Autumn leaf color
Encyclopedia
Green
Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...
leaves of many deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s and shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s by which they take on, during a few weeks in the autumn season, one or many colors that range from red
Red
Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye...
to yellow
Yellow
Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...
. The phenomenon is commonly called fall colors and autumn colors, while the expression fall foliage usually connotes the viewing of a tree or forest whose leaves have undergone the change. In some areas of Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, "leaf peeping
Leaf peeping
Leaf peeping is an informal term, commonly used in the United States, for people who travel to view and photograph the fall foliage in areas where foliage changes colors, particularly New England.The origin of the term "leaf peeping" is not well known....
" tourism
Tourism
Tourism is travel for recreational, leisure or business purposes. The World Tourism Organization defines tourists as people "traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes".Tourism has become a...
is a major contribution to economic activity. This tourist activity occurs between the beginning of color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
changes and the onset of leaf fall.
Chlorophyll and the green color
A green leafLeaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
is green because of the presence of a pigment known as chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
, which is inside an organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
called chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
. When they are abundant in the leaf's cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
, as they are during the growing season, the chlorophylls' green color dominates and masks out the colors of any other pigments that may be present in the leaf. Thus the leaves of summer are characteristically green.
Chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
has a vital function: that of capturing solar rays and utilizing the resulting energy in the manufacture of the plant's food—simple sugars which are produced from water and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
. These sugars are the basis of the plant's nourishment—the sole source of the carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
s needed for growth and development. In their food-manufacturing process, the chlorophylls themselves break down and thus are being continually "used up." During the growing season, however, the plant replenishes the chlorophyll so that the supply remains high and the leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
stay green.
In late summer, as daylight hours shorten and temperatures cool, the vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
s that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf. As this cork layer develops, water and mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
intake into the leaf is reduced, slowly at first, and then more rapidly. It is during this time that the chlorophyll begins to decrease.
Often the veins will still be green after the tissues between them have almost completely changed color.
A lot of chlorophyll is located in Photosystem II (Light Harvesting Complex II or LHC II), the most abundant membrane protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
on earth. LHC II is where light is captured in photosynthesis. It is located in the thylakoid
Thylakoid
A thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as...
membrane of the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
and it is composed of an apoprotein
Apoprotein
Apoprotein can refer to:*Apoenzyme, the protein part of an enzyme without its characteristic prosthetic group.*Apolipoprotein, a lipid-binding protein that is a constituent of the plasma lipoprotein....
along with several ligands, the most important of which are chlorophylls a and b. In the fall, this complex is broken down. Chlorophyll degradation is thought to occur first. Recent research suggests that the beginning of chlorophyll degradation is catalyzed by chlorophyll b reductase, which reduces chlorophyll b to 7-hydroxymethyl chlorophyll a, which is then reduced to chlorophyll a. This is believed to destabilize the complex, at which point breakdown of the apoprotein occurs. An important enzyme in the breakdown of the apoprotein is FtsH6, which belongs to the FtsH family of proteases.
Chlorophylls degrade into colorless tetrapyrrole
Tetrapyrrole
Tetrapyrroles are compounds containing four pyrrole rings. With the exception of corrin, the four pyrrole rings are interconnected through one-carbon bridges, in either a linear or a cyclic fashion...
s known as nonfluorescent chlorophyll catabolites (NCC's).
As the chlorophylls degrade, the hidden pigments of yellow xanthophylls and orange beta-carotene are revealed. These pigments are present throughout the year, but the red pigments, the anthocyanins, are synthesized de novo
De novo synthesis
De novo synthesis refers to the synthesis of complex molecules from simple molecules such as sugars or amino acids, as opposed to their being recycled after partial degradation. For example, nucleotides are not needed in the diet as they can be constructed from small precursor molecules such as...
once roughly half of chlorophyll has been degraded. The amino acids released from degradation of light harvesting complexes are stored all winter in the tree's roots, branches, stems, and trunk until next spring when they are recycled to re-leaf the tree.
Carotenoids
Carotenoids are present in leaves the whole year round, but their orange-yellow colors are usually masked by green chlorophyll. As autumn approaches, certain influences both inside and outside the plant cause the chlorophylls to be replaced at a slower rate than they are being used up. During this period, with the total supply of chlorophylls gradually dwindling, the "masking" effect slowly fades away. Then other pigments that have been present (along with the chlorophylls) in the cells all during the leaf's life begin to show through. These are carotenoidCarotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
s and they provide colorations of yellow, brown, orange, and the many hues in between.
