Autumn leaf color

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Japanese maple autumn leaves Momiji Hong Xie suruyamamomizi B221212.JPG
Japanese maple autumn leaves

Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees and shrubs by which they take on, during a few weeks in the autumn season, various shades of yellow, orange, red, purple, and brown. [1] The phenomenon is commonly called autumn colours [2] or autumn foliage [3] in British English and fall colors, [4] fall foliage, or simply foliage [5] in American English.

Contents

In some areas of Canada and the United States, "leaf peeping" tourism is a major contribution to economic activity. This tourist activity occurs between the beginning of color changes and the onset of leaf fall, usually around September to November in the Northern Hemisphere and March to May in the Southern Hemisphere.

Chlorophyll and the green/yellow/orange colors

Kaiserstuhl - Herbst - Rebblatt im Gegenlicht.jpg
In this leaf, the veins are still green, while the other tissue is turning red. This produces a fractal-like pattern
Multi-color leaf without saturation.jpg
A North American leaf with multiple colors across it
Leaf color change.jpg
Cross-section of a leaf showing color changes

A green leaf is green because of the presence of a pigment known as chlorophyll, which is inside an organelle called a chloroplast. When abundant in the leaf's cells, as during the growing season, the chlorophyll's 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. [6]

Chlorophyll has a vital function: it captures solar rays and uses the resulting energy in the manufacture of the plant's food – simple sugars which are produced from water and carbon dioxide. These sugars are the basis of the plant's nourishment – the sole source of the carbohydrates needed for growth and development. In their food-manufacturing process, the chlorophylls break down, thus are continually "used up". During the growing season, however, the plant replenishes the chlorophyll so that the supply remains high and the leaves stay green.

In late summer, with daylight hours shortening and temperatures cooling, the veins 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 intake into the leaf is reduced, slowly at first, and then more rapidly. During this time, the amount of chlorophyll in the leaf begins to decrease. Often, the veins are still green after the tissues between them have almost completely changed color.

Chlorophyll is located in the thylakoid membrane of the chloroplast and it is composed of an apoprotein along with several ligands, the most important of which are chlorophylls a and b. In the autumn, this complex is broken down. Chlorophyll degradation is thought to occur first. 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. [7] 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. [8]

Chlorophylls degrade into colorless tetrapyrroles known as nonfluorescent chlorophyll catabolites. [9] As the chlorophylls degrade, the hidden pigments of yellow xanthophylls and orange beta-carotene are revealed.

Pigments that contribute to other colors

Autumn coloration at the Kalevanpuisto park in Pori, Finland. Kalevanpuisto syyskuussa 2.jpg
Autumn coloration at the Kalevanpuisto park in Pori, Finland.

Carotenoids

Carotenoids are present in the leaves throughout the year, but their orange-yellow colors are usually masked by green chlorophyll. [6] 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 present (along with the chlorophylls) in the leaf's cells begin to show through. [6] These are carotenoids 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 plastids, 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 carrots, corn, canaries, and daffodils, as well as egg yolks, rutabagas, buttercups, and bananas.

Their brilliant yellows and oranges tint the leaves of such hardwood species as hickories, ash, maple, yellow poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder. Carotenoids are the dominant pigment in coloration of about 15–30% of tree species. [6]

Anthocyanins

The reds, the purples, and their blended combinations that decorate autumn foliage come from another group of pigments in the cells called anthocyanins. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. [6] They develop in late summer in the sap 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 in the leaf is reduced. [10]

Autumn foliage at Blue Mountains, Australia in April 2022 Autumn Leaves at Blue Mountains, Australia.jpg
Autumn foliage at Blue Mountains, Australia in April 2022

During the summer growing season, phosphate is at a high level. It has a vital role in the breakdown of the sugars manufactured by chlorophyll, but in autumn, phosphate, along with the other chemicals and nutrients, moves out of the leaf into the stem 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 as they unfold from the buds in early spring. They also give the familiar color to such common fruits as cranberries, red apples, blueberries, cherries, strawberries, and plums.

