The Pinophyta known as Coniferophyta or Coniferae, or as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are gymnosperms, cone-bearing seed plants. All extant conifers are perennial woody plants with secondary growth; the great majority are trees. Examples include cedars, Douglas firs, firs, kauri, pines, redwoods and yews; as of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, 629 living species. Although the total number of species is small, conifers are ecologically important, they are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations; the narrow conical shape of northern conifers, their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink.
Conifers are of great economic value for softwood paper production. The earliest conifers in the fossil record date to the late Carboniferous period arising from Cordaites, a genus of seed-bearing Gondwanan plants with cone-like fertile structures. Pinophytes and Ginkgophytes all developed at this time. An important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen and the seed, which allows the embryo to be transported and developed elsewhere. Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, were the dominant land plants of the Mesozoic, they were overtaken by the flowering plants, which first appeared in the Cretaceous, became dominant in the Cenozoic era. They were the main food of herbivorous dinosaurs, their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era. Conifer is a Latin word, a compound of conus and ferre, meaning "the one that bears cone".
The division name Pinophyta conforms to the rules of the International Code of Nomenclature for algae and plants, which state that the names of higher taxa in plants are either formed from the name of an included family, in this case Pinaceae, or are descriptive. A descriptive name in widespread use for the conifers is Coniferae. According to the ICN, it is possible to use a name formed by replacing the termination -aceae in the name of an included family, in this case preferably Pinaceae, by the appropriate termination, in the case of this division ‑ophyta. Alternatively, "descriptive botanical names" may be used at any rank above family. Both are allowed; this means that if conifers are considered a division, they may be called Coniferae. As a class they may be called Coniferae; as an order they may be called Coniferae or Coniferales. Conifers are the largest and economically most important component group of the gymnosperms, but they comprise only one of the four groups; the division Pinophyta consists of just one class, which includes both living and fossil taxa.
Subdivision of the living conifers into two or more orders has been proposed from time to time. The most seen in the past was a split into two orders and Pinales, but recent research into DNA sequences suggests that this interpretation leaves the Pinales without Taxales as paraphyletic, the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, Cupressales containing the remaining families, but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology; the conifers are now accepted as comprising seven families, with a total of 65–70 genera and 600–630 species. The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, some authors additionally recognize Phyllocladaceae as distinct from Podocarpaceae.
The family Taxodiaceae is here included in family Cupressaceae, but was recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et al; the conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period. Other classes and orders, now long extinct occur as fossils from the late Paleozoic and Mesozoic eras. Fossil conifers included many diverse forms, the most distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales and also the Czekanowskiales (possibly
Oregon is a state in the Pacific Northwest region on the West Coast of the United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho; the parallel 42 ° north delineates the southern boundary with Nevada. Oregon is one of only four states of the continental United States to have a coastline on the Pacific Ocean. Oregon was inhabited by many indigenous tribes before Western traders and settlers arrived. An autonomous government was formed in the Oregon Country in 1843 before the Oregon Territory was created in 1848. Oregon became the 33rd state on February 14, 1859. Today, at 98,000 square miles, Oregon is the ninth largest and, with a population of 4 million, 27th most populous U. S. state. The capital, Salem, is the second most populous city in Oregon, with 169,798 residents. Portland, with 647,805, ranks as the 26th among U. S. cities. The Portland metropolitan area, which includes the city of Vancouver, Washington, to the north, ranks the 25th largest metro area in the nation, with a population of 2,453,168.
Oregon is one of the most geographically diverse states in the U. S. marked by volcanoes, abundant bodies of water, dense evergreen and mixed forests, as well as high deserts and semi-arid shrublands. At 11,249 feet, Mount Hood, a stratovolcano, is the state's highest point. Oregon's only national park, Crater Lake National Park, comprises the caldera surrounding Crater Lake, the deepest lake in the United States; the state is home to the single largest organism in the world, Armillaria ostoyae, a fungus that runs beneath 2,200 acres of the Malheur National Forest. Because of its diverse landscapes and waterways, Oregon's economy is powered by various forms of agriculture and hydroelectric power. Oregon is the top timber producer of the contiguous United States, the timber industry dominated the state's economy in the 20th century. Technology is another one of Oregon's major economic forces, beginning in the 1970s with the establishment of the Silicon Forest and the expansion of Tektronix and Intel.
