Phloem

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Phloem 

 

Phloem (orange) transports products of photosynthesis to various parts of the plant.

 

Cross-section of a flax plant stem:

1. Pith
2. Protoxylem
3. Metaxylem I
4. Phloem I
5. Sclerenchyma (bast fibre)
6. Cortex
7. Epidermis

Phloem (/ˈfloʊ.əm/, FLOH-əm) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as photosynthates, in particular the sugar sucrose, to the rest of the plant. This transport process is called translocation. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Ancient Greek word φλοιός (phloiós), meaning "bark". The term was introduced by Carl Nägeli in 1858.

Structure

Cross section of some phloem cells

Phloem tissue consists of conducting cells, generally called sieve elements, parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells and supportive cells, such as fibres and sclereids.

Conducting cells (sieve elements)

Main article: Sieve tube element

 

Simplified phloem and companion cells:

1. Xylem
2. Phloem
3. Cambium
4. Pith
5. Companion cells

Sieve elements are the type of cell that are responsible for transporting sugars throughout the plant. At maturity they lack a nucleus and have very few organelles, so they rely on companion cells or albuminous cells for most of their metabolic needs. Sieve tube cells do contain vacuoles and other organelles, such as ribosomes, before they mature, but these generally migrate to the cell wall and dissolve at maturity; this ensures there is little to impede the movement of fluids. One of the few organelles they do contain at maturity is the rough endoplasmic reticulum, which can be found at the plasma membrane, often nearby the plasmodesmata that connect them to their companion or albuminous cells. All sieve cells have groups of pores at their ends that grow from modified and enlarged plasmodesmata, called sieve areas. The pores are reinforced by platelets of a polysaccharide called callose.

Parenchyma cells

Other parenchyma cells within the phloem are generally undifferentiated and used for food storage.

Companion cells

The metabolic functioning of sieve-tube members depends on a close association with the companion cells, a specialized form of parenchyma cell. All of the cellular functions of a sieve-tube element are carried out by the (much smaller) companion cell, a typical nucleate plant cell except the companion cell usually has a larger number of ribosomes and mitochondria. The dense cytoplasm of a companion cell is connected to the sieve-tube element by plasmodesmata. The common sidewall shared by a sieve tube element and a companion cell has large numbers of plasmodesmata.

There are three types of companion cells.

1. Ordinary companion cells, which have smooth walls and few or no plasmodesmatal connections to cells other than the sieve tube.
2. Transfer cells, which have much-folded walls that are adjacent to non-sieve cells, allowing for larger areas of transfer. They are specialized in scavenging solutes from those in the cell walls that are actively pumped requiring energy.
3. Intermediary cells, which possess many vacuoles and plasmodesmata and synthesize raffinose family oligosaccharides. 

Albuminous cells

Albuminous cells have a similar role to companion cells, but are associated with sieve cells only and are hence found only in seedless vascular plants and gymnosperms.

Supportive cells

Although its primary function is transport of sugars, phloem may also contain cells that have a mechanical support function. These are sclerenchyma cells which generally fall into two categories: fibres and sclereids. Both cell types have a secondary cell wall and are dead at maturity. The secondary cell wall increases their rigidity and tensile strength, especially because they contain lignin.

Fibres

Bast fibres are the long, narrow supportive cells that provide tension strength without limiting flexibility. They are also found in xylem, and are the main component of many textiles such as paper, linen, and cotton.

Sclereids

Sclereids are irregularly shaped cells that add compression strength but may reduce flexibility to some extent. They also serve as anti-herbivory structures, as their irregular shape and hardness will increase wear on teeth as the herbivores chews. For example, they are responsible for the gritty texture in pears, and in winter pears.

Function

The process of translocation within the phloem

Unlike xylem (which is composed primarily of dead cells), the phloem is composed of still-living cells that transport sap. The sap is a water-based solution, but rich in sugars made by photosynthesis. These sugars are transported to non-photosynthetic parts of the plant, such as the roots, or into storage structures, such as tubers or bulbs.

During the plant's growth period, usually during the spring, storage organs such as the roots are sugar sources, and the plant's many growing areas are sugar sinks. The movement in phloem is multidirectional, whereas, in xylem cells, it is unidirectional (upward).

After the growth period, when the meristems are dormant, the leaves are sources, and storage organs are sinks. Developing seed-bearing organs (such as fruit) are always sinks. Because of this multi-directional flow, coupled with the fact that sap cannot move with ease between adjacent sieve-tubes, it is not unusual for sap in adjacent sieve-tubes to be flowing in opposite directions.

While movement of water and minerals through the xylem is driven by negative pressures (tension) most of the time, movement through the phloem is driven by positive hydrostatic pressures. This process is termed translocation, and is accomplished by a process called phloem loading and unloading.

Phloem sap is also thought to play a role in sending informational signals throughout vascular plants. "Loading and unloading patterns are largely determined by the conductivity and number of plasmodesmata and the position-dependent function of solute-specific, plasma membrane transport proteins. Recent evidence indicates that mobile proteins and RNA are part of the plant's long-distance communication signaling system. Evidence also exists for the directed transport and sorting of macromolecules as they pass through plasmodesmata."

Organic molecules such as sugars, amino acids, certain phytohormones, and even messenger RNAs are transported in the phloem through sieve tube elements.

Phloem is also used as a popular site for oviposition and breeding of insects belonging to the order Diptera, including the fruit fly Drosophila montana.

Girdling

Main article: Girdling

Because phloem tubes are located outside the xylem in most plants, a tree or other plant can be killed by stripping away the bark in a ring on the trunk or stem. With the phloem destroyed, nutrients cannot reach the roots, and the tree/plant will die. Trees located in areas with animals such as beavers are vulnerable since beavers chew off the bark at a fairly precise height. This process is known as girdling, and can be used for agricultural purposes. For example, enormous fruits and vegetables seen at fairs and carnivals are produced via girdling. A farmer would place a girdle at the base of a large branch, and remove all but one fruit/vegetable from that branch. Thus, all the sugars manufactured by leaves on that branch have no sinks to go to but the one fruit/vegetable, which thus expands to many times its normal size.