Anthocyanins are present in about 10% of tree species in temperate regions, although in certain areas – most famously northern New England – up to 70% of tree species may produce the pigment. [6] In autumn forests, they appear vivid in the maples, oaks, sourwood, sweetgums, dogwoods, tupelos, cherry trees, and persimmons. These same pigments often combine with the carotenoids' colors to create the deeper orange, fiery reds, and bronzes typical of many hardwood species.

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. [11] In many cases, this turned out to be oversimplistic – other factors involved include insect predation, [12] 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 nonbiological factors. [6]

Photoprotection

According to the photoprotection theory, anthocyanins protect the leaf against the harmful effects of light at low temperatures. [13] [14] The leaves are about to fall, so protection is not of extreme importance for the tree. Photo-oxidation and photoinhibition, however, especially at low temperatures, make the process of reabsorbing nutrients less efficient. By shielding the leaf with anthocyanins, according to photoprotection theory, the tree manages to reabsorb nutrients (especially nitrogen) more efficiently.

Coevolution

Fall foliage peak times in the United States FallFoliageMap2.PNG
Fall foliage peak times in the United States

According to the coevolution theory, [15] the colors are warning signals to insects like aphids that use trees as a host for the winter. 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 have an advantage because they reduce their parasite load. This has been shown in the case of apple trees where some domesticated apple varieties, unlike wild ones, lack red leaves in the autumn. A greater proportion of aphids that avoid apple trees with red leaves manage to grow and develop compared to those that do not. [16] 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 leaves linked to a greater need for reduced aphid infestation. [16]

Consistent with red-leaved trees 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). [17] One study found that simulating insect herbivory (leaf-eating damage) on maple trees showed earlier red coloration than trees that were not damaged. [18]

The coevolution theory of autumn colors was proposed by W. D. Hamilton in 2001 as an example of evolutionary signalling theory. [17] [lower-alpha 1] With biological signals such as red leaves, it is argued that because they are costly to produce, they are usually honest, so signal the true quality of the signaller with low-quality individuals being unable to fake them and cheat. Autumn colors would be a signal if they were 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).[ citation needed ]

The change of leaf colors prior to fall have also been suggested as adaptations that may help to undermine the camouflage of herbivores. [19]

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 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

The brilliant red autumn color of some species of maple is created by processes separate from those in chlorophyll breakdown. 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 (allelopathy). [20]

Tourism

Autumn in Canberra, Australia Autumn in Canberra.jpg
Autumn in Canberra, Australia

Although some autumn coloration occurs wherever deciduous trees are found, the most brightly colored autumn foliage is found in the northern hemisphere, including most of southern mainland Canada, some areas of the northern United States, Northern and Western Europe, Northern Italy, the Caucasus region of Russia near the Black Sea, and Eastern Asia (including much of northern and eastern China, and as well as Korea and Japan). [21] [22]

Harvard Yard showing Autumn leaf color Fall leaves on the green lawn, at Harvard University,. November, 2019. pic.2 Cambridge, Massachusetts.jpg
Harvard Yard showing Autumn leaf color

In the southern hemisphere, colorful autumn foliage can be observed in southern and central Argentina, the south and southeast regions of Brazil, eastern and southeastern Australia (including South Australia and Tasmania) and most of New Zealand, particularly the South Island. [23]

Climate influences

Compared to Western Europe (excluding Southern Europe), North America provides many more tree species (more than 800 species and about 70 oaks, compared to 51 and three, respectively, in Western Europe) [24] which adds many more different colors to the spectacle. The main reason is the different effect of the Ice ages  – while in North America, species were protected in more southern regions along north–south ranging mountains, this was not the case in much of Europe. [25]

Global warming and rising carbon dioxide levels in the atmosphere may delay the usual autumn spectacle of changing colors and falling leaves in northern hardwood forests in the future, and increase forest productivity. [26] Specifically, higher autumn temperatures in the Northeastern United States is delaying the color change. [27] Experiments with poplar trees showed that they stayed greener longer with higher CO2 levels, independent of temperature changes. [26] However, the experiments over two years were too brief to indicate how mature forests may be affected over time. Other studies using 150 years of herbarium specimens found more than a one-month delay in the onset of autumn since the 19th century, and found that insect, viral, and drought stress can also affect the timing of fall coloration in maple trees. [27] [28] Also, other factors, such as increasing ozone levels close to the ground (tropospheric ozone pollution), can negate the beneficial effects of elevated carbon dioxide. [29]

