|Scientific Name:||Pseudotsuga menziesii|
|Species Authority:||(Mirb.) Franco|
Abies menziesii Mirb.
|Taxonomic Source(s):||Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.|
|Taxonomic Notes:||Two varieties are recognized (Farjon 2010): the typical variety which occurs from British Columbia to California and var. glauca (Beissn.) Franco, which is more widespread in the Rocky mountains from British Columbia as far south as Central Mexico. Subpopulations in Mexico are often isolated and they have been described as distinct species. Undoubtedly some of these isolated occurrences may be somewhat different genetically, but under the concept of a species used in this assessment they all belong to Pseudotsuga menziesii var. glauca (Farjon 2010, Reyes Hernandez et al. 2005). The varieties are not assessed separately.
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer(s):||Thomas, P. & Stritch, L.|
This species is a major component of the extensive coniferous forests of the Pacific Northwest of the USA and Canada. Logging has removed many large individuals but has not significantly reduced the population of mature trees. In the Rocky Mountains logging is significant in Canada, but less so farther south as the species becomes naturally more scattered. In Mexico, various subpopulations are included on their national Red List under the names Pseudotsuga flauhaulti, P. macrolepis and P. rehderi. These taxa are included with P. menziesii var. glauca (Farjon 2010). Overall, Douglas-fir is assessed as Least Concern and its varieties are also both Least Concern and are hence not assessed separately.
|Previously published Red List assessments:||
|Range Description:||Western North America: from British Columbia to Central Mexico (Puebla). This species has a very large extent of occurrence and area of occupancy although Mexican subpopulations are frequently isolated and small.|
Native:Canada (Alberta, British Columbia); Mexico (Coahuila, Colima, Durango, Hidalgo, Puebla, Sinaloa, Sonora, Zacatecas); United States (Arizona, California, Colorado, Idaho, Minnesota, Nevada, New Mexico, Oregon, Texas, Utah, Washington, Wyoming)
|Lower elevation limit (metres):||1|
|Upper elevation limit (metres):||3350|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Despite its importance as a timber species and the localized rarity of the Mexican subpopulations, the global population is thought to be stable.|
|Current Population Trend:||Stable|
|Habitat and Ecology:||Pseudotsuga menziesii occurs in a huge area from north to south (55º N to 19º N) in W North America, consequently it occupies a variety of climatic zones, landscapes and habitats. Along the coast in British Columbia and the Pacific Northwest this species attains great size and is a codominant or dominant tree in the temperate rainforests from near sea level to 1,000 m a.s.l. depending on latitude. It profits from the high rainfall, yet occupies better drained sites commonly on slopes or high, no longer flooded river terraces, where it can compete successfully with other conifers, mainly Abies, Picea, Tsuga, and Thuja, especially after fire. Giant trees attain 100 m, and there is evidence of taller trees that were logged in the days that Americans of European descent could see only the timber in them. Somewhat further inland the species grows also in valley bottoms near streams, still attaining great sizes and living to 800-1,000 years maximum. These coniferous forests are of similar composition as those on the coast. In the Rocky Mountains occurs var. glauca, a smaller, but still large tree; here it occupies a mixed conifer belt between open Pinus contorta and/or P. ponderosa woodland and a subalpine conifer forest dominated by Abies lasiocarpa, Picea engelmannii or, further south, Pinus albicaulis and P. flexilis. In the southern Rocky Mountains and into Mexico, Pseudotsuga menziesii var. glauca becomes more and more scattered and restricted to sites with permanent moisture, e.g. under north-facing canyon walls and at the highest forested altitudes, up to 2,900-3,350 m a.s.l. In canyons on the Colorado Plateau it can form small groves rising above Gambel Oaks (Quercus gambellii), or it occurs as a constituent of mixed conifer forests with Pinus spp. and sometimes Abies or Picea as well as Aspen (Populus tremuloides) on high plateaus and on NORTH-facing slopes and in moist ravines at high altitude. Winter snowfall, unlike on the Pacific coast, constitutes a high proportion of annual precipitation in these habitats.|
|Continuing decline in area, extent and/or quality of habitat:||No|
|Generation Length (years):||50|
|Use and Trade:||Douglas-fir is one of the world's most important timber trees. The huge size, especially of the coastal variety, as well as the excellent wood properties make it a choice tree providing knot-free sawn timber of great length. It is used for plywood and construction, both exterior and interior, and its reasonable good durability makes it useful for telephone wire poles and railway sleepers. However, the more continental variety P. menziesii var. glauca grows much slower and to a more moderate size and yields denser, heavier wood, excellent for cooperage for vats and tanks for breweries and distilleries. Douglas fir has been introduced to many countries in plantation forestry as well as an ornamental tree and a good number of cultivars are known and used in horticulture. Its first introduction was in England in 1827 by David Douglas; its best growth is attained in western Scotland, where one tree has made nearly 65 m in about 100 years. In the NW USA and W Canada it is also grown as a Christmas tree, needing regular shearing to obtain a pyramidal shape.|
|Major Threat(s):||Past (and to an extent) present logging has had huge negative impacts on ‘old growth’ forests dominated by Douglas-fir. This is a threat to the ecosystem peculiar to old growth conifer forests, and its biodiversity, in the region. It is not a threat to the survival of the species Douglas-fir, which in most circumstances has regenerated and will regenerate after logging. It is important to separate these issues, and this assessment is concerned with the threat to extinction of a species, not with the threat to an ecosystem unless that impinges on the survival chances of the species concerned.|
|Conservation Actions:||This variety is present in many protected areas, including some famous national parks.|
|Citation:||Farjon, A. 2013. Pseudotsuga menziesii. The IUCN Red List of Threatened Species 2013: e.T42429A2979531. . Downloaded on 27 November 2015.|
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