Origin

When the plant is an embryo, vascular tissue emerges from procambium tissue, which is at the center of the embryo. Protophloem itself appears in the mid-vein extending into the cotyledonary node, which constitutes the first appearance of a leaf in angiosperms, where it forms continuous strands. The hormone auxin, transported by the protein PIN1 is responsible for the growth of those protophloem strands, signaling the final identity of those tissues. SHORTROOT(SHR), and microRNA165/166 also participate in that process, while Callose Synthase 3(CALS3), inhibits the locations where SHORTROOT(SHR), and microRNA165 can go. Additionally, the expression of NAC45/86 genes during phloem differentiation functions to enucleate specific cells in the plants to produce the sieve elements.

In the embryo, root phloem develops independently in the upper hypocotyl, which lies between the embryonic root, and the cotyledon.

In an adult, the phloem originates, and grows outwards from, meristematic cells in the vascular cambium. Phloem is produced in phases. Primary phloem is laid down by the apical meristem and develops from the procambium. Secondary phloem is laid down by the vascular cambium to the inside of the established layer(s) of phloem.

In some eudicot families (Apocynaceae, Convolvulaceae, Cucurbitaceae, Solanaceae, Myrtaceae, Asteraceae, Thymelaeaceae), phloem also develops on the inner side of the vascular cambium; in this case, a distinction between external and internal or intraxylary phloem is made. Internal phloem is mostly primary, and begins differentiation later than the external phloem and protoxylem, though it is not without exceptions. In some other families (Amaranthaceae, Nyctaginaceae, Salvadoraceae), the cambium also periodically forms inward strands or layers of phloem, embedded in the xylem: Such phloem strands are called included or interxylary phloem.

Nutritional use

Stripping the inner bark from a pine branch

Phloem of pine trees has been used in Finland and Scandinavia as a substitute food in times of famine and even in good years in the northeast. Supplies of phloem from previous years helped stave off starvation in the great famine of the 1860s which hit both Finland and Sweden (Finnish famine of 1866-1868 and Swedish famine of 1867–1869). Phloem is dried and milled to flour (pettu in Finnish) and mixed with rye to form a hard dark bread, bark bread. The least appreciated was silkko, a bread made only from buttermilk and pettu without any real rye or cereal flour. Recently, pettu has again become available as a curiosity, and some have made claims of health benefits. However, its food energy content is low relative to rye or other cereals.

Phloem from silver birch has been also used to make flour in the past.

Dendrochronology

From Wikipedia, the free encyclopedia 

https://en.wikipedia.org/wiki/Dendrochronology 

 

Drill for dendrochronology sampling and growth ring counting

 

The growth rings of a tree at Bristol Zoo, England. Each ring represents one year; the outside rings, near the bark, are the youngest

Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmospheric conditions during different periods in history from wood. Dendrochronology derives from Ancient Greek dendron (δένδρον), meaning "tree", khronos (χρόνος), meaning "time", and -logia (-λογία), "the study of".

Dendrochronology is useful for determining the precise age of samples, especially those that are too recent for radiocarbon dating, which always produces a range rather than an exact date. However, for a precise date of the death of the tree a full sample to the edge is needed, which most trimmed timber will not provide. It also gives data on the timing of events and rates of change in the environment (most prominently climate) and also in wood found in archaeology or works of art and architecture, such as old panel paintings. It is also used as a check in radiocarbon dating to calibrate radiocarbon ages.

New growth in trees occurs in a layer of cells near the bark. A tree's growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings. Each ring marks a complete cycle of seasons, or one year, in the tree's life. As of 2020, securely dated tree-ring data for the Northern Hemisphere are available going back 13,910 years. A new method is based on measuring variations in oxygen isotopes in each ring, and this 'isotope dendrochronology' can yield results on samples which are not suitable for traditional dendrochronology due to too few or too similar rings.

History

The Greek botanist Theophrastus (c. 371 – c. 287 BC) first mentioned that the wood of trees has rings. In his Trattato della Pittura (Treatise on Painting), Leonardo da Vinci (1452–1519) was the first person to mention that trees form rings annually and that their thickness is determined by the conditions under which they grew. In 1737, French investigators Henri-Louis Duhamel du Monceau and Georges-Louis Leclerc de Buffon examined the effect of growing conditions on the shape of tree rings. They found that in 1709, a severe winter produced a distinctly dark tree ring, which served as a reference for subsequent European naturalists. In the U.S., Alexander Catlin Twining (1801–1884) suggested in 1833 that patterns among tree rings could be used to synchronize the dendrochronologies of various trees and thereby to reconstruct past climates across entire regions. The English polymath Charles Babbage proposed using dendrochronology to date the remains of trees in peat bogs or even in geological strata (1835, 1838).

During the latter half of the nineteenth century, the scientific study of tree rings and the application of dendrochronology began. In 1859, the German-American Jacob Kuechler (1823–1893) used crossdating to examine oaks (Quercus stellata) in order to study the record of climate in western Texas. In 1866, the German botanist, entomologist, and forester Julius Theodor Christian Ratzeburg (1801–1871) observed the effects on tree rings of defoliation caused by insect infestations. By 1882, this observation was already appearing in forestry textbooks. In the 1870s, the Dutch astronomer Jacobus Kapteyn (1851–1922) was using crossdating to reconstruct the climates of the Netherlands and Germany. In 1881, the Swiss-Austrian forester Arthur von Seckendorff-Gudent (1845–1886) was using crossdating. From 1869 to 1901, Robert Hartig (1839–1901), a German professor of forest pathology, wrote a series of papers on the anatomy and ecology of tree rings. In 1892, the Russian physicist Fedor Nikiforovich Shvedov (Фёдор Никифорович Шведов; 1841–1905) wrote that he had used patterns found in tree rings to predict droughts in 1882 and 1891.

During the first half of the twentieth century, the astronomer A. E. Douglass founded the Laboratory of Tree-Ring Research at the University of Arizona. Douglass sought to better understand cycles of sunspot activity and reasoned that changes in solar activity would affect climate patterns on earth, which would subsequently be recorded by tree-ring growth patterns (i.e., sunspots → climate → tree rings).

