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Douglas-fir is not a true fir and has been a taxonomic nightmare for those trying to settle on a genus name. After changing names on numerous occasions the present scientific name Pseudotsuga menziesii now uniquely belongs to Douglas-fir.01of 05
Introduction To Douglas Fir
To make things even more complicated, two different varieties of the species are recognized. There is the P. menziesii var. menziesii, called coast Douglas-fir, and P. menziesii var. glauca, called Rocky Mountain or blue Douglas-fir.
The unusual cone is also unique with, forked, snake-tongue-like bracts extending from each scale. The tree is one of the dominant trees in the foothills of the Rocky Mountains, and up the slopes to medium altitudes. It has been transplanted successfully throughout most of the North American temperate zone.
Douglas-fir grows 40 to 60 feet and spreads 15 to 25 feet in an erect pyramid in the landscape. It grows to more than 200 feet tall in its native habitat in the West. Hardiness varies with seed source, so be sure it was collected from an area with suitable cold hardiness to the area in which it will be used.
Description and Identification of Douglas Fir
Rosser1954/Wikimedia Commons/Public Domain
Common Names: alpine hemlock, black fir, British Columbia Douglas-fir, Canadian Douglas-fir, coast Douglas-fir, Colorado Douglas-fir, cork-barked Douglas spruce, Douglas pine, Douglas spruce, gray Douglas, green Douglas, groene Douglas, hallarin, hayarin, hayarin Colorado, inland Douglas-fir, interior Douglas-fir, Montana fir, Oregon, Oregon Douglas, Oregon Douglas-fir, Oregon fir, Oregon pine, Oregon spruce, Pacific Coast Douglas-fir, Patton's hemlock, pin de Douglas, pin de i'Oregon, pin d'Oregon, pinabete, pinho de Douglas, pino de corcho, pino de Douglas, pino de Oregon, pino Oregon, pino real, Puget Sound pine, red fir, red pine, red spruce, Rocky Mountain Douglas-fir, Santiam quality fir, sapin de Douglas
Habitat: The variety menziesii of Douglas-fir reaches its best growth on well-aerated, deep soils with a pH range from 5 to 6. It will not thrive on poorly drained or compacted soils.
Description: The species has been successfully introduced in the last 100 years into many regions of the temperate forest zone. Two varieties of the species are recognized: P. menziesii (Mirb.) Franco var. menziesii, called coast Douglas-fir, and P. menziesii var. glauca (Beissn.) Franco, called Rocky Mountain or blue Douglas-fir.
Uses: Douglas-fir is used mostly for building and construction purposes.
The Natural Range of Douglas Fir
The east-west range of Douglas-fir is the greatest of any commercial conifer of western North America.
Its native range is from central British Columbia, south along the Pacific Coast Ranges for about 1,367 miles south, 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 2,796 miles, 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 Silviculture and Management of Douglas Fir
Douglas-fir is most commonly used as a screen or occasionally a specimen in the landscape. Not suited for a small residential landscape (see image), it is often a fixture in a park or commercial setting. Allow room for the spread of the tree since the tree looks terrible with lower limbs removed. It is grown and shipped as a Christmas tree in many parts of the country.
The tree prefers a sunny location with moist soil and is not considered a good tree for much of the South. It grows but struggles in USDA hardiness zone 7.
Douglas-Fir transplants best when balled and burlapped and has a moderate growth rate. It tolerates pruning and shearing but will not tolerate dry soil for extended periods. Protect from direct wind exposure for best appearance. Some occasional watering in summer dry spells will help the tree stay vigorous, especially in the southern end of its range.
- Anguina: long, snake-like branches
- Brevifolia: short leaves
- Compacta: compact, conical growth
- Fastigiata: dense, pyramidal
- Fretsii: dense bush, short broad leaves
- Glauca: bluish foliage
- Nana: dwarf
- Pendula: long, drooping branchlets
- Revoluta: curled leaves
- Stairii: variegated leaves
Insects and Diseases of Douglas Fir
Walter Siegmund/Wikimedia Commons/CC BY-SA 3.0
Pest information courtesy of USFS Fact Sheets
Pests: Aphid infestations on small trees may be dislodged with a strong stream of water from the garden hose. Scale and bark beetles may infest Douglas-Fir, especially those under stress.
Diseases: Root rot can be a serious problem on clay and other wet soils. Needles infected by leaf cast fungi in spring turn brown and fall off. Several fungi cause canker diseases leading to branch dieback. Maintain tree health and prune out infected branches.