Related Research Articles

<span class="mw-page-title-main">Chlorophyll</span> Green pigments found in plants, algae and bacteria

Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words χλωρός, khloros and φύλλον, phyllon ("leaf"). Chlorophyll allows plants to absorb energy from light.

<span class="mw-page-title-main">Yellow</span> Color between orange and green on the visible spectrum of light

Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575–585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photo damage in some cases. Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths.

<span class="mw-page-title-main">Deciduous</span> Plants that shed leaves seasonally

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, after flowering; and to the shedding of ripe fruit. The antonym of deciduous in the botanical sense is evergreen.

<span class="mw-page-title-main">Carotenoid</span> Class of chemical compounds; yellow, orange or red plant pigments

Carotenoids are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Over 1,100 identified carotenoids can be further categorized into two classes – xanthophylls and carotenes.

<span class="mw-page-title-main">Chromoplast</span> Pigment-bearing organelle in plant cells

Chromoplasts are plastids, heterogeneous organelles responsible for pigment synthesis and storage in specific photosynthetic eukaryotes. It is thought that like all other plastids including chloroplasts and leucoplasts they are descended from symbiotic prokaryotes.

<span class="mw-page-title-main">Plant physiology</span> Subdiscipline of botany

Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.

<i>Agalychnis callidryas</i> Species of amphibian

Agalychnis callidryas, commonly known as the red-eyed tree frog, is a species of frog in the subfamily Phyllomedusinae. It is native to forests from Central America to north-western South America. This species is known for its bright coloration, namely its vibrant green body with blue and yellow stripes on the side. It has a white underside, brightly red and orange colored feet, and is named after its distinctive bright red eyes.

<span class="mw-page-title-main">Abscission</span> Shedding of various parts of an organism

Abscission is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. In cell biology, abscission refers to the separation of two daughter cells at the completion of cytokinesis.

Herbivores are dependent on plants for food, and have coevolved mechanisms to obtain this food despite the evolution of a diverse arsenal of plant defenses against herbivory. Herbivore adaptations to plant defense have been likened to "offensive traits" and consist of those traits that allow for increased feeding and use of a host. Plants, on the other hand, protect their resources for use in growth and reproduction, by limiting the ability of herbivores to eat them. Relationships between herbivores and their host plants often results in reciprocal evolutionary change. When a herbivore eats a plant it selects for plants that can mount a defensive response, whether the response is incorporated biochemically or physically, or induced as a counterattack. In cases where this relationship demonstrates "specificity", and "reciprocity", the species are thought to have coevolved. The escape and radiation mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation. The coevolution that occurs between plants and herbivores that ultimately results in the speciation of both can be further explained by the Red Queen hypothesis. This hypothesis states that competitive success and failure evolve back and forth through organizational learning. The act of an organism facing competition with another organism ultimately leads to an increase in the organism's performance due to selection. This increase in competitive success then forces the competing organism to increase its performance through selection as well, thus creating an "arms race" between the two species. Herbivores evolve due to plant defenses because plants must increase their competitive performance first due to herbivore competitive success.

<span class="mw-page-title-main">Maple</span> Genus of flowering plants

Acer is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family, Sapindaceae, along with lychee and horse chestnut. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, Acer laurinum, extends to the Southern Hemisphere. The type species of the genus is the sycamore maple, Acer pseudoplatanus, the most common maple species in Europe. Maples usually have easily recognizable palmate leaves and distinctive winged fruits. The closest relatives of the maples are the horse chestnuts. Maple syrup is made from the sap of some maple species. It is one of the most common genera of trees in Asia. Many maple species are grown in gardens where they are valued for their autumn colour.

