Betula spp.

 

 

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Family: Betulaceae

 

 

 

 

 

 

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American Birch

 

 

 

 

Birch (Betula spp.) is composed of 30 to 50 species growing in Asia [12], North America [4] and Europe [4]. All species look alike microscopically. The word betula is the classical Latin name of birch. The important species are yellow birch (Betula alleghaniensis), sweet birch (B. lenta), and paper birch
(B. papyrifera). Other birches of some commercial importance are river birch (B. nigra), gray birch
(B. populifolia), and western paper birch (B. papyrifera var. commutata).

Betula alleghaniensis*–black birch, Canadian silky wood, gray birch, hard birch, Quebec birch, silver birch, swamp birch, white birch, witch hazel, yellow birch

Betula lenta*–black birch, black cherry birch, cherry birch, mahogany, mahogany birch, mountain birch, mountain mahogany, red birch, river birch, spice birch, yellow birch, sweet birch

Betula nana–swamp birch

Betula nigra*–black birch, red birch, river birch, water birch

Betula occidentalis–black birch, canyon birch, cherry birch, mountain birch, red birch, red canyon birch, spring birch, swamp birch, sweet birch, water birch, western birch, western paper birch, western red birch

Betula papyrifera*–black birch, canoe birch, gray birch, large white birch, northwestern paper birch, paper birch, red birch, silver birch, western birch, western paper birch, white birch

Betula papyrifera var. papyrifera–paper birch (typical)

Betula papyrifera var. commutata–western paper birch

Betula papyrifera var. cordifolia–mountain paper birch

Betula papyrifera var. kenaica–Kenai birch

Betula papyrifera var. neoalaskana–Alaska paper birch

Betula papyrifera var. subcordata–northwestern paper birch

Betula pendula–silver birch, white birch

Betula populifolia*–blue birch, blueleaf birch, broom birch, fire birch, gray birch, oldfield birch, pin birch, poplar-leaved birch, poverty birch, small white birch, white birch, wire birch

Betula pumila–dwarf birch

Betula uber–Ashe’s birch, Virginia birch, Virginia roundleaf birch

(* = commercial species)

Distribution

North America: Yellow birch, sweet birch, and paper birch grow principally in the Northeastern and Lake States. Yellow and sweet birch also grow along the Appalachian Mountains to northern Georgia. Paper birch is also found throughout Canada and Alaska. Yellow, sweet, and paper birch are the source of most birch lumber and veneer.

The Tree

Birches can reach a height of 70 ft, with a diameter of more than 2 ft.

The Wood

General

The wood varies slightly among species. The wood of yellow birch and sweet birch is heavy, hard and strong, while that of paper birch is lighter, and less hard, strong and stiff. All birches have a fine, uniform texture. Paper birch is easy to work with hand tools; sweet birch and yellow birch are difficult to work with hand tools and difficult to glue, but easily machined. Yellow birch has white sapwood and light reddish-brown heartwood. Sweet birch has light-colored sapwood and dark brown heartwood tinged with red.

Mechanical Properties (2-inch standard)

 

 

 

 

Compression

 

 

 

 

Specific

gravity

MOE

106 lbf/in2

MOR

103 lbf/in2

Parallel

103 lbf/in2

Perpendicular

103 lbf/in2

WMLa

in-lbf/in3

Hardness

lbf

Shear

103 lbf/in2

B. alleghaniensis (yellow birch)b

Green

0.55

1.50

8.30

3.38

0.43

16.1

780

1.11

Dry

0.62

2.01

16.6

8.17

0.97

20.8

1,260

1.88

B. lenta (sweet birch)b

Green

0.60

1.65

9.4

3.74

0.47

15.7

970

1.24

Dry

0.65

2.17

16.9

8.54

1.08

18.0

1,470

2.24

B. papyrifera (paper birch)b

Green

0.48

1.17

6.4

2.36

0.27

16.2

560

0.84

Dry

0.55

1.59

12.3

5.69

0.60

16.0

910

1.21

B. papyrifera var. neoalaskana (Alaska paper birch)c

Green

0.49

1.35

7.1

3.03

0.43

11.6

560

0.92

Dry

0.55

1.9

13.6

7.45

0.82

13.9

830

1.40

B. populifolia (gray birch)c

Green

0.45

Dry

0.51

1.15

9.8

4.87

0.92

10.8

760

1.34

aWML = Work to maximum load.

bReference (98).

cReference (59).

