Mumps is highly contagious and spreads rapidly among people living in close quarters. The virus is transmitted by respiratory droplets or direct contact with an infected person. Only humans get and spread the disease. People are infectious from about 7 days before onset of parotid inflammation to about 8 days after. Once an infection has run its course, a person is typically immune for life. Reinfection is possible, but the ensuing infection tends to be mild. Diagnosis is usually suspected due to parotid swelling and can be confirmed by isolating the virus on a swab of the parotid duct.
Testing for IgM antibodies in the blood is simple and may be useful;
however, it can be falsely negative in those who have been immunized.
Mumps is preventable by two doses of the mumps vaccine. Most of the developed world includes it in their immunization programs, often in combination with measles, rubella, and varicella vaccine. Countries that have low immunization rates may see an increase in cases among older age groups and thus worse outcomes. No specific treatment is known. Efforts involve controlling symptoms with pain medication such as paracetamol (acetaminophen). Intravenous immunoglobulin may be useful in certain complications. Hospitalization may be required if meningitis or pancreatitis develops. About one in 10,000 people who are infected die.
Without immunization, about 0.1 to 1.0% of the population is affected per year. Widespread vaccination has resulted in a more than 90% decline in rates of disease. Mumps is more common in the developing world, where vaccination is less common. Outbreaks, however, may still occur in a vaccinated population. Before the introduction of a vaccine, mumps was a common childhood disease worldwide. Larger outbreaks of disease typically occurred every 2 to 5 years. Children between the ages of 5 and 9 were most commonly affected. Among immunized populations, those in their early 20s often are affected. Around the equator,
it often occurs all year round, while in the more northerly and
southerly regions of the world, it is more common in the winter and
spring. Painful swelling of the parotid glands and testicles was described by Hippocrates in the fifth century BCE.
Signs and symptoms
Mumps is usually preceded by a set of prodromal symptoms, including low-grade fever, headache, and feeling generally unwell. This is followed by progressive swelling of one or both parotid glands. Parotid gland swelling usually lasts about a week. Other symptoms of mumps can include dry mouth, sore face and/or ears, and difficulty speaking.
Complications
Painful testicular inflammation develops in 15–40% of men who have completed puberty and contract the mumps virus.
This testicular inflammation is generally one-sided (both testicles are
swollen in 15–30% of mumps orchitis cases) and typically occurs about
10 days after the parotid gland becomes inflamed. Testicular swelling has been documented as late as 6 weeks after parotid-gland swelling. Decreased fertility is an uncommon consequence of testicular inflammation from mumps and infertility is rare.
Studies have reached differing conclusions regarding whether
infection with the mumps virus during pregnancy leads to an increased
rate of spontaneous abortion.
Before vaccination, about 10% of cases of aseptic meningitis were due to mumps. The symptoms generally resolve within 10 days. Infection of the brain itself (encephalitis) occurs in between 0.02 and 0.3% of cases.
Ovarian inflammation occurs in about 5% percent of adolescent and adult females.
Brain inflammation is very rare, and fatal in about 1% of the cases when it occurs.
Profound (91 dB or more) but rare sensorineural hearing loss can occur, which can be uni- or bilateral. Acute unilateral deafness occurs in about 0.005% of cases.
Cause
The mumps virus is an enveloped, single-stranded, linear negative-senseRNA virus of the genus Rubulavirus and family Paramyxovirus.
The genome consists of 15,384 bases encoding nine proteins. Proteins
involved in viral replication are the nucleoprotein, phosphoprotein, and
polymerase protein while the genomic RNA forms the ribonucleocapsid. Humans are the only natural host for the virus.
Mumps is spread from person to person through contact with respiratory secretions, such as saliva from an infected person.
When an infected person coughs or sneezes, the droplets aerosolize and
can enter the eyes, nose, or mouth of another person. Mumps can also be
spread by sharing eating utensils or cups.
The virus can also survive on surfaces and then be spread after contact
in a similar manner. A person infected with mumps is contagious from
around 7 days before the onset of symptoms until about 8 days after
symptoms start. The incubation period (time until symptoms begin) can be from 12–25 days, but is typically 16–18 days.
About 20-40% of persons infected with the mumps virus do not show
symptoms, so being infected and spreading the virus without knowing it
is possible.
Diagnosis
During
an outbreak, a diagnosis can be made by determining recent exposure and
parotitis. However, when the disease incidence is low, other infectious
causes of parotitis should be considered, such as HIV, coxsackievirus, and influenza. Some viruses such as enteroviruses may cause aseptic meningitis that is very clinically similar to mumps.
A physical examination confirms the presence of the swollen
glands. Usually, the disease is diagnosed on clinical grounds, and no
confirmatory laboratory testing is needed. If uncertainty exists about
the diagnosis, a test of saliva or blood may be carried out; a newer diagnostic confirmation, using real-time nested polymerase chain reaction technology, has also been developed. As with any inflammation of the salivary glands, the serum level of the enzyme amylase is often elevated.
Prevention
The most common preventive measure against mumps is a vaccination with a mumps vaccine, invented by American microbiologist Maurice Hilleman at Merck. The vaccine may be given separately or as part of the MMR vaccine or MMRV vaccine. The World Health Organization
(WHO) recommends the use of mumps vaccines in all countries with
well-functioning childhood vaccination programmes. In the United
Kingdom, they are routinely given to children at age 13 months with a
booster at 3–5 years (preschool). The American Academy of Pediatrics recommends the routine administration of MMR vaccine at ages 12–15 months and at 4–6 years.
In some locations, the vaccine is given again between 4 and 6 years of
age, or between 11 and 12 years of age if not previously given. The efficacy of the vaccine depends on its strain, but is usually around 80%.
The Jeryl Lynn strain is most commonly used in developed countries,
but has been shown to have reduced efficacy in epidemic situations. The
Leningrad-Zagreb strain commonly used in developing countries appears to
have superior efficacy in epidemic situations.
Because of the outbreaks within college and university settings,
many governments have established vaccination programs to prevent
large-scale outbreaks. In Canada, provincial governments and the Public
Health Agency of Canada have all participated in awareness campaigns to
encourage students ranging from grade one to college and university to
get vaccinated.
Before the introduction of the mumps vaccine, the mumps virus was the leading cause of viral meningoencephalitis in the United States. However, encephalitis occurs rarely (less than two per 100,000).
In one of the largest studies in the literature, the most common
symptoms of mumps meningoencephalitis were found to be fever (97%),
vomiting (94%), and headache (88.8%).
The mumps vaccine was introduced into the United States in December
1967: since its introduction, a steady decrease in the incidence of
mumps has occurred, with 151,209 cases of mumps reported in 1968. From
2001 to 2008, the case average was only 265 per year, excluding an
outbreak of less than 6000 cases in 2006 attributed largely to
university contagion in young adults.
