service,
FPL-GTR-57; 1988.
2. Dallimore,
W.; Jackson, A. B., and Harrison, S. G. A handbook of Coniferae and
Ginkgoaceae. London, UK: Edward Arnold Ltd.; 1966.
3. Elias, T. S.
The complete trees of North America, field guide and natural history. New York,
NY: van Nostrand Reinhold Co.; 1980.
4. Henderson,
F. Y. A handbook of softwoods. London: HMSO; 1977.
5. Johnson, R.
P. A. and Bradner, M. I. Properties of western larch and their relation to uses
of the wood. Washington, DC, USA: USDA, Forest Service Technical Bulletin No.
285; 1932.
6. Little, jr.
E. L. Checklist of United States trees (native and naturalized). Washington,
DC: USGPO, USDA Forest Service, Ag. Handbook No. 541; 1979.
7. Lowery, D.
P. Western Larch, an American wood. Washington, DC, USA: USDA Forest Service,
FS-243; 1984.
8. Mitchell, R.
L. and Ritter, G. J. Galactan in western larch wood. FPRS Journal. 1953; 2:3pp.
9. Schmidt, W.
C. and Shearer, R. C. Larix occidentalis Nutt. Western Larch.
in: Burns, R. M. and Honkala, B. H., tech. coords. Silvics of North America.
Volume 1, Conifers. Washington, DC: USDA Forest Service; 1990; pp. 160-172.
10. Simpson, W.
T. Dry kiln operator's manual. Madison, WI: USDA Forest Service, FPL Ag.
Handbook No. 188; 1991.
11. Summitt, R.
and Sliker, A. CRC handbook of materials science. Vol. 4. Boca Raton, FL: CRC
Press, Inc.; 1980.
12. USDA. Wood
handbook: wood as an engineering material. Madison, WI: USDA Forest Service,
FPL Ag. Handbook No. 72; 1974.
13. Western
Pine Association. Larch of the western pine region, its properties, uses and
grades. Portland, OR, USA: Western Pine Association; 1948.