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Home , Douglas fir, Fir, Pseudotsuga

Forest An American Service Douglas- Department of Agriculture FS-235 Douglas-fir is one of the fastest growing in the temperate zone and grows to a magnificent size in older stands. An abundant supply and excel- lent wood characteristics make it the single most important in the United States. It is used extensively for dimensional lumber, , and .

An American Wood

Douglas-Flr ( menziesii (Mirb.) Franco) Bernard T. Bormann1

Distribution

Douglas-fir is widely scattered throughout western from the mountains of Mexico to Brit- ish Columbia, Canada (fig. 1). Two have been identified. Coastal Douglas-fir (variety menziesii ) is found west of the and from sea level to 5,000 feet. Rocky Mountain Douglas-fir (variety glauca (Biessn.) Franco) is found in the eastern and Sierra Nevada and throughout the at elevations of 1,800 to 8,000 feet in the north and to nearly 11,000 feet in the south. Both varieties are adapted to an ex- tremely wide variety of soils and climates. In the coastal region, the species is commonly found in pure, even-aged stands thought to have developed following clearcutting or wildfires. Approaching its latitudinal or elevational limits, Douglas-fir is more commonly found growing with other species.

1Research Physiologist, U.S.Department of Agriculture, Service, Forest and Range Experiment Station, Sciences Laboratory, Juneau, . Figure l—Natural range of Douglas-fir. F-532736 3 An American Wood

Description and Growth Douglas-fir is a coniferous that often reaches magnificent size. Heights of 150 to 250 feet and diameters of 3 to 6 feet are common in coastal stands that are 200 to 800 or more years old. The tallest intact standing tree that has been documented was 330 feet tall and grew near Littlerock, Wash. The max- imum size of Rocky Mountain Douglas- fir is 150 feet in height and 4 feet in diameter on the best sites. Douglas-fir is distinguished by a dense, cone-shaped crown, sharp- pointed buds, and three-pronged that protrude between cone scales (fig. 2). The needlelike are dark yellow green in the coastal variety or blue green in the Rocky Mountain variety. They are 3/4 to 1-1/4 inches long, flattened, and flexible. Stems are long, very straight, and cylin- drical. The on young is gray, thin, and smooth. In older trees it becomes brownish red, medium to very thick, and deeply fissured. production varies from tree to Figure 2- Douglas-fir leaves and cones. F-308969 tree and from year to year, large crops occur at intervals of 2 to 11 years. are dispersed by the wind and dense stands is often improved by pre- pest of the Rocky Mountain variety, germinate readily on most soils, pro- commercial and commercial thinning. and the cone gall midges (Contarinia vided there is sufficient moisture. To In unmanaged stands on the best sites, oregonensis and C. washingtonensis) survive, seedlings must receive light and yields of 20,000 cubic feet (130,000 are pests of Pacific coast trees. Large their roots must reach mineral soil board feet, Scribner rule) per acre can stands of Rocky Mountain Douglas-fir quickly. be achieved in 110 years, but on aver- can be defoliated by the Douglas-fir This species is especially well adapted age sites, even old-growth stands rarely tussock moth () to silvicultural systems that involve contain more than 17,000 cubic feet and the budworm (Choristo- complete removal of overstory trees on (100,000 board feet, Scribner rule) per neura occidentalis). Browsing and clip- all but the harshest sites. Large clear- acre. ping by hares, mountain beaver, deer, cuts usually require planting of nursery- Although Douglas-fir is considered and elk can damage and kill large grown seedlings to insure full stocking. generally free of pests compared to numbers of seedlings and saplings. Where there is a large amount of log- most other species, many agents can Bears have been known to strip bark of ging residue, some site preparation is cause damage to seeds, seedlings, and larger trees. Strong winds, especially necessary to establish a suitable plant- mature trees. Several parasitic fungi, after heavy rains, blow down trees, and ing site. such as the (Phel- ice and snow storms can result in Juvenile growth of Douglas-fir is less linus weirii) and the shoestring root rot broken tops. Crown fires destroy trees rapid than that of some native hard- (Armillariella mellea), can cause exten- of all ages. The thick bark on older and shrub species, especially on sive damage to trees of all ages. Red trees makes them resistant to ground the better sites. Consequently, mechan- ring rot (Fomes pini) is an important fires. ical or chemical removal of competing heartrot. Dwarf mistletoe (Arceutho- species is often necessary to establish bium douglasii), a , Other Names pure stands. Tree growth in pure stands causes stem malformation. Many in- The variety of names, both scientific 20 to 80 years old is extremely rapid, sects devour Douglas-fir seeds while and common, applied to the Douglas- outproducing most other species in they are still in the cone. The cone fir tree, reflects the confusion that has North America. The profitability of moth (Barbara colfaxiana) is a serious historically surrounded its botanical

