| Douglas fir | |
|---|---|
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Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Pseudotsuga |
| Species: | P. menziesii |
| Binomial name | |
| Pseudotsuga menziesii | |
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Green: Coast Douglas-fir (Pseudotsuga menziesii var.menziesii) Blue: Rocky Mountain Douglas-fir (Pseudotsuga menziesii var.glauca) | |
| Synonyms | |
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TheDouglas fir (Pseudotsuga menziesii)[4] is anevergreenconiferspecies in the pine family,Pinaceae. It isnative to westernNorth America and is also known asDouglas-fir,[5]Douglas spruce,[6]Oregon pine,[7] andColumbian pine.[8] There are three varieties:coast Douglas-fir (P. menziesii var.menziesii),Rocky Mountain Douglas-fir (P. menziesii var.glauca) andMexican Douglas-fir (P. menziesii var.lindleyana).[9]
Despite itscommon names, it is not a truefir (genusAbies),spruce (genusPicea), orpine (genusPinus). It is also not ahemlock; the genus namePseudotsuga means "false hemlock".
Douglas-firs are medium-sized to extremely largeevergreen trees, 20–100 metres (70–330 feet) tall (although onlycoast Douglas-firs reach heights near 100 m)[10] and commonly reach 2.4 m (8 ft) in diameter,[11] although trees with diameters of almost 5 m (16 ft) exist.[12] The largest coast Douglas-firs regularly live over 500 years, with the oldest specimens living for over 1,300 years.[13]Rocky Mountain Douglas-firs, found further to the east,[14] are less long-lived, usually not exceeding 400 years in age.[15]
There are records of former coast Douglas-firs exceeding 120 m (390 ft)[16][17] in height, which if alive today would make it the tallest tree species on Earth. Particular historical specimens with heights exceeding 400 ft include theLynn Valley Tree and theNooksack Giant.
Theleaves are flat, soft, linear needles 1.5–4 centimetres (1⁄2–1+1⁄2 in) long,[18] generally resembling those of the firs, occurring singly rather than infascicles; they completely encircle the branches, which can be useful in recognizing the species. As the trees grow taller in denser forest, they lose their lower branches, such that the foliage may start as high as 34 m (110 ft) off the ground.[19] Douglas-firs in environments with more light may have branches much closer to the ground.
Thebark on young trees is thin, smooth, gray, and contains numerousresin blisters. On mature trees, usually exceeding 80 years,[citation needed] it is very thick and corky, growing up to 36 cm (14 in) thick with distinctive, deep vertical fissures caused by the gradual expansion of the growing tree. Some of the mature bark is brown, while other parts are lighter colored with a cork-like texture; these develop in multiple layers.[20] This thick bark makes the Douglas-fir one of the most fire-resistant tree native to the Pacific Northwest.[21]
The malecones are yellowish red,5–12 mm (1⁄4–1⁄2 in) long. The female cones are green when young, maturing to reddish-brown or gray,6–10 cm (2+1⁄4–4 in) long;[18] they are pendulous, with persistent scales, unlike those of true firs. They have distinctive long,trifid (three-pointed)bracts which protrude prominently above each scale and are said to resemble the back half of a mouse, with two feet and a tail.[22] The seeds are5 mm (1⁄4 in) long, with a longer wing.[18]
The massive mega-genome of Douglas-fir was sequenced in 2017 by the large PineRefSeq consortium, revealing a specialized photosynthetic apparatus in the light-harvesting complex of genes.[23]
The common name honorsDavid Douglas, a Scottish botanist and collector who first reported the extraordinary nature and potential of the species. The common name is misleading since it is not a true fir, i.e., not a member of the genusAbies. For this reason, the name is often written asDouglas-fir (a name also used for the genusPseudotsuga as a whole).[24][14]
The specific epithetmenziesii is afterArchibald Menzies, a Scottish physician and rivalnaturalist to David Douglas. Menzies first documented the tree onVancouver Island in 1791. Colloquially, the species is also known simply asDoug fir[8] orDouglas pine[8] (although the latter common name may also refer toPinus douglasiana).[25] Other names for this tree have includedOregon pine,[7]British Columbian pine,[8]Puget Sound pine,[8]Douglas spruce,[8]false hemlock,[7]red fir,[7] orred pine[7] (although again red pine may refer to a different tree species,Pinus resinosa, and red fir may refer toAbies magnifica).[26]
OneCoast Salish name for the tree, used in theHalkomelem language, islá:yelhp.[27] In theLushootseed language, the tree is calledčəbidac.[28]
