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A controlled or prescribed burn, also known as hazard reduction burning, backfire, swailing, or a burn-off, is a fire set intentionally for purposes of forest management,
farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
,
prairie restoration Prairie restoration is a conservation effort to restore prairie lands that were destroyed due to industrial, agricultural, commercial, or residential development. For example, the U.S. state of Illinois alone once held over of prairie land an ...
or greenhouse gas abatement. A controlled burn may also refer to the intentional burning of slash and fuels through burn piles.
Fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames ...
is a natural part of both forest and grassland
ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
and controlled fire can be a tool for foresters. Hazard reduction or controlled burning is conducted during the cooler months to reduce fuel buildup and decrease the likelihood of serious hotter fires. Controlled burning stimulates the
germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fe ...
of some desirable forest
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s, and reveals soil mineral layers which increases seedling vitality, thus renewing the forest. Some cones, such as those of lodgepole pine and sequoia, are pyriscent, as well as many chaparral shrubs, meaning they require heat from fire to open cones to disperse seeds. In industrialized countries, controlled burning is usually overseen by fire control authorities for regulations and permits.


History

There are two basic causes of
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...
s. One is natural, mainly through lightning, and the other is human activity. Controlled burns have a long history in wildland management. Pre-agricultural societies used fire to regulate both plant and animal life. Fire history studies have documented periodic wildland fires ignited by indigenous peoples in North America and
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
. Fires, both naturally caused and prescribed, were once part of natural landscapes in many areas. In the US these practices ended in the early 20th century, when federal fire policies were enacted with the goals of suppressing all fires. Since 1995, the US Forest Service has slowly incorporated burning practices into its forest management policies.


Back burning

''Back burning'' is the term given to the process of lighting vegetation in such a way that it has to burn against the prevailing wind. This produces a slower moving and more controllable fire. However this term is also colloquially used to mean all of controlled burning as well. This process is commonly used for hazard reduction burns and the preparation of fire breaks to enable controlled or hazard reduction burns. Back burning involves starting small fires along a man-made or natural
firebreak A firebreak or double track (also called a fire line, fuel break, fireroad and firetrail in Australia) is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebr ...
in front of a main fire front. Back burning reduces the amount of fuel that is available to the main fire by the time that it reaches the burnt area. Back burning is utilized in controlled burning and during wildfire events. While controlled burns utilize back burning during planned fire events to create a "black line", back burning or backfiring is also done to stop a wildfire that is already in progress. Firebreaks are also often used as an anchor point to start a line of fires along natural or manmade features such as a river, road or a bulldozed clearing. It is called ''back burning'' because the small fires are designed to "burn back" towards the main fire front and are usually burning and traveling against ground level winds. The expression ''fight fire with fire'' is derived from the concept of back burning.