Methods

Growth rings

Further information: Wood

 

Diagram of secondary growth in a tree showing idealised vertical and horizontal sections. A new layer of wood is added in each growing season, thickening the stem, existing branches and roots, to form a growth ring.

Horizontal cross sections cut through the trunk of a tree can reveal growth rings, also referred to as tree rings or annual rings. Growth rings result from new growth in the vascular cambium, a layer of cells near the bark that botanists classify as a lateral meristem; this growth in diameter is known as secondary growth. Visible rings result from the change in growth speed through the seasons of the year; thus, critical for the title method, one ring generally marks the passage of one year in the life of the tree. Removal of the bark of the tree in a particular area may cause deformation of the rings as the plant overgrows the scar.

The rings are more visible in trees which have grown in temperate zones, where the seasons differ more markedly. The inner portion of a growth ring forms early in the growing season, when growth is comparatively rapid (hence the wood is less dense) and is known as "early wood" (or "spring wood", or "late-spring wood"); the outer portion is the "late wood" (sometimes termed "summer wood", often being produced in the summer, though sometimes in the autumn) and is denser.

Pinus taeda cross section showing annual rings, Cheraw, South Carolina

Many trees in temperate zones produce one growth-ring each year, with the newest adjacent to the bark. Hence, for the entire period of a tree's life, a year-by-year record or ring pattern builds up that reflects the age of the tree and the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring, while a drought year may result in a very narrow one.

Direct reading of tree ring chronologies is a complex science, for several reasons. First, contrary to the single-ring-per-year paradigm, alternating poor and favorable conditions, such as mid-summer droughts, can result in several rings forming in a given year. In addition, particular tree species may present "missing rings", and this influences the selection of trees for study of long time-spans. For instance, missing rings are rare in oak and elm trees.

Critical to the science, trees from the same region tend to develop the same patterns of ring widths for a given period of chronological study. Researchers can compare and match these patterns ring-for-ring with patterns from trees which have grown at the same time in the same geographical zone (and therefore under similar climatic conditions). When one can match these tree-ring patterns across successive trees in the same locale, in overlapping fashion, chronologies can be built up—both for entire geographical regions and for sub-regions. Moreover, wood from ancient structures with known chronologies can be matched to the tree-ring data (a technique called cross-dating), and the age of the wood can thereby be determined precisely. Dendrochronologists originally carried out cross-dating by visual inspection; more recently, they have harnessed computers to do the task, applying statistical techniques to assess the matching. To eliminate individual variations in tree-ring growth, dendrochronologists take the smoothed average of the tree-ring widths of multiple tree-samples to build up a ring history, a process termed replication. A tree-ring history whose beginning- and end-dates are not known is called a floating chronology. It can be anchored by cross-matching a section against another chronology (tree-ring history) whose dates are known.

A fully anchored and cross-matched chronology for oak and pine in central Europe extends back 12,460 years, and an oak chronology goes back 7,429 years in Ireland and 6,939 years in England. Comparison of radiocarbon and dendrochronological ages supports the consistency of these two independent dendrochronological sequences. Another fully anchored chronology that extends back 8,500 years exists for the bristlecone pine in the Southwest US (White Mountains of California).

Dendrochronological equation

A typical form of the function of the wood ring width in accordance with the dendrochronological equation

 

A typical form of the function of the wood ring (in accordance with the dendrochronological equation) with an increase in the width of wood ring at initial stage

The dendrochronological equation defines the law of growth of tree rings. The equation was proposed by Russian biophysicist Alexandr N. Tetearing in his work "Theory of populations" in the form:

$${\displaystyle \mathrm{\Delta }L(t)=\frac{1}{k_v{\rho }^{\frac{1}{3}}}\frac{d\left(M^{\frac{1}{3}}(t)\right)}{dt},}$$

where ΔL is width of annual ring, t is time (in years), ρ is density of wood, k_v is some coefficient, M(t) is function of mass growth of the tree.

Ignoring the natural sinusoidal oscillations in tree mass, the formula for the changes in the annual ring width is:

$${\displaystyle \mathrm{\Delta }L(t)=-\frac{c_1{e}^{-a_{1}t}+c_2{e}^{-a_{2}t}}{3k_v{\rho }^{\frac{1}{3}}{\left(c_4+c_1{e}^{-a_{1}t}+c_2{e}^{-a_{2}t}\right)}^{\frac{2}{3}}}}$$

where c₁, c₂, and c₄ are some coefficients, a₁ and a₂ are positive constants.

The formula is useful for correct approximation of samples data before data normalization procedure. The typical forms of the function ΔL(t) of annual growth of wood ring are shown in the figures.

Sampling and dating

Dendrochronology allows specimens of once-living material to be accurately dated to a specific year. Dates are often represented as estimated calendar years B.P., for before present, where "present" refers to 1 January 1950.

Timber core samples are sampled and used to measure the width of annual growth rings; by taking samples from different sites within a particular region, researchers can build a comprehensive historical sequence. The techniques of dendrochronology are more consistent in areas where trees grew in marginal conditions such as aridity or semi-aridity where the ring growth is more sensitive to the environment, rather than in humid areas where tree-ring growth is more uniform (complacent). In addition, some genera of trees are more suitable than others for this type of analysis. For instance, the bristlecone pine is exceptionally long-lived and slow growing, and has been used extensively for chronologies; still-living and dead specimens of this species provide tree-ring patterns going back thousands of years, in some regions more than 10,000 years. Currently, the maximum span for fully anchored chronology is a little over 11,000 years B.P.

IntCal20 is the 2020 "Radiocarbon Age Calibration Curve", which provides a calibrated carbon 14 dated sequence going back 55,000 years. The most recent part, going back 13,900 years, is based on tree rings.

Reference sequences

European chronologies derived from wooden structures initially found it difficult to bridge the gap in the fourteenth century when there was a building hiatus, which coincided with the Black Death. However, there do exist unbroken chronologies dating back to prehistoric times, for example the Danish chronology dating back to 352 BC.

