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Home , Abies grandis, Tsuga, Western larch

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Forest U An Service Western American Department of Agriculture FS-243

The spectacular western larch, which is the largest of the American , occurs throughout the of west- em , northern , and east- em and . Western larch wood ranks among the strongest of the . It is especially suited for construction purposes and is exten- sively used in the manufacture of and plywood. The species has also been used for poles. Water-soluble gums, readily extracted from the wood chips, are used in the printing and pharmaceutical industries.

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F-S2253 An American Wood

Western Larch (Larix occidentalis Nutt.)

David P. Lowery1

Distribution Western larch grows in the upper Co- 125° f 20° 15° lumbia River Basin of southeastern , northeastern Wash- 500 ington, northwest Montana, aid north-

em and west-central Idaho . It also grows on the east slopes of the Cascade Mountains in Washington and north- central Oregon and in the Blue and of southeast Wash- ington and northeast Oregon (fig. 1). Western larch grows best in the cool climates of mountain slopes and valleys on deep porous soils that may be gray- pÍIíp elly, sandy, or loamy in texture. The largest grow in western Montana and northern Idaho. Western larch characteristically occu- 450 pies northerly exposures, valley bot- toms, benches, and rolling topography. It occurs at elevations of from 2,000 to S5,500 feet in the northern part of its range and up to 7,000 feet in the south- em part of its range. The species some- times grows in nearly pure stands, but is most often found in association with other northern Rocky Mountain con- ifers. Associated species include: o ponderosa (Pinus ponderosa), too 200 300 400 MILES I i I I i I i I i i I Douglas- ( menziesii), i I I I I ' I I I I grand fir (Abies grandis), western white 1125° o 00 200 300 400 500 600 KILOMETERS pine (Pinus monticola), western red- cedar (Thujaplicata), western hemlock Figure 1-Natural range of western larch. F-532734. (), Engelmann (Picea engelmannii), subalpine fir (Abies lasiocarpa), and mountain hem- lock (). Description and Growth Western larch is one of the few in . Its needles are shed each winter and are replaced by new ones in the spring. The boles of mature trees are frequently free of branches to considerable height and usually have little taper. The crowns are usually short, open, and essentially pyramidal. The light-green foliage of the spring usually becomes a pale or bright green before turning yellow and . dropping in the fall (fig. 2). 1Wood Technologist, U.S. Department of Agri- culture, Service, Intermountain Forest and Range Experiment Station, Forestry Sciences Lab- oratory, Missoula, Mont. Figure 2-NeedleS and cones otwestern larch. F-308977 An American Wood s

The needles are i to l-3/4 inches long and are borne singly on elongate twigs or are densely clustered on short spur . New needles generally ap- pear in May or June along with new growth. Needles, like hardwood , drop in October or November after the fall frosts. Cones are from i to l-1/2 inches long, oblong or rounded, and dark or grayish brown. The trunks of mature and overmature trees have reddish- brown , which is 3 to 6 inches thick and composed of rounded plates with deep irregular fissures (fig. 3). The thick bark protects the older trees from fire. Western larch is long lived; some trees live to be more than 700 years old. At this age, trees may have heights of over 200 feet and diameters of 5 to 8 feet. Trees 250 to 400 years old may be loo to 180 feet tall and 3 to 4 feet in s diameter. Average height at 120 years is about 90 feet. Larch is moderately to highly resist- ant to windthrow because its deep, widespreading system provides ex- cellent anchorage. Although some are produced in all areas every year, good crops occur only at about 5-year intervals in most locations.

Common Names Western larch is frequently called tamarack or western tamarack. It is also known as hackamatack larch, Montana larch, mountain larch, and larch. Products manufactured from this species are almost always referred to as "made of larch."

Related Commercial Species In the construction-lumber industry, western larch and Douglas-fir are gen- erally sold together under the name Doug fir-larch. However, plywood, poles, and interior paneling are sold, almost without exception, as larch. For these uses, it is rarely mixed with other species.

Supply In 1977, western larch occupied an estimated 2.5 million acres in Montana, Figure 3-Bark of western larch. F-5OO63 An American Wood

