United States Forest Service
The United States Forest Service is an agency of the U. S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands, which encompass 193 million acres. Major divisions of the agency include the National Forest System and Private Forestry, Business Operations, the Research and Development branch. Managing 25% of federal lands, it is the only major national land agency, outside the U. S. Department of the Interior; the concept of the National Forests was born from Theodore Roosevelt’s conservation group and Crockett Club, due to concerns regarding Yellowstone National Park beginning as early as 1875. In 1876, Congress formed the office of Special Agent in the Department of Agriculture to assess the quality and conditions of forests in the United States. Franklin B. Hough was appointed the head of the office. In 1881, the office was expanded into the newly formed Division of Forestry; the Forest Reserve Act of 1891 authorized withdrawing land from the public domain as "forest reserves," managed by the Department of the Interior.
In 1901, the Division of Forestry was renamed the Bureau of Forestry. The Transfer Act of 1905 transferred the management of forest reserves from the General Land Office of the Interior Department to the Bureau of Forestry, henceforth known as the United States Forest Service. Gifford Pinchot was the first United States Chief Forester in the Presidency of Theodore Roosevelt. Significant federal legislation affecting the Forest Service includes the Weeks Act of 1911, the Multiple Use – Sustained Yield Act of 1960, P. L. 86-517. L. 88-577. L. 94-588. L. 91-190. L. 95-313. L. 95-307. In February 2009, the Government Accountability Office evaluated whether the Forest Service should be moved from the Department of Agriculture to the Department of the Interior, which includes the National Park Service, the Fish and Wildlife Service, the Bureau of Land Management, managing some 438,000,000 acres of public land; as of 2009, the Forest Service has a total budget authority of $5.5 billion, of which 42% is spent fighting fires.
The Forest Service employs 34,250 employees in 750 locations, including 10,050 firefighters, 737 law enforcement personnel, 500 scientists. The mission of the Forest Service is "To sustain the health and productivity of the Nation's forests and grasslands to meet the needs of present and future generations." Its motto is "Caring for the land and serving people." As the lead federal agency in natural resource conservation, the US Forest Service provides leadership in the protection and use of the nation's forest and aquatic ecosystems. The agency's ecosystem approach to management integrates ecological and social factors to maintain and enhance the quality of the environment to meet current and future needs. Through implementation of land and resource management plans, the agency ensures sustainable ecosystems by restoring and maintaining species diversity and ecological productivity that helps provide recreation, timber, fish, wildlife and aesthetic values for current and future generations of people.
The everyday work of the Forest Service balances resource extraction, resource protection, providing recreation. The work includes managing 193,000,000 acres of national forest and grasslands, including 59,000,000 acres of roadless areas. Further, the Forest Service fought fires on 2,996,000 acres of land in 2007; the Forest Service organization includes ranger districts, national forests, research stations and research work units and the Northeastern Area Office for State and Private Forestry. Each level has responsibility for a variety of functions; the Chief of the Forest Service is a career federal employee. The Chief reports to the Under Secretary for Natural Resources and Environment in the U. S. Department of Agriculture, an appointee of the President confirmed by the Senate; the Chief's staff provides broad policy and direction for the agency, works with the Administration to develop a budget to submit to Congress, provides information to Congress on accomplishments, monitors activities of the agency.
There are five deputy chiefs for the following areas: National Forest System and Private Forestry and Development, Business Operations, Finance. The Forest Service Research and Development deputy area includes five research stations, the Forest Products Laboratory, the International Institute of Tropical Forestry, in Puerto Rico. Station directors, like regional foresters, report to the Chief. Research stations include Northern, Pacific Northwest, Pacific Southwest, Rocky Mountain, Southern. There are 92 research work units located at 67 sites throughout the United States. There are 80 Experimental Forests and Ranges that have been established progressively since 1908; the system provides places for long-term science and management studies in major vegetation types of the 195 million acres of public land administered by the Forest Service. Individual sites range from 47 to 22,500 ha in size. Operations of Experimental Forests and Ranges are directed by local research teams for the individual sites, by Research Stations for the regions in which they are located, at the level of the Forest Service.