Management
The treatment of mumps is supportive. Symptoms may be relieved by the application of intermittent ice or heat to the affected neck/testicular area and by acetaminophen for pain relief. Warm saltwater gargles, soft foods, and extra fluids may also help relieve symptoms. Acetylsalicylic acid (aspirin) is not used to treat children due to the risk of Reye syndrome.
No effective postexposure recommendation is made to prevent secondary transmission, nor is the postexposure use of vaccine or immunoglobulin effective.
Mumps is considered most contagious in the 5 days after the onset of symptoms, and isolation
is recommended during this period. In someone who has been admitted to
the hospital, standard and droplet precautions are needed. People who
work in healthcare cannot work for 5 days.
Epidemiology
In the United States, typically between a few hundred and few thousand cases occur in a year.
History
Mumps has been known to humans since antiquity. It was mentioned by Hippocrates in his Of the Epidemics written in 400 BC, wherein he described the painful swelling of the parotid glands and testicles. The disease was first described scientifically as late as 1790 by a British physician Robert Hamilton (1721–1793) in the Transactions of the Royal Society of Edinburgh. The disease was one of the most medically significant diseases among the armies involved in the fighting both World War I and World War II.
A number of attempts to prove that mumps is contagious failed. Its
contagiousness was finally proved in 1934 by Claude D. Johnson and
Ernest William Goodpasture (1886–1960), who demonstrated that mumps was
transmitted by a filterable virus.
Contemporary illustration of the 1868 Washita Massacre by the 7th Cavalry against Black Kettle's band of Cheyennes, during the American Indian Wars.
Violence and conflict with colonists were also important causes of the
decline of certain indigenous American populations since the 16th
century.
The population figure of indigenous peoples of the Americas before the 1492 Spanish voyage of Christopher Columbus
has proven difficult to establish. Scholars rely on archaeological data
and written records from European settlers. Most scholars writing at
the end of the 19th century estimated that the pre-Columbian
population was as low as 10 million; by the end of the 20th century
most scholars gravitated to a middle estimate of around 50 million, with
some historians arguing for an estimate of 100 million or more. Contact with the Europeans led to the European colonization of the Americas, in which millions of immigrants from Europe eventually settled in the Americas.
The population of African and Eurasian peoples in the Americas grew steadily, while the indigenous population plummeted. Eurasian diseases such as influenza, pneumonic plagues, and smallpox
devastated the Native Americans, who did not have immunity to them.
Conflict and outright warfare with Western European newcomers and other
American tribes further reduced populations and disrupted traditional
societies. The extent and causes of the decline have long been a subject
of academic debate, along with its characterization as a genocide.
Population overview
Given
the fragmentary nature of the evidence, even semi-accurate
pre-Columbian population figures are impossible to obtain. Scholars have
varied widely on the estimated size of the indigenous populations prior
to colonization and on the effects of European contact. Estimates are made by extrapolations from small bits of data. In 1976, geographer William Denevan
used the existing estimates to derive a "consensus count" of about
54 million people. Nonetheless, more recent estimates still range
widely.
Using an estimate of approximately 37 million people in Mexico, Central and South America in 1492 (including 6 million in the Aztec Empire, 5-10 million in the Mayan States, 11 million in what is now Brazil, and 12 million in the Inca Empire), the lowest estimates give a death toll due from disease of 80% by the end of the 17th century (nine million people in 1650).
Latin America would match its 15th-century population early in the 19th
century; it numbered 17 million in 1800, 30 million in 1850, 61 million
in 1900, 105 million in 1930, 218 million in 1960, 361 million in 1980,
and 563 million in 2005. In the last three decades of the 16th century, the population of present-day Mexico dropped to about one million people. The Maya
population is today estimated at six million, which is about the same
as at the end of the 15th century, according to some estimates.
In what is now Brazil, the indigenous population declined from a
pre-Columbian high of an estimated four million to some 300,000.
While it is difficult to determine exactly how many Natives lived in North America before Columbus, estimates range from a low of 2.1 million to 7 million people to a high of 18 million.
The aboriginal population of Canada during the late 15th century is estimated to have been between 200,000 and two million, with a figure of 500,000 currently accepted by Canada's Royal Commission on Aboriginal Health. Repeated outbreaks of Old World infectious diseases such as influenza, measles and smallpox
(to which they had no natural immunity), were the main cause of
depopulation. This combined with other factors such as dispossession
from European/Canadian settlements and numerous violent conflicts resulted in a forty- to eighty-percent aboriginal population decrease after contact. For example, during the late 1630s, smallpox killed over half of the Wyandot (Huron), who controlled most of the early North American fur trade in what became Canada. They were reduced to fewer than 10,000 people.
Historian David Henige
has argued that many population figures are the result of arbitrary
formulas selectively applied to numbers from unreliable historical
sources. He believes this is a weakness unrecognized by several
contributors to the field, and insists there is not sufficient evidence
to produce population numbers that have any real meaning. He
characterizes the modern trend of high estimates as "pseudo-scientific
number-crunching." Henige does not advocate a low population estimate,
but argues that the scanty and unreliable nature of the evidence renders
broad estimates inevitably suspect, saying "high counters" (as he calls
them) have been particularly flagrant in their misuse of sources.
Many population studies acknowledge the inherent difficulties in
producing reliable statistics, given the scarcity of hard data.
The population debate has often had ideological underpinnings. Low estimates were sometimes reflective of European notions of cultural and racial superiority. Historian Francis Jennings
argued, "Scholarly wisdom long held that Indians were so inferior in
mind and works that they could not possibly have created or sustained
large populations."
The indigenous population of the Americas in 1492 was not
necessarily at a high point and may actually have been in decline in
some areas. Indigenous populations in most areas of the Americas reached
a low point by the early 20th century. In most cases, populations have
since begun to climb.
Pre-Columbian Americas
Genetic diversity and population structure in the American land mass using DNA micro-satellite markers (genotype) sampled from North, Central, and South America have been analyzed against similar data available from other indigenous populations worldwide. The Amerindian populations show a lower genetic diversity than populations from other continental regions. Observed is both a decreasing genetic diversity as geographic distance from the Bering Strait occurs and a decreasing genetic similarity to Siberian populations from Alaska (genetic entry point).
Also observed is evidence of a higher level of diversity and lower
level of population structure in western South America compared to
eastern South America. A relative lack of differentiation between Mesoamerican and Andean populations is a scenario that implies coastal routes were easier than inland routes for migrating peoples (Paleo-Indians) to traverse.