Given a sample of wood, the variation of the tree-ring growths not only provides a match by year, but can also match location because climate varies from place to place. This makes it possible to determine the source of ships as well as smaller artifacts made from wood, but which were transported long distances, such as panels for paintings and ship timbers.

Solar storms

Solar storms of known date, such as the ones in 774-775 and 993-994, can provide a fixed reference point in an unknown sequence as they cause a spike in carbon 14 in tree rings for that year all round the world. For example, wooden houses in the Viking site at L'Anse aux Meadows in Newfoundland were dated by finding the layer with the 993 spike, which showed that the wood is from a tree felled in 1021.

Applications

Radiocarbon dating calibration

Dates from dendrochronology can be used as a calibration and check of radiocarbon dating. This can be done by checking radiocarbon dates against long master sequences, with Californian bristle-cone pines in Arizona being used to develop this method of calibration as the longevity of the trees (up to c.4900 years) in addition to the use of dead samples meant a long, unbroken tree ring sequence could be developed (dating back to c.6700 BC). Additional studies of European oak trees, such as the master sequence in Germany that dates back to c.8500 BC, can also be used to back up and further calibrate radiocarbon dates.

Climatology

Main article: dendroclimatology

Dendroclimatology is the science of determining past climates from trees primarily from the properties of the annual tree rings. Other properties of the annual rings, such as maximum latewood density (MXD) have been shown to be better proxies than simple ring width. Using tree rings, scientists have estimated many local climates for hundreds to thousands of years previous.

Art history

Dendrochronology has become important to art historians in the dating of panel paintings. However, unlike analysis of samples from buildings, which are typically sent to a laboratory, wooden supports for paintings usually have to be measured in a museum conservation department, which places limitations on the techniques that can be used.

In addition to dating, dendrochronology can also provide information as to the source of the panel. Many Early Netherlandish paintings have turned out to be painted on panels of "Baltic oak" shipped from the Vistula region via ports of the Hanseatic League. Oak panels were used in a number of northern countries such as England, France and Germany. Wooden supports other than oak were rarely used by Netherlandish painters.

A portrait of Mary Queen of Scots, determined to date from the sixteenth century by dendrochronology

Since panels of seasoned wood were used, an uncertain number of years has to be allowed for seasoning when estimating dates. Panels were trimmed of the outer rings, and often each panel only uses a small part of the radius of the trunk. Consequently, dating studies usually result in a "terminus post quem" (earliest possible) date, and a tentative date for the arrival of a seasoned raw panel using assumptions as to these factors. As a result of establishing numerous sequences, it was possible to date 85–90% of the 250 paintings from the fourteenth to seventeenth century analysed between 1971 and 1982; by now a much greater number have been analysed.

A portrait of Mary, Queen of Scots in the National Portrait Gallery, London was believed to be an eighteenth-century copy. However, dendrochronology revealed that the wood dated from the second half of the sixteenth century. It is now regarded as an original sixteenth-century painting by an unknown artist.

On the other hand, dendrochronology was applied to four paintings depicting the same subject, that of Christ expelling the money-lenders from the Temple. The results showed that the age of the wood was too late for any of them to have been painted by Hieronymus Bosch.

While dendrochronology has become an important tool for dating oak panels, it is not effective in dating the poplar panels often used by Italian painters because of the erratic growth rings in poplar.

The sixteenth century saw a gradual replacement of wooden panels by canvas as the support for paintings, which means the technique is less often applicable to later paintings. In addition, many panel paintings were transferred onto canvas or other supports during the nineteenth and twentieth centuries.

Archaeology

Main article: Dendroarchaeology

The dating of buildings with wooden structures and components is also done by dendrochronology; dendroarchaeology is the term for the application of dendrochronology in archaeology. While archaeologists can date wood and when it was felled, it may be difficult to definitively determine the age of a building or structure in which the wood was used; the wood could have been reused from an older structure, may have been felled and left for many years before use, or could have been used to replace a damaged piece of wood. The dating of building via dendrochronology thus requires knowledge of the history of building technology. Many prehistoric forms of buildings used "posts" that were whole young tree trunks; where the bottom of the post has survived in the ground these can be especially useful for dating.

Examples:

• The Post Track and Sweet Track, ancient timber trackways in the Somerset levels, England, have been dated to 3838 BC and 3807 BC.
• Navan Fort where in Prehistoric Ireland a large structure was built with more than two hundred posts. The central oak post was felled in 95 BC.
• The Fairbanks House in Dedham, Massachusetts. While the house had long been claimed to have been built circa 1640 (and being the oldest wood-framed house in North America), core samples of wood taken from a summer beam confirmed the wood was from an oak tree felled in 1637–8, as wood was not seasoned before use in building at that time in New England. An additional sample from another beam yielded a date of 1641, thus confirming the house had been constructed starting in 1638 and finished sometime after 1641.
• The burial chamber of Gorm the Old, who died c. 958, was constructed from wood of timbers felled in 958.
• Veliky Novgorod, where, between the tenth and the fifteenth century, numerous consecutive layers of wooden log pavement have been placed over the accumulating dirt.

Measurement Platforms, Software and Data Formats

There are many different file formats used to store tree ring width data. Effort for standardisation was made with the development of TRiDaS. Further development led to the database software Tellervo, which is based on the new standard format whilst being able to import lots of different data formats. The desktop application can be attached to measurement devices and works with the database server that is installed separately.

Related chronologies

Herbchronology is the analysis of annual growth rings (or simply annual rings) in the secondary root xylem of perennial herbaceous plants. Similar seasonal patterns also occur in ice cores and in varves (layers of sediment deposition in a lake, river, or sea bed). The deposition pattern in the core will vary for a frozen-over lake versus an ice-free lake, and with the fineness of the sediment. Sclerochronology is the study of algae deposits.