The carotenoids occur, along with the chlorophyll pigments, in tiny structures called plastid
Plastid
Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...
s within the cells of leaves. Sometimes they are in such abundance in the leaf that they give a plant a yellow-green color, even during the summer. Usually, however, they become prominent for the first time in autumn, when the leaves begin to lose their chlorophyll.
Carotenoids are common in many living things, giving characteristic color to carrot
Carrot
The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...
s, corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, canaries
Domestic Canary
The Domestic Canary, often simply known as the canary, is a domesticated form of the wild Canary, a small songbird in the finch family originating from the Macaronesian Islands ....
, and daffodils, as well as egg yolk
Egg yolk
An egg yolk is a part of an egg which feeds the developing embryo. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae...
s, rutabaga
Rutabaga
The rutabaga, swede , turnip or yellow turnip is a root vegetable that originated as a cross between the cabbage and the turnip; see Triangle of U...
s, buttercups, and banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
s.
Their brilliant yellows and oranges tint the leaves of such hardwood species as hickories
Hickory
Trees in the genus Carya are commonly known as hickory, derived from the Powhatan language of Virginia. The genus includes 17–19 species of deciduous trees with pinnately compound leaves and big nuts...
, ash, maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
, yellow poplar, aspen
Aspen
Populus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by...
, birch
Birch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
, black cherry
Black Cherry
Prunus serotina, commonly called black cherry, wild black cherry, rum cherry, or mountain black cherry, is a woody plant species belonging to the genus Prunus...
, sycamore
Sycamore
Sycamore is a name which is applied at various times and places to three very different types of trees, but with somewhat similar leaf forms....
, cottonwood, sassafras
Sassafras
Sassafras is a genus of three extant and one extinct species of deciduous trees in the family Lauraceae, native to eastern North America and eastern Asia.-Overview:...
, and alder
Alder
Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...
. Carotenoids are the dominant pigment in coloration of about 15-30% of tree species.
Anthocyanins
The reds, the purples, and their blended combinations that decorate autumn foliage come from another group of pigments in the cells called anthocyaninAnthocyanin
Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH...
s. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. They develop in late summer in the sap
Sap
Sap may refer to:* Plant sap, the fluid transported in xylem cells or phloem sieve tube elements of a plant* Sap , a village in the Dunajská Streda District of Slovakia...
of the cells of the leaf, and this development is the result of complex interactions of many influences — both inside and outside the plant. Their formation depends on the breakdown of sugars in the presence of bright light as the level of phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
in the leaf is reduced.
During the summer growing season, phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
is at a high level. It has a vital role in the breakdown of the sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s manufactured by chlorophyll. But in the fall, phosphate, along with the other chemicals and nutrients, moves out of the leaf into the stem
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
of the plant. When this happens, the sugar-breakdown process changes, leading to the production of anthocyanin pigments. The brighter the light during this period, the greater the production of anthocyanins and the more brilliant the resulting color display. When the days of autumn are bright and cool, and the nights are chilly but not freezing, the brightest colorations usually develop.
Anthocyanins temporarily color the edges of some of the very young leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
as they unfold from the bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s in early spring. They also give the familiar color to such common fruits as cranberries
Cranberry
Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus Oxycoccus of the genus Vaccinium. In some methods of classification, Oxycoccus is regarded as a genus in its own right...
, red apples
Red Delicious
The Red Delicious is a clone of apple cultigen, now comprising more than 50 cultivars, that was recognized in Madison County, Iowa, United States, in 1880...
, blueberries
Blueberry
Blueberries are flowering plants of the genus Vaccinium with dark-blue berries and are perennial...
, cherries
Cherry
The cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, strawberries
Strawberry
Fragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
, and plums.
Anthocyanins are present in about 10% of tree species in temperate regions, although in certain areas — most famously Maine, New England — up to 70% of tree species may produce the pigment. In autumn
Autumn
Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....
forests they appear vivid in the maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
s, oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
s, sourwood
Sourwood
Sourwood or sorrel tree is the sole species in the genus Oxydendrum, in the family Ericaceae. It is native to eastern North America, from southern Pennsylvania south to northwest Florida and west to southern Illinois; it is most common in the lower chain of the Appalachian Mountains...