The overall pattern that is emerging suggests that the Americas were
recently colonized by a small number of individuals (effective size of
about 70-250), and then they grew by a factor of 10 over 800 – 1000
years. The data also show that there have been genetic exchanges between Asia, the Arctic and Greenland since the initial peopling of the Americas. A new study in early 2018 suggests that the effective population size of the original founding population of Native Americans was about 250 people.
Depopulation from disease
Sixteenth-century Aztec drawings of victims of smallpox (above) and measles (below)
Graph demonstrating the population collapse in Central Mexico brought on by successive epidemics in the early colonial period.
According to Noble David Cook, a community of scholars has recently,
albeit slowly, "been quietly accumulating piece by piece data on early
epidemics in the Americas and their relation to the subjugation of
native peoples." They now believe that widespread epidemic disease, to
which the natives had no prior exposure or resistance, was the primary
cause of the massive population decline of the Native Americans.
Earlier explanations for the population decline of the American natives
include the European immigrants' accounts of the brutal practices of
the Spanish conquistadores, as recorded by the Spaniards themselves. This was applied through the encomienda,
which was a system ostensibly set up to protect people from warring
tribes as well as to teach them the Spanish language and the Catholic religion, but in practice was tantamount to serfdom and slavery. The most notable account was that of the DominicanfriarBartolomé de las Casas, whose writings vividly depict Spanish atrocities committed in particular against the Taínos. It took five years for the Taíno rebellion to be quelled by both the Real Audiencia—through diplomatic sabotage, and through the Indian auxiliaries fighting with the Spanish. After Emperor Charles V
personally eradicated the notion of the encomienda system as a use for
slave labour, there were not enough Spanish to have caused such a large
population decline. The second European explanation was a perceived divine approval, in which God removed the natives as part of His "divine plan" to make way for a new Christian
civilization. Many Native Americans viewed their troubles in terms of
religious or supernatural causes within their own belief systems.
Soon after Europeans and enslaved Africans arrived in the New
World, bringing with them the infectious diseases of Europe and Africa,
observers noted immense numbers of indigenous Americans began to die
from these diseases. One reason this death toll was overlooked is that
once introduced, the diseases raced ahead of European immigration in
many areas. The disease killed a sizable portion of the populations
before European written records were made. After the epidemics had
already killed massive numbers of natives, many newer European
immigrants assumed that there had always been relatively few indigenous
peoples. The scope of the epidemics over the years was tremendous,
killing millions of people—possibly in excess of 90% of the population
in the hardest-hit areas—and creating one of "the greatest human
catastrophe in history, far exceeding even the disaster of the Black Death of medieval Europe", which had killed up to one-third of the people in Europe and Asia between 1347 and 1351.
This transfer of disease between the Old and New Worlds was later studied as part of what has been labeled the "Columbian Exchange".
The epidemics had very different effects in different regions of
the Americas. The most vulnerable groups were those with a relatively
small population and few built-up immunities. Many island-based groups
were annihilated. The Caribs and Arawaks of the Caribbean nearly ceased to exist, as did the Beothuks of Newfoundland. While disease raged swiftly through the densely populated empires of Mesoamerica, the more scattered populations of North America saw a slower spread.
The colonization of the Americas killed so many people it resulted in climate change and temporary global cooling, according to scientists from University College London.
According to one of the researchers, UCL Geography Professor Mark
Maslin, the large death toll also boosted the economies of Europe: "the
depopulation of the Americas may have inadvertently allowed the
Europeans to dominate the world. It also allowed for the Industrial
Revolution and for Europeans to continue that domination."
Historian Andrés Reséndez of University of California, Davis
asserts that evidence suggests "slavery has emerged as major killer" of
the indigenous populations of the Caribbean between 1492 and 1550
rather than diseases such as smallpox, influenza and malaria. He posits that unlike the populations of Europe who rebounded following the Black Death,
no such rebound occurred for the indigenous populations of the
Americas. He concludes that, even though the Spanish were aware of
deadly diseases such as smallpox, there is no mention of them in the New
World until 1519, meaning perhaps they didn't spread as fast as
initially believed, and that unlike Europeans, the indigenous
populations were subjected to brutal forced labor in gold and silver
mines on a massive scale. Anthropologist Jason Hickel of the London School of Economics estimates that a third of Arawak workers died every six months from lethal forced labor in these mines.
Historian David Stannard
says that by "focusing almost entirely on disease . . . contemporary
authors increasingly have created the impression that the eradication of
those tens of millions of people was inadvertent - a sad, but both
inevitable and "unintended consequence" of human migration and
progress," and asserts that their destruction "was neither inadvertent
not inevitable," but the result of microbial pestilence and purposeful
genocide working in tandem.
Virulence and mortality
Viral and bacterial
diseases that kill victims before the illnesses spread to others tend
to flare up and then die out. A more resilient disease would establish
an equilibrium; if its victims lived beyond infection, the disease would spread further. The evolutionary process selects against quick lethality, with the most immediately fatal diseases being the most short-lived.
A similar evolutionary pressure acts upon victim populations, as
those lacking genetic resistance to common diseases die and do not leave
descendants, whereas those who are resistant procreate and pass
resistant genes to their offspring. For example, in the first fifty
years of the sixteenth century, an unusually strong strain of syphilis
killed a high proportion of infected Europeans within a few months;
over time, however, the disease has become much less virulent.
Thus both infectious diseases and populations tend to evolve
towards an equilibrium in which the common diseases are non-symptomatic,
mild or manageably chronic.
When a population that has been relatively isolated is exposed to new
diseases, it has no resistance to the new diseases (the population is
"biologically naive"). These people die at a much higher rate, resulting
in what is known as a "virgin soil" epidemic.
Before the European arrival, the Americas had been isolated from the
Eurasian-African landmass. The peoples of the Old World had had
thousands of years for their populations to accommodate to their common
diseases.
The fact that all members of an immunologically naive population
are exposed to a new disease simultaneously increases the fatalities.
In populations where the disease is endemic, generations of individuals
acquired immunity; most adults had exposure to the disease at a young
age. Because they were resistant to reinfection, they are able to care
for individuals who caught the disease for the first time, including the
next generation of children. With proper care, many of these "childhood diseases"
are often survivable. In a naive population, all age groups are
affected at once, leaving few or no healthy caregivers to nurse the
sick. With no resistant individuals healthy enough to tend to the ill, a
disease may have higher fatalities.
The natives of the Americas were faced with several new diseases
at once creating a situation where some who successfully resisted one
disease might die from another. Multiple simultaneous infections (e.g.,
smallpox and typhus at the same time) or in close succession (e.g.,
smallpox in an individual who was still weak from a recent bout of
typhus) are more deadly than just the sum of the individual diseases. In
this scenario, death rates can also be elevated by combinations of new
and familiar diseases: smallpox in combination with American strains of yaws, for example.