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Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
Pennsylvania the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle; the Commonwealth is bordered by Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and the Canadian province of Ontario to the northwest, New York to the north, New Jersey to the east. Pennsylvania is the 33rd-largest state by area, the 6th-most populous state according to the most recent official U. S. Census count in 2010, it is the 9th-most densely populated of the 50 states. Pennsylvania's two most populous cities are Philadelphia, Pittsburgh; the state capital and its 10th largest city is Harrisburg. Pennsylvania has 140 miles of waterfront along the Delaware Estuary; the state is one of the 13 original founding states of the United States. Part of Pennsylvania, together with the present State of Delaware, had earlier been organized as the Colony of New Sweden.
It was the second state to ratify the United States Constitution, on December 12, 1787. Independence Hall, where the United States Declaration of Independence and United States Constitution were drafted, is located in the state's largest city of Philadelphia. During the American Civil War, the Battle of Gettysburg was fought in the south central region of the state. Valley Forge near Philadelphia was General Washington's headquarters during the bitter winter of 1777–78. Pennsylvania is 170 miles north to south and 283 miles east to west. Of a total 46,055 square miles, 44,817 square miles are land, 490 square miles are inland waters, 749 square miles are waters in Lake Erie, it is the 33rd-largest state in the United States. Pennsylvania has 51 miles of coastline along Lake Erie and 57 miles of shoreline along the Delaware Estuary. Of the original Thirteen Colonies, Pennsylvania is the only state that does not border the Atlantic Ocean; the boundaries of the state are the Mason–Dixon line to the south, the Twelve-Mile Circle on the Pennsylvania-Delaware border, the Delaware River to the east, 80° 31' W to the west and the 42° N to the north, with the exception of a short segment on the western end, where a triangle extends north to Lake Erie.
Cities include Philadelphia, Reading and Lancaster in the southeast, Pittsburgh in the southwest, the tri-cities of Allentown and Easton in the central east. The northeast includes the former anthracite coal mining cities of Scranton, Wilkes-Barre and Hazleton. Erie is located in the northwest. State College serves the central region while Williamsport serves the commonwealth's north-central region as does Chambersburg the south-central region, with York and the state capital Harrisburg on the Susquehanna River in the east-central region of the Commonwealth and Altoona and Johnstown in the west-central region; the state has five geographical regions, namely the Allegheny Plateau and Valley, Atlantic Coastal Plain and the Erie Plain. New York Ontario Maryland Delaware West Virginia New Jersey Ohio Pennsylvania's diverse topography produces a variety of climates, though the entire state experiences cold winters and humid summers. Straddling two major zones, the majority of the state, with the exception of the southeastern corner, has a humid continental climate.
The southern portion of the state has a humid subtropical climate. The largest city, has some characteristics of the humid subtropical climate that covers much of Delaware and Maryland to the south. Summers are hot and humid. Moving toward the mountainous interior of the state, the winter climate becomes colder, the number of cloudy days increases, snowfall amounts are greater. Western areas of the state locations near Lake Erie, can receive over 100 inches of snowfall annually, the entire state receives plentiful precipitation throughout the year; the state may be subject to severe weather from spring through summer into fall. Tornadoes occur annually in the state, sometimes in large numbers, such as 30 recorded tornadoes in 2011; as of 1600, the tribes living in Pennsylvania were the Algonquian Lenape, the Iroquoian Susquehannock & Petun and the Siouan Monongahela Culture, who may have been the same as a little known tribe called the Calicua, or Cali. Other tribes who entered the region during the colonial era were the Trockwae, Saponi, Nanticoke, Conoy Piscataway, Iroquois Confederacy—possibly among others.