, sweetgums, dogwood
Dogwood
The genus Cornus is a group of about 30-60 species of woody plants in the family Cornaceae, commonly known as dogwoods. Most dogwoods are deciduous trees or shrubs, but a few species are nearly herbaceous perennial subshrubs, and a few of the woody species are evergreen...
s, tupelo
Tupelo
The tupelo , black gum, or pepperidge tree, genus Nyssa , is a small genus of about 9 to 11 species of trees with alternate, simple leaves...
s, cherry trees
Cherry
The cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
and persimmon
Persimmon
A persimmon is the edible fruit of a number of species of trees in the genus Diospyros in the ebony wood family . The word Diospyros means "the fire of Zeus" in ancient Greek. As a tree, it is a perennial plant...
s. These same pigments often combine with the carotenoids' colors to create the deeper orange, fiery reds, and bronzes typical of many hardwood species.
Cell walls
The brown color of leaves is not the result of a pigment, but rather cell walls, which may be evident when no coloring pigment is visible.Function of autumn colors
Deciduous plants were traditionally believed to shed their leaves in autumn primarily because the high costs involved in their maintenance would outweigh the benefits from photosynthesis during the winter period of low light availability and cold temperatures. In many cases this turned out to be over-simplistic — other factors involved include insect predation, water loss, and damage from high winds or snowfall.Anthocyanins, responsible for red-purple coloration, are actively produced in autumn, but not involved in leaf-drop. A number of hypotheses on the role of pigment production in leaf-drop have been proposed, and generally fall into two categories: interaction with animals, and protection from non-biological factors.
Photoprotection
According to the photoprotection theory, anthocyanins protects the leaf against the harmful effects of light at low temperatures. It is true that the leaves are about to fall and therefore it is not of extreme importance for the tree to protect them. Photo-oxidation and photo-inhibition, however, especially at low temperatures, make the process of reabsorbing nutrients less efficient. By shielding the leaf with anthocyanins, according to the photoprotection theory, the tree manages to reabsorb nutrients (especially nitrogen) more efficiently.Coevolution
According to the coevolution theory, the colors are warning signals towards insects that use the trees as a host for the winter, for example aphids. If the colors are linked to the amount of chemical defenses against insects, then the insects will avoid red leaves and increase their fitness; at the same time trees with red leaves will have an advantage because they reduce their parasite load. This has been shown in the case of apple treeMalus
Malus , the apples, are a genus of about 30–35 species of small deciduous trees or shrubs in the family Rosaceae. Other studies go as far as 55 species including the domesticated Orchard Apple, or Table apple as it was formerly called...
s where some but not all domesticated apple varieties
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
unlike wild ones lack red leaves in autumn. A greater proportion of aphids that avoid apple trees with red leafs manage to grow and develop compared to those that do not. A trade off moreover exists between fruit size, leaf color and aphids resistance as varieties with red leaves have smaller fruits suggesting a cost to the production of red leafs linked to a greater need for reduced aphid infestation. Consistent with red leaved tree providing reduced survival for aphids, tree species with bright leaves tend to select for more specialist aphid pests than do trees lacking bright leaves (autumn colors are useful only in those species coevolving with insect pests in autumn).
The coevolution theory of autumn colors was proposed by W. D. Hamilton
W. D. Hamilton
William Donald Hamilton FRS was a British evolutionary biologist, widely recognised as one of the greatest evolutionary theorists of the 20th century....
as an example of evolutionary signalling theory
Signalling theory
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals. The central question is when organisms with conflicting interests should be expected to communicate "honestly"...
. Biological signals such a red leafs it is argued because they are costly to produce are usually honest and so signal the true quality of the signaller with low quality individuals being unable to fake them and so cheat. Autumn colors would be a signal if they are costly to produce, or be impossible to fake (for example if autumn pigments were produced by the same biochemical pathway that produces the chemical defenses against the insects).
The change of leaf colors prior to fall have also been suggested as adaptations that may help to undermine the camouflage of herbivores.