Other contributing factors:
Native American medical treatments such as sweat baths and cold water immersion (practiced in some areas) weakened some patients and probably increased mortality rates.
Europeans brought many diseases with them because they had many more domesticated animals than the Native Americans. Domestication
usually means close and frequent contact between animals and people,
which allows diseases of domestic animals to migrate into the human
population when the necessary mutations occur.
The Eurasian landmass extends many thousands of miles along an
east-west axis. Climate zones also extend for thousands of miles, which
facilitated the spread of agriculture, domestication of animals, and the
diseases associated with domestication. The Americas extend mainly
north and south, which, according to the environmental determinist
theory popularized by Jared Diamond in Guns, Germs, and Steel, meant that it was much harder for cultivated plant species, domesticated animals, and diseases to migrate.
Biological warfare
When
Old World diseases were first carried to the Americas at the end of the
fifteenth century, they spread throughout the southern and northern
hemispheres, leaving the indigenous populations in near ruins.
No evidence has been discovered that the earliest Spanish colonists
and missionaries deliberately attempted to infect the American natives,
and some effort was actually made to limit the devastating effects of
disease before it killed off what remained of their forced slave labor
under their encomienda system.
The cattle introduced by the Spanish contaminated various water
reserves which Native Americans dug in the fields to accumulate
rainwater. In response, the Franciscans and Dominicans created public fountains and aqueducts to guarantee access to drinking water. But when the Franciscans lost their privileges in 1572, many of these fountains were no longer guarded and so deliberate well poisoning may have happened.
Although no proof of such poisoning has been found, some historians
believe the decrease of the population correlates with the end of
religious orders' control of the water.
In the centuries that followed, accusations and discussions of
biological warfare were common. Well-documented accounts of incidents
involving both threats and acts of deliberate infection are very rare,
but may have occurred more frequently than scholars have previously
acknowledged.
Many of the instances likely went unreported, and it is possible that
documents relating to such acts were deliberately destroyed, or sanitized.
By the middle of the 18th century, colonists had the knowledge and
technology to attempt biological warfare with the smallpox virus. They
well understood the concept of quarantine, and that contact with the
sick could infect the healthy with smallpox, and those who survived the
illness would not be infected again. Whether the threats were carried
out, or how effective individual attempts were, is uncertain.
One such threat was delivered by fur trader James McDougall,
who is quoted as saying to a gathering of local chiefs, "You know the
smallpox. Listen: I am the smallpox chief. In this bottle I have it
confined. All I have to do is to pull the cork, send it forth among you,
and you are dead men. But this is for my enemies and not my friends." Likewise, another fur trader threatened Pawnee Indians that if they didn't agree to certain conditions, "he would let the smallpox out of a bottle and destroy them." The Reverend Isaac McCoy was quoted in his History of Baptist Indian Missions
as saying that the white men had deliberately spread smallpox among the
Indians of the southwest, including the Pawnee tribe, and the havoc it
made was reported to General Clark and the Secretary of War. Artist and writer George Catlin
observed that Native Americans were also suspicious of vaccination,
"They see white men urging the operation so earnestly they decide that
it must be some new mode or trick of the pale face by which they hope to
gain some new advantage over them." So great was the distrust of the settlers that the Mandan chief Four Bears denounced the white man, whom he had previously treated as brothers, for deliberately bringing the disease to his people.
During the Seven Years' War, British militia took blankets from their smallpox hospital and gave them as gifts to two neutral Lenape
Indian dignitaries during a peace settlement negotiation, according to
the entry in the Captain's ledger, "To convey the Smallpox to the
Indians".
In the following weeks, the high commander of the British forces in
North America conspired with his Colonel to "Extirpate this Execreble
Race" of Native Americans, writing, "Could it not be contrived to send
the small pox among the disaffected tribes of Indians? We must on this
occasion use every stratagem in our power to reduce them." His Colonel
agreed to try. Most scholars have asserted that the 1837 Great Plains smallpox epidemic was "started among the tribes of the upper Missouri River by failure to quarantine steamboats on the river", and Captain Pratt of the St. Peter
"was guilty of contributing to the deaths of thousands of innocent
people. The law calls his offense criminal negligence. Yet in light of
all the deaths, the almost complete annihilation of the Mandans, and the
terrible suffering the region endured, the label criminal negligence is
benign, hardly befitting an action that had such horrendous
consequences."
However, some sources attribute the 1836–40 epidemic to the deliberate
communication of smallpox to Native Americans, with historian Ann F.
Ramenofsky writing, "Variola Major can be transmitted through
contaminated articles such as clothing or blankets. In the nineteenth
century, the U. S. Army sent contaminated blankets to Native Americans,
especially Plains groups, to control the Indian problem."
Well into the 20th century, deliberate infection attacks continued as
Brazilian settlers and miners transported infections intentionally to
the native groups whose lands they coveted."
Vaccination
After Edward Jenner's 1796 demonstration that the smallpox vaccination
worked, the technique became better known and smallpox became less
deadly in the United States and elsewhere. Many colonists and natives
were vaccinated, although, in some cases, officials tried to vaccinate
natives only to discover that the disease was too widespread to stop. At
other times, trade demands led to broken quarantines. In other cases,
natives refused vaccination because of suspicion of whites. The first
international healthcare expedition in history was the Balmis expedition which had the aim of vaccinating indigenous peoples against smallpox all along the Spanish Empire in 1803. In 1831, government officials vaccinated the Yankton Sioux at Sioux Agency. The Santee Sioux refused vaccination and many died.
Depopulation from European Conquest
War and violence
Storming of the Teocalli by Cortez and His Troops by Emanuel Leutze
While epidemic disease was a leading factor of the population decline
of the American indigenous peoples after 1492, there were other
contributing factors, all of them related to European contact and
colonization. One of these factors was warfare. According to demographer
Russell Thornton, although many lives were lost in wars over the
centuries, and war sometimes contributed to the near extinction of
certain tribes, warfare and death by other violent means was a
comparatively minor cause of overall native population decline.
From the U.S. Bureau of the Census in 1894: "The Indian wars
under the government of the United States have been more than 40 in
number [Over the previous 100 years]. They have cost the lives of about
19,000 white men, women and children, including those killed in
individual combats, and the lives of about 30,000 Indians. The actual
number of killed and wounded Indians must be very much higher than the
given... Fifty percent additional would be a safe estimate..."