Other tribes, like the Erie, may have once held some land in Pennsylvania, but no longer did so by the year 1600. Both the Dutch and the English claimed both sides of the Delaware River as part of their colonial lands in America; the Dutch were the first to take possession. By June 3, 1631, the Dutch had begun settling the Delmarva Peninsula by establishing the Zwaanendael Colony on the site of present-day Lewes, Delaware. In 1638, Sweden established the New Sweden Colony, in the region of Fort Christina, on the site of present-day Wilmington, Delaware. New Sweden claimed and, for the most part, controlled the lower Delaware River region (parts of present-day Delaware, New Jersey, Pe
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fiber crops, waste paper, or rags. Many kinds of paper are made from wood with nothing else mixed into them; this includes newspapers and toilet paper. Pulp is one of the most abundant raw materials. Pulp for papermaking was produced by macerating mulberry bark as early as the 2nd century in Han dynasty China, where the invention of paper is traditionally attributed to Cai Lun. Lu Ji, in his 3rd century commentary on the Classic of Poetry, mentions that people residing south of the Yangtze River would traditionally pound mulberry bark to make paper or clothing. By the 6th century, the mulberry tree was domesticated by farmers in China for the purpose of producing pulp to be used in the papermaking process. In addition to mulberry, pulp was made from bamboo, hibiscus bark, blue sandalwood and cotton. Papermaking using pulp made from hemp and linen fibers from tattered clothing, fishing nets and fabric bags spread to Europe in the 13th century, with an ever-increasing use of rags being central to the manufacture and affordability of rag paper, a factor in the development of printing.
By the 1800s, demand exceeding the available supply of rags, the manual labor of papermaking resulted in paper being still a pricey product. Using wood pulp to make paper is a recent innovation, concurrent to the invention of automatic papermaking machines, both together resulting in paper and cardboard becoming an inexpensive commodity in modern times. Although the first use of paper made from wood pulp dates from 1800, as seen in some pages of a book published by Matthias Koops that year in London, large-scale wood paper production began with the development of mechanical pulping in Germany by Friedrich Gottlob Keller in the 1840s, by the Canadian inventor Charles Fenerty in Nova Scotia, Chemical processes followed, first with J. Roth's use of sulfurous acid to treat wood by Benjamin Tilghman's U. S. patent on the use of calcium bisulfite, Ca2, to pulp wood in 1867. A decade the first commercial sulfite pulp mill was built, in Sweden, it was based on work by Carl Daniel Ekman. By 1900, sulfite pulping had become the dominant means of producing wood pulp, surpassing mechanical pulping methods.
The competing chemical pulping process, the sulfate, or kraft, was developed by Carl F. Dahl in 1879; the invention of the recovery boiler, by G. H. Tomlinson in the early 1930s, allowed kraft mills to recycle all of their pulping chemicals. This, along with the ability of the kraft process to accept a wider variety of types of wood and to produce stronger fibres, made the kraft process the dominant pulping process, starting in the 1940s. Global production of wood pulp in 2006 was 175 million tons. In the previous year, 63 million tons of market pulp was sold, with Canada being the largest source at 21 percent of the total, followed by the United States at 16 percent; the wood fiber sources required for pulping are "45% sawmill residue, 21% logs and chips, 34% recycled paper". Chemical pulp made up 93 percent of market pulp; the timber resources used to make wood pulp are referred to as pulpwood. While in theory, any tree can be used for pulp-making, coniferous trees are preferred because the cellulose fibers in the pulp of these species are longer, therefore make stronger paper.
Some of the most used softwood trees for paper making include spruce, fir and hemlock, hardwoods such as eucalyptus and birch. There is increasing interest in genetically modified tree species, because of several major benefits these can provide, such as increased ease of breaking down lignin and increased growth rate. A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fiberboard which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical or chemical methods; the finished product may be either non-bleached, depending on the customer requirements. Wood and other plant materials used to make pulp contain three main components: cellulose fibers and hemicelluloses; the aim of pulping is to break down the bulk structure of the fibre source, be it chips, stems or other plant parts, into the constituent fibres. Chemical pulping achieves this by degrading the lignin and hemicellulose into small, water-soluble molecules which can be washed away from the cellulose fibres without depolymerizing the cellulose fibres.
