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Aspen is a common name for certain
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
species; some, but not all, are classified by botanists in the section ''Populus'', of the ''
Populus ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...
''
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
.


Species

These species are called aspens: *''
Populus adenopoda ''Populus adenopoda'', known commonly as the Chinese aspen, is a species of poplar found in the subtropical regions of China. The trees can reach a maximum height of 30 metres, and occur on mountain slopes at elevations of 300–2500 metres. Woo ...
'' – Chinese aspen (China, south of ''P. tremula'') *''
Populus davidiana ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...
'' – Korean aspen (Eastern Asia) *'' Populus grandidentata'' – Bigtooth aspen (eastern North America, south of ''P. tremuloides'') *''
Populus sieboldii ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...
'' – Japanese aspen (Japan) *'' Populus tremula'' – Eurasian aspen (northern Europe and Asia) *''
Populus tremuloides ''Populus tremuloides'' is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, mountain or golden aspen, tr ...
'' – Quaking aspen or trembling aspen (northern and western North America)


Habitat and longevity

The trembling of the leaves of the trembling aspen Aspen trees are all native to cold regions with cool summers, in the north of the
northern hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, extending south at high-altitude areas such as mountains or high plains. They are all medium-sized
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, aft ...
trees reaching tall. In North America, the aspen is referred to as quaking aspen or trembling aspen because the leaves "quake" or tremble in the wind. This is due to their flattened petioles which reduce
aerodynamic drag In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fl ...
on the trunk and branches. Aspens typically grow in environments that are otherwise dominated by
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
ous tree species, and which are often lacking other large deciduous tree species. Aspens have evolved several adaptations that aid their survival in such environments. One is the flattened leaf petiole, which reduces aerodynamic drag during high winds and decreases the likelihood of trunk or branch damage. Dropping leaves in the winter (like most but not all other deciduous plants) also helps to prevent damage from heavy winter snow. Additionally, the bark is photosynthetic, meaning that growth is still possible after the leaves have been dropped. The bark also contains
lenticel A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a ...
s that serve as pores for gas exchange (similar to the
stomata In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...
on leaves). Aspens are also aided by the
rhizomatic In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hor ...
nature of their root systems. Most aspens grow in large clonal colonies, derived from a single seedling, and spread by means of root suckers; new stems in the colony may appear at up to from the parent tree. Each individual tree can live for 40–150 years above ground, but the
root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
system of the colony is long-lived. In some cases, this is for thousands of years, sending up new trunks as the older trunks die off above ground. For this reason, it is considered to be an indicator of ancient woodlands. One such colony in Utah, given the nickname of " Pando", has been estimated to be as old as 80,000 years, if validated, this would be making it possibly the oldest living colony of aspens. Some aspen colonies become very large with time, spreading about per year, eventually covering many hectares. They are able to survive forest fires, because the roots are below the heat of the fire, and new sprouts appear after the fire burns out. The high stem turnover rate combined with the clonal growth leads to proliferation in aspen colonies. The high stem turnover regime supports a diverse herbaceous understory. Aspen seedlings do not thrive in the shade, and it is difficult for seedlings to establish in an already mature aspen stand. Fire indirectly benefits aspen trees, since it allows the saplings to flourish in open sunlight in the burned landscape, devoid of other competing tree species. Aspens have increased in popularity as a forestry cultivation species, mostly because of their fast growth rate and ability to regenerate from sprouts. This lowers the cost of
reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debate ...
after harvesting since no planting or
sowing Sowing is the process of planting seeds. An area or object that has had seeds planted in it will be described as a sowed or sown area. Plants which are usually sown Among the major field crops, oats, wheat, and rye are sown, grasses and leg ...
is required. Recently, aspen populations have been declining in some areas ("Sudden Aspen Death"). This has been attributed to several different factors, such as
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, which exacerbates drought and modifies precipitation patterns. Recruitment failure from herbivory or grazing prevents new trees from coming up after old trees die. Additionally, successional replacement by conifers due to fire suppression alters forest diversity and creates conditions where aspen may be at less of an advantage. In contrast with many trees, aspen
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, ...
is
base-rich In ecology, base-richness is the level of chemical bases in water or soil, such as calcium or magnesium ions. Many organisms prefer base-rich environments. Chemical bases are alkalis, hence base-rich environments are either neutral or alkaline. ...
, meaning aspens are important hosts for
bryophytes The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited i ...
and act as food plants for the
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
of butterfly (
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
) species—see
List of Lepidoptera that feed on poplars Populus, Poplars, ''Populus'' species, are used as food plants by the larvae of a large number of Lepidoptera species: phagy, Monophagous Species which feed exclusively on ''Populus'' * Bucculatricidae ** ''Bucculatrix staintonella'' * Gelechiida ...
. Young aspen bark is an important seasonal forage for the European hare and other animals in early spring. Aspen is also a preferred food of the
European beaver The Eurasian beaver (''Castor fiber'') or European beaver is a beaver species that was once widespread in Eurasia, but was hunted to near-extinction for both its fur and castoreum. At the turn of the 20th century, only about 1,200 beavers surviv ...
.
Elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
,
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
, and
moose The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult mal ...
not only eat the leaves but also strip the bark with their front teeth.