Forest use

Another consideration is the issue of
fire prevention Fire prevention is a function of many fire departments. The goal of fire prevention is to educate the public on the precautions which should be taken to prevent potentially harmful fires and how to survive these fires in the event that they do o ...
. In
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
, during the drought in 1995, catastrophic
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...
s burned numerous homes. Each year, additional
leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ...
litter and dropped branches increased the likelihood of a hot and uncontrollable fire. Controlled burns are sometimes ignited using a tool known as the
driptorch A driptorch is a tool used in wildfire suppression, controlled burning, and other forestry applications to intentionally ignite fires by dripping flaming fuel onto the ground. Description The driptorch consists of a canister for holding fuel ...
, which allows a steady stream of flaming fuel to be directed to the ground as needed. Variations on the driptorch can be used such as the helitorch, which is mounted on a
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribu ...
, or other improvised devices such as mounting a driptorch-like device on the side of a
vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...
. A pyrotechnic device known as a fusee can be used for ignition in nearby fuels while a flare gun can be used to ignite fuels farther away. For the burning of
slash Slash may refer to: * Slash (punctuation), the "/" character Arts and entertainment Fictional characters * Slash (Marvel Comics) * Slash (''Teenage Mutant Ninja Turtles'') Music * Harry Slash & The Slashtones, an American rock band * Nash ...
,
waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste pr ...
materials left over from
logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply cha ...
, there are several types of controlled burns. Broadcast burning is the burning of scattered slash over a wide area. Pile burning is gathering up the slash into piles before burning. These burning piles may be referred to as
bonfire A bonfire is a large and controlled outdoor fire, used either for informal disposal of burnable waste material or as part of a celebration. Etymology The earliest recorded uses of the word date back to the late 15th century, with the Catho ...
s. High temperatures can harm the
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
, damaging it physically, chemically or sterilizing it. Broadcast burns tend to have lower temperatures and will not harm the soil as much as pile burning, though steps can be taken to treat the soil after a burn. In lop and scatter burning, slash is left to compact over time, or is compacted with machinery. This produces a lower intensity fire, as long as the slash is not packed too tightly. However, soil may be damaged if machinery is used to compress the slash. Controlled burning reduces
fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy b ...
s, may improve
wildlife Wildlife refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced by humans. Wildlife was also synonymous to game: those birds and mammals that were hunted ...
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
, controls competing vegetation, improves short term forage for grazing, improves accessibility, helps control tree
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
, and perpetuates fire dependent species. In mature longleaf pine forest, it helps maintain habitat for
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
red-cockaded woodpeckers in their sandhill and flatwoods habitats. Fire is also felt to be a crucial element of the recovery of the threatened Louisiana pine snake in the longleaf pine forests of central Louisiana and eastern Texas. To improve the application of prescribed burns for conservation goals, which may involve mimicking historical or natural fire regimes, scientists assess the impact of variation in fire attributes. Fire frequency is the most discussed fire attribute in the scientific literature, likely because it is considered the most critical fire regime aspect. Scientists less often report data concerning the effects of variation in other fire attributes (i.e., intensity, severity, patchiness, spatial scale, or phenology), even though these also likely impact conservation goals. In the wild, many trees depend on fire as a successful way to clear out the competition and release their seeds. In particular, the giant sequoia depends on fire to reproduce: the cones of the tree open after a fire releases their seeds, the fire having cleared all competing vegetation. Due to fire suppression efforts during the early and mid 20th century, low-intensity fires no longer occurred naturally in many groves, and still do not occur in some groves today. The suppression of fires also led to ground fuel build-up and the dense growth which posed the risk of catastrophic wildfires. In the 1970s, the National Park Service began systematic fires for the purpose of new seed growth. '' Eucalyptus regnans'' or mountain ash of Australia also depends on fire but in a different fashion. They carry their seeds in capsules which can deposit at any time of the year. Being flammable, during a fire the capsules drop nearly all of their seeds and the fire consumes the eucalypt adults, but most of the seeds survive using the ash as a source of nutrients; at their rate of growth, they quickly dominate the land and a new eucalyptus forest grows. The province of Ontario, Canada implements safety procedures and regulations to manage and control wild land fires. They follow these procedures strictly to protect the safety of locals and ensure that the fire does not spread into other areas on land, thus protecting the biodiversity of the forests' ecosystem.


Agricultural use

In addition to forest management, controlled burning is also used in agriculture. In the developing world, this is often referred to as
slash and burn Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed veget ...
. In industrialized nations, it is seen as one component of
shifting cultivation Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cu ...
, as a part of field preparation for planting. Often called field burning, this technique is used to clear the land of any existing crop residue as well as kill weeds and weed seeds. Field burning is less expensive than most other methods such as herbicides or tillage, but because it produces smoke and other fire-related pollutants, its use is not popular in agricultural areas bounded by residential housing. In the United States, field burning is a legislative and regulatory issue at both the federal and state levels of government. In Northern-India, especially, In Punjab and Haryana, Crop Residue Burning is a major problem. CRB leads to degradation in environmental quality in these and neighboring states including capital of India, New Delhi. In East Africa, bird densities increased months after controlled burning had occurred.


Grouse moors

In the north of
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It ...
, large areas of grouse moors are managed by burning in a practice known as muirburn. This kills trees and grasses, preventing natural succession, and generates the mosaic of
ling Ling may refer to: Fictional characters * Ling, an ally of James Bond's from the film ''You Only Live Twice'' * Ling, a character in the ''Mulan'' franchise * Ling, a playable character from the mobile game '' Mobile Legends: Bang Bang'' * Ling ...
(heather) of different ages which allows very large populations of red grouse to be reared for shooting.


Controversies

In
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
, field burning has been widely used by grass seed farmers as a method for clearing fields for the next round of planting, as well as revitalizing serotinous grasses that require fire in order to grow seed again. The Oregon Department of Environmental Quality began requiring a permit for farmers to burn their fields in 1981, but the requirements became stricter in 1988 following a multi-car collision in which smoke from field burning near
Albany, Oregon Albany is the county seat of Linn County, Oregon, and is the eleventh largest city in that state. Albany is located in the Willamette Valley at the confluence of the Calapooia River and the Willamette River in both Linn and Benton counties, just ...
, obscured the vision of drivers on Interstate 5, leading to a 23-car collision in which 7 people died and 37 were injured. This resulted in more scrutiny of field burning and proposals to ban field burning in the state altogether. In the European Union, burning crop stubble after harvest is used by farmers for plant health reasons under several restrictions in the cross compliance regulations. Driven Grouse shooting is practiced on
moors The term Moor, derived from the ancient Mauri, is an exonym first used by Christian Europeans to designate the Muslim inhabitants of the Maghreb, the Iberian Peninsula, Sicily and Malta during the Middle Ages. Moors are not a distinc ...
managed through controlled burning. With controlled burns, there is also a risk that the fires get out of control. For example, the Calf Canyon/Hermits Peak Fire, the largest wildfire in the history of
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
, was started by two distinct instances of controlled burns, which had both been set by the
US Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency in ...
, getting out of control and merging.