Pseudotsuga menziesii var.menziesii, the coast Douglas-fir, grows in the coastal regions from west-centralBritish Columbia southward toCentral California. InOregon andWashington, its range is continuous from the eastern edge of theCascades west to thePacific Coast Ranges and Pacific Ocean. In California, it is found in theKlamath andCalifornia Coast Ranges as far south as theSanta Lucia Range, with a small stand as far south as thePurisima Hills in Santa Barbara County.[29][30] One of the last remaining old growth stands of conifers is in the Mattole Watershed, and is under threat of logging.[31][32] In theSierra Nevada, it ranges as far south as theYosemite region. It occurs from sea level along the coast to elevations of 1,500 m (4,900 ft) or higher, and inland in some cases up to 2,100 m (6,900 ft).[14]
Another variety exists further inland,Pseudotsuga menziesii var.glauca, the Rocky Mountain Douglas-fir or interior Douglas-fir. Interior Douglas-fir intergrades with coast Douglas-fir in the Cascades of northern Washington and southern British Columbia, and from there ranges northward to central British Columbia and southeastward to the Mexican border, becoming increasingly disjunct as latitude decreases and altitude increases.Mexican Douglas-fir (P. lindleyana), which ranges as far south asOaxaca, is often considered a variety ofP. menziesii.
Fossils (wood, pollen) ofPseudotsuga are recorded from theMiocene andPliocene of Europe (Siebengebirge,Gleiwitz, Austria).[33]
It is alsonaturalised throughout Europe,[34] Argentina and Chile (calledPino Oregón). In New Zealand it is considered to be an invasive species, called awilding conifer, and is subject to control measures. But is also one of the most common lumber trees used in forestry alongside Radiata pine with large plantations throughout the country. The species was introduced in the 20th century for its wood.[35][36]
Douglas-fir prefers acidic or neutral soils, such asOlympic soil.[37] However, it exhibits considerable morphological plasticity, and on drier sitesP. menziesii var.menziesii will generate deeper taproots.Pseudotsuga menziesii var.glauca exhibits even greater plasticity, occurring in stands of interior temperate rainforest in British Columbia, as well as at the edge of semi-arid sagebrush steppe throughout much of its range, where it generates even deeper taproots still.
The coast Douglas-fir variety is the dominant tree west of the Cascade Mountains in thePacific Northwest. It occurs in nearly all forest types and competes well on most parent materials, aspects, and slopes. Adapted to a more moist, mild climate than the interior subspecies, it grows larger and faster than Rocky Mountain Douglas-fir. Associated trees includewestern hemlock,Sitka spruce,sugar pine,western white pine,ponderosa pine,grand fir,coast redwood,western redcedar,California incense-cedar,Lawson's cypress,tanoak,bigleaf maple and several others. Pure stands are also common, particularly north of theUmpqua River in Oregon. It is most dominant in areas with a more frequent fire regime that suppresses less fire-resistant conifers.[20]
Douglas-fir seeds are an extremely important food source for small mammals such asmoles,shrews, andchipmunks, which consume an estimated 65% of each annual seed crop. TheDouglas squirrel harvests and hoards great quantities of Douglas-fir cones, and also consumes mature pollen cones, the inner bark, terminal shoots, and developing young needles.[13]
Mature or "old-growth" Douglas-fir forest is the primary habitat of thered tree vole (Arborimus longicaudus) and thespotted owl (Strix occidentalis). Home range requirements for breeding pairs of spotted owls are at least 400 hectares (4.0 km2; 990 acres) of old growth. Red tree voles may also be found in immature forests if Douglas-fir is a significant component. The red vole nests almost exclusively in the foliage of the trees, typically 2–50 metres (5–165 ft) above the ground, and its diet consists chiefly of Douglas-fir needles.[13]
Douglas-fir needles are generally poorbrowse forungulates, although in the winter when other food sources are lacking it can become important, andblack-tailed deer browse new seedlings and saplings in spring and summer. The spring diet of theblue grouse features Douglas-fir needles prominently.[13]
The leaves are also used by thewoolly conifer aphidAdelges cooleyi; this 0.5 mm-longsap-suckinginsect is conspicuous on the undersides of the leaves by the small white "fluff spots" of protective wax that it produces. It is often present in large numbers, and can cause the foliage to turn yellowish from the damage it causes. Exceptionally, trees may be partially defoliated by it, but the damage is rarely this severe. AmongLepidoptera, apart from some that feed onPseudotsuga in general, thegelechiid mothsChionodes abella andC. periculella as well as the cone scale-eatingtortrix mothCydia illutana have been recorded specifically onP. menziesii.
