Thomas Jefferson
Thomas Jefferson was an American Founding Father who was the principal author of the Declaration of Independence and served as the third President of the United States from 1801 to 1809. Previously, he was elected the second Vice President of the United States, Jefferson was primarily of English ancestry and educated in colonial Virginia. He graduated from the College of William & Mary and briefly practiced law and he became the United States Minister to France in May 1785, and subsequently the nations first Secretary of State in 1790–1793 under President George Washington. Jefferson and James Madison organized the Democratic-Republican Party to oppose the Federalist Party during the formation of the First Party System, as President, Jefferson pursued the nations shipping and trade interests against Barbary pirates and aggressive British trade policies. He organized the Louisiana Purchase, almost doubling the countrys territory, as a result of peace negotiations with France, his administration reduced military forces.
Jeffersons second term was beset with difficulties at home, including the trial of former Vice President Aaron Burr, American foreign trade was diminished when Jefferson implemented the Embargo Act of 1807, responding to British threats to U. S. shipping. In 1803, Jefferson began a process of Indian tribe removal to the newly organized Louisiana Territory. Jefferson mastered many disciplines, which ranged from surveying and mathematics to horticulture and he was a proven architect in the classical tradition. Jeffersons keen interest in religion and philosophy earned him the presidency of the American Philosophical Society and he shunned organized religion, but was influenced by both Christianity and deism. He was well versed in linguistics and spoke several languages and he founded the University of Virginia after retiring from public office. He was a letter writer and corresponded with many prominent and important people throughout his adult life. His only full-length book is Notes on the State of Virginia, Jefferson owned several plantations which were worked by hundreds of slaves.
Most historians now believe that, after the death of his wife in 1782, he had a relationship with his slave Sally Hemings and fathered at least one of her children. Various modern scholars are more critical of Jeffersons private life, pointing out the discrepancy between his ownership of slaves and his political principles, for example. Presidential scholars, consistently rank Jefferson among the greatest presidents, Thomas Jefferson was born on April 13,1743, at the family home in Shadwell in the Colony of Virginia, the third of ten children. He was of English and possibly Welsh descent and was born a British subject and his father Peter Jefferson was a planter and surveyor who died when Jefferson was fourteen, his mother was Jane Randolph. Peter Jefferson moved his family to Tuckahoe Plantation in 1745 upon the death of a friend who had named him guardian of his children, the Jeffersons returned to Shadwell in 1752, where Peter died in 1757, his estate was divided between his sons Thomas and Randolph.
Thomas inherited approximately 5,000 acres of land, including Monticello and he assumed full authority over his property at age 21
Mammoth
A mammoth is any species of the extinct genus Mammuthus, proboscideans commonly equipped with long, curved tusks and, in northern species, a covering of long hair. They lived from the Pliocene epoch into the Holocene at about 4,500 years ago in Africa, Europe and they were members of the family Elephantidae, which contains the two genera of modern elephants and their ancestors. Mammoths stem from a species called M. africanavus, the African mammoth. These mammoths lived in northern Africa and disappeared about 3 or 4 million years ago, descendants of these mammoths moved north and eventually covered most of Eurasia. These were M. meridionalis, the southern mammoths, the earliest known proboscideans, the clade that contains the elephants, existed about 55 million years ago around the Tethys Sea area. The closest relatives of the Proboscidea are the sirenians and the hyraxes, the family Elephantidae is known to have existed six million years ago in Africa, and includes the living elephants and the mammoths.
Among many now extinct clades, the mastodon is only a distant relative of the mammoths, and part of the separate Mammutidae family, which diverged 25 million years before the mammoths evolved. At the same time, the crowns of the teeth became longer, the first known members of the genus Mammuthus are the African species M. subplanifrons from the Pliocene and M. africanavus from the Pleistocene. The former is thought to be the ancestor of forms, Mammoths entered Europe around 3 million years ago, the earliest known type has been named M. rumanus, which spread across Europe and China. Only its molars are known, which show it had 8–10 enamel ridges, a population evolved 12–14 ridges and split off from and replaced the earlier type, becoming M. meridionalis. In turn, this species was replaced by the mammoth, M. trogontherii, with 18–20 ridges. Mammoths derived from M. trogontherii evolved molars with 26 ridges 200,000 years ago in Siberia, the Columbian mammoth, M. columbi, evolved from a population of M.