Some columnar cacti also exhibit similar seasonal patterns in the isotopes of carbon and oxygen in their spines (acanthochronology). These are used for dating in a manner similar to dendrochronology, and such techniques are used in combination with dendrochronology, to plug gaps and to extend the range of the seasonal data available to archaeologists and paleoclimatologists.

A similar technique is used to estimate the age of fish stocks through the analysis of growth rings in the otolith bones.

Arboreal locomotion

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Arboreal_locomotion 

 

Leopards are great climbers and can carry their kills up their trees to keep them out of reach from scavengers and other predators

Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose numerous mechanical challenges to animals moving through them and lead to a variety of anatomical, behavioral and ecological consequences as well as variations throughout different species. Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains.

Some animals are exclusively arboreal in habitat, such as the tree snail.

Biomechanics

Arboreal habitats pose numerous mechanical challenges to animals moving in them, which have been solved in diverse ways. These challenges include moving on narrow branches, moving up and down inclines, balancing, crossing gaps, and dealing with obstructions.

Diameter

Moving along narrow surfaces, such as a branch of a tree, can create special difficulties to animals who are not adapted to deal with balancing on small diameter substrates. During locomotion on the ground, the location of the center of mass may swing from side to side. But during arboreal locomotion, this would result in the center of mass moving beyond the edge of the branch, resulting in a tendency to topple over and fall. Not only do some arboreal animals have to be able to move on branches of varying diameter, but they also have to eat on these branches, resulting in the need for the ability to balance while using their hands to feed themselves. This resulted in various types of grasping such as pedal grasping in order to clamp themselves onto small branches for better balance.

Incline

Branches are frequently oriented at an angle to gravity in arboreal habitats, including being vertical, which poses special problems. As an animal moves up an inclined branch, it must fight the force of gravity to raise its body, making the movement more difficult. To get past this difficulty many animals have to grasp the substrate with all four limbs and increase the frequency of their gait sequence. Conversely, as the animal descends, it must also fight gravity to control its descent and prevent falling. Descent can be particularly problematic for many animals, and highly arboreal species often have specialized methods for controlling their descent. One way animals prevent falling while descending is to increase the amount of contact their limbs are making with the substrate to increase friction and braking power.

Balance

Gibbons are very good brachiators because their elongated arms enable them to easily swing and grasp on to branches

Due to the height of many branches and the potentially disastrous consequences of a fall, balance is of primary importance to arboreal animals. On horizontal and gently sloped branches, the primary problem is tipping to the side due to the narrow base of support. The narrower the branch, the greater the difficulty in balancing a given animal faces. On steep and vertical branches, tipping becomes less of an issue, and pitching backwards or slipping downwards becomes the most likely failure. In this case, large-diameter branches pose a greater challenge since the animal cannot place its forelimbs closer to the center of the branch than its hindlimbs.

Crossing gaps

Some arboreal animals need to be able to move from tree to tree in order to find food and shelter. To be able to get from tree to tree, animals have evolved various adaptations. In some areas trees are close together and can be crossed by simple brachiation. In other areas trees are not close together and animals need to have specific adaptations to jump far distances or glide.

Obstructions

Arboreal habitats often contain many obstructions, both in the form of branches emerging from the one being moved on and other branches impinging on the space the animal needs to move through. These obstructions may impede locomotion, or may be used as additional contact points to enhance it. While obstructions tend to impede limbed animals, they benefit snakes by providing anchor points.

Anatomical specializations

Arboreal organisms display many specializations for dealing with the mechanical challenges of moving through their habitats.

Limb length

See also: Intermembral index

Arboreal animals frequently have elongated limbs that help them cross gaps, reach fruit or other resources, test the firmness of support ahead, and in some cases, to brachiate. However, some species of lizard have reduced limb size that helps them avoid limb movement being obstructed by impinging branches.

Prehensile tails

Many arboreal species, such as tree porcupines, green tree pythons, emerald tree boas, chameleons, silky anteaters, spider monkeys, and possums, use prehensile tails to grasp branches. In the spider monkey and crested gecko, the tip of the tail has either a bare patch or adhesive pad, which provide increased friction.

Clawed

The silky anteater uses its prehensile tail as a third arm for stabilization and balance, while its claws help better grasp and climb onto branches

Claws can be used to interact with rough substrates and re-orient the direction of forces the animal applies. This is what allows squirrels to climb tree trunks that are so large as to be essentially flat, from the perspective of such a small animal. However, claws can interfere with an animal's ability to grasp very small branches, as they may wrap too far around and prick the animal's own paw.

Adhesion

Adhesion is an alternative to claws, which works best on smooth surfaces. Wet adhesion is common in tree frogs and arboreal salamanders, and functions either by suction or by capillary adhesion. Dry adhesion is best typified by the specialized toes of geckos, which use van der Waals forces to adhere to many substrates, even glass.

Gripping

Frictional gripping is used by primates, relying upon hairless fingertips. Squeezing the branch between the fingertips generates a frictional force that holds the animal's hand to the branch. However, this type of grip depends upon the angle of the frictional force, thus upon the diameter of the branch, with larger branches resulting in reduced gripping ability. Animals other than primates that use gripping in climbing include the chameleon, which has mitten-like grasping feet, and many birds that grip branches in perching or moving about.

Reversible feet

To control descent, especially down large diameter branches, some arboreal animals such as squirrels have evolved highly mobile ankle joints that permit rotating the foot into a 'reversed' posture. This allows the claws to hook into the rough surface of the bark, opposing the force of gravity.

Low center of mass

Many arboreal species lower their center of mass to reduce pitching and toppling movement when climbing. This may be accomplished by postural changes, altered body proportions, or smaller size.

Small size

Small size provides many advantages to arboreal species: such as increasing the relative size of branches to the animal, lower center of mass, increased stability, lower mass (allowing movement on smaller branches), and the ability to move through more cluttered habitat. Size relating to weight affects gliding animals such as the reduced weight per snout-vent length for 'flying' frogs.

Hanging under perches

The gecko's toes adhere to surfaces via dry adhesion, to allow them to stay firmly attached to a branch or even a flat wall

Some species of primate, bat, and all species of sloth achieve passive stability by hanging beneath the branch. Both pitching and tipping become irrelevant, as the only method of failure would be losing their grip.