<span class="mw-page-title-main">Biological pigment</span> Substances produced by living organisms

Biological pigments, also known simply as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, feathers, fur and hair contain pigments such as melanin in specialized cells called chromatophores. In some species, pigments accrue over very long periods during an individual's lifespan.

<i>Coleus scutellarioides</i> Species of flowering plant

Coleus scutellarioides, commonly known as coleus, is a species of flowering plant in the family Lamiaceae, native to southeast Asia through to Australia. Typically growing to 60–75 cm (24–30 in) tall and wide, it is a bushy, woody-based evergreen perennial, widely grown for the highly decorative variegated leaves found in cultivated varieties. Another common name is painted nettle, reflecting its relationship to deadnettles, which are in the same family. The synonyms Coleus blumei, Plectranthus scutellarioides and Solenostemon scutellarioides are also widely used for this species.

<span class="mw-page-title-main">Animal coloration</span> General appearance of an animal

Animal colouration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible.

<span class="mw-page-title-main">Anthocyanin</span> Class of chemical compounds

Anthocyanins, also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compound that gives flowers a blue color, Anthokyan, in his treatise "Die Farben der Blüthen". Food plants rich in anthocyanins include the blueberry, raspberry, black rice, and black soybean, among many others that are red, blue, purple, or black. Some of the colors of autumn leaves are derived from anthocyanins.

<span class="mw-page-title-main">Blue tomato</span> Various tomato cultivars

Blue tomatoes, also called purple tomatoes, are tomatoes that have been bred to produce high levels of anthocyanins, a class of pigments responsible for the blue and purple colours of many fruits, including blueberries, blackberries and chokeberries. Anthocyanins may provide protection for the plant against insects, diseases, and ultraviolet radiation. Some of these tomatoes have been commercialized under the names "Indigo Rose" and "SunBlack".

<span class="mw-page-title-main">Psittacofulvin</span> Pigment in parrots

Psittacofulvin pigments, sometimes called psittacins, are responsible for the bright-red, orange, and yellow colors specific to parrots. In parrots, psittacofulvins are synthesized by a polyketide synthase enzyme that is expressed in growing feathers. They consist of linear polyenes terminated by an aldehyde group. There are five known psittacofulvin pigments - tetradecahexenal, hexadecaheptenal, octadecaoctenal and eicosanonenal, in addition to a fifth, currently-unidentified pigment found in the feathers of scarlet macaws. Colorful feathers with high levels of psittacofulvin resist feather-degrading Bacillus licheniformis better than white ones.

<i>Acer palmatum</i> Species of maple

Acer palmatum, commonly known as Japanese maple, palmate maple, or smooth Japanese maple (Korean: danpungnamu, 단풍나무, Japanese: irohamomiji, イロハモミジ, or momiji,, is a species of woody plant native to Korea, Japan, China, eastern Mongolia, and southeast Russia. Many different cultivars of this maple have been selected and they are grown worldwide for their large variety of attractive forms, leaf shapes, and spectacular colors.

<span class="mw-page-title-main">Autumn in New England</span>

Autumn in New England begins in late September and ends in late December. It marks the transition from summer to winter and is known for its vibrant colors and picturesque beauty. The autumn color of the trees and flora in New England has been reported to be some of the most brilliant natural color in the United States; as such, it is a popular tourist destination, attracting visitors from across North America and overseas. Travelers flock to Vermont, New Hampshire, Maine, and parts of Massachusetts to see the colors each fall, a practice known as leaf peeping. Hiking during Autumn has become popular, and several areas offer guided tours.

<span class="mw-page-title-main">Leaf flushing</span>

Leaf flushing or leaf out is the production of a flush of new leaves typically produced simultaneously on all branches of a bare plant or tree. Young leaves often have less chlorophyll and the leaf flush may be white or red, the latter due to presence of pigments, particularly anthocyanins. Leaf flushing succeeds leaf fall, and is delayed by winter in the temperate zone or by extreme dryness in the tropics. Leaf fall and leaf flushing in tropical deciduous forests can overlap in some species, called leaf-exchanging species, producing new leaves during the same period when old leaves are shed or almost immediately after. Leaf-flushing may be synchronized among trees of a single species or even across species in an area. In the seasonal tropics, leaf flushing phenology may be influenced by herbivory and water stress.

