Pseudotsuga menziesii var. caesia (Schwer.) Franco
Pseudotsuga taxifolia var. caesia (Schwer.) Asch. & Graebn.
Pseudotsuga taxifolia var. glauca (Beissn.) Sudw.
Pseudotsuga menziesii var. glauca, or Rocky Mountain Douglas-fir, is an evergreenconifer native to the interior mountainous regions of western North America, from central British Columbia and southwest Alberta in Canada southward through the United States to the far north of Mexico.[2] The range is continuous in the northern Rocky Mountains south to eastern Washington, eastern Oregon, Idaho, western and south-central Montana and western Wyoming, but becomes discontinuous further south, confined to "sky islands" on the higher mountains in Utah, Colorado, Arizona and New Mexico, with only very isolated small populations in eastern Nevada, westernmost Texas, and northern Mexico. It occurs from 600m altitude in the north of the range, up to 3,000m, rarely 3,200m, in the south. Further west towards the Pacific coast, it is replaced by the related coast Douglas-fir (Pseudotsuga menziesii var. menziesii), and to the south, it is replaced by Mexican Douglas-fir in high mountains as far south as Oaxaca. Some botanists have grouped Mexican Douglas-fir with P. menziesii var. glauca,[3] but genetic[4] and morphological[5] evidence suggest that Mexican populations should be considered a different variety (Pseudotsuga menziesii var. lindleyana).[6]
Rocky Mountain Douglas-fir is most commonly treated as a variety (Pseudotsuga menziesii var. glauca),[3][7] but has also been called a subspecies (Pseudotsuga menziesii subsp. glauca)[8] or more rarely (mainly in the past) a distinct species (Pseudotsuga glauca).[9] The strong ecological and genetic differentiation with intergradation limited primarily to postglacial contact zones in British Columbia[10][11] supports infraspecific groupings. Some botanists have further split Rocky Mountain Douglas-fir into two varieties,[12] but these are not widely acknowledged and have only limited support from genetic testing.[8][10][11]
Characteristics
Young seed cone
Rocky Mountain Douglas-fir is a large tree, typically reaching 35–45m (115–148ft) in height and 1m (3ft 3in) in diameter, with exceptional specimens known to 67m (220ft) tall, and 2m (6ft 7in) in diameter. It commonly lives more than 500 years and occasionally more than 1,200 years. The bark on young trees is thin, smooth, gray, and covered with resin blisters. On mature trees, it is moderately thick (3–6cm, 1+1⁄4–2+1⁄4in), furrowed and corky though much less so than coast Douglas-fir.
Foliage
The shoots are brown to gray-brown, smooth, though not as smooth as fir shoots, and finely pubescent with scattered short hairs. The buds are a distinctive narrow conic shape, 3–6mm (1⁄8–1⁄4in) long, with red-brown bud scales. The leaves are spirally arranged but slightly twisted at the base to be upswept above the shoot, needle-like, 2–3cm (3⁄4–1+1⁄4in) long, gray-green to blue-green above with a single broad stomatal patch, and with two whitish stomatal bands below.
The male (pollen) cones are 2–3cm (3⁄4–1+1⁄4in) long, and are typically restricted to, or more abundant on, lower branches. Pollen cones develop over 1 year and wind-dispersed pollen is released for several weeks in the spring.
The mature female seed cones are pendent, 4–7cm (1+1⁄2–2+3⁄4in) long, 2cm (3⁄4in) broad when closed, opening to 3–4cm (1+1⁄4–1+1⁄2in) broad. They are produced in spring, purple (sometimes green) at first, maturing orange-brown in the autumn 5–7 months later. The seeds are 5–6mm (3⁄16–1⁄4in) long and 3–4mm (1⁄8–3⁄16in) broad, with a 12–15mm (1⁄2–9⁄16in) wing. Both coast Douglas-fir and Rocky Mountain Douglas-fir produce abundant crops of seed approximately every 2–11years. Seed is produced annually except for about 1 year in any 4-to-5-year period.
Rocky Mountain Douglas-fir grows more slowly than coast Douglas-fir and is also much more cold tolerant. Tolerance of different environmental conditions varies among populations of Rocky Mountain Douglas-fir, especially among populations from the northern and southern Rockies.[13] However, even nearby populations can differ in cold hardiness.[14]
Root morphology is variable, but when unimpeded, a taproot forms within several years. "Platelike" root morphologies occur where growth is impeded. The most prominent lateral roots begin in the 1st or 2nd year of growth. Most roots in surface soil are "long ropelike laterals of secondary and tertiary origin". Fine-root production is episodic in response to changing environmental conditions; the average lifespan of fine roots is usually between several days and several weeks.