trogontherii that had entered North America. A2011 genetic study showed that two examined specimens of the Columbian mammoth were grouped within a subclade of woolly mammoths and this suggests that the two populations interbred and produced fertile offspring. It suggested that a North American form known as M. jeffersonii may be a hybrid between the two species, variations in environment, climate change, and migration surely played roles in the evolutionary process of the mammoths. Take M. primigenius for example, Woolly mammoths lived in opened grassland biomes, the cool steppe-tundra of the Northern Hemisphere was the ideal place for mammoths to thrive because of the resources it supplied. With occasional warmings during the ice age, climate would change the landscape, the word mammoth was first used in Europe during the early 1600s, when referring to maimanto tusks discovered in Siberia. John Bell, who was on the Ob River in 1722 and they were called mammons horn and were often found in washed-out river banks.
Some local people claimed to have seen a living mammoth, but they came out at night
Deer
Deer are the ruminant mammals forming the family Cervidae. The two main groups are the Cervinae, including the muntjac, the deer and the chital, and the Capreolinae, including the elk, the Western roe deer. Female reindeer, and male deer of all species, grow, in this they differ from permanently horned antelope, which are in the same order, Artiodactyla. The musk deer of Asia and water chevrotain of tropical African and Asian forests are not usually regarded as true deer and form their own families and Tragulidae, respectively. Deer appear in art from Palaeolithic cave paintings onwards, and they have played a role in mythology and their economic importance includes the use of their meat as venison, their skins as soft, strong buckskin, and their antlers as handles for knives. Deer hunting has been a sport since at least the Middle Ages. Deer live in a variety of biomes, ranging from tundra to the tropical rainforest, while often associated with forests, many deer are ecotone species that live in transitional areas between forests and thickets and prairie and savanna.
The majority of deer species inhabit temperate mixed deciduous forest, mountain mixed coniferous forest, tropical seasonal/dry forest. Clearing open areas within forests to some extent may actually benefit deer populations by exposing the understory and allowing the types of grasses, additionally, access to adjacent croplands may benefit deer. However, adequate forest or brush cover must still be provided for populations to grow, fallow deer have been introduced to South Africa. There are species of deer that are highly specialized, and live almost exclusively in mountains, swamps. Some deer have a distribution in both North America and Eurasia. Examples include the caribou that live in Arctic tundra and taiga and moose that inhabit taiga, huemul deer of South Americas Andes fill the ecological niches of the ibex and wild goat, with the fawns behaving more like goat kids. Mountain slope habitats vary from moist coniferous/mixed forested habitats to dry forests with alpine meadows higher up. The foothills and river valleys between the mountain provide a mosaic of cropland and deciduous parklands.
The rare woodland caribou have the most restricted range living at altitudes in the subalpine meadows. Elk and mule deer both migrate between the alpine meadows and lower coniferous forests and tend to be most common in this region, elk inhabit river valley bottomlands, which they share with White-tailed deer. They live in the aspen parklands north of Calgary and Edmonton, the adjacent Great Plains grassland habitats are left to herds of elk, American bison, and pronghorn antelope
Elk
The elk, or wapiti, is one of the largest species within the deer family, Cervidae, in the world, and one of the largest land mammals in North America and Eastern Asia. This animal should not be confused with the still larger moose to which the name elk applies in British English, apart from the moose, the only other member of the deer family to rival the elk in size is the south Asian sambar. Elk range in forest and forest-edge habitat, feeding on grasses, leaves, male elk have large antlers which are shed each year. Although they are native to North America and eastern Asia, they have adapted well to countries in which they have introduced, including Argentina. Their great adaptability may threaten endemic species and ecosystems into which they have been introduced, Elk are susceptible to a number of infectious diseases, some of which can be transmitted to livestock. Efforts to eliminate infectious diseases from elk populations, largely by vaccination, have had mixed success, some cultures revere the elk as a spiritual force.