There is some disagreement among scholars about how widespread warfare was in pre-Columbian America, but there is general agreement that war became deadlier after the arrival of the Europeans and their firearms. The South or Central American infrastructure allowed for thousands of European conquistadors and tens of thousands of their Indian auxiliaries to attack the dominant indigenous civilization. Empires such as the Incas
depended on a highly centralized administration for the distribution of
resources. Disruption caused by the war and the colonization hampered
the traditional economy, and possibly led to shortages of food and
materials. The Arauco War, Chichimeca War, Red Cloud's War, Seminole Wars, War of 1812, Pontiac's Rebellion, Beaver Wars, French-Indian War, American Civil War, American Revolution, Modoc War, Oka Crisis, Battle of Cut Knife, all represented either pyrrhic victories by colonial forces, outright defeat, military stalemates, or further alliance-politics.
Across the western hemisphere, war with various Native American
civilizations constituted alliances based out of both necessity or
economic prosperity and, resulted in mass-scale intertribal warfare.
European colonization in the North American continent also contributed
to a number of wars between Native Americans, who fought over which of
them should have first access to new technology and weaponry—like in the
Beaver Wars.
Exploitation
Some Spaniards objected to the encomienda system, notably Bartolomé de las Casas, who insisted that the Indians were humans with souls and rights. Due to many revolts and military encounters, Emperor Charles V
helped relieve the strain on both the Indian laborers and the Spanish
vanguards probing the Caribana for military and diplomatic purposes. Later on New Laws
were promulgated in Spain in 1542 to protect isolated natives, but the
abuses in the Americas were never entirely or permanently abolished. The
Spanish also employed the pre-Columbian draft system called the mita, and treated their subjects as something between slaves and serfs.
Serfs stayed to work the land; slaves were exported to the mines, where
large numbers of them died. In other areas the Spaniards replaced the
ruling Aztecs and Incas and divided the conquered lands among themselves
ruling as the new feudal lords with often, but unsuccessful lobbying to the viceroys of the Spanish crown to pay Tlaxcalan war demnities. The infamous Bandeirantes from São Paulo, adventurers mostly of mixed Portuguese and native ancestry, penetrated steadily westward in their search for Indian slaves. Serfdom existed as such in parts of Latin America well into the 19th century, past independence.
Massacres
Friar Bartolomé de las Casas
and Antonius Flávio Chesta (Tony Chesta) and other dissenting Spaniards
from the colonial period described the manner in which the natives were
treated by colonials. This has helped to create an image of the Spanish
conquistadores as cruel in the extreme.
Great revenues were drawn from Hispaniola so the advent of losing manpower didn't benefit the Spanish crown. At best, the reinforcement of vanguards sent by the Council of the Indies
to explore the Caribana country and gather information on alliances or
hostilities was the main goal of the local viceroys and their adelantados. Although mass killings and atrocities
were not a significant factor in native depopulation, no mainstream
scholar dismisses the sometimes humiliating circumstances now believed
to be precipitated by civil disorder as well as Spanish cruelty.
While some California
tribes were settled on reservations, others were hunted down and
massacred by 19th century American settlers. It is estimated that at
least 9,400 to 16,000 California Indians were killed by non-Indians,
mostly occurring in more than 370 massacres (defined as the "intentional
killing of five or more disarmed combatants or largely unarmed
noncombatants, including women, children, and prisoners, whether in the
context of a battle or otherwise").
Displacement and disruption
The populations of many Native American peoples were reduced by the common practice of intermarrying with Europeans.
Although many Indian cultures that once thrived are extinct today,
their descendants exist today in some of the bloodlines of the current
inhabitants of the Americas.
Formal apology from the United States government
On 8 September 2000, the head of the United States Bureau of Indian Affairs (BIA) formally apologized for the agency's participation in the "ethnic cleansing" of Western tribes.
In a speech before representatives of Native American peoples in June, 2019, California governor Gavin Newsom apologized for the California Genocide.
Newsom said, "That’s what it was, a genocide. No other way to describe
it. And that’s the way it needs to be described in the history books."
Fire ecology is a scientific discipline concerned with natural processes involving fire in an ecosystem and the ecological
effects, the interactions between fire and the abiotic and biotic
components of an ecosystem, and the role as an ecosystem process. Many
ecosystems, particularly prairie, savanna, chaparral and coniferous forests, have evolved with fire as an essential contributor to habitat vitality and renewal. Many plant species in fire-affected environments require fire to germinate, establish, or to reproduce. Wildfire suppression not only eliminates these species, but also the animals that depend upon them.
Campaigns in the United States have historically molded public opinion to believe that wildfires
are always harmful to nature. This view is based on the outdated belief
that ecosystems progress toward an equilibrium and that any
disturbance, such as fire, disrupts the harmony of nature. More recent
ecological research has shown, however, that fire is an integral
component in the function and biodiversity
of many natural habitats, and that the organisms within these
communities have adapted to withstand, and even to exploit, natural
wildfire. More generally, fire is now regarded as a 'natural
disturbance', similar to flooding, wind-storms, and landslides, that has driven the evolution of species and controls the characteristics of ecosystems.
Fire suppression, in combination with other human-caused
environmental changes, may have resulted in unforeseen consequences for
natural ecosystems. Some large wildfires in the United States have been
blamed on years of fire suppression and the continuing expansion of
people into fire-adapted ecosystems, but climate change is more likely responsible. Land managers are faced with tough questions regarding how to restore a natural fire regime, but allowing wildfires to burn is the least expensive and likely most effective method.
A
combination of photos taken at a photo point at Florida Panther NWR.
The photos are panoramic and cover a 360 degree view from a monitoring
point. These photos range from pre-burn to 2 year post burn.
Fire components
A fire regime describes the characteristics of fire and how it interacts with a particular ecosystem.
Its "severity" is a term that ecologists use to refer to the impact
that a fire has on an ecosystem. Ecologists can define this in many
ways, but one way is through an estimate of plant mortality. Fire can
burn at three levels. Ground fires will burn through soil that is rich
in organic matter. Surface fires will burn through dead plant material
that is lying on the ground. Crown fires will burn in the tops of shrubs
and trees. Ecosystems generally experience a mix of all three.
Fires will often break out during a dry season, but in some areas
wildfires may also commonly occur during a time of year when lightning
is prevalent. The frequency over a span of years at which fire will
occur at a particular location is a measure of how common wildfires are
in a given ecosystem. It is either defined as the average interval
between fires at a given site, or the average interval between fires in
an equivalent specified area.
Defined as the energy released per unit length of fireline (kW m−1), wildfire intensity can be estimated either as
Fires
can affect soils through heating and combustion processes. Depending on
the temperatures of the soils caused by the combustion processes,
different effects will happen- from evaporation of water at the lower
temperature ranges, to the combustion of soil organic matter and formation of pyrogenic organic matter, otherwise known as charcoal.