Political history

The conflict of controlled burn policy in the United States has roots in the historical campaigns to combat wildfires and to the eventual acceptance of fire as a necessary ecological phenomenon. The notion of fire as a tool had somewhat evolved by the late 1970s as the National Park Service authorized and administered controlled burns. While the methodology was still relatively new, the Yellowstone fires of 1988 occurred, which significantly politicized fire management. The ensuing media coverage was a spectacle that was vulnerable to misinformation. Reports drastically inflated the scale of the fires which disposed politicians in Wyoming, Idaho, and Montana to believe that all fires represented a loss of revenue from tourism. Partially as a result of millions of dollars lost in estimates, stricter data recording was enforced and thresholds were established for determining which fires must be suppressed. Paramount to the new action plans is the suppression of fires that threaten the loss of human life with leniency toward areas of historic, scientific, or special ecological interest. Since 1988, many states have made progress toward controlled burns but with a proclivity toward forgetfulness between fire events. Senators Ron Wyden and Mike Crapo of Oregon and Idaho have been moving to reduce the shifting of capital from fire prevention to fire suppression following the harsh fires of 2017 in both states.


Procedure

Depending on the context and goals of a prescribed fire, additional planning may be necessary. While the most common driver of fuel treatment is the prevention of loss of human life, certain parameters can also be changed to promote biodiversity and to rearrange stand ages appropriately. The risk of fatal fires can also be reduced proactively by reducing ground fuels before they can create a fuel ladder and begin an active crown fire. Predictions show thinned forests lead to mitigated fire intensity and flame length compared to untouched or fire-proofed areas. Furthermore, low-intensity fire treatments can be administered in places where mechanized treatments such as disc harrowing cannot. In the interests of conservation, electing for a mixed mosaic of unburnt islands within the targeted area maintains biodiversity and provides cover for wildlife. Because of this, some suggest fuel reductions of about 75% to be sufficient, though each burn plan should have its own target set by ecological and management goals. In some areas where grasses and herbaceous plants thrive, species variation and cover can drastically increase a few years after fuel treatments.


Greenhouse gas abatement

Controlled burns on Australian
savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground ...
s can result in an overall reduction of greenhouse gas emissions. One working example is the West Arnhem Fire Management Agreement, started to bring "strategic fire management across of Western Arnhem Land" to partially offset greenhouse gas emissions from a liquefied natural gas plant in Darwin, Australia. Deliberately starting controlled burns early in the dry season results in a mosaic of burnt and unburnt country which reduces the area of stronger, late dry season fires; it is also known as "patch burning". To minimise the impact of smoke, burning should be restricted to daylight hours whenever possible.Guidelines for Low Intensity Brush Fire Hazard Reduction http://www.hillside.rfsa.org.au/lowintensityhrburn.pdf Retrieved on May 8, 2016


See also

*
Agroecology Agroecology (US: a-grō-ē-ˈkä-lə-jē) is an academic discipline that studies ecological processes applied to agricultural production systems. Bringing ecological principles to bear can suggest new management approaches in agroecosystems. Th ...
* Fire ecology * Fire-stick farming * Native American use of fire in ecosystems * Wildfire suppression


References


Further reading

* Beese, W.J., Blackwell, B.A., Green, R.N. & Hawkes, B.C. (2006). "Prescribed burning impacts on some coastal British Columbia ecosystems." ''Information Report'' BC-X-403. Victoria B.C.: Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre. Retrieved from: http://hdl.handle.net/10613/2740 * Casals P, Valor T, Besalú A, Molina-Terrén D
Understory fuel load and structure eight to nine years after prescribed burning in Mediterranean pine forests
DOI: 10.1016/j.foreco.2015.11.050 * Valor T, González-Olabarria JR, Piqué M
Assessing the impact of prescribed burning on the growth of European pines
DOI: 10.1016/j.foreco.2015.02.002.


External links


The Nature Conservancy's Global Fire Initiative
{{DEFAULTSORT:Controlled Burn Wildfire ecology Wildfire prevention Habitat management equipment and methods Agriculture and the environment Wildfires Forestry and the environment Ecological techniques