Controlled burn

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"Back-burn" redirects here. For the village in Scotland, see Backburn.

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Firing the woods in a South Carolina forest with a custom made igniter mounted on an all terrain vehicle. The device spits flaming fuel oil from the side, instantly firing the leaf litter.

A prescribed burn in a Pinus nigra stand in Portugal

Controlled field burn off in preparation for Spring planting in South Georgia.

Prescribed or controlled burning (back burning or Swailing) is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for foresters. Controlled burning stimulates the germination of some desirable forest trees, thus renewing the forest. Some seeds, such as sequoia, remain dormant until fire breaks down the seed coating.

In industrialized countries, controlled burning is usually overseen by fire control authorities for regulations and permits. The party responsible must delineate the intended time and place. Obtaining a permit may not limit liability if the fire burns out of control.

1 Forest use
- 1.1 Controversy
2 Agricultural use
- 2.1 Controversy
3 Heathland Use
4 Greenhouse gas abatement
5 See also
6 References
7 External links

[edit] Forest use

Another consideration is the issue of fire prevention. In Florida, during the drought in 1998, catastrophic wildfires burned numerous homes. But forestry managers note that the underlying problem was prior cessation of controlled burning, due to complaints by homeowners. Each year additional leaf 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, 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, or other improvised devices such as mounting a driptorch-like device on the side of a vehicle. A pyrotechnic device known as the fusee can also be used in ignition.

For the burning of slash, waste materials left over from logging, 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 bonfires. High temperatures can harm the soil, 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.

[edit] Controversy

George D. Kessler, professor of forestry, and extension forester at Clemson University notes that controlled burning reduces fuels, may improve wildlife habitat, controls competing vegetation, improves short term forage for grazing, improves accessibility, helps control tree disease, and perpetuates fire dependent species. In old growth longleaf pine forest, it helps maintain habitat for endangered Red-cockaded Woodpeckers in their sandhill and flatwoods habitats. However many scientists disagree with such a simplistic approach, and indicate that each forest must be assessed on its own merit.

There are critics of controlled burns as a forest management practice. Ohio environmentalist Barbara A. Lund believes that burnings are harmful to the environment. Her assertion is that controlled burning may be harmful to eastern hardwood forests because animals that may not be able to flee the flames will die during the burns.^[1]

[edit] 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. In industrialized nations, it is seen as one component of shifting cultivators 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 does produce 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. First used significantly in the Neolithic Revolution (i.e. about 9-11,000 years ago at the end of the last ice age when hunter gatherers turned to farming).

[edit] Controversy

In Oregon, 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 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 accident^[2] in which smoke from field burning near Albany, Oregon obscured the vision of drivers on Interstate 5, leading to 23-car accident in which seven people died and 37 were injured. ^[3] This resulted in more scrutiny of field burning and proposals to ban field burning in the state altogether.^[4]

[edit] Heathland Use

Gorse and Heather are burnt on the Cornish cliffs.

The controlled burning or Swailing of heathland is used in the UK and other countries as a conservation tool. Often it is used as a tool for creating fire breaks to reduce the risk of dangerous outbreaks but is also an important mechanism for preventing succession to woodier vegetation and plays an important role in the life cycle of heather species. ^[5]

[edit] Greenhouse gas abatement

Controlled burns on Australian savannas 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 28,000 km² of Western Arnhem Land" to partially offsetting 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.^[6]