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able for entry of other diseases and in- sects; and causing burls, brashness, and 600 some mortality, the most serious impact on the is decreased height and diameter growth. Proper harvest-cutting 500 systems, particularly clearcutting, can substantially reduce the mistletoe 400 problem. Three other important diseases are found in larch: needlecast caused by 300 Hypodermella laricis, the quinine Fomitopsis officinalis, and red ring rot caused by Phellinuspini. Many f200 other less common, but potentially dan- gerous fungi, such as Encoeliopsis lan- cina, infect larch, but have not caused 100 significant problems in the past. Larch casebearer (Coleophona laricella) and western spruce budworm 0 (Chonistoneuna occidentalis) are cur- 1940 1950 1960 1970 1980 1915 1920 1930 rently the two most serious pests of western larch. The casebearer was first detected in the northern Rockies in Figure 4-Western larch lumber production, 1915-80. 1957 and since then has essentially spread throughout the entire larch Idaho, Washington, and Oregon. More 1945, the true value ofthe species was forest type. However, introduced and than half of this acreage is in western recognized and lumber production in- native parasites, plus adverse weather Montana. Idaho has the second largest creased steadily. During the past 20 conditions on many larch sites, appear area of this species. years, it has averaged more than 500 to be reducing the casebearer problem. The total estimated net volume of million board feet per year. The great- Severe defoliation by the casebearer can commercial sawtimber was 30.3 billion est single year so far was 1968, when an substantially reduce tree growth, but board feet with Montana, again, con- estimated 592 million board feet of mortality usually is low. taming about half. The net volume of lumber was produced (fig. 4). Western spruce budworm has been a growing stock, which includes smaller Western larch has been used for tele- persistent problem wherever heavy pop- trees, was estimated to be about 6.5 phone and transmission poles, piling, ulations of budworm overlap the range damage to billion cubic feet, with Montana having and other related roundwood products. of larch . The most serious the major portion. In Montana, Idaho, and northeastern larch is severance of the terminal Washington, an estimated i .4 million leader, which results in an average loss Production poles were produced between 1947 and of about 25 to 30 percent of the height Western larch lumber production is 1962. growth for that year. not recorded separately, but is corn- Western larch has been a preferred bined with Douglas-fir throughout the plywood species in Montana and Idaho Characteristics and Properties species' range. Therefore, the annual for many years. Most of the rotary-cut The heartwood of western larch is amount of larch lumber produced has veneer is used to produce construction- russet or reddish brown, and the sap- been estimated by using the total of or sheathing-grade plywood. wood is a straw-brown color and very larch-Douglas-fir production and the Western larch is susceptible to attack narrow, rarely greater than 1 inch in percentage of larch included in Na- by various destructive and width. The growth rings are distinct, tional Forest larch-Douglas-fir timber diseases, thus decreasing production. quite uniform in width, and very nar- sales. Since larch has other uses besides Dwarf mistletoe (Arceuthobium larith) row (30 to 60 per inch). The earlywood lumber, the estimates may be somewhat is the most serious disease-causing zone is usually about twice the thick- high. parasite of larch. It can infest seedlings ness of the darker latewood zone, and Before 1940, larch was considered a as young as 3 to 7 years old and con- the transition between the zones is . lumber tinue throughout the life of the tree. In abrupt. The wood often has an oily weed species, and the annual production fluctuated around 200 addition to killing tree tops; reducing appearance, but has neither odor nor million board feet. However, after seed viability; creating conditions suit- taste and is only slightly resinous. It is An American Wood

one of the heavier and harder soft- use is declining. The heartwood is References , with a density of about 36 moderately difficult to penetrate with Fowells, H. A., comp. Silvics of for- pounds per cubic foot at 12 percent preservative solutions. However, the est trees of the United States. Agric. moisture content and with an average species is used extensively for transmis- Handb. 271. Washington, DC: U.S. specific gravity of 0.48, based on green sion and telephone poles, especially Department of Agriculture; 1965. volume and ovendry weight. It is strong where long lengths and high strengths 762 p. in bending and endwise compression, are required. Incising is a necessary pre- Furniss, R. L.; Carolin, V. M. West- stiff, and moderately high in shock requisite to obtain adequate preserva- em forest insects. Misc. Publ. 1339. resistance. The species is generally tive retention. Washington, DC: U.S. Department straight grained with a coarse texture; Larch is also a leading veneer and ofAgriculture; 1977. 654 p. and although it splits easily, the wood plywood species. Most of the veneer is Harlow, W. M.; Harrar, E. S.; White, has a moderately high nail-holding rotary cut, and the plywood is used for F. M. Textbook of dendrology. 6th capacity when blunt-pointed nails are sheathing by the construction industry. ed. New York: McGraw-Hifi; 1979. used. It is easy to glue, but is low in Because of its hardness and resistance Slop. paint-holding ability. The wood is rated to splintering, larch has been used for Hepting, G. H. Diseases offorest and as intermediate in resistance to decay. It mine-shaft guides. High-speed under- shade trees of the United States. is somewhat difficult to work, but takes ground mine hoists run along these Agric. Handb. 386. Washington, DC: a smooth, hard finish. The wood guides to lift personnel and ore. Mine U.S. Department of Agriculture; shrinks moderately and seasons fairly timbers have also been made from 1971. 658 p. well, though difficulty is encountered larch. Little, E. L. , Jr. Atlas of United States with warping and checking. Western Sawmill and plywood residues trees. Misc. Publ. 1 146. Washington, larch butt logs often contain large of western larch are chipped and used DC: U.S. Department of Agriculture; amounts of shake, which is a separation in the manufacture of and paper. 1971. . along the grain between annual rings. Before being processed into paper, the Panshin, A. J.; de Zeeuw, C. Text- chips may be subjected to a water treat- book of wood technology. 4th ed. Principal Uses ment for the extraction of a gum called New York: McGraw-Hifi; 1980. Construction lumber is the principal arabinoglactan. This chemical is used as 722 p. product of western larch. Because it is a coating for lithographic plates by the U.S. Department of Agriculture, For- strong, timbers, planks, boards, and printing industry, as a pill or tablet est Service. An analysis of the timber other dimension sizes are made from binder by the pharmaceutical trade, and situation in the United States the species. Boards are used for interior as an industrial emulsifier. 1952-2030. For. Resour. Rep. 23. finish, edge-grain flooring, water-tank The tree provides considerable pleas- Washington, DC: U.S. Department stock, boxes and crates, railway car ure to many recreationists as it is fre- ofAgriculture; 1982. 528 p. construction, and electrical machinery. quently a large, dominant tree, and its U.S. Department of Agriculture, For- For most purposes, western larch is fall foliage contrasts with the neighbor- est Service, Forest Products Labora- used interchangeably with Douglas-fir. ing greens. tory. Wood handbook: wood as an Although western larch has some- engineering material. Agric. Handb. times been used for railway ties, this 72. Rev. ed. Washington, DC: U.S. Department of Agriculture; 1974. 428 p.

s An American Wood .

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kevi.,d Ocfober 1984