Picea engelmannii
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Picea engelmannii, with the common names Engelmann spruce,<ref name=Montana>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> white spruce,<ref name=Montana/> mountain spruce,<ref name=Montana/> and silver spruce,<ref name=Montana/> is a species of spruce native to western North America. It is highly prized for producing distinctive tone wood for acoustic guitars and other instruments, it is mostly a high-elevation mountain tree but also appears in watered canyons.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
DescriptionEdit
Picea engelmannii is a medium-sized to large evergreen tree growing to Template:Convert tall, exceptionally to Template:Convert tall, and with a trunk diameter of up to Template:Convert. The reddish bark is thin and scaly,<ref name=":02">Template:Cite book</ref> flaking off in small circular plates Template:Convert across. The crown is narrow conic in young trees, becoming cylindric in older trees. The shoots are buff-brown to orange-brown, usually densely pubescent, and with prominent pulvini. The leaves are needle-like, Template:Convert long, flexible,<ref name=":02" /> rhombic in cross-section, glaucous blue-green above with several thin lines of stomata, and blue-white below with two broad bands of stomata. The needles have a pungent odour when crushed.<ref name=":02" />
Purple cones of about Template:Cvt appear in spring, releasing yellow pollen when windy.<ref name=":02" /> The cones are pendulous, slender cylindrical, Template:Cvt long<ref name=":02" /> and Template:Cvt broad when closed, opening to Template:Cvt broad. They have thin, flexible scales Template:Cvt long, with a wavy margin. They are reddish to dark purple, maturing to light brown<ref name=":02" /> 4–7 months after pollination. The seeds are black, Template:Cvt long, with a slender, Template:Cvt long light brown wing.
The tree grows in a krummholz form along the fringe of alpine tundras.<ref name=":02" />
DistributionEdit
Engelmann spruce is mostly a higher-elevation mountain tree, in many areas reaching the tree line, but at lower elevations occupies cool watered canyons.<ref name=":02" /> It grows from Template:Convert above sea level,<ref name=":02" /> rarely lower towards the northwest.
Englemann spruce is native to western North America, common in the Rocky Mountains and east slopes of the Cascade Range from central British Columbia to Southern Oregon in the Cascades and Montana, Idaho, and Colorado, and more sparsely towards Arizona and New Mexico in the Sky islands;<ref name=":02" /> there are also two isolated populations in Northern Mexico.
It appears in the canyons of the Idaho Panhandle and more limitedly in the northeastern Olympic Mountains, which features some exceptionally large specimens, including one Template:Convert in diameter and Template:Convert tall.<ref name=":02" /> It can be found in the Cascade Range, mostly on the eastern slopes, from elevations of Template:Convert and liberally in the Rocky Mountains.<ref name=":02" /> It can also be found in the Monashee and Selkirk Mountains, as well as the highlands surrounding the Interior Plateau.
EcologyEdit
Because transpiration is greatly reduced in small saplings while engulfed in snowpack, increased rates of transpiration in response to loss of snowpack, coupled with low sapwood water reserves and an extended period of soil frost in windswept areas, may prevent Engelmann spruce from regenerating in open areas both above and below the tree line. Both water uptake and water stored in roots appear to be critical for the survival of subalpine Engelmann spruce saplings that are exposed above the snowpack in later winter to early spring.<ref name="boyce">Boyce, R.L. and Lucero, S.A. 1999. Role of roots in winter water relations of Engelmann spruce saplings. Tree Physiol. 19:893–898.</ref>
For exposed trees, the availability of soil water may be critical in late winter, when transpirational demands increase. Cuticular damage by windblown ice is probably more important at the tree line,<ref name="hadley1">Hadley, J.L.; Smith, W.K. 1983. Influence of wind exposure on needle desiccation and mortality for timberline conifers in Wyoming, USA. Arctic Alpine Res. 15:127–135. (Cited in Coates et al. 1994).</ref><ref name="hadley2">Hadley, J.L.; Smith, W.K. 1986. Wind effects on needles of timberline conifers seasonal influence on mortality. Ecology 67:12–19. Cited in Coates et al. (1994).</ref> but damage caused by desiccation is likely to be more important at lower elevations.<ref name="boyce" />
Despite wind damage, the species tends to grow taller than others at the tree line.<ref name=":02" /> It is shade tolerant, but not so much as subalpine fir, rendering it somewhat dependent on fires to outgrow competitors, although its thin bark and shallow roots make it vulnerable to fire.<ref name=":02" /> Spruce bark beetles attack the tree, being particularly deadly to groups which have stood for centuries.<ref name=":02" /> It is also susceptible to avalanches.<ref name=":02" />
Although older spruce forests are not very useful to animals for forage, they can become so after fires, as they often burn completely, allowing many other plants, especially deciduous, to rise.<ref name=":02" /> Engelmann spruce-shaded streams are exploited by trout, <ref name=":02" /> and aphids produce galls which hang from the tree and look similar to cones when they dry out.<ref name=":02" />
Subspecies and hybridsEdit
Two geographical subspecies (treated as varieties by some authors, and as distinct species by others) occur:
- Picea engelmannii subsp. engelmannii (Engelmann spruce). All of the range except as below.
- Picea engelmannii subsp. mexicana (Mexican spruce). Two isolated populations on high mountains in northern Mexico, on the Sierra del Carmen in Coahuila (Sierra Madre Oriental) and on Cerro Mohinora in Chihuahua (Sierra Madre Occidental). Engelmann spruces of the Madrean sky islands mountains in the extreme southeast of Arizona and southwest of New Mexico also probably belong to this subspecies, though this is disputed.
The Engelmann spruce hybridises and intergrades extensively with the closely related white spruce<ref name=":02" /> (forming a species complex known as Picea × albertiana; Alberta spruce, or interior spruce) in interior Canada, and to a lesser extent with the closely related Sitka spruce where they meet on the western fringes of the Cascades.
UsesEdit
Native Americans made various medicines from the resin and foliage.<ref name=":02" />
Engelmann spruce is of economic importance for its wood, being light and fairly strong.<ref name=":02" /> It is harvested for paper-making and general construction.<ref name=":02" /> Wood from slow-grown trees at high elevation is especially prized for making soundboards for musical instruments such as acoustic guitars, harps, violins, and pianos.<ref name=":02" />
Because it is odourless and has little resin, it has been used for food containers such as barrels.<ref name=":02" /> It is also used to a small extent as a Christmas tree.
GalleryEdit
- Picea engelmannii foliage cones.jpg
Forest, with mature female cones in foreground
- Picea engelmannii UGA1.jpg
Dangling somewhat immature (unopened) female cone
- Picea engelmannii UGA2.jpg
Dangling mature female cone
- Engelmann Spruce cones RMNP.jpg
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ReferencesEdit
Further readingEdit
- The Gymnosperm Database
- US Forest Service: Fire Effects Information System
- Little, Elbert L. (1980), National Audubon Society Field Guide to Trees: Western Region
External linksEdit
- Jepson Manual Treatment
- Arboretum de Villardebelle – Photographs related spruce cones
- CalPhotos