Sportswear company Nike, Inc. headquartered in Beaverton, is the state's largest public corporation with an annual revenue of $30.6 billion. The earliest evidence of the name Oregon has Spanish origins; the term "orejón" comes from the historical chronicle Relación de la Alta y Baja California written by the new Spaniard Rodrigo Montezuma and made reference to the Columbia River when the Spanish explorers penetrated into the actual North American territory that became part of the Viceroyalty of New Spain. This chronicle is the first topographical and linguistic source with respect to the place name Oregon. There are two other sources with Spanish origins, such as the name Oregano, which grows in the southern part of the region, it is most probable that the American territory was named by the Spaniards, as there are some populations in Spain such as "Arroyo del Oregón" considering that the individualization in Spanish language "El Orejón" with the mutation of the letter "g" instead of "j". Another early use of the name, spelled Ouragon, was in a 1765 petition by Major Robert Rogers to the Kingdom of Great Britain.
The term referred to the then-mythical River of the West. By 1778, the spelling had shifted to Oregon. In his 1765 petition, Rogers wrote: The rout...is from the Great Lakes towards the Head of the Mississippi, from thence to the River called by the Indians Ouragon... One theory is that the name comes from the French word ouragan, applied to the River of the West based on Native American tales of powerful Chinook winds on the lower Columbia River, or from firsthand French experience with the Chinook winds of the Great Plains. At the time, the River of the West was thought to rise in western Minnesota and flow west through the Great Plains. Joaquin Miller explained in Sunset magazine, in 1904, how Oregon's name was derived: The name, Oregon, is rounded down phonetically, from Ouve água—Oragua, Or-a-gon, Oregon—given by the same Portuguese navigator that named the Farallones after his first officer, it in a large way, means cascades:'Hear the waters.' You should steam up the Columbia and hear and feel the waters falling out of the clouds of Mount Hood to understand the full meaning of the name Ouve a água, Oregon.
Another account, endorsed as the "most plausible explanation" in the book Oregon Geographic Names, was advanced by George R. Stewart in a 1944 article in American Speech. According to Stewart, the name came from an engraver's error in a French map published in the early 18th century, on which the Ouisiconsink River was spelled "Ouaricon-sint", broken on two lines with the -sint below, so there appeared to be a river flowing to the west named "Ouaricon". According to the Oregon Tourism Commission, present-day Oregonians pronounce the state's name as "or-uh-gun, never or-ee-gone". After being drafted by the Detroit Lions in 2002, former Oregon Ducks quarterback Joey Harrington distributed "Orygun" stickers to members of the media as a reminder of how to pronounce the name of his home state; the stickers are sold by the University of Oregon Bookstore. Oregon is 295 miles north to south at longest distance, 395 miles east to west. With an area of 98,381 square miles, Oregon is larger than the United Kingdom.
It is the ninth largest state in the United States. Oregon's highest point is the summit of Mount Hood, at 11,249 feet, its lowest point is the sea level of the Pacific Ocean along the Oregon Coas
The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa Barbara, Los Angeles, San Bernardino and Riverside counties; the Peninsular Ranges lie to the south. The name Transverse Ranges is due to their east–west orientation, making them transverse to the general northwest–southeast orientation of most of California's coastal mountains; the ranges extend from west of Point Conception eastward 500 kilometers into the Mojave and Colorado Desert. The geology and topography of the ranges express three distinct segments that have contrasting elevations, rock types, vegetation; the western segment extends to the San Gabriel Mountains and San Gabriel fault. The central segment includes; the eastern segment extends from the San Andreas fault eastward to the Colorado Desert. The central and eastern segments have the highest elevations.
Most of the ranges lie in the California chaparral and woodlands ecoregion. Lower elevations are dominated by chaparral and scrubland, while higher elevations support large conifer forests. Most of the ranges in the system are fault blocks, were uplifted by tectonic movements late in the Cenozoic Era. West of Tejon Pass, the primary rock types are varied, with a mix of sedimentary and metamorphic rocks, while regions east of the pass are dominated by plutonic granitic and metasedimentary rocks; the western and central segments of the Transverse Ranges are bounded to the north and east by the San Andreas Fault, which separates those segments from the Mojave Desert. The eastern segment bounds the southern Mojave Desert. Notable passes along the San Andreas fault include Tejon Pass, Cajon Pass, San Gorgonio Pass. Components of Transverse Ranges to the north and east of the fault include the San Bernardino Mountains, Little San Bernardino Mountains and Eagle Mountains; the western and southern boundaries are acknowledged to be the Pacific Ocean and the northern Channel Islands.