Many plants with berries attract birds with especially visible berry and/or leaf color, particularly bright red. The birds get a meal while the shrub, vine or typically small tree gets undigested seeds carried off and deposited with the birds' manure. Poison Ivy
Poison Ivy
Poison Ivy is a fictional character, a DC Comics supervillainess who is primarily an enemy of Batman. Created by Robert Kanigher and Sheldon Moldoff, she first appeared in Batman #181 ....
is particularly notable for having bright red foliage drawing birds to its off-white seeds (which are edible for birds, but not most mammals).
Allelopathy
Researchers at New York's Colgate University have found evidence that the brilliant red colors of maple leaves is created by a separate processes than those in chlorophyll breakdown. At the very time when the tree is struggling to cope with the energy demands of a changing and challenging season maple trees are involved in an additional metabolic expenditure to create anthocyanins. These anthocyanins, which create the visual red hues, have been found to aid in interspecific competition by stunting the growth of nearby saplings in what is known as allelopathy. (Frey & Eldridge, 2005)Tourism
Although some autumn coloration occurs wherever deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
trees are found, the most brightly colored autumn foliage is found in four or five regions of the world: most of southern mainland Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
; Most of the eastern part of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
as well as smaller areas of forest further west
Western United States
.The Western United States, commonly referred to as the American West or simply "the West," traditionally refers to the region comprising the westernmost states of the United States. Because the U.S. expanded westward after its founding, the meaning of the West has evolved over time...
; Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
, Northern, and Western Europe north of the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
; the Caucasus
Caucasus
The Caucasus, also Caucas or Caucasia , is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea...
region near the Black Sea, Russia and Eastern Asia, including much of northern and eastern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, as well as Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
, and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
Eastern Canada and the New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
region of the United States are famous around the world for the brilliance of their "fall foliage," and a seasonal tourist industry has grown up around the few weeks in autumn when the leaves are at their peak. Thick forest cover and distinct seasonal changes make this part of the world an ideal setting for the types of deciduous trees that produce wonderful fall foliage. Fall colors are typically at their peaks in early to mid October for much of the northern and interior parts of the area, late October for areas further south, and early November for the warmer subtropical areas of the region. Some television and web-based weather forecasts even report on the status of the fall foliage throughout the season as a service to tourists, the most well-known of which is The Weather Channel
The Weather Channel
The Weather Channel is a US cable and satellite television network since May 2, 1982, that broadcasts weather forecasts and weather-related news, along with entertainment programming related to weather 24 hours a day...
. Fall foliage tourists are often referred to as "leaf peepers". Fall foliage tours to the Rocky Mountain states, the northwestern United States and far western Canada are becoming more popular as well. The Japanese momijigari
Momijigari
, from the Japanese , "red leaves" or "maple tree" and , "hunting", is the Japanese tradition of going to visit scenic areas where leaves have turned red in the autumn. It is also called . in Hokkaidō...
tradition is similar, though more closely related to hanami
Hanami
is the Japanese traditional custom of enjoying the beauty of flowers, "flower" in this case almost always meaning cherry blossoms or ume blossoms. From the end of March to early May, sakura bloom all over Japan, and around the first of February on the island of Okinawa...
. In Finland the time of the year is called ruska (russeting). In Latvia during russeting, leaf peeping is promoted both internationally and locally. Other lands may also promote this, but mushrooming may be more culturally significant, for example in Lithuania.
Climate influences
Compared to western Europe, North America provides many more arbor species (more than 800 species, about 70 oaks compared to 51 and three in Western Europe) which adds many more different colors to the spectacle. The main reason was the different effect of the ice ages—while in North America, species could evade to warmer regions along north–south ranging mountains, this was not feasible in Europe.According to a study in the journal Global Change Biology, climate change delays the autumn spectacle of multi-colored leaves but increases forest productivity. The study suggests that rising carbon dioxide levels in the atmosphere act directly to delay the usual autumn spectacle of changing colors and falling leaves in northern hardwood forests. The researchers found that the forests in North America and Europe stayed greener longer as CO2 levels rose, independent of temperature changes. However, the experiments were too brief to indicate how mature forests may be impacted over time. Also, the research suggests that other factors, such as increasing ozone levels in the part of the atmosphere closest to the ground, can negate the beneficial effects of elevated carbon dioxide.