Fires can cause changes in soil nutrients through a variety of
mechanisms, which include oxidation, volatilization, erosion, and
leaching by water, but the event must usually be of high temperatures in
order of significant loss of nutrients to occur. However, quantity of
nutrients available in soils are usually increased due to the ash that
is generated, and this is made quickly available, as opposed to the slow
release of nutrients by decomposition. Rock spalling (or thermal exfoliation) accelerates weathering of rock and potentially the release of some nutrients.
Increase in the pH of the soil following a fire is commonly
observed, most likely due to the formation of calcium carbonate, and the
subsequent decomposition of this calcium carbonate to calcium oxide
when temperatures get even higher.
It could also be due to the increased cation content in the soil due to
the ash, which temporarily increases soil pH. Microbial activity in the
soil might also increase due to the heating of soil and increased
nutrient content in the soil, though studies have also found complete
loss of microbes on the top layer of soil after a fire. Overall, soils become more basic (higher pH) following fires because of acid combustion. By driving novel chemical reactions at high temperatures, fire can even alter the texture and structure of soils by affecting the clay content and the soil's porosity.
Removal of vegetation following a fire can cause several effects
on the soil, such as increasing the temperatures of the soil during the
day due to increased solar radiation on the soil surface, and greater
cooling due to loss of radiative heat at night. Fewer leaves to
intercept rain will also cause more rain to reach the soil surface, and
with fewer plants to absorb the water, the amount of water content in
the soils might increase. However, it might be seen that ash can be
water repellent when dry, and therefore water content and availability
might not actually increase.
Biotic responses and adaptations
Plants
Lodgepole pine cones
Plants have evolved many adaptations to cope with fire. Of these adaptations, one of the best-known is likely pyriscence,
where maturation and release of seeds is triggered, in whole or in
part, by fire or smoke; this behaviour is often erroneously called serotiny,
although this term truly denotes the much broader category of seed
release activated by any stimulus. All pyriscent plants are serotinous,
but not all serotinous plants are pyriscent (some are necriscent,
hygriscent, xeriscent, soliscent, or some combination thereof). On the
other hand, germination of seed activated by trigger is not to be confused with pyriscence; it is known as physiological dormancy.
In chaparral communities in Southern California, for example, some plants have leaves coated in flammable oils that encourage an intense fire.
This heat causes their fire-activated seeds to germinate (an example of
dormancy) and the young plants can then capitalize on the lack of competition in a burnt landscape. Other plants have smoke-activated seeds, or fire-activated buds. The cones of the Lodgepole pine (Pinus contorta) are, conversely, pyriscent: they are sealed with a resin that a fire melts away, releasing the seeds. Many plant species, including the shade-intolerant giant sequoia (Sequoiadendron giganteum),
require fire to make gaps in the vegetation canopy that will let in
light, allowing their seedlings to compete with the more shade-tolerant
seedlings of other species, and so establish themselves.
Because their stationary nature precludes any fire avoidance, plant
species may only be fire-intolerant, fire-tolerant or fire-resistant.
Fire intolerance
Fire-intolerant
plant species tend to be highly flammable and are destroyed completely
by fire. Some of these plants and their seeds may simply fade from the
community after a fire and not return; others have adapted to ensure
that their offspring survives into the next generation. "Obligate
seeders" are plants with large, fire-activated seed banks that
germinate, grow, and mature rapidly following a fire, in order to
reproduce and renew the seed bank before the next fire.
Seeds may contain the receptor protein KAI2, that is activated by the growth hormones karrikin released by the fire.
Fire tolerance. Typical regrowth after an Australian bushfire
Fire tolerance
Fire-tolerant
species are able to withstand a degree of burning and continue growing
despite damage from fire. These plants are sometimes referred to as "resprouters."
Ecologists have shown that some species of resprouters store extra
energy in their roots to aid recovery and re-growth following a fire. For example, after an Australian bushfire, the Mountain Grey Gum tree (Eucalyptus cypellocarpa)
starts producing a mass of shoots of leaves from the base of the tree
all the way up the trunk towards the top, making it look like a black
stick completely covered with young, green leaves.
Fire resistance
Fire-resistant
plants suffer little damage during a characteristic fire regime. These
include large trees whose flammable parts are high above surface fires.
Mature ponderosa pine (Pinus ponderosa)
is an example of a tree species that suffers virtually no crown damage
under a naturally mild fire regime, because it sheds its lower,
vulnerable branches as it matures.
Animals, birds and microbes
A mixed flock of hawks hunting in and around a bushfire
Like plants, animals display a range of abilities to cope with fire,
but they differ from most plants in that they must avoid the actual fire
to survive. Although birds
are vulnerable when nesting, they are generally able to escape a fire;
indeed they often profit from being able to take prey fleeing from a
fire and to recolonize burned areas quickly afterwards. Some
anthropological and ethno-ornithological evidence suggests that certain
species of fire-foraging raptors may engage in intentional fire
propagation to flush out prey. Mammals are often capable of fleeing a fire, or seeking cover if they can burrow. Amphibians and reptiles
may avoid flames by burrowing into the ground or using the burrows of
other animals. Amphibians in particular are able to take refuge in water
or very wet mud.
Some arthropods also take shelter during a fire, although the heat and smoke may actually attract some of them, to their peril. Microbial
organisms in the soil vary in their heat tolerance but are more likely
to be able to survive a fire the deeper they are in the soil. A low fire
intensity, a quick passing of the flames and a dry soil will also help.
An increase in available nutrients after the fire has passed may result
in larger microbial communities than before the fire.
The generally greater heat tolerance of bacteria relative to fungi
makes it possible for soil microbial population diversity to change
following a fire, depending on the severity of the fire, the depth of
the microbes in the soil, and the presence of plant cover. Certain species of fungi, such as Cylindrocarpon destructans
appear to be unaffected by combustion contaminants, which can inhibit
re-population of burnt soil by other microorganisms, and therefore have a
higher chance of surviving fire disturbance and then recolonizing and
out-competing other fungal species afterwards.
Fire and ecological succession
Fire
behavior is different in every ecosystem and the organisms in those
ecosystems have adapted accordingly. One sweeping generality is that in
all ecosystems, fire creates a mosaic of different habitat
patches, with areas ranging from those having just been burned to those
that have been untouched by fire for many years. This is a form of ecological succession
in which a freshly burned site will progress through continuous and
directional phases of colonization following the destruction caused by
the fire.