In parts of Asia and their velvet are used in traditional medicines, Elk are hunted as a game species. The meat is leaner and higher in protein than beef or chicken and it was long believed to be a subspecies of the European red deer, but evidence from a number of mitochondrial DNA genetic studies beginning in 1998 show that the two are distinct species. Key morphological differences that distinguish C. canadensis from C. elaphus are the formers wider rump patch and paler-hued antlers. The word elk is related to the Latin alces, Old Norse elgr, Scandinavian elg/älg and German Elch, the name wapiti is from the Shawnee and Cree word waapiti, meaning white rump. This name is used in particular for the Asian subspecies, because in Eurasia the name elk continues to be used for the moose, Asian subspecies are sometimes referred to as the maral, but this name applies primarily to the Caspian red deer, a subspecies of red deer. There is a subspecies of elk in Mongolia called the Altai wapiti, members of the genus Cervus first appear in the fossil record 25 million years ago, during the Oligocene in Eurasia, but do not appear in the North American fossil record until the early Miocene.
The extinct Irish elk was not a member of the genus Cervus, until recently, red deer and elk were considered to be one species, Cervus elaphus. However, the two species have freely inter-bred in New Zealands Fiordland National Park, where the animals have all. There are numerous subspecies of elk described, with six from North America and four from Asia, populations vary as to antler shape and size, body size and mating behavior. DNA investigations of the Eurasian subspecies revealed that phenotypic variation in antlers, mane, of the six subspecies of elk known to have inhabited North America in historical times, four remain, including the Roosevelt, tule and Rocky Mountain. The eastern elk and Merriams elk subspecies have been extinct for at least a century, four subspecies described in Asia include the Altai wapiti and the Tianshan wapiti. Two distinct subspecies found in China and Korea are the Manchurian wapiti, the Manchurian wapiti is darker and more reddish in coloration than the other populations
Grassland
Grasslands are areas where the vegetation is dominated by grasses, however sedge and rush families can be found. Grasslands occur naturally on all continents except Antarctica, grasslands are found in most ecoregions of the Earth. For example, there are five terrestrial ecoregion classifications of the grasslands and shrublands biome. Grassland vegetation can vary in height from short, as in chalk grassland, to quite tall, as in the case of North American tallgrass prairie, South American grasslands. Woody plants, shrubs or trees, may occur on some grasslands – forming savannas, scrubby grassland or semi-wooded grassland, as flowering plants and trees, grasses grow in great concentrations in climates where annual rainfall ranges between 500 and 900 mm. The root systems of perennial grasses and forbs form complex mats that hold the soil in place, graminoids are among the most versatile life forms. Existing forest biomes declined, and grasslands became much more widespread, following the Pleistocene ice ages, grasslands expanded in range in the hotter, drier climates, and began to become the dominant land feature worldwide.
Grasslands often occur in areas with annual precipitation between 600 mm and 1,500 mm and average annual temperatures ranges from −5 and 20 °C. However, some occur in colder and hotter climatic conditions. Grassland can exist in habitats that are disturbed by grazing or fire. Grasslands dominated by unsown wild-plant communities can be called natural or semi-natural habitats. The majority of grasslands in temperate climates are semi-natural and these grasslands contain many species of wild plants – grasses, sedges and herbs –25 or more species per square metre is not unusual. Chalk downlands in England can support over 40 species per square metre, in many parts of the world, few examples have escaped agricultural improvement. For example, original North American prairie grasslands or lowland wildflower meadows in the UK are now rare and their associated wild flora equally threatened. Some of the worlds largest expanses of grassland are found in African savanna, grasslands may occur naturally or as the result of human activity.