<span class="mw-page-title-main">Floral color change</span> Changes due to age or pollination

Floral color change occurs in flowers in a wide range of angiosperm taxa that undergo a color change associated with their age, or after successful pollination.

References

PD-icon.svg This article incorporates public domain material from the USDA Forest Service

  1. ↑ "The Science of Color in Autumn Leaves". usna.usda.gov. United States National Arboretum. October 6, 2011. Archived from the original on January 11, 2018. Retrieved June 18, 2015.
  2. ↑ Wade, Paul; Arnold, Kathy (September 16, 2014). "New England in the Fall: Trip of a Lifetime - Telegraph". telegraph.co.uk. The Daily Telegraph . Retrieved June 18, 2015.
  3. ↑ "BBC - Gardening - How to be a gardener - The gardening year - Autumn's theme". bbc.co.uk. BBC. September 17, 2014. Retrieved June 18, 2015.
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  5. ↑ "MaineFoliage.com - Maine's Official Fall Foliage Website". MaineFoliage.com. 2013. Retrieved June 18, 2015.
  6. 1 2 3 4 5 6 7 Archetti, Marco; Döring, Thomas F.; Hagen, Snorre B.; Hughes, Nicole M.; Leather, Simon R.; Lee, David W.; Lev-Yadun, Simcha; Manetas, Yiannis; Ougham, Helen J. (2011). "Unravelling the evolution of autumn colours: an interdisciplinary approach". Trends in Ecology & Evolution. 24 (3): 166–73. doi:10.1016/j.tree.2008.10.006. PMID   19178979.
  7. ↑ Horie, Y.; Ito, H.; Kusaba, M.; Tanaka, R.; Tanaka, A. (2009). "Participation of Chlorophyll b Reductase in the Initial Step of the Degradation of Light-harvesting Chlorophyll a/b-Protein Complexes in Arabidopsis". Journal of Biological Chemistry. 284 (26): 17449–56. doi: 10.1074/jbc.M109.008912 . PMC   2719385 . PMID   19403948.
  8. ↑ Zelisko, A.; Garcia-Lorenzo, M.; Jackowski, G.; Jansson, S.; Funk, C. (2005). "AtFtsH6 is involved in the degradation of the light-harvesting complex II during high-light acclimation and senescence". Proceedings of the National Academy of Sciences. 102 (38): 13699–704. Bibcode:2005PNAS..10213699Z. doi: 10.1073/pnas.0503472102 . PMC   1224624 . PMID   16157880.
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  10. ↑ Davies, Kevin M. (2004). Plant pigments and their manipulation. Wiley-Blackwell. p. 6. ISBN   978-1-4051-1737-1.
  11. ↑ Thomas, H; Stoddart, J L (1980). "Leaf Senescence". Annual Review of Plant Physiology. 31: 83–111. doi:10.1146/annurev.pp.31.060180.000503.
  12. ↑ Labandeira, C. C.; Dilcher, DL; Davis, DR; Wagner, DL (1994). "Ninety-seven million years of angiosperm-insect association: paleobiological insights into the meaning of coevolution". Proceedings of the National Academy of Sciences. 91 (25): 12278–82. Bibcode:1994PNAS...9112278L. doi: 10.1073/pnas.91.25.12278 . PMC   45420 . PMID   11607501.
  13. ↑ Lee, David; Gould, Kevin (2002). "Why Leaves Turn Red". American Scientist. 90 (6): 524–531. Bibcode:2002AmSci..90..524L. doi:10.1511/2002.6.524. S2CID   209833569.
  14. ↑ Lee, D; Gould, K (2002). "Anthocyanins in leaves and other vegetative organs: An introduction". Advances in Botanical Research. 37: 1–16. doi:10.1016/S0065-2296(02)37040-X. ISBN   978-0-12-005937-9.