The various mechanical pulping methods, such as groundwood and refiner mechanical pulping, physically tear the cellulose fibres one from another. Much of the lignin remains adhering to the fibres. Strength is impaired. There are a number of related hybrid pulping methods that use a combination of chemical and thermal treatment to begin an abbreviated chemical pulping process, followed by a mechanical treatment to separate the fibres; these hybrid methods include thermomechanical pulping known as TMP, chemithermomechanical pulping known as CTMP. The chemical and thermal treatments reduce the amount of energy subsequently required by the mechanical treatment, al
A tornado is a rotating column of air, in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The windstorm is referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, they are visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 110 miles per hour, are about 250 feet across, travel a few miles before dissipating; the most extreme tornadoes can attain wind speeds of more than 300 miles per hour, are more than two miles in diameter, stay on the ground for dozens of miles. Various types of tornadoes include the multiple vortex tornado and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud.
They are classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air develop in tropical areas close to the equator and are less common at high latitudes. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirl, steam devil. Tornadoes occur most in North America in central and southeastern regions of the United States colloquially known as tornado alley, as well as in Southern Africa and southeast Europe and southeastern Australia, New Zealand and adjacent eastern India, southeastern South America. Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes or debris balls, as well as through the efforts of storm spotters. There are several scales for rating the strength of tornadoes; the Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale.
An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers; the similar TORRO scale ranges from a T0 for weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data and ground swirl patterns may be analyzed to determine intensity and assign a rating; the word tornado comes from the Spanish word tornado. Tornadoes opposite phenomena are the derechoes. A tornado is commonly referred to as a "twister", is sometimes referred to by the old-fashioned colloquial term cyclone; the term "cyclone" is used as a synonym for "tornado" in the often-aired 1939 film The Wizard of Oz. The term "twister" is used in that film, along with being the title of the 1996 tornado-related film Twister. A tornado is "a violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, visible as a funnel cloud".
For a vortex to be classified as a tornado, it must be in contact with both the ground and the cloud base. Scientists have not yet created a complete definition of the word. Tornado refers to the vortex of wind, not the condensation cloud. A tornado is not visible; this results in the formation of a visible funnel condensation funnel. There is some disagreement over the definition of a condensation funnel. According to the Glossary of Meteorology, a funnel cloud is any rotating cloud pendant from a cumulus or cumulonimbus, thus most tornadoes are included under this definition. Among many meteorologists, the'funnel cloud' term is defined as a rotating cloud, not associated with strong winds at the surface, condensation funnel is a broad term for any rotating cloud below a cumuliform cloud. Tornadoes begin as funnel clouds with no associated strong winds at the surface, not all funnel clouds evolve into tornadoes. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.
A single storm will produce more than one tornado, either or in succession. Multiple tornadoes produced by the same storm cell are referred to as a "tornado family". Several tornadoes are sometimes spawned from the same large-scale storm system. If there is no break in activity, this is considered a tornado outbreak. A period of several successive days with tornado outbreaks in the same general area is a tornado outbreak sequence called an extended tornado outbreak. Most tornadoes take on the appearance of a narrow funnel, a few hundred yards across, with a small cloud of debris near the ground. Tornadoes may
Pittsburgh is a city in the Commonwealth of Pennsylvania in the United States, is the county seat of Allegheny County. As of 2018, a population of 308,144 lives within the city limits, making it the 63rd-largest city in the U. S; the metropolitan population of 2,362,453, is the largest in both the Ohio Valley and Appalachia, the second-largest in Pennsylvania, the 26th-largest in the U. S. Pittsburgh is located in the south west of the state, at the confluence of the Allegheny and Ohio rivers. Pittsburgh is known both as "the Steel City" for its more than 300 steel-related businesses and as the "City of Bridges" for its 446 bridges; the city features 30 skyscrapers, two inclined railways, a pre-revolutionary fortification and the Point State Park at the confluence of the rivers. The city developed as a vital link of the Atlantic coast and Midwest, as the mineral-rich Allegheny Mountains made the area coveted by the French and British empires, Whiskey Rebels, Civil War raiders. Aside from steel, Pittsburgh has led in manufacturing of aluminum, shipbuilding, foods, transportation, computing and electronics.