Grasslands created and maintained by human activity are called anthropogenic grasslands, hunting peoples around the world often set regular fires to maintain and extend grasslands, and prevent fire-intolerant trees and shrubs from taking hold. The tallgrass prairies in the U. S. Midwest may have been extended eastward into Illinois, much grassland in northwest Europe developed after the Neolithic Period, when people gradually cleared the forest to create areas for raising their livestock. Grassland types by Schimper, meadow steppe savannah Grassland types by Ellenberg & Mueller-Dombois, terrestrial herbaceous communities A. Savannas and related grasslands B
Lexington, Kentucky
Lexington, consolidated with Fayette County, is the second-largest city in Kentucky and the 61st largest in the United States. Known as the Horse Capital of the World, it is the heart of the states Bluegrass region, with a mayor-alderman form of government, it is one of two cities in Kentucky designated by the state as first-class, the other is the states largest city of Louisville. In the 2016 U. S. Census Estimate, the population was 318,449, anchoring a metropolitan area of 506,751 people. Lexington ranks tenth among US cities in college education rate, with 39. 5% of residents having at least a bachelors degree and this area of fertile soil and abundant wildlife was long occupied by varying tribes of Native Americans. European explorers began to trade with them but settlers did not come in force until the late 18th century, Lexington was founded by European Americans in June 1775, in what was considered Fincastle County, Virginia,17 years before Kentucky became a state. A party of frontiersmen, led by William McConnell, camped on the Middle Fork of Elkhorn Creek at the site of the present-day McConnell Springs, upon hearing of the colonists victory in the Battles of Lexington and Concord on April 19,1775, they named their campsite Lexington.
It was the first of what would be many American places to be named after the Massachusetts town, the risk of Indian attacks delayed permanent settlement for four years. In 1779, during the American Revolutionary War, Col. Robert Patterson and 25 companions came from Fort Harrod and they built cabins and a stockade, establishing a settlement known as Bryan Station. In 1780, Lexington was made the seat of Virginias newly organized Fayette County, colonists defended it against a British and allied Shawnee attack in 1782, during the last part of the American Revolutionary War. The town was chartered on May 6,1782, by an act of the Virginia General Assembly, the First African Baptist Church was founded c. 1790 by Peter Durrett, a Baptist preacher and slave held by Joseph Craig. Durrett helped guide The Travelling Church, a migration of several hundred pioneers led by the preacher Lewis Craig and Captain William Ellis from Orange County. It is the oldest black Baptist congregation in Kentucky and the third oldest in the United States, I would suppose it contains about five hundred dwelling houses, many of them elegant and three stories high.
The country around Lexington for many miles in every direction, is equal in beauty and fertility to anything the imagination can paint and is already in a state of cultivation. Residents have fondly continued to refer to Lexington as The Athens of the West since Espys poem dedicated to the city, in the early 19th century, planter John Wesley Hunt became the first millionaire west of the Alleghenies. London Ferrill, second preacher of First African Baptist, was one of three clergy who stayed in the city to serve the suffering victims, additional cholera outbreaks occurred in 1848–49 and the early 1850s. Cholera was spread by using contaminated water supplies, but its transmission was not understood in those years. Often the wealthier people would flee town for outlying areas to try to avoid the spread of disease, planters held slaves for use as field hands, laborers and domestic servants. In the city, slaves worked primarily as servants and artisans, although they worked with merchants, shippers
Pleistocene megafauna
Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch and became extinct during the Quaternary extinction event. Megafauna is a used to describe an animal with an adult body weight of over 44 kg. The Ice Age reached its peak during the last glacial maximum, a vast mammoth steppe stretched from the Iberian peninsula across Eurasia and over the Bering land bridge into Alaska and the Yukon where it was stopped by the Wisconsin glaciation. This land bridge existed because more of the water was locked up in glaciation than now. When the sea began to rise this bridge was inundated around 11,000 years BP. During the last glacial maximum, the continent of Europe was much colder and drier than it is today, with polar desert in the north and woodland was almost non-existent, except for isolated pockets in the mountain ranges of southern Europe. The fossil evidence from many points to the extinction mainly of large animals at or near the end of the last glaciation.
These animals have been termed Pleistocene megafauna, the most common definition of megafauna is an animal with an adult body weight of over 44 kg. Across Eurasia, the elephant became extinct between 100, 000–50,000 years BP. The hippopotamus, interglacial rhinoceros, cave bear, and heavy-bodied Asian antelope died out between 50, 000-16,000 years BP, the spotted hyena, woolly rhinoceros and mammoths died out between 16, 000-11,500 years BP. The musk ox died out after 11,500 BP, as did the giant deer with the last pocket having survived until about 7,700 years BP in western Siberia, a pocket of mammoths survived on Wrangel Island until 4,500 years BP. As some species became extinct, so too did their predators, among the top predators, the sabre-toothed cat died out 28,000 years BP, the cave lion 11,900 years BP, and the leopard in Europe died out 27,000 years BP. The Late Pleistocene was characterized by a series of severe and rapid climate oscillations with regional temperature changes of up to 16 °C, there is no evidence of megafaunal extinctions at the height of the LGM, indicating that increasing cold and glaciation were not factors.
