Tsuga mertensiana

Last updated

Tsuga mertensiana
Tsuga mertensiana 0261.JPG
Mountain hemlock in Henry M. Jackson Wilderness, Washington
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Pinaceae
Genus: Tsuga
Species:
T. mertensiana
Binomial name
Tsuga mertensiana
Natural distribution map for Tsuga mertensiana (Herring et al. 2017).png
Natural range

Tsuga mertensiana, known as mountain hemlock, [2] is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California.

Contents

Description

Tsuga mertensiana is a large evergreen conifer growing up to 20 to 40 metres (66 to 131 feet) tall, with exceptional specimens as tall as 59 m (194 ft) tall. They have a trunk diameter of up to 2 m (6+1⁄2 ft). The bark is about 3 centimetres (1+1⁄4 inches) thick and square-cracked or furrowed, and purplish-brown [3] to gray in color. The crown is a neat, slender, conic shape in young trees with a tilted or drooping lead shoot, becoming cylindric in older trees. At all ages, it is distinguished by the slightly pendulous branchlet tips. The shoots are orange–brown, with dense pubescence about 1 millimetre (1⁄16 in) long. The leaves are needle-like, 7 to 25 mm (1⁄4 to 1 in) long and 1 to 1.5 mm (1⁄32 to 1⁄16 in) broad, soft, blunt-tipped, only slightly flattened in cross-section, pale glaucous blue-green above, and with two broad bands of bluish-white stomata below with only a narrow green midrib between the bands; they differ from those of any other species of hemlock in also having stomata on the upper surface, and are arranged spirally all around the shoot.

The cones are small (but much longer than those of any other species of hemlock), pendulous, cylindrical, 3 to 8 cm (1 to 3 in) long and 8 to 10 mm (5⁄16 to 3⁄8 in) broad when closed, opening to 12 to 35 mm (1⁄2 to 1+3⁄8 in) broad, superficially somewhat like a small spruce cone. They have thin, flexible scales 8 to 18 mm (5⁄16 to 11⁄16 in) long. The immature cones are dark purple (rarely green), maturing red–brown 5 to 7 months after pollination. The seeds are red–brown, 2 to 3 mm (1⁄16 to 1⁄8 in) long, with a slender, 7 to 12 mm (1⁄4 to 1⁄2 in)-long pale pink–brown wing. [4] [5] [6]

Taxonomy

There are three taxa, two subspecies and a minor variety: [4] [6]

Etymology

Mertensiana refers to Karl Heinrich Mertens (1796–1830), a German botanist who collected the first specimens as a member of a Russian expedition in 1826–1829.

Distribution

The distribution of T. mertensiana stretches from Kenai Peninsula, Alaska, to northern Tulare County, California. [4] [5] [6] Its range fairly closely matches that of T. heterophylla (western hemlock), found less than 100 kilometres (62 miles) from the Pacific Ocean, apart from an inland population in the Rocky Mountains in southeast British Columbia, northern Idaho, and western Montana. The inland populations most likely established after deglaciation by remarkable long-distance dispersal of more than 200 km (120 mi) from the coast populations. [7] Their ranges differ in California, where western hemlock is restricted to the Coast Ranges and mountain hemlock is found in the Klamath Mountains and Sierra Nevada. Unlike western hemlock, mountain hemlock mostly grows at high altitudes except in the far north, from sea level to 1,000 m (3,300 ft) in Alaska, 1,600 to 2,300 m (5,200 to 7,500 ft) in the Cascades in Oregon, and 2,500 to 3,050 m (8,200 to 10,010 ft) in the Sierra Nevada. [4] [5] [6]

Ecology

Mountain hemlock is usually found on cold, snowy subalpine sites where it grows slowly, sometimes attaining more than 800 years in age. Arborescent individuals that have narrowly conical crowns until old age (300 to 400 years) and shrubby krummholz on cold, windy sites near timberline add beauty to mountain landscapes. Areas occupied by mountain hemlock generally have a cool to cold maritime climate that includes mild to cold winters, a short, warm-to-cool growing season and moderate to high precipitation. [8]

Best development of mountain hemlock is on loose, coarse-textured, well-drained soils with adequate moisture, and in British Columbia, on thick and very acidic organic matter and decayed wood. [9] Adequate soil moisture appears to be especially important in California and Montana, where summer drought is most pronounced. [8] [10]