The inner bark is the primary winter food for theNorth American porcupine.[13]
Poriol is a flavanone, a type of flavonoid, produced byP. menziesii in reaction to infection byPoria weirii.[38]
Aparasitic plant which usesP. menziesii is theDouglas-fir dwarf mistletoe (Arceuthobium douglasii).Epiphytes such ascrustose lichens and mosses are common sights on Douglas-firs.[20] As it is only moderatelyshade tolerant,[14] undisturbed Douglas-fir stands in humid areas will eventually give way to later successional, more shade-tolerant associates such as the western redcedar and western hemlock—though this process may take a thousand years or more.[13] It is more shade tolerant than some associated fire-dependent species, such aswestern larch and ponderosa pine, and often replaces these species further inland.[14]
Fungal diseases such aslaminated root rot andshoestring root-rot can cause significant damage, and in plantation settings dominated by Douglas-fir monocultures may cause extreme damage to vast swathes of trees.[13] Interplanting with resistant or nonhost species such as western redcedar andbeaked hazelnut[39] can reduce this risk. Other threats to Douglas-fir includered ring rot and theDouglas-fir beetle.[13]
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Many differentNative American groups used the bark, resin, and needles to make herbal treatments for various diseases.[40]Native Hawaiians builtwaʻa kaulua (double-hulled canoes) from coast Douglas-fir logs that haddrifted ashore.[41] The wood has historically been favored asfirewood, especially from the coastal variety.[14] In addition early settlers used Douglas-fir for all forms of building construction, including floors, beams, and fine carving.
The species is extensively used inforestry management as aplantation tree for softwoodtimber. Douglas-fir is one of the world's best timber-producing species and yields more timber than any other species in North America, making the forestlands of western Oregon, Washington, and British Columbia the most productive on the continent. In 2011, Douglas-fir represented 34.2% of US lumber exports, to a total of 1.053 billion board-feet.[42][13] Douglas-fir timber is used fortimber frame construction andtimber trusses using traditional joinery,veneer, andflooring due to its strength, hardness and durability.[43] As of 2024, the only wooden ships still currently in use by theU.S. Navy in conventional naval operations areAvenger-class minesweepers, made of Douglas-fir.[44]
Douglas-fir sees wide use in heavy timber structures, as its wood is strong, available in a number of specifications including kiln dried and grade stamped, and can be supplied in very long lengths to 60 feet. West coast mills are sophisticated in their processing of timbers, making lead times predictable and availability reliable.Paints adhere well to Douglas-fir.Stains perform well on Douglas-fir timbers with the mild caution that the natural color of this species varies and care must be taken to ensure uniformity of color. Pitch pockets that may ooze resin can be present in timbers that have not been kiln dried. Because of the timber sizes available, stamped timber grading, and relatively short lead times, Douglas-fir sees wide use in both public and residential projects.[citation needed]
The species has ornamental value in large parks and gardens.[45] It has been commonly used as aChristmas tree since the 1920s, and the trees are typically grown on plantations.[46]
The buds have been used to flavoreau de vie, a clear, colorless fruit brandy.[47] Douglas-fir pine leaves can be used to makepine needle tea.[48] They possess a tangy citrus flavor and may serve in some recipes as a wild substitute forrosemary.[49]
This was the preferred species for Hawaiian war canoes. The Hawaiians, of course, did not log the trees; they had to rely on driftwood.
wooden hulls—typically oak, Douglas-fir, or Nootka Cypress—coated in glass-reinforced plastic
