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50-478: The roan antelope ( Hippotragus equinus ) is a large, savanna -dwelling antelope found in Western , Southern , and parts of Central and Eastern Africa . Named for its roan colour (a slightly reddish , sandy-brown ), it has a lighter-toned underbelly and a (mostly) white face and snout , but with a black "mask" around the eyes and on the bridge of the snout, being somewhat lighter in females. Additionally,

100-438: A continuous tree canopy which would prevent further grass growth. Prior to European settlement aboriginal land use practices, including fire, influenced vegetation and may have maintained and modified savanna flora. It has been suggested by many authors that aboriginal burning created a structurally more open savanna landscape. Aboriginal burning certainly created a habitat mosaic that probably increased biodiversity and changed

150-491: A dramatic reduction in basal area and canopy cover, often leaves a high percentage of woody plants alive either as seedlings too small to be affected or as plants capable of re-sprouting from lignotubers and broken stumps. A population of woody plants equal to half or more of the original number often remains following pulling of eucalypt communities, even if all the trees over 5 metres are uprooted completely. A number of exotic plants species have been introduced to savannas around

200-797: A high tree density. It is often believed that savannas feature widely spaced, scattered trees. However, in many savannas, tree densities are higher and trees are more regularly spaced than in forests. The South American savanna types cerrado sensu stricto and cerrado dense typically have densities of trees similar to or higher than that found in South American tropical forests, with savanna ranging from 800 to 3300 trees per hectare (trees/ha) and adjacent forests with 800–2000 trees/ha. Similarly Guinean savanna has 129 trees/ha, compared to 103 for riparian forest , while Eastern Australian sclerophyll forests have average tree densities of approximately 100 per hectare , comparable to savannas in

250-402: A means of clearing land. In the 1950s arboricides suitable for stem injection were developed. War-surplus heavy machinery was made available, and these were used for either pushing timber, or for pulling using a chain and ball strung between two machines. These two new methods of timber control, along with the introduction and widespread adoption of several new pasture grasses and legumes promoted

300-411: A pair of formidable, recurved horns (made of keratin -covered bone ) are present on the heads of both males and females, albeit larger on the males, growing up to 100 cm (39 in) long. Males and females have short, erect, mohawk -like manes running down their back and very light, shaggy neckbeards, both of which are more pronounced in males. Both mane and neckbeard are tinted with darker tips, which run

350-444: A reduction in the need to burn to produce a flush of green growth because legumes retain high nutrient levels throughout the year, and because fires can have a negative impact on legume populations which causes a reluctance to burn. The closed forest types such as broadleaf forests and rainforests are usually not grazed owing to the closed structure precluding grass growth, and hence offering little opportunity for grazing. In contrast

400-485: A result of global climate change, particularly at ecotones such as savannas so often represent. A savanna can simply be distinguished by the open savanna, where grass prevails and trees are rare; and the wooded savanna, where the trees are densest, bordering an open woodland or forest. Specific savanna ecoregions of several different types include: Withers The term (pronounced / ˈ w ɪ ð . ər z / ) derives from Old English wither ("against'), because

450-469: A resurgence in tree clearing. The 1980s also saw the release of soil-applied arboricides, notably tebuthiuron , that could be utilised without cutting and injecting each individual tree. In many ways "artificial" clearing, particularly pulling, mimics the effects of fire and, in savannas adapted to regeneration after fire as most Queensland savannas are, there is a similar response to that after fire. Tree clearing in many savanna communities, although causing

500-476: A shoulder height of around 130–140 cm (51–55 in). The roan antelope shares the genus Hippotragus with the extinct bluebuck ( H. leucophaeus ) and the sable antelope ( H. niger ), and is a member of the family Bovidae . It was first described by French naturalist Étienne Geoffroy Saint-Hilaire in 1803. The specific epithet equinus derives from the Latin equus ("horse-like"), referring to

550-455: A simplified yet widespread climatic concept. The divergence has sometimes caused areas such as extensive savannas north and south of the Congo and Amazon Rivers to be excluded from mapped savanna categories. In different parts of North America, the word "savanna" has been used interchangeably with " barrens ", " prairie ", " glade ", "grassland" and " oak opening ". Different authors have defined

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600-604: Is a mixed woodland - grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses. Four savanna forms exist; savanna woodland where trees and shrubs form a light canopy, tree savanna with scattered trees and shrubs, shrub savanna with distributed shrubs, and grass savanna where trees and shrubs are mostly nonexistent. Savannas maintain an open canopy despite

650-403: Is also important in jumping, as the shoulder must rotate back for the horse to bring its foreleg parallel to the ground, which will then raise the animal's knees upward and get the lower part of the forelegs out of the way. Therefore, the withers have a direct impact on one of the most important points of conformation : the shoulder. In dogs , the height of the withers is often used to determine