Mountain hemlock will grow on most landforms, but individuals typically develop best in mixed stands of forest on sheltered slopes or in draws. From southern British Columbia south, the tree grows better on northerly exposures. The preference for relatively moist, cool sites evidently becomes a necessity as the climate becomes more continental in western Montana and more mediterranean in the central Sierra Nevada at these extremes of its range. [10] In these locations, mountain hemlock typically grows in isolated populations in north-facing glens and cirque basins where snow collects and may remain well into summer. [8]

Mountain hemlock is adapted to sites with long-lasting snowpacks. In the spring, mountain hemlocks emerging through 2 to 4 m (6+1⁄2 to 13 ft) of snow were transpiring, whereas nearby whitebark pines did not transpire until the soil beneath them was free of snow. [8] Mountain hemlock is well adapted to cope with heavy snow and ice loads, with tough branches and the drooping branchlets shedding snow readily. [6]

Mountain hemlock is tolerant of shade [3] and other forms of competition. It is more shade-tolerant than all of its associates except Pacific silver fir, western hemlock, and Alaska cedar. [11] Mountain hemlock is considered a minor climax species on most of its habitats, and pioneers on glacial moraines in British Columbia and Alaska. In many communities of the mountain hemlock forest in British Columbia and Washington and northern Oregon, Pacific silver fir is a major climax species. [9] [11] Alaska cedar, western redcedar, and western hemlock are climax associates on some sites. Mountain hemlock is more commonly the major climax species in the mountain hemlock zone south of central Oregon where Pacific silver fir does not occur. [8]

Mountain hemlock often succeeds lodgepole pine or subalpine fir when these species pioneer on drier sites. It also tends to replace Engelmann spruce when the two species occur together, possibly because hemlock is better able to withstand the allelopathic effects of spruce than are other associated species. [8]

The species is attacked by the root rot Phellinus weirii . Stands lost to fire can be populated by lodgepole pine, which is in turn succeeded by mountain hemlock. [3]

Uses

Native Americans used the species less often than western hemlock, but specifically used mountain hemlock boughs as beds and bathing brushes. [3]

Since the mid-20th century, the species has been used for lumber, often mixed with western hemlock. [3]

Cultivation

Outside of its native range, mountain hemlock is grown as an ornamental tree. It is planted as a specimen tree in native plant landscapes in California, and particularly in gardens in northern Great Britain and Scandinavia, where it is appreciated for its blue–green color and tolerance of severe weather. Cultivation is limited by the very slow growth of young plants and its susceptibility to urban air pollution.

Several cultivars have been selected, mainly for intensely glaucous foliage color including:

Related Research Articles

<span class="mw-page-title-main">Douglas fir</span> Species of tree

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.

<span class="mw-page-title-main">Western white pine</span> Pine tree found in North America

Western white pine, also called silver pine and California mountain pine, is a species of pine in the family Pinaceae. It occurs in mountain ranges of northwestern North America and is the state tree of Idaho.

<i>Tsuga</i> Genus of conifers

Tsuga is a genus of conifers in the subfamily Abietoideae of Pinaceae, the pine family. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock. Unlike the latter, Tsuga species are not poisonous.

<i>Alnus rubra</i> Species of tree

Alnus rubra, the red alder, is a deciduous broadleaf tree native to western North America.

<i>Abies grandis</i> Species of conifer tree

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.

<i>Abies concolor</i> Species of conifer tree

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.

<i>Tsuga canadensis</i> Species of conifer

Tsuga canadensis, also known as eastern hemlock, eastern hemlock-spruce, or Canadian hemlock, and in the French-speaking regions of Canada as pruche du Canada, is a coniferous tree native to eastern North America. It is the state tree of Pennsylvania. Eastern hemlocks are widespread throughout much of the Great Lakes region, the Appalachian Mountains, the Northeastern United States, and Maritime Canada. They have been introduced in the United Kingdom and mainland Europe, where they are used as ornamental trees.

<i>Tsuga heterophylla</i> Species of conifer

Tsuga heterophylla, the western hemlock or western hemlock-spruce, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma County, California. The Latin species name means 'variable leaves'.

<i>Picea engelmannii</i> Species of North American spruce tree

Picea engelmannii, with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is mostly a high-elevation mountain tree but also appears in watered canyons.

<i>Abies magnifica</i> Species of tree found in North America

Abies magnifica, the red fir or silvertip fir, is a western North American fir, native to the mountains of southwest Oregon and California in the United States. It is a high-elevation tree, typically occurring at 1,400–2,700 metres (4,600–8,900 ft) elevation, though only rarely reaching tree line. The name red fir derives from the bark color of old trees.