Onshore the Los Angeles Basin lies at the southern boundary of the western and central segments of the ranges. Major passes not along the San Andreas Fault include Gaviota Pass, San Marcos Pass, the Conejo Grade, Newhall Pass, Cahuenga Pass; the Transverse Ranges manifest themselves as a series of parallel ridges with an average height of 3,000–8,000 feet. The ranges are dissected by young, steep streams of low flow rate; the mountains are notable for being difficult to traverse. There are few passes that are sufficiently low or wide enough to accommodate significant volumes of traffic; this has resulted in situations where major cities are linked to the rest of the state by few roads. This results in significant traffic issues throughout Southern California when a pass has to be shut down due to heavy snow or construction. Major cities, such as Santa Barbara during the 2005 La Conchita landslide, may be cut off from timely road access to the rest of Southern California. Major peaks of the Transverse Ranges with at least 500 feet of prominence, listed by height: This segment begins at Point Conception in Santa Barbara County, include the Santa Ynez Mountains that run parallel to the coast behind Santa Barbara.
The western Transverse Ranges include the Topatopa Mountains and the Santa Susana Mountains of Ventura County and Los Angeles County, the Simi Hills, the Santa Monica Mountains that run along the Pacific coast behind Malibu, whose eastern portion are known as the Hollywood Hills, the Chalk Hills. The northern Channel Islands of California are part of the Transverse Ranges; the Ranges include the steep San Gabriel Mountains northeast of Los Angeles, the Verdugo Mountains, the Liebre-Sawmill Mountains, the San Rafael Hills, Puente Hills, San Jose Hills, Chino Hills. The San Bernardino Mountains, Little San Bernardino Mountains, the Pinto and Orocopia Mountains are within the eastern segment; the Mojave Desert and California's low desert, including the Coachella Valley, are at the eastern end of the ranges. Ranges north of the western segment that are nearly transverse but are part of the California Coast Ranges include the San Rafael Mountains and the Sierra Madre Mountains; the Tehachapi Mountains north of the Mojave Desert, although nearly transverse, are the southern end of the Sierra Nevada.
The climate in most of the range is Csb under the Köppen climate classification. Snow falls above 6,000 feet most winters, above 3,000 feet every few years, it is rare for elevations above 8,000 feet to go multiple winters without snow during severe droughts. Due to low humidity, the regional snow line lies at about 14,000–16,000 feet, above the highest elevation of the range.
Owls are birds from the order Strigiformes, which includes about 200 species of solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, feathers adapted for silent flight. Exceptions include the gregarious burrowing owl. Owls hunt small mammals and other birds, although a few species specialize in hunting fish, they are found in all regions of the Earth except some remote islands. Owls are divided into two families: the true owl family and the barn-owl family, Tytonidae. Owls possess large, forward-facing eyes and ear-holes, a hawk-like beak, a flat face, a conspicuous circle of feathers, a facial disc, around each eye; the feathers making up this disc can be adjusted to focus sounds from varying distances onto the owls' asymmetrically placed ear cavities. Most birds of prey have eyes on the sides of their heads, but the stereoscopic nature of the owl's forward-facing eyes permits the greater sense of depth perception necessary for low-light hunting.
Although owls have binocular vision, their large eyes are fixed in their sockets—as are those of most other birds—so they must turn their entire heads to change views. As owls are farsighted, they are unable to see anything within a few centimeters of their eyes. Caught prey can be felt by owls with the use of filoplumes—hairlike feathers on the beak and feet that act as "feelers", their far vision in low light, is exceptionally good. Owls can rotate their heads and necks as much as 270°. Owls have 14 neck vertebrae compared to seven in humans, they have adaptations to their circulatory systems, permitting rotation without cutting off blood to the brain: the foramina in their vertebrae through which the vertebral arteries pass are about 10 times the diameter of the artery, instead of about the same size as the artery as in humans. Other anastomoses between the carotid and vertebral arteries support this effect; the smallest owl—weighing as little as 31 g and measuring some 13.5 cm —is the elf owl.
Around the same diminutive length, although heavier, are the lesser known long-whiskered owlet and Tamaulipas pygmy owl. The largest owls are two sized eagle owls; the largest females of these species are 71 cm long, have 54 cm long wings, weigh 4.2 kg. Different species of owls produce different sounds; as noted above, their facial discs help owls to funnel the sound of prey to their ears. In many species, these discs are placed asymmetrically, for better directional location. Owl plumage is cryptic, although several species have facial and head markings, including face masks, ear tufts, brightly coloured irises; these markings are more common in species inhabiting open habitats, are thought to be used in signaling with other owls in low-light conditions. Sexual dimorphism is a physical difference between females of a species. Reverse sexual dimorphism, when females are larger than males, has been observed across multiple owl species; the degree of size dimorphism varies across multiple populations and species, is measured through various traits, such as wing span and body mass.
