''Populus tremuloides'' is a
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
tree native to cooler areas of
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, one of several species referred to by the common name
aspen
Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus.
Species
These species are called aspens:
*'' Populus adenopoda'' – Chinese aspen (C ...
. It is commonly called quaking aspen,
trembling aspen,
American aspen,
mountain or golden aspen,
trembling poplar,
white poplar,
and popple,
as well as others.
The trees have tall trunks, up to 25 meters (82 feet) tall, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden to yellow, rarely red, in autumn. The species often propagates through its roots to form large clonal groves originating from a shared root system. These roots are not
rhizomes, as new growth develops from
adventitious buds on the parent root system (the
ortet).
''Populus tremuloides'' is the most widely distributed tree in North America, being found from Canada to central Mexico.
It is the defining species of the
aspen parkland biome
A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
in the
Prairie Provinces of Canada and extreme northwest
Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
.
Description
Quaking aspen is a tall, fast-growing tree, usually at maturity, with a trunk in diameter;
records are in height and in diameter. The
bark
Bark may refer to:
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Places
* Bark, Germany
* Bark, Warmian-Masurian Voivodeship, Poland
Arts, e ...
is relatively smooth, whitish (light green when young),
and is marked by thick black horizontal scars and prominent black knots. Parallel vertical scars are tell-tale signs of elk, which strip off aspen bark with their front teeth.
The
leaves on mature trees are nearly round, in diameter
with small rounded teeth, and a long flattened
petiole. The leaves are green above and gray below.
Young trees and root sprouts have much larger ( long), nearly triangular leaves. (Some species of ''Populus'' have petioles flattened partially along their length, while the aspens and some other poplars have them flattened from side to side along the entire length of the petiole.)
Aspens are
dioecious, with separate male and female clones. The flowers are catkins long, produced in early spring before the leaves. The fruit is a pendulous string of capsules, each capsule containing about ten minute seeds embedded in cottony fluff, which aids wind dispersal of the seeds when they are mature in early summer. Trees as young as 2–3 years old may begin seed production, but significant output begins starting at 10 years of age. Best seed production is obtained between the ages of 50 and 70 years.
Quaking aspen grows more slowly in the dry conditions of western North America than it does in the more humid east and also lives longer—ages of 80–100 years are typical,
with some individuals living 200 years; the root system can live much longer.
In the east, stands decay faster, sometimes in 60 years or less depending on the region.
Name
The quaking or trembling of the leaves that is referred to in the common names is due to the flexible flattened petioles. The specific epithet, ''tremuloides'', evokes this trembling behavior and can be literally translated as "like
''(Populus) tremula''", the European trembling aspen.
Distribution
Quaking aspen occurs across
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
in all provinces and territories, with the possible exception of regions of
Nunavut north of the James Bay islands. In the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, it can be found as far north as the northern foothills of the
Brooks Range
The Brooks Range ( Gwich'in: ''Gwazhał'') is a mountain range in far northern North America stretching some from west to east across northern Alaska into Canada's Yukon Territory. Reaching a peak elevation of on Mount Isto, the range is b ...
in
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
, where road margins and gravel pads provide islands of well-drained habitat in a region where soils are often waterlogged due to underlying
permafrost. It occurs at low elevations as far south as northern
Nebraska
Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...
and central
Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...
. In the Western United States, this tree rarely survives at elevations lower than due to hot summers experienced below that elevation, and is generally found at . It grows at high altitudes as far south as
Guanajuato, Mexico.
Quaking aspen grows in a wide variety of climatic conditions. January and July average temperatures range from and in the
Alaska Interior
Interior Alaska is the central region of Alaska's territory, roughly bounded by the Alaska Range to the south and the Brooks Range to the north. It is largely wilderness. Mountains include Denali in the Alaska Range, the Wrangell Mountains, and ...
to and in
Fort Wayne, Indiana. Average annual precipitation ranges from in
Gander, Newfoundland and Labrador to as little as in the Alaska Interior. The southern limit of the species' range roughly follows the mean July
isotherm.
In the
sagebrush steppe, aspens occur with
chokecherry,
serviceberry, and hawthorn, forming a habitable haven for animal life.
Shrub-like dwarf clones exist in marginal environments too cold and dry to be hospitable to full-size trees, for example at the species' upper elevation limits in the
White Mountains.
