The Douglas fir is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Puget Sound pine, Oregon pine, Red pine or Columbian pine. Despite its common names, it is not a true fir (genius Abies), spruce (genus Picea) or pine (genus Pinus). It is also not a hemlock; the genus name Pseudotsuga means “false hemlock”. There are three varieties: coast Douglas-fir, Rocky Mountain Douglas-fir and Mexican Douglas-fir.
Douglas-firs are medium-size to extremely large evergreen trees, about 60 or 70 metres tall (although only coast Douglas-firs, reach heights near 100 m) and commonly reach 8 ft in diameter although trees with diameters of almost 5 metres (16 feet) exist. The largest coast Douglas-firs regularly live over 500 years, with the oldest specimens living for over 1,300 years. Rocky Mountain Douglas-firs, found further to the east, are less long-lived, usually not exceeding 400 years in age.
There are records of former coast Douglas-firs exceeding 120 metres in height, which if alive today would make it the tallest tree species on Earth. Particular historical specimens with heights exceeding 400 feet include the Lynn Valley Tree and the Nooksack Giant.
Native Range
The latitudinal range of Douglas-fir is the greatest of any commercial conifer of western North America. Its native range, extending from latitude 19° to 55° N., resembles an inverted V with uneven sides. From the apex in central British Columbia, the shorter arm extends south along the Pacific Coast Ranges for about 2200 km (1,367 mi) to latitude 34° 44′ N., representing the range of the typical coastal or green variety, menziesii; the longer arm stretches along the Rocky Mountains into the mountains of central Mexico over a distance of nearly 4500 km (2,796 mi), comprising the range of the other recognized variety, glauca– Rocky Mountain or blue.
Nearly pure stands of Douglas-fir continue south from their northern limit on Vancouver Island through western Washington, Oregon, and the Klamath and Coast Ranges of northern California as far as the Santa Cruz Mountains. In the Sierra Nevada, Douglas-fir is a common part of the mixed conifer forest as far south as the Yosemite region. The range of Douglas-fir is fairly continuous through northern Idaho, western Montana, and northwestern Wyoming. Several outliers are present in Alberta and the eastern-central parts of Montana and Wyoming, the largest being in the Bighorn Mountains of Wyoming. In northeastern Oregon, and from southern Idaho south through the mountains of Utah, Nevada, Colorado, New Mexico, Arizona, extreme western Texas, and northern Mexico, the distribution becomes discontinuous.
Douglas Fir Characteristics
- Genus: Pseudotsuga
- Species: menziesii
- Common Names: Douglas Fir, Douglas-spruce, Oregon Pine, Red Fir
- Native Range: Western North America, from British Columbia, Canada, to California, USA
- Evergreen coniferous tree
- Medium to large size, up to 100 meters (330 feet) tall
- Trunk diameter: 2-5 meters (6-16 feet)
- Bark: Reddish-brown, thick, and develops ridges and deep furrows
- Needles: Flat, spirally arranged, dark green to yellow-green or bluish-green, 1.25 inches long, with white banding on the undersides
- Cones: Pendulous, 3-4 inches long, with forked bracts
- Fragrant when bruised or crushed
Uses
- Timber production: Economically important softwood, used for lumber, plywood, and paper products
- Christmas trees: Popular selection for Christmas tree plantations, particularly in the United States
- Dendrochronology: Used for climate reconstruction, archeological dating, and ecological studies
- Landscaping: Ornamental tree, often used in parks and gardens for its attractive foliage and conical shape
Cultivation
- Soil: Prefers acidic to neutral, moist, well-drained, and organically rich soil
- Sunlight: Full sun to partial shade
- Watering: Requires consistent moisture, intolerant to drought
- Temperature: Cool summers, intolerant to heat and humidity
- Propagation: Seeds or cuttings
- Pruning: Regular pruning recommended for Christmas tree cultivation
Varieties
Douglas-fir has one of the broadest ranges of any North American conifer, much of it over extremely dissected terrain, and the species exhibits a great deal of genetic differentiation. Much of this variation is strongly associated with geographic or topographic features .
- Coast Douglas-fir (Pseudotsuga menziesii var. menziesii): Large tree, dark yellow-green needles, large cones
- Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca): Medium-sized tree, bluish-green needles, small cones
- Dwarf cultivars: Available for ornamental purposes
Ecological Notes
- Native distribution: Mainly found on southerly slopes in the northern part of its range, and on northerly exposures in the southern part
- Sympatric subspecies: Pseudotsuga menziesii subsp. glauca and P. m. subsp. menziesii co-occur in southern British Columbia and northeastern Washington
- Terpene compositions: Consistent differences between coastal, Sierra Nevada, northern interior, and southern interior regions.
Douglas-fir is grown as a Christmas tree on rotations ranging from 4 to 7 years. Trees are sheared each year to obtain a pyramid-shaped crown. Attempts to grow Douglas-fir as a Christmas tree in North America outside its native range have failed. Coastal Douglas-fir is usually killed by frost, and the interior variety suffers too much from the needle cast disease Phaeocryptopus gaeumanni.