 

Drying and Shrinkage

Type of shrinkage

Percentage of shrinkage
(green to final moisture content)

0% MC

6% MC

20% MC

B. alleghaniensis (yellow birch)

Tangential

9.5

7.4

3.1

Radial

7.3

5.8

2.4

Volumetric

16.8

13.4

5.6

B. lenta (sweet birch)

Tangential

9.0

Radial

6.5

Volumetric

15.6

B. nigra (river birch)

Tangential

9.2

Radial

4.7

Volumetric

13.5

B. papyrifera (paper birch)

Tangential

8.6

6.9

2.9

Radial

6.3

5.0

2.1

Volumetric

16.2

13.0

5.4

B. papyrifera var. neoalaskana (Alaska paper birch)

Tangential

9.9

Radial

6.5

Volumetric

16.7

B. populifolia (gray birch)

Tangential

Radial

5.2

Volumetric

14.7

aBirch shrinks considerably during drying. References: 0% MC (98),
6% and 20% MC (90).

Kiln Drying Schedulesa

 

Stock

Condition

4/4, 5/4, 6/4

8/4

10/4

12/4

16/4

B. lenta, B. nigra, B. populifolia, B. papyrifera

Standard

T10-C4

T8-D3

1-in. squares

T10-C6

Whiter 1-in.squares

T5-C6

2-in. squares

T8-C4

Whiter 2-in. squares

T5-C4

B. alleghaniensis

Standard

T10-C4

T8-D3

1-in. squares

T10-C6

Whiter 1-in.squares

T5-C6

2-in. squares

T8-C4

Whiter 2-in. squares

T5-C4

aReferences (6, 86).

Working Properties: Working properties may vary with species. In general, birches split during nailing; if successfully nailed, they have good nail-holding properties.

Durability: Rated as slightly or nonresistant to heartwood decay.

Preservation: No information available at this time.

Uses: Yellow and sweet birch lumber and veneer are used principally in the manufacture of furniture, boxes, baskets, crates, wooden ware, cooperage, interior finish, and doors. Birch veneer goes into plywood used for flush doors, furniture, paneling, radio and television cabinets, aircraft, and other specialty uses. Paper birch is used for turned products, including spools, bobbins, small handles, and toys. Also used for pulp wood, fuel wood, turnery, distillation products, toothpicks, ice cream sticks and tongue depressors.

Toxicity: Birches can cause dermatitis (40, 64, 105).

Additional Reading and References Cited (in parentheses)

6. Boone, R.S.; Kozlik, C.J.; Bois, P.J.; Wengert, E.M. 1988. Dry kiln schedules for commercial woods-temperate and tropical. Gen. Tech. Rep. FPL-GTR-57. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.

8. Brisbin, R.L.; Sonderman, D.L. 1973. Birch, an American wood. FS-221.Washington, DC: U.S. Department of Agriculture, Forest Service.

9. Brown, H.P.; Panshin, A.J. 1940. Commercial timbers of the United States, their structure, identification, properties and uses. New York: McGraw-Hill Book Co.

29. Elias, T.S. 1980. The complete trees of North America, field guide and natural history. New York: van Nostrand Reinhold Company.

40. Hausen, B.M. 1981. Woods injurious to human health. A manual. New York: Walter de Gruyter.

55. Little, Jr., E.L. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. U.S. Government Printing Office.

59. Markwardt, L.J.; Wilson, T.R.C. 1935. Strength and related properties of woods grown in the United States. Tech. Bull. 479. Washington, DC: U.S. Department of Agriculture, Forest Service. U.S. Government Printing Office.

64. Mitchell, J.; Rook, A. 1979. Botanical dermatology: plants and plant products injurious to the skin. Vancouver, BC: Greenglass Ltd.

68. Panshin, A.J.; de Zeeuw, C. 1980. Textbook of wood technology, 4th ed. New York: McGraw-Hill Book Co.

74. Record, S.J.; Hess R.W. 1943. Timbers of the new world. New Haven, CT: Yale University Press.

86. Simpson, W.T. 1991. Dry kiln operator's manual. Ag. Handb. 188. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.

90. Summitt, R.; Sliker, A. 1980. CRC handbook of materials science. Boca Raton, FL: CRC Press, Inc. Vol. 4.

98. U.S. Department of Agriculture. 1987. Wood handbook: wood as an engineering material. Agric. Handb. 72. (Rev.) Washington, DC: U.S. Department of Agriculture. 466 p.

105. Woods, B.; Calnan, C.D. 1976. Toxic woods. British Journal of Dermatology. 95(13): 1-97.