Overall, female owls tend to be larger than males. The exact explanation for this development in owls is unknown. However, several theories explain the development of sexual dimorphism in owls. One theory suggests that selection has led males to be smaller because it allows them to be efficient foragers; the ability to obtain more food is advantageous during breeding season. In some species, female owls stay at their nest with their eggs while it is the responsibility of the male to bring back food to the nest. However, if food is scarce, the male first feeds himself before feeding the female. Small birds, which are agile, are an important source of food for owls. Male burrowing owls have been observed to have longer wing chords than females, despite being smaller than females. Furthermore, owls have been observed to be the same size as their prey; this has been observed in other predatory birds, which suggests that owls with smaller bodies and long wing chords have been selected for because of the increased agility and speed that allows them to catch their prey.
Another popular theory suggests that females have not been selected to be smaller like male owls because of their sexual roles. In many species, female owls may not leave the nest. Therefore, females may have a larger mass to allow them to go for a longer period of time without starving. For example, one hypothesized sexual role is that larger females are more capable of dismembering prey and feeding it to their young, hence female owls are larger than their male counterparts. A different theory suggests that the size difference between male and females is due to sexual selection: since large females can choose their mate and may violently reject a male's sexual advances, smaller male owls that have the ability to escape unreceptive females are more to have been selected. All owls are carnivorous bi
A wildfire or wildland fire is a fire in an area of combustible vegetation occurring in rural areas. Depending on the type of vegetation present, a wildfire can be classified more as a brush fire, desert fire, forest fire, grass fire, hill fire, peat fire, vegetation fire, or veld fire. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago. Wildfire's occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems' flora and fauna. Earth is an intrinsically flammable planet owing to its cover of carbon-rich vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning and volcanic ignitions. Wildfires can be characterized in terms of the cause of ignition, their physical properties, the combustible material present, the effect of weather on the fire. Wildfires can cause damage to property and human life, although occurring wildfires may have beneficial effects on native vegetation and ecosystems that have evolved with fire.
High-severity wildfire creates complex early seral forest habitat, which has higher species richness and diversity than unburned old forest. Many plant species depend on the effects of fire for reproduction. Wildfires in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behavior and severity result from a combination of factors such as available fuels, physical setting, weather. Analyses of historical meteorological data and national fire records in western North America show the primacy of climate in driving large regional fires via wet periods that create substantial fuels, or drought and warming that extend conducive fire weather. Strategies for wildfire prevention and suppression have varied over the years. One common and inexpensive technique is controlled burning: intentionally igniting smaller fires to minimize the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain high species diversity and limit the accumulation of plants and other debris that may serve as fuel.
Wildland fire use is the cheapest and most ecologically appropriate policy for many forests. Fuels may be removed by logging, but fuels treatments and thinning have no effect on severe fire behavior when under extreme weather conditions. Wildfire itself is "the most effective treatment for reducing a fire's rate of spread, fireline intensity, flame length, heat per unit of area", according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station. Building codes in fire-prone areas require that structures be built of flame-resistant materials and a defensible space be maintained by clearing flammable materials within a prescribed distance from the structure. Three major natural causes of wildfire ignitions exist: dry climate lightning volcanic eruptionThe most common direct human causes of wildfire ignition include arson, discarded cigarettes, power-lines arcs, sparks from equipment. Ignition of wildland fires via contact with hot rifle-bullet fragments is possible under the right conditions.
Wildfires can be started in communities experiencing shifting cultivation, where land is cleared and farmed until the soil loses fertility, slash and burn clearing. Forested areas cleared by logging encourage the dominance of flammable grasses, abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in southern Vietnam stem in part from the destruction of forested areas by US military herbicides and mechanical land-clearing and -burning operations during the Vietnam War; the most common cause of wildfires varies throughout the world. In Canada and northwest China, lightning operates as the major source of ignition. In other parts of the world, human involvement is a major contributor. In Africa, Central America, Mexico, New Zealand, South America, Southeast Asia, wildfires can be attributed to human activities such as agriculture, animal husbandry, land-conversion burning. In China and in the Mediterranean Basin, human carelessness is a major cause of wildfires.