700-477: Is not prominent but that rivers in savanna landscapes erode more by lateral migration . Flooding and associated sheet wash have been proposed as dominant erosion processes in savanna plains. The savannas of tropical America comprise broadleaved trees such as Curatella , Byrsonima , and Bowdichia , with grasses such as Leersia and Paspalum . Bean relative Prosopis is common in the Argentinian savannas. In

750-473: Is possible for there to be multiple stable biomes. The annual rainfall ranges from 500 mm (19.69 in) to 1,270 mm (50.00 in) per year, with the precipitation being more common in six or eight months of the year, followed by a period of drought. Savannas may at times be classified as forests. In climatic geomorphology it has been noted that many savannas occur in areas of pediplains and inselbergs . It has been posited that river incision

800-419: Is vague and therefore the two can be combined into a single biome as both woodlands and savannas feature open-canopied trees with crowns not usually interlinking (mostly forming 25-60% cover). Over many large tropical areas, the dominant biome (forest, savanna or grassland) can not be predicted only by the climate, as historical events plays also a key role, for example, fire activity. In some areas, indeed, it

850-455: The Mediterranean region were likewise created and maintained by anthropogenic fire. Intentional controlled burns typically create fires confined to the herbaceous layer that do little long term damage to mature trees. This prevents more catastrophic wildfires that could do much more damage. However, these fires either kill or suppress tree seedlings, thus preventing the establishment of

900-476: The greenhouse effect may result in an alteration of the structure and function of savannas. Some authors have suggested that savannas and grasslands may become even more susceptible to woody plant encroachment as a result of greenhouse induced climate change . However, a recent case described a savanna increasing its range at the expense of forest in response to climate variation, and potential exists for similar rapid, dramatic shifts in vegetation distribution as

950-717: The prairies in North America and steppes in Eurasia , which feature cold winters, savannas are mostly located in areas having warm to hot climates, such as in Africa, Australia, Thailand, South America and India. The word derives from the Spanish sabana , which is itself a loanword from Taíno , which means "treeless grassland" in the West Indies . The letter b in Spanish, when positioned in

1000-467: The 1996 analysis: blesbok ( Damaliscus pygargus phillipsi ) bontebok ( Damaliscus pygargus pygarus ) bluebuck ( Hippotragus leucophaeus )† extinct roan antelope ( Hippotragus equinus ) sable antelope ( Hippotragus niger ) In 1974, palaeoanthropologist Richard Klein studied the fossils of Hippotragus species in South Africa. Most of these were found to represent the bluebuck and

1050-544: The Australian savanna, mammals in the family Macropodidae predominate, such as kangaroos and wallabies, though cattle, horses, camels, donkeys and the Asian water buffalo , among others, have been introduced by humans. It is estimated that less than three percent of savanna ecosystems can be classified as highly intact. Reasons for savanna degradation are manifold, as outlined below. Savannas are subject to regular wildfires and

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1100-499: The East African savannas, Acacia , Combretum , baobabs , Borassus , and Euphorbia are a common vegetation genera. Drier savannas there feature spiny shrubs and grasses, such as Andropogon , Hyparrhenia , and Themeda . Wetter savannas include Brachystegia trees and Pennisetum purpureum , and elephant grass type. West African savanna trees include Anogeissus , Combretum , and Strychnos . Indian savannas are mostly cleared, but

1150-513: The Northern Territory, Australia savanna, and 480,000 ha of savanna were being cleared annually in Queensland in the 2000s, primarily to improve pasture production. Substantial savanna areas have been cleared of woody vegetation and much of the area that remains today is vegetation that has been disturbed by either clearing or thinning at some point in the past. Clearing is carried out by

1200-415: The court of the cacique Carlos in present-day Panama . The accounts are inexact, but this is usually placed in present-day Madugandí or at points on the nearby Guna Yala coast opposite Ustupo or on Point Mosquitos . These areas are now either given over to modern cropland or jungle . Many grassy landscapes and mixed communities of trees, shrubs, and grasses were described as savanna before

1250-555: The ecosystem appears to be the result of human use of fire. For example, Native Americans created the Pre-Columbian woodlands of North America by periodically burning where fire-resistant plants were the dominant species. Aboriginal burning appears to have been responsible for the widespread occurrence of savanna in tropical Australia and New Guinea , and savannas in India are a result of human fire use. The maquis shrub savannas of

1300-467: The establishment, growth and survival of plant species and in turn can lead to a change in woodland structure and composition. That being said, impact of grazing animals can be reduced. Looking at Elephant impact on Savannas, the overall impact is reduced in the presence of rainfall and fences. Large areas of Australian and South American savannas have been cleared of trees, and this clearing continues today. For example, land clearing and fracking threaten