Ecologists usually characterize succession through the changes in
vegetation that successively arise. After a fire, the first species to
re-colonize will be those with seeds are already present in the soil, or
those with seeds are able to travel into the burned area quickly. These
are generally fast-growing herbaceous
plants that require light and are intolerant of shading. As time
passes, more slowly growing, shade-tolerant woody species will suppress
some of the herbaceous plants.
Conifers are often early successional species, while broad leaf trees
frequently replace them in the absence of fire. Hence, many conifer
forests are themselves dependent upon recurring fire.
Different species of plants, animals, and microbes specialize in
exploiting different stages in this process of succession, and by
creating these different types of patches, fire allows a greater number
of species to exist within a landscape. Soil characteristics will be a
factor in determining the specific nature of a fire-adapted ecosystem,
as will climate and topography.
Some examples of fire in different ecosystems
Forests
Mild to moderate fires burn in the forestunderstory, removing small trees and herbaceous groundcover.
High-severity fires will burn into the crowns of the trees and kill
most of the dominant vegetation. Crown fires may require support from
ground fuels to maintain the fire in the forest canopy (passive crown
fires), or the fire may burn in the canopy independently of any ground
fuel support (an active crown fire). High-severity fire creates complex early seral forest habitat, or snag forest
with high levels of biodiversity. When a forest burns frequently and
thus has less plant litter build-up, below-ground soil temperatures rise
only slightly and will not be lethal to roots that lie deep in the
soil. Although other characteristics of a forest will influence the impact of fire upon it, factors such as climate and topography play an important role in determining fire severity and fire extent. Fires spread most widely during drought years, are most severe on upper
slopes and are influenced by the type of vegetation that is growing.
Forests in British Columbia
In Canada,
forests cover about 10% of the land area and yet harbor 70% of the
country’s bird and terrestrial mammal species. Natural fire regimes are
important in maintaining a diverse assemblage of vertebrate species in up to twelve different forest types in British Columbia.
Different species have adapted to exploit the different stages of
succession, regrowth and habitat change that occurs following an episode
of burning, such as downed trees and debris. The characteristics of the
initial fire, such as its size and intensity, cause the habitat to
evolve differentially afterwards and influence how vertebrate species
are able to use the burned areas.
Shrublands
Lightning-sparked wildfires are frequent occurrences on shrublands and grasslands in Nevada.
Shrub fires typically concentrate in the canopy and spread continuously if the shrubs are close enough together. Shrublands
are typically dry and are prone to accumulations of highly volatile
fuels, especially on hillsides. Fires will follow the path of least
moisture and the greatest amount of dead fuel material. Surface and
below-ground soil temperatures during a burn are generally higher than
those of forest fires because the centers of combustion lie closer to
the ground, although this can vary greatly. Common plants in shrubland or chaparral include manzanita, chamise and Coyote Brush.
California shrublands
California shrubland, commonly known as chaparral, is a widespread plant community of low growing species, typically on arid sloping areas of the California Coast Ranges or western foothills of the Sierra Nevada. There are a number of common shrubs and tree shrub forms in this association, including salal, toyon, coffeeberry and Western poison oak. Regeneration following a fire is usually a major factor in the association of these species.
South African Fynbos shrublands
Fynbos shrublands occur in a small belt across South Africa.
The plant species in this ecosystem are highly diverse, yet the
majority of these species are obligate seeders, that is, a fire will
cause germination of the seeds and the plants will begin a new
life-cycle because of it. These plants may have coevolved into obligate seeders as a response to fire and nutrient-poor soils.
Because fire is common in this ecosystem and the soil has limited
nutrients, it is most efficient for plants to produce many seeds and
then die in the next fire. Investing a lot of energy in roots to survive
the next fire when those roots will be able to extract little extra
benefit from the nutrient-poor soil would be less efficient. It is
possible that the rapid generation time that these obligate seeders
display has led to more rapid evolution and speciation in this ecosystem, resulting in its highly diverse plant community.
Grasslands
Grasslands
burn more readily than forest and shrub ecosystems, with the fire
moving through the stems and leaves of herbaceous plants and only
lightly heating the underlying soil, even in cases of high intensity. In
most grassland ecosystems, fire is the primary mode of decomposition, making it crucial in the recycling of nutrients.
In some grassland systems, fire only became the primary mode of
decomposition after the disappearance of large migratory herds of
browsing or grazing megafauna driven by predator pressure. In the
absence of functional communities of large migratory herds of
herbivorous megafauna and attendant predators, overuse of fire to
maintain grassland ecosystems may lead to excessive oxidation, loss of
carbon, and desertification in susceptible climates. Some grassland ecosystems respond poorly to fire.
North American grasslands
In North America fire-adapted invasive grasses such as Bromus tectorum
contribute to increased fire frequency which exerts selective pressure
against native species. This is a concern for grasslands in the Western United States.
In less arid grassland presettlement fires worked in concert with grazing to create a healthy grassland ecosystem as indicated by the accumulation of soil organic matter significantly altered by fire.
The tallgrass prairie ecosystem in the Flint Hills of eastern Kansas and Oklahoma is responding positively to the current use of fire in combination with grazing.
South African savanna
In the savanna of South Africa,
recently burned areas have new growth that provides palatable and
nutritious forage compared to older, tougher grasses. This new forage
attracts large herbivores
from areas of unburned and grazed grassland that has been kept short by
constant grazing. On these unburned "lawns", only those plant species
adapted to heavy grazing are able to persist; but the distraction
provided by the newly burned areas allows grazing-intolerant grasses to
grow back into the lawns that have been temporarily abandoned, so
allowing these species to persist within that ecosystem.
Longleaf pine savannas
Yellow pitcher plant is dependent upon recurring fire in coastal plain savannas and flatwoods.
Much of the southeastern United States was once open longleaf pine
forest with a rich understory of grasses, sedges, carnivorous plants
and orchids. The above maps shows that these ecosystems (coded as pale
blue) had the highest fire frequency of any habitat, once per decade or
less. Without fire, deciduous forest trees invade, and their shade
eliminates both the pines and the understory. Some of the typical
plants associated with fire include Yellow Pitcher Plant and Rose pogonia. The abundance and diversity of such plants is closely related to fire frequency. Rare animals such as gopher tortoises and indigo snakes also depend upon these open grasslands and flatwoods. Hence, the restoration of fire is a priority to maintain species composition and biological diversity.
Fire in wetlands
Although
it may seem strange, many kinds of wetlands are also influenced by
fire.
This usually occurs during periods of drought.
In landscapes with peat soils, such as bogs, the peat substrate itself
may burn, leaving holes that refill with water as new ponds.
Fires that are less intense will remove accumulated litter and allow
other wetland plants to regenerate from buried seeds, or from rhizomes.
Wetlands that are influenced by fire include coastal marshes, wet prairies, peat bogs, floodplains, prairie marshes and flatwoods.