For part of the 20th century, Pittsburgh was behind only New York and Chicago in corporate headquarters employment. S. stockholders per capita. America's 1980s deindustrialization laid off area blue-collar workers and thousands of downtown white-collar workers when the longtime Pittsburgh-based world headquarters moved out; this heritage left the area with renowned museums, medical centers, research centers, a diverse cultural district. Today, Apple Inc. Bosch, Uber, Autodesk, Microsoft and IBM are among 1,600 technology firms generating $20.7 billion in annual Pittsburgh payrolls. The area has served as the long-time federal agency headquarters for cyber defense, software engineering, energy research and the nuclear navy; the area is home to 68 colleges and universities, including research and development leaders Carnegie Mellon University and the University of Pittsburgh. The nation's eighth-largest bank, eight Fortune 500 companies, six of the top 300 U. S. law firms make their global headquarters in the area, while RAND, BNY Mellon, FedEx, Bayer and NIOSH have regional bases that helped Pittsburgh become the sixth-best area for U.
S. job growth. In 2015, Pittsburgh was listed among the "eleven most livable cities in the world"; the region is a hub for Environmental Design and energy extraction. In 2019, Pittsburgh was deemed “Food City of the Year” by the San Francisco-based restaurant and hospitality consulting firm af&co. Many restaurants were mentioned favorable, among them were Superior Motors in Braddock, Driftwood Oven in Lawrenceville, Spork in Bloomfield, Fish nor Fowl in Garfield and Bitter Ends Garden & Luncheonette in Bloomfield. Pittsburgh was named in 1758 by General John Forbes, in honor of British statesman William Pitt, 1st Earl of Chatham; as Forbes was a Scot, he pronounced the name PITS-bər-ə. Pittsburgh was incorporated as a borough on April 22, 1794, with the following Act: "Be it enacted by the Pennsylvania State Senate and Pennsylvania House of Representatives of the Commonwealth of Pennsylvania... by the authority of the same, that the said town of Pittsburgh shall be... erected into a borough, which shall be called the borough of Pittsburgh for ever."
From 1891 to 1911, the city's name was federally recognized as "Pittsburg", though use of the final h was retained during this period by the city government and other local organizations. After a public campaign, the federal decision to drop the h was reversed; the area of the Ohio headwaters was long inhabited by the Shawnee and several other settled groups of Native Americans. The first known European to enter the region was the French explorer/trader Robert de La Salle from Quebec during his 1669 expedition down the Ohio River. European pioneers Dutch, followed in the early 18th century. Michael Bezallion was the first to describe the forks of the Ohio in a 1717 manuscript, that year European fur traders established area posts and settlements. In 1749, French soldiers from Quebec launched an expedition to the forks to unite Canada with French Louisiana via the rivers. During 1753–54, the British hastily built Fort Prince George before a larger French force drove them off; the French built Fort Duquesne based on LaSalle's 1669 claims.
The French and Indian War, the North American front of the Seven Years' War, began with the future Pittsburgh as its center. British General Edward Braddock was dispatched with Major George Washington as his aide to take Fort Duquesne; the British and colonial force were defeated at Braddock's Field. General John Forbes took the forks in 1758. Forbes began construction on Fort Pitt, named after William Pitt the Elder while the settlement was named "Pittsborough". During Pontiac's Rebellion, native tribes conducted a siege of Fort Pitt for two months until Colonel Henry Bouquet relieved it after the Battle of Bushy Run. Fort Pitt is notable as the site of an early use of smallpox for biological warfare. Lord Jeffery Amherst ordered blankets contaminated from smallpox victims to be distributed in 1763 to the tribes surrounding the fort; the disease spread into other areas, infected other tribes, killed hundreds of thousands. During this period, the powerful nations of the Iroquois Confederacy, based in New York, had maintained control of much of the Ohio Valley as hunting grounds by right of conquest after defeating other tribes.
By the terms of the 1768 Treaty of
Acer is a genus of trees and shrubs known as maple. The genus is placed in the family Sapindaceae. There are 128 species, most of which are native to Asia, with a number appearing in Europe, northern Africa, North America. Only one species, Acer laurinum, extends to the Southern Hemisphere; the type species of the genus is the sycamore maple, Acer pseudoplatanus, the most common maple species in Europe. The maples have recognizable palmate leaves and distinctive winged fruits; the closest relatives of the maples are the horse chestnuts. Most maples are trees growing to a height of 10–45 m. Others are shrubs less than 10 meters tall with a number of small trunks originating at ground level. Most species are deciduous, many are renowned for their autumn leaf colour, but a few in southern Asia and the Mediterranean region are evergreen. Most are shade-tolerant when young and are riparian, understory, or pioneer species rather than climax overstory trees. There are a few exceptions such as sugar maple.