In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, they can flare up unexpectedly and ignite nearby flammable material. The spread of wildfires varies based on the flammable material present, its vertical arrangement and moisture content, weather conditions. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight and water for plant growth. Overall, fire types can be characterized by their fuels as follows: Ground fires are fed by subterranean roots and other buried organic matter; this fuel type is susceptible to ignition due to spotting. Ground fires burn by smoldering, can burn for days to months, such as peat fires in Kalimantan and Eastern Sumatra, which resulted from a riceland creation project that unintentionally drained and dried the peat.
Crawling or surface fires are fueled by low-lying vegetation on the forest floor such as leaf and timber litter, debris and low-lying shrubbery. This kind of fire burns at a lower temperature than crown fires and may spread
The Bullock's oriole is a small New World blackbird. At one time, this species and the Baltimore oriole were considered to be a single species, the northern oriole; this bird was named after an English amateur naturalist. Bullock's orioles are sexually dimorphic, with males being more brightly colored than females. In addition, adult males tend to be larger and heavier than females. In general, adults range in mass from 29 to 43 g. Adults have a pointed bill with a straight culmen. In adult males, the tail is long and jet black. All exposed skin is black, as are the claws and bill, though the base of the lower mandible lightens to bluish-gray. Adult males are characterized by contrasting orange and black plumage, a black throat patch and a white wing bar; the underparts and face are orange or yellow. A black line extends from each eye to the black crown; the wing coverts are fringed forming a wing patch. Although the tail is black, the outermost three or four retrices are tipped orange, forming a T shape.
Adult females, by contrast, have gray-brown upperparts, duller yellow on the breast and underparts, an olive crown. Some females may have a dark throat patch, similar to the one found in adult males, it is hypothesized. Following the general pattern observed among icterids, the overall plumage pattern seen in immature male Bullock's orioles resembles that seen in adult females. Juveniles resemble adult females but have darker wings, fresh wing coverts, a pink or whitish bill. Sexual dimorphism is not obvious in juveniles. Bullock's orioles are seasonally monogamous; the breeding season lasts from May until July. The exact timing of the beginning of the breeding season tends to vary geographically: in general, breeding begins in the northernmost and westernmost portions of its geographic range. Mated pairs of Bullock's orioles cooperate to weave deep, pendant baskets in which are deposited between three and six eggs, though females tend to do much of the work; the nest is woven of plant fibers bark and fine grass fiber, though animal hair is commonly used.
The nest is lined with down and moss. Both males and females defend the nest from predators and nest parasites. Bullock's orioles and Baltimore orioles hybridize in the Midwest where their geographic ranges overlap. Both males and females sing. While males have a sweeter voice, females tend to be more prolific singers; this bird's song is similar to that of the Baltimore oriole, but somewhat more harsh. Bullock's orioles are native to western North America, though according to Jaramillo they are sometimes found as vagrants in the eastern half of the continent. During the breeding season, they are found as far west as the eastern foothills of the Cascade range, their breeding range stretches east to the Dakotas and northern central Texas. This species can be found as far north as British Columbia in Canada and as far south as Sonora or Durango in Mexico, it is common throughout its range, but is absent in parts of Arizona and Idaho where a combination of extreme elevation and an arid climate make for poor living conditions.
During winter, this species retreats to northern Central America. Its winter range extends east from Sinaloa to Oaxaca. Like other members of Icteridae, Bullock's orioles prefer habitat edges, they prefer riparian corridors, open deciduous woodland, scrub forest. Observations during the breeding season indicate that members of this species prefer areas with an abundance of cottonwood and willow. In dry areas, this species prefers salt mesquite. In California, eucalyptus trees are used as major sources of nectar; these birds forage in trees and shrubs making short flights to catch insects. They eat insects and nectar. Other fruits eaten include oranges and sometimes grapes. In some locations, they may be seen using hummingbird feeders; these birds will come to a dish filled with grape jelly. Their parents lead the fledglings, feed them jelly and the adult males leave the area; the young leave late September. A member of the northern oriole group, Bullock's orioles were once considered to be conspecific with Baltimore orioles and black-backed orioles.