Since wetlands can store large amounts of carbon in peat, the fire
frequency of vast northern peatlands is linked to processes controlling
the carbon dioxide levels of the atmosphere, and to the phenomenon of
global warming.
Dissolved organic carbon (DOC) is abundant in wetlands and plays a critical role in their ecology. In the Florida Everglades, a significant portion of the DOC is "dissolved charcoal" indicating that fire can play a critical role in wetland ecosystems.
Fire suppression
Fire serves many important functions within fire-adapted ecosystems.
Fire plays an important role in nutrient cycling, diversity maintenance
and habitat structure. The suppression of fire can lead to unforeseen
changes in ecosystems that often adversely affect the plants, animals
and humans that depend upon that habitat. Wildfires that deviate from a
historical fire regime because of fire suppression are called
"uncharacteristic fires".
Chaparral communities
In 2003, southern California witnessed powerful chaparral
wildfires. Hundreds of homes and hundreds of thousands of acres of land
went up in flames. Extreme fire weather (low humidity, low fuel
moisture and high winds) and the accumulation of dead plant material
from 8 years of drought, contributed to a catastrophic outcome. Although
some have maintained that fire suppression contributed to an unnatural
buildup of fuel loads, a detailed analysis of historical fire data has showed that this may not have been the case.
Fire suppression activities had failed to exclude fire from the
southern California chaparral. Research showing differences in fire size
and frequency between southern California and Baja has been used to
imply that the larger fires north of the border are the result of fire
suppression, but this opinion has been challenged by numerous
investigators and is no longer supported by the majority of fire
ecologists.
One consequence of the fires in 2003 has been the increased density of invasive and non-native
plant species that have quickly colonized burned areas, especially
those that had already been burned in the previous 15 years. Because
shrubs in these communities are adapted to a particular historical fire
regime, altered fire regimes may change the selective pressures on plants and favor invasive and non-native species that are better able to exploit the novel post-fire conditions.
Fish impacts
The Boise National Forest is a US national forest located north and east of the city of Boise, Idaho.
Following several uncharacteristically large wildfires, an immediately
negative impact on fish populations was observed, posing particular
danger to small and isolated fish populations. In the long term, however, fire appears to rejuvenate fish habitats by causing hydraulic changes that increase flooding and lead to silt
removal and the deposition of a favorable habitat substrate. This leads
to larger post-fire populations of the fish that are able to recolonize
these improved areas.
But although fire generally appears favorable for fish populations in
these ecosystems, the more intense effects of uncharacteristic
wildfires, in combination with the fragmentation of populations by human
barriers to dispersal such as weirs and dams, will pose a threat to fish populations.
Fire as a management tool
Restoration ecology is the name given to an attempt to reverse or mitigate some of the changes that humans have caused to an ecosystem. Controlled burning
is one tool that is currently receiving considerable attention as a
means of restoration and management. Applying fire to an ecosystem may
create habitats for species that have been negatively impacted by fire
suppression, or fire may be used as a way of controlling invasive
species without resorting to herbicides or pesticides. However, there is
debate as to what state managers should aim to restore their ecosystems
to, especially as to whether "natural" means pre-human or pre-European.
Native American use of fire, not natural fires, historically maintained the diversity of the savannas of North America. When, how, and where managers should use fire as a management tool is a subject of debate.
The Great Plains shortgrass prairie
A combination of heavy livestock grazing and fire-suppression has
drastically altered the structure, composition, and diversity of the
shortgrass prairie ecosystem on the Great Plains,
allowing woody species to dominate many areas and promoting
fire-intolerant invasive species. In semi-arid ecosystems where the
decomposition of woody material is slow, fire is crucial for returning
nutrients to the soil and allowing the grasslands to maintain their high
productivity.
Although fire can occur during the growing or the dormant
seasons, managed fire during the dormant season is most effective at
increasing the grass and forb cover, biodiversity and plant nutrient uptake in shortgrass prairies.
Managers must also take into account, however, how invasive and
non-native species respond to fire if they want to restore the integrity
of a native ecosystem. For example, fire can only control the invasive spotted knapweed (Centaurea maculosa)
on the Michigan tallgrass prairie in the summer, because this is the
time in the knapweed's life cycle that is most important to its
reproductive growth.
Mixed conifer forests in the US Sierra Nevada
Mixed conifer forests in the United States Sierra Nevada
used to have fire return intervals that ranged from 5 years up to 300
years, depending on the local climate. Lower elevations had more
frequent fire return intervals, whilst higher and wetter elevations saw
much longer intervals between fires. Native Americans tended to set
fires during fall and winter, and land at a higher elevation was
generally occupied by Native Americans only during the summer.
Finnish boreal forests
The
decline of habitat area and quality has caused many species populations
to be red-listed by the International Union for Conservation of Nature.
According to a study on forest management of Finnish boreal forests,
improving the habitat quality of areas outside reserves can help in
conservation efforts of endangered deadwood-dependent beetles. These
beetles and various types of fungi both need dead trees in order to
survive. Old growth forests can provide this particular habitat.
However, most Fennoscandian boreal forested areas are used for timber
and therefore are unprotected. The use of controlled burning and tree
retention of a forested area with deadwood was studied and its effect on
the endangered beetles. The study found that after the first year of
management the number of species increased in abundance and richness
compared to pre-fire treatment. The abundance of beetles continued to
increase the following year in sites where tree retention was high and
deadwood was abundant. The correlation between forest fire management
and increased beetle populations shows a key to conserving these
red-listed species.
Australian eucalypt forests
Much
of the old growth eucalypt forest in Australia is designated for
conservation. Management of these forests is important because species
like Eucalyptus grandis rely on fire to survive. There are a few eucalypt species that do not have a lignotuber,
a root swelling structure that contains buds where new shoots can then
sprout. During a fire a lignotuber is helpful in the reestablishment of
the plant. Because some eucalypts do not have this particular mechanism,
forest fire management can be helpful by creating rich soil, killing
competitors, and allowing seeds to be released.
Management policies
United States
Fire policy
in the United States involves the federal government, individual state
governments, tribal governments, interest groups, and the general
public. The new federal outlook on fire policy parallels advances in
ecology and is moving towards the view that many ecosystems depend on
disturbance for their diversity and for the proper maintenance of their
natural processes. Although human safety is still the number one
priority in fire management, new US government objectives include a
long-term view of ecosystems. The newest policy allows managers to gauge
the relative values of private property and resources in particular
situations and to set their priorities accordingly.
One of the primary goals in fire management is to improve public education in order to suppress the "Smokey Bear" fire-suppression mentality and introduce the public to the benefits of regular natural fires.
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