Image gallery

File:Large-toothed aspen leaf (Grasett Twp).JPG, Leaf of '' Populus grandidentata''. File:Populus tremula.JPG, Autumn colour of '' Populus tremula''. File:Aspen aa.jpg, Male flowers (
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...
) of '' Populus tremula''. File:Fall Colors at Kebler Pass, Colorado USA.JPG, Aspen grove in fall.


Uses

Aspen wood is white and soft, but fairly strong, and has low flammability. It has a number of uses, notably for making
match A match is a tool for starting a fire. Typically, matches are made of small wooden sticks or stiff paper. One end is coated with a material that can be ignited by friction generated by striking the match against a suitable surface. Wooden matc ...
es and
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
where its low flammability makes it safer to use than most other woods. Shredded aspen wood is used for packing and stuffing, sometimes called
excelsior (wood wool) Wood wool, known primarily as excelsior in North America, is a product made of wood slivers cut from logs. It is mainly used in packaging, for cooling pads in home evaporative cooling systems known as swamp coolers, for erosion control mats, an ...
. Aspen flakes are the most common species of wood used to make
oriented strand board Oriented strand board (OSB) is a type of engineered wood similar to particle board, formed by adding adhesives and then compressing layers of wood strands (flakes) in specific orientations. It was invented by Armin Elmendorf in California in 1963. ...
s. It is also a popular animal bedding, since it lacks the
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...
s associated with
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
and
juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...
, which are thought to cause
respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...
ailments in some animals. Heat-treated aspen is a popular material for the interiors of saunas. While standing trees sometimes tend to rot from the heart outward, the dry timber weathers very well, becoming silvery-grey and resistant to rotting and warping, and has traditionally been used for rural construction in the northwestern regions of Russia (especially for roofing, in the form of thin slats).


References


Further reading

* Fox, Mark, Linda E. Tackaberry, Pascal Drouin, Yves Bergeron, Robert L. Bradley, Hughes B. Massicotte, and Han Chen (2013). "Microbial community structure of soils under four productivity classes of aspen forests in Northern British Columbia". ''Ecoscience'' 20(3):264–275. .


External links


Aspen Information Resource, U.K.




bigtooth aspen
Aspen Research Bibliography

Aspen Photo Gallery

Aspen Compounds, Medicinal Benefits and Uses

Loyola Medicine: Aspen
Dosage, Interaction, Warnings and Side Effects
Steens Aspen
Video produced by
Oregon Field Guide ''Oregon Field Guide'' is a weekly television program produced by Oregon Public Broadcasting focusing on recreation, the outdoors, and environmental issues in the state of Oregon. The show has become part of the Oregon zeitgeist. Steve Amen is th ...
{{Authority control Medicinal plants Negligibly senescent organisms Plant common names Populus