<i>Abies procera</i> Species of conifer

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).

<span class="mw-page-title-main">Fraser fir</span> Species of conifer

The Fraser fir, sometimes spelled" Frasier fir, is an endangered species of fir native to the Appalachian Mountains of the Southeastern United States. They are endemic to only seven montane regions in the Appalachian Mountains.

<i>Abies lasiocarpa</i> North American fir tree species

Abies lasiocarpa, the subalpine fir or Rocky Mountain fir, is a western North American fir tree.

<i>Abies amabilis</i> Species of conifer

Abies amabilis, commonly known as the Pacific silver fir, is a fir native to the Pacific Northwest of North America, occurring in the Pacific Coast Ranges and the Cascade Range. It is also commonly referred to in English as the white fir, red fir, lovely fir, amabilis fir, Cascades fir, or silver fir. The species name is Latin for 'lovely'.

<span class="mw-page-title-main">Abietoideae</span> Subfamily of the conifer family Pinaceae

Abietoideae is a subfamily of the conifer family Pinaceae. The name is from the genus Abies (firs), which contains most of the species in the genus. Six genera are currently assigned to this subfamily: Abies, Cedrus, Keteleeria, Nothotsuga, Pseudolarix, and Tsuga.

<i>Juniperus deppeana</i> Species of conifer

Juniperus deppeana is a small to medium-sized tree reaching 10–15 metres in height. It is native to central and northern Mexico and the southwestern United States.

<i>Abies vejarii</i> Species of conifer

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.

<i>Juniperus tibetica</i> Species of conifer

Juniperus tibetica, the Tibetan juniper, is a species of juniper, native to western China in southern Gansu, southeastern Qinghai, Sichuan, and Tibet Autonomous Region, where it grows at high to very high altitudes of 2,600–4,900 metres. This species has the highest known elevation treeline in the northern hemisphere.

<i>Pseudotsuga menziesii <span style="font-style:normal;">var.</span> menziesii</i> Variety of conifer

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.

References

  1. ↑ Farjon, A. (2013). "Tsuga mertensiana". IUCN Red List of Threatened Species . 2013: e.T42436A2980162. doi: 10.2305/IUCN.UK.2013-1.RLTS.T42436A2980162.en . Retrieved 12 November 2021.
  2. ↑ USDA, NRCS (n.d.). "Tsuga mertensiana". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 12 December 2015.
  3. 1 2 3 4 5 Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. pp. 117–122. ISBN   978-1-68051-329-5. OCLC   1141235469.
  4. 1 2 3 4 Farjon, A. (1990). Pinaceae. Drawings and Descriptions of the Genera. Koeltz Scientific Books. ISBN   3-87429-298-3.
  5. 1 2 3 Taylor, Ronald J. (1993). "Tsuga mertensiana". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 2. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  6. 1 2 3 4 5 Earle, Christopher J., ed. (2018). "Tsuga mertensiana". The Gymnosperm Database.
  7. ↑ Herring, E.M.; Gavin, D.G.; Dobrowski, S.Z.; Fernandez, M.; Hu, F.S. (2017). "Ecological history of a long-lived conifer in a disjunct population". Journal of Ecology. 106: 319–332. doi: 10.1111/1365-2745.12826 .
  8. 1 2 3 4 5 6 Means, Joseph E. (1990). "Tsuga mertensiana". In Burns, Russell M.; Honkala, Barbara H. (eds.). Conifers. Silvics of North America. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA). Vol. 1 – via Southern Research Station.
  9. 1 2 Brooke, Robert C.; Peterson, E. G.; Krajina, V. J. (1970). "The subalpine mountain hemlock zone". In Krajina, V. J. (ed.). Ecology of western North America. Vol. 2. Vancouver: University of British Columbia Department of Botany. pp. 147–349.
  10. 1 2 Habeck, James R. (1967). "Mountain hemlock communities in western Montana". Northwest Science. 41 (4): 169–177.
  11. 1 2 Krajina, V. J. (1969). "Ecology of forest trees in British Columbia". In Krajina, V. J. (ed.). Ecology of western North America. Vol. 2. Vancouver, BC: University of British Columbia, Department of Biology. pp. 1–147.
  12. ↑ Rushforth, K. (1987). Conifers. Helm ISBN   0-7470-2801-X.

Further reading

PD-icon.svg This article incorporates public domain material from Joseph E. Means. Silvics Manual, Volume 1, Tsuga mertensiana. United States Department of Agriculture.

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.