1350-471: The eyes and the mouth on the otherwise black face, and long, narrow ears with 3–5 cm (1.2–2.0 in) long tufts. The horns are ringed and arched backwards, which can reach 100 cm (39 in) long in males, slightly shorter in females. The long legs are supported by large hooves. The short, smooth coat is brown to amber. The ventral parts are yellow to white, while the neck and the manes are gray to black. They are somewhat similar in appearance to

1400-483: The grazing industry in an attempt to increase the quality and quantity of feed available for stock and to improve the management of livestock. The removal of trees from savanna land removes the competition for water from the grasses present, and can lead to a two to fourfold increase in pasture production, as well as improving the quality of the feed available. Since stock carrying capacity is strongly correlated with herbage yield, there can be major financial benefits from

1450-404: The horse are considered in evaluating conformation. Generally, a horse should have well-defined withers, as they are considered an important attachment point for the muscles of the torso. Withers of medium height are preferred, as high withers make it difficult to fit a saddle and are often associated with a narrow chest, and low withers (known as "mutton withers") do not provide a ridge to help keep

1500-465: The horse's head does, the withers are used as the measuring point for the height of a horse. Horses are sometimes measured in hands – one hand is 4 inches (10.2 cm). Horse heights are extremely variable, from small pony breeds to large draft breeds. The height at the withers of an average thoroughbred is 163 centimetres (16.0 hands; 5 ft 4 in), and ponies are up to 147 centimetres (14.2 hands; 4 ft 10 in). The withers of

1550-434: The horse-like appearance of this antelope. In 1996, an analysis of mitochondrial DNA extracted from a mounted specimen of the bluebuck found that it was outside the clade containing the roan and sable antelopes. The study therefore concluded that the bluebuck is a distinct species, and not merely a subspecies of the roan antelope. The cladogram below shows the position of the roan antelope among its relatives, following

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1600-494: The length of the animal's back and belly, ending in a dark-coloured tail. The ears are long, erect, and donkey -like. The roan is among the world's largest antelopes, after the elands ( Taurotragus sp.) and the nilgai ( Boselaphus tragocamelus ), measuring 190–240 cm (75–94 in) from the head to the base of the tail, with a 37–48 cm (15–19 in)-long tail. Males weigh upwards of 242–300 kg (534–661 lb) and females 223–280 kg (492–617 lb), with

1650-554: The lower limits of savanna tree coverage as 5–10% and upper limits range as 25–80% of an area. Two factors common to all savanna environments are rainfall variations from year to year, and dry season wildfires . In the Americas , e.g. in Belize , Central America , savanna vegetation is similar from Mexico to South America and to the Caribbean . The distinction between woodland and savanna

1700-461: The middle of a word, is pronounced almost like an English v; hence the change of grapheme when transcribed into English. The word originally entered English as the Zauana in a description of the ilands of the kinges of Spayne from 1555. This was equivalent in the orthography of the times to zavana (see history of V ). Peter Martyr reported it as the local name for the plain around Comagre,

1750-425: The middle of the 19th century, when the concept of a tropical savanna climate became established. The Köppen climate classification system was strongly influenced by effects of temperature and precipitation upon tree growth, and oversimplified assumptions resulted in a tropical savanna classification concept which considered it as a "climatic climax" formation. The common usage to describe vegetation now conflicts with

1800-469: The open structure of savannas allows the growth of a herbaceous layer and is commonly used for grazing domestic livestock. As a result, much of the world's savannas have undergone change as a result of grazing by sheep, goats and cattle, ranging from changes in pasture composition to woody plant encroachment . The removal of grass by grazing affects the woody plant component of woodland systems in two major ways. Grasses compete with woody plants for water in

1850-438: The potential to significantly alter the structure and composition of savannas worldwide, and have already done so in many areas through a number of processes including altering the fire regime, increasing grazing pressure, competing with native vegetation and occupying previously vacant ecological niches. Other plant species include: white sage, spotted cactus, cotton seed, rosemary. Human induced climate change resulting from

1900-431: The removal of trees, such as assisting with grazing management: regions of dense tree and shrub cover harbors predators, leading to increased stock losses, for example, while woody plant cover hinders mustering in both sheep and cattle areas. A number of techniques have been employed to clear or kill woody plants in savannas. Early pastoralists used felling and girdling , the removal of a ring of bark and sapwood , as

1950-580: The reserved ones feature Acacia, Mimosa , and Zizyphus over a grass cover comprising Sehima and Dichanthium . The Australian savanna is abundant with sclerophyllous evergreen vegetation, which include the eucalyptus , as well as Acacia, Bauhinia , Pandanus with grasses such as Heteropogon and kangaroo grass (Themeda). Animals in the African savanna generally include the giraffe, elephant, buffalo, zebra, gnu, hippopotamus, rhinoceros, and antelope, where they rely on grass and/or tree foliage to survive. In