Ecology
Quaking aspen propagates itself primarily through root sprouts, and extensive
clonal colonies are common. Each colony is its own clone, and all trees in the clone have identical characteristics and share a single root structure. A clone may turn color earlier or later in the fall than its neighbouring aspen clones. Fall colors are usually bright tones of yellow; in some areas, red blushes may be occasionally seen. As all trees in a given clonal colony are considered part of the same organism, one clonal colony, named
Pando, is considered the heaviest
[Genetic Variation and the Natural History of Quaking Aspen, Jeffry B. Mitton; Michael C. Grant, ''BioScience'', Vol. 46, No. 1. (Jan., 1996), pp. 25-31.] and oldest
[Quaking Aspen]
by the Bryce Canyon National Park Service
The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properti ...
living organism at six million kilograms and perhaps 80,000 years old. Aspens do produce seeds, but seldom grow from them. Pollination is inhibited by the fact that aspens are either male or female, and large stands are usually all clones of the same sex. Even if pollinated, the small seeds (three million per pound) are only viable a short time as they lack a stored food source or a protective coating.
[Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.]
The buds and bark supply food for snowshoe hares, moose, black bears, cottontail rabbits, porcupines, deer, grouse, and mountain beavers. The shoots are eaten by sheep, goats, and cattle. Sheep and goats also browse the foliage, as do game animals including elk.
Grouse and quail especially eat the buds in winter. Mammals such as beavers and rabbits eat the bark, foliage, and buds.
Beavers also store aspen logs for winter food. Other animals nest in aspen groves.
The leaves of the quaking aspen and other
species in the genus ''Populus'' serve as food for
caterpillars of various moths and butterflies.
Dieback
Beginning in the 1990s, North American scientists noticed an increase in dead or dying aspen trees. As this accelerated in 2004, a debate over causes began. No insect, disease, or environmental condition has yet been definitively identified as a cause. Trees adjacent to one another are often stricken or not. In other instances, entire groves have died.
Many areas of the Western US have experienced increased diebacks which are often attributed to ungulate grazing and
wildfire suppression. At high altitudes where grasses can be rare,
ungulates can browse young aspen sprouts and prevent those young trees from reaching maturity. As a result, some aspen groves close to cattle or other grazing animals, such as deer or elk, have very few young trees and can be invaded by
conifers, which are not typically browsed. Another possible deterrent to aspen regeneration is widespread wildfire suppression. Aspens are vigorous
resprouters and even though the above-ground portion of the organism may die in a wild-fire, the roots, which are often protected from lethal temperatures during a fire, will sprout new trees soon after a fire. Disturbances such as fires seem to be a necessary ecological event in order for aspens to compete with conifers, which tend to replace aspens over long, disturbance-free intervals. The current dieback in the American West may have roots in the strict fire suppression policy in the United States. On the other hand, the widespread decimation of conifer forests by the
mountain pine beetle may provide increased opportunities for aspen groves to proliferate under the right conditions.
Because of vegetative regeneration by aspen, where an entire group of trees are essentially clones, there is a concern that something that hits one will eventually kill all of the trees, presuming they share the same vulnerability. A conference was held in
Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
in September 2006 to share notes and consider investigative methodology.
Uses
Aspen bark contains a substance that was extracted by indigenous North Americans and European settlers of the western U.S. as a
quinine
Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
substitute.
Like other poplars, aspens make poor
fuel wood, as they dry slowly, rot quickly, and do not give off much heat. Yet they are still widely used in campgrounds because they are cheap and plentiful and not widely used in building lumber. Pioneers in the North American west used them to create
log cabins and
dugouts, though they were not the preferred species.
Aspen wood is used for
pulp products
(its main application in Canada) such as books, newsprint, and fine printing paper. It is especially good for panel products such as
oriented strand board and
waferboard
Waferboard belongs to the subset of reconstituted wood panel products called flakeboards. It is a structural material made from rectangular wood flakes of controlled length and thickness bonded together with waterproof phenolic resin under extrem ...
. It is light in weight and is used for furniture, boxes and crates, core stock in plywood, and wall panels.
Culture
The quaking aspen is the state tree of Utah.
See also
*
Pando, an exceptionally large clonal colony of ''P. tremuloides'' determined to be a single male tree
References
External links
US Forest Service Fire Effects Information System: ''Populus tremuloides''*
ttp://www.plantmaps.com/nrm/populus-tremuloides-quaking-aspen-native-range-map.php Interactive Distribution Map for ''Populus tremuloides''* Farrar, John Laird. ''Trees In Canada''. Fitzhenry and Whiteside, 1995
* Hickman, James C., ed.
The Jepson Manual: Higher Plants of California', . University of California Press, 1993.
*
{{Taxonbar, from=Q469576
tremuloides
Trees of North America
Taxa named by André Michaux
Plants used in traditional Native American medicine