Many of the root systems are dense and fibrous, inhibiting the growth of other vegetation underneath them. A few species, notably Acer cappadocicum produce root sprouts, which can develop into clonal colonies. Maples are distinguished by opposite leaf arrangement; the leaves in most species are palmate veined and lobed, with 3 to 9 veins each leading to a lobe, one of, central or apical. A small number of species differ in having palmate compound, pinnate compound, pinnate veined or unlobed leaves. Several species, including Acer griseum, Acer mandshuricum, Acer maximowiczianum and Acer triflorum, have trifoliate leaves. One species, Acer negundo, has pinnately compound leaves that may be trifoliate or may have five, seven, or nine leaflets. A few, such as Acer laevigatum and Acer carpinifolium, have pinnately veined simple leaves. Maple species, such as Acer rubrum, may be dioecious or polygamodioecious; the flowers are regular and borne in racemes, corymbs, or umbels. They have four or five sepals, four or five petals about 1 – 6 mm long, four to ten stamens about 6 – 10 mm long, two pistils or a pistil with two styles.
The ovary is superior and has two carpels, whose wings elongate the flowers, making it easy to tell which flowers are female. Maples flower in late winter or early spring, in most species with or just after the appearance of the leaves, but in some before the trees leaf out. Maple flowers are green, orange or red. Though individually small, the effect of an entire tree in flower can be striking in several species; some maples are an early spring source of nectar for bees. The distinctive fruits are called samaras, "maple keys", "helicopters", "whirlybirds" or "polynoses"; these seeds occur in distinctive pairs each containing one seed enclosed in a "nutlet" attached to a flattened wing of fibrous, papery tissue. They are shaped to carry the seeds a considerable distance on the wind. People call them "helicopters" due to the way that they spin as they fall. During World War II, the US Army developed a special air drop supply carrier that could carry up to 65 pounds of supplies and was based on the Maple seed.
Seed maturation is in a few weeks to six months after flowering, with seed dispersal shortly after maturity. However, one tree can release hundreds of thousands of seeds at a time. Depending on the species, the seeds can be green to orange and big with thicker seed pods; the green seeds are released in pairs, sometimes with the stems still connected. The yellow seeds are released individually and always without the stems. Most species require stratification in order to germinate, some seeds can remain dormant in the soil for several years before germinating; the genus Acer together with genus Dipteronia are either classified in a family of their own, the Aceraceae, or else classified as members of the family Sapindaceae. Recent classifications, including the Angiosperm Phylogeny Group system, favour inclusion in Sapindaceae; when put in family Sapindaceae, genus Acer is put in subfamily Hippocastanoideae. The genus is subdivided by its morphology into a multitude of subsections. Fifty-four species of maples meet the International Union for Conservation of Nature criteria for being under threat of extinction in their native habitat.
The leaves are used as a food plant for the larvae of a number of the Lepidoptera order.. In high concentrations, like the greenstriped mapleworm, can feed on the leaves so much that they cause temporary defoliation of host maple trees. Aphids are very common sap-feeders on maples. In horticultural applications a dimethoate spray will solve this. In the United States and Canada, all maple species are threatened by the Asian long-horned beetle. Infestations have resulted in the destruction of thousands of maples and other tree species in Illinois, New Jersey and New York. Maples are affected by a number of fungal diseases. Several are susceptible to Verticillium wilt caused by Verticillium species, which can cause significant local mortality. Sooty bark disease, caused by Cryptostroma species, can kill trees that are under stress due to drought. Death of maples can be caused by Phytophthora root rot and Ganoderma root decay. Maple leaves in late summer and autumn are disfigured by "tar spot" caused by Rhytisma species and mildew caused by Uncinula species, though these diseases do not have an adverse effect on th