Multiple events appear to involve the rapid replacement of one species by one within the same genus, or one population by another within the same species. The ancestors of humans first appeared in East Africa 195,000 years ago. Some migrated out of Africa 60,000 years ago with one group reaching Central Asia 50,000 years ago. From there they reached Europe, with human remains dated 43, 000-45,000 years BP discovered in Italy, another group left Central Asia and reached the Yana River, well above the Arctic circle 27,000 years ago. Remains of mammoth that had been hunted by humans 45,000 YBP have been found at Yenisei Bay in the central Siberian Arctic and these people populated the Americas
Muskox
This musky odor is used to attract females during mating season. Its Inuktitut name umingmak translates to the bearded one. Muskoxen primarily live in the Canadian Arctic and Greenland, with introduced populations in Sweden, Norway. As members of the subfamily Caprinae of the family Bovidae, muskoxen are more related to sheep and goats than to oxen, they are placed in their own genus. The muskox is one of the two largest extant members of Caprinae, along with the similarly sized takin, the muskoxs closest living relatives appear to be the gorals of the genus Naemorhedus, nowadays common in many countries of central and east Asia. The vague similarity between takin and muskox must therefore be considered an example of convergent evolution, the modern muskox is the last member of a line of ovibovines that first evolved in temperate regions of Asia and adapted to a cold tundra environment late in its evolutionary history. Later migration waves of Asian ungulates that included high-horned muskoxen reached Europe, Euceratherium was larger yet more lightly built than modern muskoxen, looking like a giant sheep with massive horns, and preferred hilly grasslands.
A genus with horns, inhabited Eurasia in the early Pleistocene, from Spain to Siberia. The low-horned Praeovibos was present in Europe and the Mediterranean 1.5 million years ago, colonized Alaska, Praeovibos was a highly adaptable animal that appears associated with cold tundra and temperate woodland faunas alike. It is debated, however, if Praeovibos was directly ancestral to Ovibos, modern Ovibos appeared in Germany almost one million years ago and was common in the region through the Pleistocene. By the Mindel, muskoxen had reached the British Isles, the muskox is known to have survived in Britain during warm interglacial periods. After migrating south during one of the periods of the Illinoian glaciation. The muskox was already present in its current stronghold of Banks Island 34,000 years ago, but the existence of other ice-free areas in the Canadian Arctic Archipelago at the time is disputed. Along with the bison and the pronghorn, the muskox was one of a few species of Pleistocene megafauna in North America to survive the Pleistocene/Holocene extinction event, the muskox is thought to have been able to survive the Last glacial period by finding ice-free areas away from prehistoric peoples.
Fossil DNA evidence suggests that muskoxen were not only more geographically widespread during the Pleistocene, during that time, other populations of muskoxen lived across the Arctic, from the Ural Mountains to Greenland. By contrast, the current genetic makeup of the species is more homogenous, both male and female muskoxen have long, curved horns. Muskoxen stand 1.1 to 1.5 m high at the shoulder, with females measuring 135 to 200 cm in length, the small tail, often concealed under a layer of fur, measures only 10 cm long. Adults, on average, weigh 285 kg and range from 180 to 410 kg, the thick coat and large head suggests a larger animal than the muskox truly is, the bison, to which the muskox is often compared, can weigh up to twice as much. However, heavy zoo-kept specimens have weighed up to 650 kg and their coat, a mix of black and brown, includes long guard hairs that almost reach the ground
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain.
This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation provided that the Hayden and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it maintains long-term archives of earthquake data for scientific and engineering research.
It conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System database
The Cincinnati Post
The Cincinnati Post was an afternoon daily newspaper published in Cincinnati, United States. In Northern Kentucky, it was bundled inside a local edition called The Kentucky Post, the Post was a founding publication and onetime flagship of Scripps-Howard Newspapers, a division of the E. W. Scripps Company. For much of its history, the Post was the most widely read paper in the Cincinnati market and its readership was concentrated on the West Side of Cincinnati, as well as in Northern Kentucky, where it was considered the newspaper of record. The Post began publishing in 1881 and launched its Northern Kentucky edition in 1890 and it acquired The Cincinnati Times-Star in 1958. The Post ceased publication at the end of 2007, after 30 years in a joint operating agreement with The Cincinnati Enquirer, the Post was known throughout its history for investigative journalism and focus on local coverage, characteristics common to Scripps papers. As one of the first successful penny presses outside the East Coast and its articles were written to be easily readable.
In its heyday, the paper consistently championed good governance and labor rights, though the Post considered itself politically independent, it historically tended to support progressive politicians relative to the Times-Star and Enquirer. The Posts editorial position became uniformly conservative in the years following its merger with the Times-Star, by the early 1990s, the papers political stance had become a grumpily conservative sigh of resentment according to journalist William Greider. The Post published regular editions on weekday afternoons and a Weekender edition on Saturday mornings, in keeping with Scripps tradition, the Post did not publish on Sundays for most of its history. However, it did publish a Sunday edition from November 30,1924, the Post published on schedule from its founding as The Penny Paper in 1881 until 1967. From October 30 to November 2,1967,300 Newspaper Guild members struck along with Pressmen and Stereotypers, the Cincinnati Post began on January 3,1881, as The Penny Paper, published from a second floor office at Vine and Longworth streets.
Wellman and his brother Frank, hoped to emulate the success of the Cleveland Penny Press, by March, they ran out of funds and took an investment from James E. Scripps and half-brother Edward Willis Scripps, who ran the Penny Press. They used the funds to purchase a press and move the paper to larger facility on Home Street, in October, Walter Wellman was framed for blackmail in retaliation for exposés of policy racketeers and the police. Wellman fled to Kentucky, where he was unlikely to face extradition, E. W. Scripps estimated daily circulation at 7,000 in the city and 6,000 in the countryside, before countryside distribution was discontinued to save money. With an editorial staff that leaned Republican and included a minister, The Penny Paper was seen as the spokesman. On February 11,1883, the paper was given a distinctive name, The Penny Post. In July, the Scripps family assumed ownership of the company. It was the first paper that he had ever owned and it became The Evening Post on October 11,1883 – though the price would remain at one penny until 1918
Savanna
A savanna or savannah is a mixed woodland grassland 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 a herbaceous layer consisting primarily of grasses. Savannas maintain an open canopy despite a high tree density and it is often believed that savannas feature widely spaced, scattered trees. However, in savannas, tree densities are higher and trees are more regularly spaced than in forests. Savanna covers approximately 20% of the Earths land area, the word originally entered English in 1555 as the Latin Zauana, equivalent in the orthography of the times to zavana. Peter Martyr reported it as the name for the plain around Comagre. The accounts are inexact, but this is placed in present-day Madugandí or at points on the nearby Guna Yala coast opposite Ustupo or on Point Mosquitos. These areas are now given over to modern cropland or jungle. The common usage meaning to describe vegetation now conflicts with a simplified yet widespread climatic concept meaning, 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.
Barrens has been used almost interchangeably with savanna in different parts of North America, sometimes midwestern savanna were described as grassland with trees. Different authors have defined the limits of savanna tree coverage as 5–10%. Two factors common to all environments are rainfall variations from year to year. In the Americas, e. g. in Belize, Central America, savanna vegetation is similar from Mexico to South America, savannas are subject to regular wildfires and the ecosystem appears to be the result of human use of fire. For example, Native Americans created the Pre-Columbian savannas of North America by periodically burning where fire-resistant plants were the dominant species, pine barrens in scattered locations from New Jersey to coastal New England are remnants of these savannas. Aboriginal burning appears to have responsible for the widespread occurrence of savanna in tropical Australia and New Guinea. The maquis shrub savannas of the Mediterranean region were created and maintained by anthropogenic fire.
These fires are usually confined to the layer and do little long term damage to mature trees. However, these either kill or suppress tree seedlings, thus preventing the establishment of a continuous tree canopy which would prevent further grass growth