Behavioral specializations

Arboreal species have behaviors specialized for moving in their habitats, most prominently in terms of posture and gait. Specifically, arboreal mammals take longer steps, extend their limbs further forwards and backwards during a step, adopt a more 'crouched' posture to lower their center of mass, and use a diagonal sequence gait.

Ecological consequences

Arboreal locomotion allows animals access to different resources, depending upon their abilities. Larger species may be restricted to larger-diameter branches that can support their weight, while smaller species may avoid competition by moving in the narrower branches.

Climbing without trees

Lions on a rock at Serengeti National Park, Tanzania

Many animals climb in other habitats, such as in rock piles or mountains, and in those habitats, many of the same principles apply due to inclines, narrow ledges, and balance issues. However, less research has been conducted on the specific demands of locomotion in these habitats.

Perhaps the most exceptional of the animals that move on steep or even near vertical rock faces by careful balancing and leaping are the various types of mountain dwelling caprid such as the Barbary sheep, markhor, yak, ibex, tahr, rocky mountain goat, and chamois. Their adaptations may include a soft rubbery pad between their hooves for grip, hooves with sharp keratin rims for lodging in small footholds, and prominent dew claws. The snow leopard, being a predator of such mountain caprids, also has spectacular balance and leaping abilities; being able to leap up to ≈17m (~50 ft). Other balancers and leapers include the mountain zebra, mountain tapir, and hyraxes.

Brachiation

Main article: Brachiation

Brachiation is a specialized form of arboreal locomotion, used by primates to move very rapidly while hanging beneath branches. Arguably the epitome of arboreal locomotion, it involves swinging with the arms from one handhold to another. Only a few species are brachiators, and all of these are primates; it is a major means of locomotion among spider monkeys and gibbons, and is occasionally used by female orangutans. Gibbons are the experts of this mode of locomotion, swinging from branch to branch distances of up to 15 m (50 ft), and traveling at speeds of as much as 56 km/h (35 mph).

Gliding and parachuting

To bridge gaps between trees, many animals such as the flying squirrel have adapted membranes, such as patagia for gliding flight. Some animals can slow their descent in the air using a method known as parachuting, such as Rhacophorus (a "flying frog" species) that has adapted toe membranes allowing it to fall more slowly after leaping from trees.

Limbless climbing

Many species of snake are highly arboreal, and some have evolved specialized musculature for this habitat. While moving in arboreal habitats, snakes move slowly along bare branches using a specialized form of concertina locomotion, but when secondary branches emerge from the branch being moved on, snakes use lateral undulation, a much faster mode. As a result, snakes perform best on small perches in cluttered environments, while limbed organisms seem to do best on large perches in uncluttered environments.

Arboreal animals

Arboreal snails use their sticky slime to help in climbing up trees since they lack limbs to do so

Many species of animals are arboreal, far too many to list individually. This list is of prominently or predominantly arboreal species and higher taxa.

• Primates
• Cats
• Fruit bats
• brushtail possums
• opossums
• Sloths
• Anteaters
• Treeshrews
• Goats
• Colugos
• Kinkajous
• Viverrids
• Tree squirrels and many other rodents
• Parrots
• Geckos
• Chameleons
• Many other lizards
• Green tree pythons
• Emerald tree boas
• Mambas
• Brown Tree Snakes
• Many other snakes
• Stick insects
• Many other arthropods
• Tree snails
• Koalas
• Red pandas

Evolutionary history

The earliest known climbing tetrapod is the varanopid amniote Eoscansor from the Late Carboniferous (Pennsylvanian) of North America which is clearly specialised with adaptations for grasping, likely onto tree trunks. Suminia, a anomodont synapsid from Russia dating to the Late Permian, about 260 million years ago, was also likely a specialised climber.

Japanese macaque

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Japanese_macaque 

 

Japanese macaque
A Japanese macaque mother grooming her child
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Family:	Cercopithecidae
Genus:	Macaca
Species:	M. fuscata
Binomial name
Macaca fuscata Blyth, 1875
Subspecies
Macaca fuscata fuscata Macaca fuscata yakui
Japanese macaque range

The Japanese macaque (Macaca fuscata), also known as the snow monkey, is a terrestrial Old World monkey species that is native to Japan. Colloquially, they are referred to as "snow monkeys" because some live in areas where snow covers the ground for months each year – no other non-human primate lives further north, nor in a colder climate. Individuals have brownish grey fur, pinkish-red faces, and short tails. Two subspecies are known.

In Japan, the species is known as Nihonzaru (ニホンザル, a combination of Nihon 日本 "Japan" + saru 猿 "monkey") to distinguish it from other primates, but the Japanese macaque is very familiar in Japan — as it’s the only species of monkey in Japan — so when Japanese people simply say saru, they usually have the Japanese macaque in mind.

Physical characteristics

Skull of a Japanese macaque

The Japanese macaque is sexually dimorphic. Males weigh on average 11.3 kg (25 lb), while females average 8.4 kg (19 lb). Macaques from colder areas tend to weigh more than ones from warmer areas. The average height for males is 57.0 cm (22.4 in), while the average female height is 52.3 cm (20.6 in). The size of their brain is approximately 95 g (3.4 oz). Japanese macaques have short stumps for tails that average 92.5 mm (3.64 in) in males and 79.1 mm (3.11 in) in females. The macaque has a pinkish face and posterior. The rest of its body is covered in brown or greyish hair. The coat of the macaque is well-adapted to the cold and its thickness increases as temperatures decrease. The macaque can cope with temperatures as low as −20 °C (−4 °F).

Macaques mostly move on all fours. They are semiterrestrial, with females spending more time in the trees and males spending more time on the ground. Macaques are known to leap. They are very good swimmers and have been reported to swim a distance of more than half a kilometer. The lifespan of Japanese macaques is up to 32 years for females and up to 28 years for males, which is high when compared to what typically is seen in other macaque species.

