Larix occidentalis

 

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Family: Pinaceae

 

 

 

 

 

 

 

 

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Western Larch

 

 

 

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.

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Mechanical Properties (2-inch standard)

 

 

 

 

Compression

 

 

 

 

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
(green to final moisture content)

0% MC

6% MC

20% MC

Tangential

9.1

6.3

2.6

Radial

4.5

3.4

1.4

Volumetric

14.0

9.5

4.0

References: 0% (185)
6% (56) 20% (192)

Kiln Drying Schedulesa

 

Conventional temperature/moisture content-controlled schedulesa


Condition

4/4, 5/4
stock

6/4 stock

8/4
stock

10/4
stock

12/4
stock

British schedule
4/4 stock

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

 

Lower grades

Upper grades


Condition

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


Condition

4/4, 5/4 stock

6/4 stock

8/4 stock


Other products

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.

.

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.