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Figure 3–Production of Douglas-fir from 1930 to 1980. relationship. The tree was first de- combination, however, overlooked an usually marketed with western scribed in 1803 by a British botanist earlier published name for the tree, and (Larix occidentalis). from a specimen collected by Archibald in 1950, in accordance with intern- Menzies while on an expedition to the ational rules governing botanical nomen- supply west coast of North America. It was al- clature, the name was changed to its The estimated volume of Douglas-fir ternately considered to be a kind of present form, Pseudotsuga menziesii. sawtimber (trees greater than 9 inches (Pinus), a true fir (Abies), a spruce Common names applied to this tree in diameter at breast height) in the (Picea), and a hemlock (). Final- also reflect the past confusion regarding United States in 1977 was 514 billion ly, in 1825, Scottish botanist David its botanical affiliation. The name board feet (International 1/4-inch rule) Douglas was sent to America by the Douglas-fir commemorates the Scottish (USDA FS 1982). Most of this volume British Royal Horticultural Society to botanist and is the name by which this was in and (46 and study this species. tree is most frequently known today 23 percent, respectively). had In 1867, based on specimens collected worldwide. Many other common names 14 percent and the Rocky Mountain re- by Douglas, the tree was recognized as have been used, some of the more gion 17 percent. a separate among conifers and widely known being Douglas-spruce, given the new name Pseudotsuga. This Douglas-yew, and Oregon-pine. Production was a rather unfortunate choice, since it Douglas-fir lumber has been mar- Douglas-fir is the most important literally means “false hemlock,” a genus keted under the names yellow-fir and species for lumber production in the to which it is only remotely related. red-fir, depending on color variations United States. Over the past decade, it Even after the new genus was es- of the wood, which are supposedly has accounted for 64 percent of all tablished for it, confusion continued associated with property differences. In lumber produced in the Pacific coast re- about the correct combination for the foreign markets, the wood of Douglas- gion. Peak production was achieved in botanical name. Pseudotsuga douglasii fir is still sometimes marketed as 1952. Since then utilization of other and Pseudotsuga mucronata can be Oregon-pine or merely as Oregon. species has increased while Douglas-fir found in the literature, but it was the production has declined in the region combination Pseudotsuga taxifolia that Related Commercial Species (fig. 3). Recession in 1980 cut produc- became most widely accepted and was Coastal Douglas-fir is marketed by it- tion to about half the 1952 figure and in use for over half a century. This self. Rocky Mountain Douglas-fir is resulted in the lowest production since

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the 1930’s. For the inland region, where dense southern pine in decay resistance Douglas-fir is marketed with larch, but is less durable than the cedars, bald combined production of these species cypress, and redwood. The wood is dif- rose steadily after 1930, peaking from ficult to impregnate with preservatives 1959 to 1967. and must often be incised to allow pen- etration. Douglas-fir ranks low in - Characteristics and Properties holding ability, especially on exterior The sapwood of Douglas-fir is surfaces, but has good staining whitish or pale yellow; it is narrow in properties. slow-growing trees and up to 3 inches Douglas-fir fibers are relatively long, thick in rapidly growing trees. Heart- large in diameter and have thick cell wood is yellow or pale red in Rocky walls. Paper products made from them Mountain trees and slow-growing have high tearing strength, but their coastal trees, and orange to red in fast- tensile strength is lower than that of growing coastal trees. Although wood paper products made from fibers of quality of both varieties is extremely western hemlock (). variable, average material is rated as strong, moderately hard, and very stiff. Wood specific gravity ranges from 0.43 Principal Uses to 0.46, based on green volume and Douglas-fir predominates in struc- ovendry weight. The wood density tural wood markets primarily because ranges from 32 to 35 pounds per cubic of its strength and availability in foot at 12 percent moisture content. large sizes. It also leads in use for Coastal trees are stronger and denser construction-grade plywood and high- than Rocky Mountain trees. Boards cut grade veneer. Principal uses are in con- from old-growth trees of both varieties struction and for poles, pilings, and are generally stronger and denser than railroad ties. It is also used extensively boards cut from second-growth trees. in paper products and various types of The wood is rather difficult to work millwork, flooring, pallets, boxes, with handtools, splits easily, but has crates, ladders, and furniture. In the good machining properties. It can be Western States, firewood, hog fuel, and readily kiln-dried using normal Christmas trees are important uses. It is procedures. widely used as an ornamental tree and High density Douglas-fir wood is of is planted throughout the world. intermediate durability, ranking with

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