Rocky Mountain Douglas-fir reaches reproductive maturity at 12–15 years. It has winged seeds that are dispersed primarily by wind and gravity. In western Montana clearcuts, seeds were dispersed up to 250m (820ft) uphill from their source, but seedfall between 180–250m (590–820ft) was only 7% of that found in uncut stands. Other studies determined that seedfall in clearcuts beyond 80m (260ft) from seed trees was about 3% of seedfall in uncut stands where seed trees are close together. Well-stocked stands have resulted from seedfall from sources 1–2km (0.62–1.24mi) distant, but most Douglas-fir seeds fall within 100m (330ft) of their source. Small amounts of seed are dispersed by mice, chipmunks, and squirrels. Rocky Mountain Douglas-fir seeds are disseminated about twice as far as seeds of ponderosa pine.
Longevity
The oldest accurately-dated Rocky Mountain Douglas-fir, 1275 years old, is in New Mexico. This longevity is apparently uncommon; growing on a relatively barren lava field has protected it from fire, animals, and humans. Growth typically slows dramatically between 90 and 140 years of age.
In the dry-belt forests of central British Columbia, ages can exceed 500 years on sites normal for the region. The oldest accurately-dated growth ring available for the region is 1475; dates in the 1500s and 1600s are more common for remnant patches that have escaped logging, fire, and other disturbances.
Rocky Mountain Douglas-fir grows on a variety of sites across its wide geographic range. It grows at lower elevations adjacent to and within bunchgrass communities and is also found in upper-elevation subalpine forests. It tends to be most abundant in low- and middle-elevation forests, where it grows over a wide range of aspects, slopes, landforms, and soils.
In spring and winter (in British Columbia, Idaho, and Montana) elk browse on south- and southwest-facing Rocky Mountain Douglas-fir and ponderosa pine stands, particularly when shrubs and/or grasses are productive. In summer, elk generally are found at higher elevations (outside the Rocky Mountain Douglas-fir and Pacific ponderosa pine zones). During fall, elk use stands of Rocky Mountain lodgepole pine, subalpine fir, western larch, or grand fir with high canopy cover.
In parts of Yellowstone National Park, elk browsing is so intensive that young Rocky Mountain Douglas-fir are stunted at 1–1.5m (3.3–4.9ft) in height, with live branches trailing very close to the ground, and branches on the upper two thirds of the tree dead. Low-elevation and south-facing open-structure Rocky Mountain Douglas-fir types are often important winter range for white-tailed deer and mule deer. Moose winter in low-elevation Rocky Mountain Douglas-fir types in areas where willow thickets, the preferred winter habitat, are lacking; in such areas Rocky Mountain Douglas-fir is an important moose food.
Chipmunks, mice, voles, and shrews eat large quantities of conifer seeds from the forest floor, and clipped cones are a staple and major part of storage of red squirrels. These animals store a large amount of Rocky Mountain Douglas-fir cones or seeds. American marten commonly den in hollow logs.
Rocky Mountain Douglas-fir is a valuable timber tree. The wood is exceptionally strong and is used for structural timber as well as poles, plywood, pulp, dimensional lumber, railroad ties, mine timbers, log cabins, posts and poles, fencing, and firewood. Other uses listed include "machine-stress-rated lumber", glued-laminated (Glulam) beams, pallets, furniture, cabinets, doors, flooring, window frames, and other miscellaneous woodwork and millwork. Rocky Mountain Douglas-firs are also cut and sold as Christmas trees.
Related Research Articles
Pseudotsuga is a genus of evergreen coniferous trees in the family Pinaceae. Common names for species in the genus include Douglas fir, Douglas-fir, Douglas tree, Oregon pine and Bigcone spruce. Pseudotsuga menziesii is widespread in western North America and is an important source of timber. The number of species has long been debated, but two in western North America and two to four in eastern Asia are commonly acknowledged.
Pseudotsuga macrocarpa, commonly called the bigcone spruce or bigcone Douglas-fir, is an evergreen conifer native to the mountains of southern California. It is notable for having the largest cones in the genus Pseudotsuga, hence the name.
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, Oregon pine, and Columbian pine. There are three varieties: coast Douglas-fir, Rocky Mountain Douglas-fir and Mexican Douglas-fir.
Pinus ponderosa, commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the most widely distributed pine species in North America.
Abies grandis is a fir native to the Pacific Northwest and Northern California of North America, occurring at altitudes of sea level to 1,700 metres (5,600 ft). It is a major constituent of the Grand Fir/Douglas Fir Ecoregion of the Cascade Range.
Abies concolor, the white fir, concolor fir, or Colorado fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Cascade Range and southern Rocky Mountains, and into the isolated mountain ranges of southern Arizona, New Mexico, and Northern Mexico. It naturally occurs at elevations between 900 and 3,400 metres.