Behavior

Group structure

Japanese macaques grooming

Japanese macaques live in matrilineal societies, and females stay in their natal groups for life, while males move out before they are sexually mature. Macaque groups tend to contain several adults of both genders. In addition, a Japanese macaque troop contains several matrilines. These matrilines may exist in a dominance hierarchy with all members of a specific group ranking over members of a lower-ranking group. Temporary all-male groups also exist, composed of those who have recently left their natal groups and are about to transfer to another group. However, many males spend ample time away from any group, and may leave and join several groups.

Japanese macaques at Jigokudani Hotspring in Nagano have become notable for their winter visits to the spa

Females of the troop exist in a stable dominance hierarchy and a female's rank depends on that of her mother. Younger females tend to rank higher than their older siblings. Higher-ranking matrilines have greater social cohesion. Strong relationships with dominant females can allow dominant males to retain their rank when they otherwise would not. Males within a group normally have a dominance hierarchy, with one male having alpha status. The dominance status of male macaques usually changes when a former alpha male leaves or dies. Other ways in which status of male hierarchy changes, is when an alpha male loses his rank or when a troop splits, leaving a new alpha male position open. The longer a male is in a troop, the higher his status is likely to be.

Females typically maintain both social relationships and hygiene through grooming. Grooming occurs regardless of climate or season. Females who are matrilineally related groom each other more often than unrelated individuals. Females will groom unrelated females to maintain group cohesion and social relationships between different kinships in a troop. Nevertheless, a female will only groom a limited number of other females, even if the group expands. Females will groom males, usually for hygienic purposes, but that behavior also may serve to attract dominant males to the group. Mothers pass their grooming techniques to their offspring, most probably through social rather than genetic means, as a cultural characteristic.

Documented female troop leadership

Yakei is a female who rose to leadership of her troop at Takasakiyama Natural Zoological Garden in 2021. Her troop consists of 677 Japanese macaque monkeys who live in a sanctuary that was established in 1952 at the zoological garden. At age nine, she overthrew the dominant males in her troop and displaced her high-ranking mother as well. She became the first female leader of the troop during its recorded history of seventy years. Yakei has retained her leadership position through her first breeding season that had been thought to be a time when she might have been challenged successfully. Both scientific and popular interest is leading to extensive coverage of Yakei's behavior.

Mating and parenting

Macaques mating

A male and female macaque form a pair bond and mate, feed, rest, and travel together during the mating season, and on average, this relationship typically lasts 16 days. Females enter into consortships with an average of four males a season. Higher-ranking males have longer consortships than their subordinates. In addition, higher-ranking males try to disrupt consortships of lower-ranking males. Females may choose to mate with males of any rank. However, dominant males mate more frequently than others, as they are more successful in mate guarding. The female decides whether mating takes place. In addition, a dominant position does not mean a male will successfully mate with a female. Males may join other troops temporarily during the mating season and mate with those females.

During the mating season, the face and genitalia of males redden and their tails stand erect, and the faces and anogenital regions of females turn scarlet. Macaques copulate both on the ground and in the trees. Roughly one in three copulations leads to ejaculation. Macaques signal when they are ready to mate by looking backward over a shoulder, staying still, or walking backward toward their potential partner. A female emits a "squawk", a "squeak", or produces an atonal "cackle" during copulation. Males have no copulatory vocalizations.

Females engage in same-sex mounting unrelated to the mating season and therefore, are mounted more often by other females than by males. This behavior has led to proposals in literature that female Japanese macaques are generally bisexual, rather than preferentially homo- or heterosexual.

Mother macaque with infant

 

Macaque juvenile yawning

A macaque mother moves to the periphery of her troop to give birth in a secluded spot, unless the group is moving, when the female must stay with it. Macaques usually give birth on the ground. Infants are born with dark-brown hair. A mother and her infant tend to avoid other troop members. The infants consume their first solid food at five to six weeks old, and by seven weeks, can forage independently from their mothers. A mother carries her infant on her belly for its first four weeks. After this time, the mother carries her infant on her back, as well. Infants continue to be carried past a year. The mother may socialize again very slowly. However, alloparenting has been observed, usually by females who have not had infants of their own. Male care of infants occurs in some groups, but not in others; when they do, usually, older males protect, groom, and carry an infant as a female would.

Infants have fully developed their locomotive abilities within three to four months. When an infant is seven months old, its mother discourages suckling; full weaning happens by its eighteenth month.

In some populations, male infants tend to play in larger groups more often than females. However, female infants have more social interaction than their male counterparts, and female infants will associate with individuals of all ages and genders. When males are two years old, they prefer to associate with other males around the same age.

Communication

During feeding or moving, Japanese macaques often emit sounds that are called "coos". These vocalizations most likely serve to keep the troop together and strengthen social relations among females. Macaques usually respond to coos with coos of their own. Coos also are uttered before grooming along with vocalizations identified as "girney" calls. Variants of the "girney" calls are made in different contexts. This call also serves as appeasement between individuals in aggressive encounters. Macaques have alarm calls for alerting to danger and other calls to signal estrus that sound similar to danger alerts. Threat calls are heard during aggressive encounters and are often uttered by supporters of those involved in antagonistic interactions. The individual being supported supports those callers in the future.

Intelligence and culture

Macaques at a hot spring

 

The famous Japanese warrior Kato Kiyomasa was depicted with his macaque who holds a writing brush, by Tsukioka Yoshitoshi (1883)

The Japanese macaque is an intelligent species. Researchers studying this species at Koshima Island in Japan left sweet potatoes out on the beach for them to eat, then witnessed one female, named Imo (Japanese for yam or potato), washing the food off with river water rather than brushing it off as the others were doing, and later even dipping her clean food into salty seawater. After a while, other members of her troop started to copy her behavior. This trait was then passed on from generation to generation, until eventually all except the oldest members of the troop were washing their food and even seasoning it in the sea. Similarly, she was the first observed balling up wheat with air pockets and soil, throwing it all into the water, and waiting for the wheat to float back up free from the soil to consume it. An altered misaccount of this incident is the basis for the "hundredth monkey" effect. That behavior also spread among her troop members.