  15. ↑ Archetti, M; Brown, S. P. (June 2004). "The coevolution theory of autumn colours". Proc. Biol. Sci. 271 (1545): 1219–23. doi:10.1098/rspb.2004.2728. PMC   1691721 . PMID   15306345.
  16. 1 2 Archetti, M. (2009). "Evidence from the domestication of apple for the maintenance of autumn colours by coevolution". Proceedings of the Royal Society B: Biological Sciences. 276 (1667): 2575–80. doi:10.1098/rspb.2009.0355. PMC   2684696 . PMID   19369261.
  17. 1 2 Hamilton, W. D.; Brown, S. P. (2001). "Autumn tree colours as a handicap signal". Proceedings of the Royal Society B: Biological Sciences. 268 (1475): 1489–93. doi:10.1098/rspb.2001.1672. PMC   1088768 . PMID   11454293.
  18. ↑ Forkner, Rebecca E. (May 1, 2014). "Simulated herbivory advances autumn phenology in Acer rubrum". International Journal of Biometeorology. 58 (4): 499–507. Bibcode:2014IJBm...58..499F. doi:10.1007/s00484-013-0701-8. PMID   23832182. S2CID   24879283.
  19. ↑ Lev-Yadun, Simcha; Dafni, Amots; Flaishman, Moshe A.; Inbar, Moshe; Izhaki, Ido; Katzir, Gadi; Ne'eman, Gidi (2004). "Plant coloration undermines herbivorous insect camouflage". BioEssays. 26 (10): 1126–30. doi:10.1002/bies.20112. PMID   15382135.
  20. ↑ (Frey & Eldridge, 2005)[ citation needed ]
  21. ↑ "Pest Alert". South Dakota State University. August 30, 1998. Archived from the original on October 20, 2006. Retrieved November 28, 2006.
  22. ↑ Altman, Daniel (November 8, 2006). "Fall foliage sets Japan ablaze". Taipei Times. Retrieved November 28, 2006.
  23. ↑ Hutchinson, Carrie (March 2, 2019). "The 5 Best Places in Australia to See Autumn Colours". Qantas . Retrieved July 22, 2019.
  24. ↑ Heinz Ellenberg, H. Ellenberg: Vegetation Mitteleuropas mit den Alpen: In ökologischer, dynamischer und historischer Sicht, UTB, Stuttgart; 5th edition, in German, ISBN   3-8252-8104-3, 1996[ page needed ]
  25. ↑ "Botanik online: Pflanzengesellschaften - Sommergrüne Laub- und Mischlaubwälder" (in German). University of Hamburg Biology Server. Archived from the original on October 6, 2014. Retrieved July 29, 2020.
  26. 1 2 Taylor, Gail; Tallis, Matthew J.; Giardina, Christian P.; Percy, Kevin E.; Miglietta, Franco; Gupta, Pooja S.; Gioli, Beniamino; Calfapietra, Carlo; Gielen, Birgit (2007). "Future atmospheric CO2 leads to delayed autumnal senescence". Global Change Biology. 14 (2): 264–75. Bibcode:2008GCBio..14..264T. CiteSeerX   10.1.1.384.1142 . doi:10.1111/j.1365-2486.2007.01473.x. S2CID   86176515.
  27. 1 2 Gibbens, Sarah (November 24, 2021). "Fall foliage was disrupted by climate change. It might be the new normal". Environment. National Geographic. Archived from the original on November 24, 2021.
  28. ↑ Garretson, Alexis; Forkner, Rebecca E. (2021). "Herbaria Reveal Herbivory and Pathogen Increases and Shifts in Senescence for Northeastern United States Maples Over 150 Years". Frontiers in Forests and Global Change. 4: 185. Bibcode:2021FrFGC...4.4763G. doi: 10.3389/ffgc.2021.664763 .
  29. ↑ "Forests Could Benefit When Fall Color Comes Late". Newswise. Retrieved August 17, 2008.

Notes

  1. ↑ Hamilton died in 2000. The paper was submitted by coauthor S.P. Brown in December of the same year and published in 2001.

Further reading

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