The San Francisco Peaks are a volcanic mountain range in the San Francisco volcanic field in north central Arizona, just north of Flagstaff and a remnant of the former San Francisco Mountain. The highest summit in the range, Humphreys Peak, is the highest point in the state of Arizona at 12,637 feet (3,852 m) in elevation. The San Francisco Peaks are the remains of an eroded stratovolcano. An aquifer within the caldera supplies much of Flagstaff's water while the mountain itself is in the Coconino National Forest, a popular recreation site. The Arizona Snowbowl ski area is on the western slopes of Humphreys Peak, and has been the subject of major controversy involving several tribes and environmental groups.
Abies procera, the noble fir, also called red fir and Christmas tree, is a species of fir native to the Cascade Range and Pacific Coast Ranges of the northwestern Pacific Coast of the United States. It occurs at altitudes of 300–1,500 meters (980–4,920 ft).
The Northern California coastal forests are a temperate coniferous forests ecoregion of coastal Northern California and southwestern Oregon.
Abies lasiocarpa, the subalpine fir or Rocky Mountain fir, is a western North American fir tree.
The Sierra Madre Occidental pine–oak forests are a Temperate broadleaf and mixed forests ecoregion of the Sierra Madre Occidental range from the southwest USA region to the western part of Mexico. They are home to a large number of endemic plants and important habitat for wildlife.
California mixed evergreen forest is a plant community found in the mountain ranges of California and southwestern Oregon.
Abies vejarii is a species of fir native to northeastern Mexico, in the states of Coahuila, Nuevo León, and Tamaulipas, where it grows at high altitudes in the Sierra Madre Oriental.
Pseudotsuga menziesii var. lindleyana, commonly known as the Mexican Douglas-fir, is a conifer in the genus Pseudotsuga that is endemic to Mexico. DNA sequence and morphological evidence suggests it is most closely related to Rocky Mountain Douglas-fir and might best be treated as an additional variety within P. menziesii.
The South Central Rockies forests is a temperate coniferous forest ecoregion of the United States located mainly in Wyoming, Idaho, and Montana. It has a considerably drier climate than the North Central Rockies forest.
The Colorado Rockies forests is a temperate coniferous forest ecoregion of the United States.
The North Central Rockies forests is a temperate coniferous forest ecoregion of Canada and the United States. This region overlaps in large part with the North American inland temperate rainforest and gets more rain on average than the South Central Rockies forests and is notable for containing the only inland populations of many species from the Pacific coast.
Pseudotsuga menziesii var. menziesii, commonly known as Coast Douglas-fir, Pacific Douglas-fir, Oregon pine, or Douglas spruce, is an evergreen conifer native to western North America from west-central British Columbia, Canada southward to central California, United States. In Oregon and Washington its range is continuous from the Cascades crest west to the Pacific Coast Ranges and Pacific Ocean. In California, it is found in the Klamath and California Coast Ranges as far south as the Santa Lucia Mountains with a small stand as far south as the Purisima Hills, Santa Barbara County. In the Sierra Nevada it ranges as far south as the Yosemite region. It occurs from near sea level along the coast to 1,800 metres (5,900 ft) in the California Mountains. Further inland, coast Douglas-fir is replaced by Rocky Mountain or interior Douglas-fir. Interior Douglas-fir intergrades with coast Douglas-fir in the Cascades of northern Washington and southern British Columbia.
Symphoricarpos oreophilus is a North American species of flowering plant in the Caprifoliaceae, or honeysuckle family, known by the common name mountain snowberry. It has a wide distribution in western Canada, the United States, and northwestern Mexico. It is found in mountainous areas such as the Cascades, the Sierra Nevada, the Rockies, and the Sierra Madre Occidental from British Columbia to the Copper Canyon region of Chihuahua, from the coastal states as far inland as the Black Hills, the Oklahoma Panhandle, and trans-Pecos Texas.
Pinus washoensis, the Washoe pine, is a rare, semi-disputed species of large-sized conifer in the family Pinaceae. The species was described by Herbert Louis Mason and William Palmer Stockwell in 1945. It is in the Pinussubsect. Ponderosae with the Ponderosa pine.
1 2 Grimshaw, J., & Bayton, R. (2009). New Trees. International Dendrology Society / Kew. ISBN978-1-84246-173-0.
↑ Mayr, H. (1906). Fremdländische Wald- und Parkbäume für Europap.404. Berlin.
1 2 Li, P.; Adams, W.T. (1989). "Rangewide patterns of allozyme variation in Douglas-fir". Canadian Journal of Forest Research. 19 (2): 149–161. doi:10.1139/x89-022.
1 2 Gugger, Paul F.; Sugita, Shinya; Cavender-Bares, Jeannine (2010). "Phylogeography of Douglas-fir based on mitochondrial and chloroplast DNA sequences: testing hypotheses from the fossil record". Molecular Ecology. 19 (9): 1877–1897. doi:10.1111/j.1365-294X.2010.04622.x. PMID20374486. S2CID23254018.
↑ Dallimore, W., & Jackson, A. B. (1966). A Handbook of Coniferae and Ginkgoaceae, 4th ed. Arnold, London.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