The macaque has other unusual behaviours, including bathing together in hot springs and rolling snowballs for fun. Also, in recent studies, the Japanese macaque has been found to develop different accents, similar to human cultures. Macaques in areas separated by only a few hundred miles may have very different pitches in their calls, their form of communication. The Japanese macaque has been involved in many studies concerning neuroscience and also is used in drug testing.

Ecology

The Japanese macaque is diurnal. In colder areas, from autumn to early winter, macaques feed in between different activities. In the winter, macaques have two to four feeding bouts each day, with fewer daily activities. In the spring and summer, they have two or three bouts of feeding daily. In warmer areas such as Yakushima, daily activities are more varied. The typical day for a macaque is 20.9% inactive, 22.8% traveling, 23.5% feeding, 27.9% social grooming, 1.2% self-grooming, and 3.7% other activities. Macaques usually sleep in trees, but they also sleep on the ground, as well as on or near rocks and fallen trees. During the winter, macaques huddle together for warmth on sleeping grounds. Macaques at Jigokudani Monkey Park are notable for visiting the hot springs in the winter to warm up.

Diet

A macaque eating yakiimo

 

A Japanese macaque eating various fruits and vegetables

The Japanese macaque is omnivorous and eats a variety of foods. More than 213 species of plants are included in the macaque's diet. They also eat insects, bark, and soil. On Yakushima Island, fruit, mature leaves, and fallen seeds are primarily eaten. The macaque also eats fungi, ferns, invertebrates, and other parts of plants. In addition, in Yakushima, their diets vary seasonally with fruits being eaten in the summer and herbs being eaten in the winter. Farther north, macaques mostly eat seasonal foods such as fruit and nuts to store fat for the winter, when food is scarce. On the northern island of Kinkasan, macaques mostly eat fallen seeds, herbs, young leaves, and fruits. When preferred food items are not available, macaques dig up underground plant parts (roots or rhizomes) or eat soil and fish.

Distribution and habitat

The Japanese macaque is the northernmost-living non-human primate. It is found on three of the four main Japanese islands: Honshu, Shikoku, and Kyushu. The northernmost populations live on the Shimokita Peninsula, the northernmost point of Honshu. Several of Japan's smaller islands are inhabited by macaques as well. The southernmost population living on Yakushima Island is a subspecies of the mainland macaques, M. fuscata yakui. A study in 1989 estimated the total population of wild Japanese macaques to be 114,431 individuals.

The Japanese macaque lives in a variety of habitats. It inhabits subtropical forests in the southern part of its range and subarctic forests in mountainous areas in the northern part of its range. It can be found in both warm and cool forests, such as the deciduous forests of central and northern Japan and the broadleaf evergreen forests in the southwest of the islands. Warm temperate evergreen and broadleaf forests and cool temperate deciduous broadleaf forests are the most important habitats for macaques.

In 1972, a troop of approximately 150 Japanese macaques was relocated from Kyoto to a primate observatory in southwest Texas, United States. The observatory is an enclosed ranch-style environment and the macaques have been allowed to roam with minimal human interference. At first, many perished in the unfamiliar habitat, which consists of arid brushland. The macaques eventually adapted to the environment, learned to avoid predators (such as eagles, coyotes, and rattlesnakes), and they learned to forage for mesquite beans, cactus fruits, and other foods. The surviving macaques flourished, and by 1995, the troop consisted of 500 to 600 individuals. In 1996, hunters maimed or killed four escaped macaques; as a result, legal restrictions were publicly clarified and funds were raised to establish a new 186-acre (75 ha) sanctuary near Dilley, Texas. In 1999, the Animal Protection Institute took over management of the sanctuary and began to rescue other species of primates. As of 2017, the troop cohabitated with six other species of macaque.

Relationship with humans

Macaques gathering for yakiimo (sweet potato) being handed out by an attendant at the Iwatayama Monkey Park

Traditional human behaviors that are threats to macaques have been slash-and-burn agriculture, use of forest woods for construction and fuel, and hunting. Since World War II, these threats have declined due to social and economic changes in Japan, but other threats have emerged. The replacement of natural forests with lumber plantations is the most serious threat. As human prosperity has grown, macaques have lost their fear of humans and have increased their presence in both rural and urban areas, with one macaque recorded living in central Tokyo for several months.

Cultural depictions

Main article: Monkeys in Japanese culture

 

Monkeys in a plum tree, Mori Sosen, 1808

The Japanese macaque (snow monkey) has featured prominently in the religion, folklore, and art of Japan, as well as in proverbs and idiomatic expressions in the Japanese language.

In Shinto belief, mythical beasts known as raijū sometimes appeared as monkeys and kept Raijin, the god of lightning, company. The "three wise monkeys", who warn people to "see no evil, hear no evil and speak no evil", are carved in relief over the door of the famous Tōshō-gū shrine in Nikkō.

The Japanese macaque is a feature of several fairy tales, such as the tale of Momotarō and the fable about The Crab and the Monkey.

The monkey is part of the Chinese zodiac. That zodiac has been used for centuries in Japan and led to many representations of the macaque for that figure.

The creature was sometimes portrayed in paintings of the rich cultural epoch, the Edo period that flourished from 1603 to 1867, as a tangible metaphor for a particular year. The early nineteenth-century artist and samurai, Watanabe Kazan (1793-1841), created a painting of a macaque. The last great master of the ukiyo-e genre of woodblock printing and painting, Tsukioka Yoshitoshi, also featured the macaques in his prints. Also during the Edo period, numerous clasps for kimono or tobacco pouches (collectively called netsuke) were carved in the shape of macaques.

Spoken references to macaques abound in the history of Japan. Originating from before his rise to power, the famed samurai, Toyotomi Hideyoshi, was compared to a monkey in appearance and nicknamed Kozaru ("Little Monkey"). In modern Japanese culture, because monkeys are considered to indulge their libido openly and frequently (much the same way as rabbits are thought to in some Western cultures), a man who is preoccupied with sex might be compared to or metaphorically referred to as a monkey, as might a romantically involved couple who are exceptionally amorous.