However, recent phylogenetic data suggest that Bullock's orioles are members of a distinct species that does not share a most-recent common ancestor with Baltimore orioles, as was once assumed. Bullock's oriole Species Account - Cornell Lab of Ornithology Bullock's oriole - Encyclopedia of Life Bullock's oriole - Icterus bullockii - USGS Patuxent Bird Identification InfoCenter Bullock's oriole - BirdHouses101.com BirdLife species factsheet for Icterus bullockii "Icterus bullockii". Avibase. "Bullock's oriole media". Internet Bird Collection. Bullock's oriole photo gallery at VIREO Audio recordings of Bullock's oriole on Xeno-canto
Native Americans in the United States
Native Americans known as American Indians, Indigenous Americans and other terms, are the indigenous peoples of the United States, except Hawaii. There are over 500 federally recognized tribes within the US, about half of which are associated with Indian reservations; the term "American Indian" excludes Native Hawaiians and some Alaska Natives, while Native Americans are American Indians, plus Alaska Natives of all ethnicities. Native Hawaiians are not counted as Native Americans by the US Census, instead being included in the Census grouping of "Native Hawaiian and other Pacific Islander"; the ancestors of modern Native Americans arrived in what is now the United States at least 15,000 years ago much earlier, from Asia via Beringia. A vast variety of peoples and cultures subsequently developed. Native Americans were affected by the European colonization of the Americas, which began in 1492, their population declined precipitously due to introduced diseases as well as warfare, territorial confiscation and slavery.
After the founding of the United States, many Native American peoples were subjected to warfare and one-sided treaties, they continued to suffer from discriminatory government policies into the 20th century. Since the 1960s, Native American self-determination movements have resulted in changes to the lives of Native Americans, though there are still many contemporary issues faced by Native Americans. Today, there are over five million Native Americans in the United States, 78% of whom live outside reservations; when the United States was created, established Native American tribes were considered semi-independent nations, as they lived in communities separate from British settlers. The federal government signed treaties at a government-to-government level until the Indian Appropriations Act of 1871 ended recognition of independent native nations, started treating them as "domestic dependent nations" subject to federal law; this law did preserve the rights and privileges agreed to under the treaties, including a large degree of tribal sovereignty.
For this reason, many Native American reservations are still independent of state law and actions of tribal citizens on these reservations are subject only to tribal courts and federal law. The Indian Citizenship Act of 1924 granted U. S. citizenship to all Native Americans born in the United States. This emptied the "Indians not taxed" category established by the United States Constitution, allowed natives to vote in state and federal elections, extended the Fourteenth Amendment protections granted to people "subject to the jurisdiction" of the United States. However, some states continued to deny Native Americans voting rights for several decades. Bill of Rights protections do not apply to tribal governments, except for those mandated by the Indian Civil Rights Act of 1968. Since the end of the 15th century, the migration of Europeans to the Americas has led to centuries of population and agricultural transfer and adjustment between Old and New World societies, a process known as the Columbian exchange.
As most Native American groups had preserved their histories by oral traditions and artwork, the first written sources of the conflict were written by Europeans. Ethnographers classify the indigenous peoples of North America into ten geographical regions with shared cultural traits, called cultural areas; some scholars combine the Plateau and Great Basin regions into the Intermontane West, some separate Prairie peoples from Great Plains peoples, while some separate Great Lakes tribes from the Northeastern Woodlands. The ten cultural areas are as follows: Arctic, including Aleut and Yupik peoples Subarctic Northeastern Woodlands Southeastern Woodlands Great Plains Great Basin Northwest Plateau Northwest Coast California Southwest At the time of the first contact, the indigenous cultures were quite different from those of the proto-industrial and Christian immigrants; some Northeastern and Southwestern cultures, in particular, were matrilineal and operated on a more collective basis than that with which Europeans were familiar.
The majority of Indigenous American tribes maintained their hunting grounds and agricultural lands for use of the entire tribe. Europeans at that time had patriarchal cultures and had developed concepts of individual property rights with respect to land that were different; the differences in cultures between the established Native Americans and immigrant Europeans, as well as shifting alliances among different nations in times of war, caused extensive political tension, ethnic violence, social disruption. Before the European settlement of what is now the United States, Native Americans suffered high fatalities from contact with new European diseases, to which they had not yet acquired immunity. Smallpox epidemics are thought to have caused the greatest loss of life for indigenous populations. William M Denevan, noted author and Professor Emeritus of Geography at the University of Wisconsin-Madison, said on this subject in his essay "The Pristine Myth: The Landscape of the Americas in 1492".
Old World diseases were the primary killer. In many regions the tropical lowlands, populations fell by 90 percent or more in the first century after the contact. "Estimates of the pre-Columbian population of what today constitutes the U. S. vary ranging from William M Denevan's 3.8 million in his 1992 w