2000-616: The roan antelope. The roan antelope seems to have appeared in the Nelson Bay Cave region following climatic changes in the Holocene . Six subspecies are recognised: The roan antelope is a large antelope with a horse-like build. It is the largest antelope in the genus Hippotragus , and one of the largest species of antelopes in the world. Only elands , bongos and large male greater kudus can exceed them in weight on average. The roan antelope stands 135–160 centimetres (53–63 in) at

2050-768: The sable antelopes and can be confused where their ranges overlap. Sable antelope males are notably darker, being brownish-black rather than dark brown. Roan antelopes can be found in woodland, grassland, and savannah; mainly in the tropical and subtropical grasslands, savannas, and shrublands biome , which range in tree density from forest with a grassy understory (such as the central Zambezian Miombo woodlands) to grasslands dotted with few trees, where they eat mid-length grasses . They live in small groups and form harem groups of 5 to 15 animals with one dominant male. Males commonly fight among themselves for dominance of their herd, brandishing their horns while both animals are on their knees. Savanna A savanna or savannah

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2100-401: The saddle in place. More importantly, the dorsal spinal processes provide an attachment for the muscles that support the shoulder and neck. Horses do not have a clavicle , so the shoulder can freely rotate backwards. If the vertebrae of the withers are long front-to-back, the shoulder is freer to move backwards. This allows for an increase of stride length. thus increasing the horse's speed. It

2150-449: The same region. Savannas are also characterised by seasonal water availability, with the majority of rainfall confined to one season. They are associated with several types of biomes , and are frequently in a transitional zone between forest and desert or grassland , though mostly a transition between desert to forest. Savanna covers approximately 20% of the Earth's land area. Unlike

2200-419: The shoulder, and weighs 230–320 kilograms (510–710 pounds). The head-and-body length is typically between 235 and 285 centimetres (93 and 112 inches). The dark tail, terminating in a black tuft, measures up to 54 cm (21 in). Characteristic features include a short, erect mane of grayish brown hair extending from the back of the neck along the midline of the back up to the withers , white patches around

2250-515: The soil caused by the hooves of animals and through the erosion effects caused by the removal of protective plant cover. Such effects are most likely to occur on land subjected to repeated and heavy grazing. The effects of overstocking are often worst on soils of low fertility and in low rainfall areas below 500 mm, as most soil nutrients in these areas tend to be concentrated in the surface so any movement of soils can lead to severe degradation. Alteration in soil structure and nutrient levels affects

2300-606: The spread of weeds in savannas by the removal or reduction of the plants which would normally compete with potential weeds and hinder establishment. In addition to this, cattle and horses are implicated in the spread of the seeds of weed species such as prickly acacia ( Acacia nilotica ) and stylo ( Stylosanthes species). Alterations in savanna species composition brought about by grazing can alter ecosystem function, and are exacerbated by overgrazing and poor land management practices. Introduced grazing animals can also affect soil condition through physical compaction and break-up of

2350-519: The structure of woodlands and geographic range of numerous woodland species. It has been suggested by many authors that with the removal or alteration of traditional burning regimes many savannas are being replaced by forest and shrub thickets with little herbaceous layer. The consumption of herbage by introduced grazers in savanna woodlands has led to a reduction in the amount of fuel available for burning and resulted in fewer and cooler fires. The introduction of exotic pasture legumes has also led to

2400-463: The topsoil and removal by grazing reduces this competitive effect, potentially boosting tree growth. In addition to this effect, the removal of fuel reduces both the intensity and the frequency of fires which may control woody plant species. Grazing animals can have a more direct effect on woody plants by the browsing of palatable woody species. There is evidence that unpalatable woody plants have increased under grazing in savannas. Grazing also promotes

2450-409: The withers are the part of a draft animal that pushes against a load . The withers in horses are formed by the dorsal spinal processes of roughly the 3rd through 11th thoracic vertebrae , which are unusually long in this area. Most horses have 18 thoracic vertebrae. The processes at the withers can be more than 30 centimetres (12 in) long. Since they do not move relative to the ground as

2500-665: The world. Amongst the woody plant species are serious environmental weeds such as Prickly Acacia ( Acacia nilotica ), Rubbervine ( Cryptostegia grandiflora ), Mesquite ( Prosopis spp.), Lantana ( Lantana camara and L. montevidensis ) and Prickly Pear ( Opuntia spp.). A range of herbaceous species have also been introduced to these woodlands, either deliberately or accidentally including Rhodes grass and other Chloris species, Buffel grass ( Cenchrus ciliaris ), Giant rat's tail grass ( Sporobolus pyramidalis ) parthenium ( Parthenium hysterophorus ) and stylos ( Stylosanthes spp.) and other legumes . These introductions have

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