Forestry

Controlled burning reduces fuels, improves wildlife habitat,^[12] controls competing vegetation,^[13] helps control tree disease and pests,^[14] perpetuates fire dependent species^[5][15] and improves accessibility^{[citation needed]}. 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.^[16] Parameters measured are fire frequency, intensity, severity, patchiness, spatial scale and phenology.^[17]

Furthermore, controlled fire can be used for site preparation when mechanized treatments are not possible because of terrain that prevents equipment access.^[18][19] Species variation and competition can drastically increase a few years after fuel treatments because of the increase in soil nutrients and availability of space and sunlight.^[20]

Many trees depend on fire as a way to clear out other plant species and release their seeds. The giant sequoia, among other fire-adapted conifer species, depends on fire to reproduce.^[7] The cones are pyriscent so they will only open after exposed to a certain temperature. This reduces competition for the giant sequoia seedlings because the fire has cleared non fire-adapted, competing species.^[21][22] Pyriscent species benefit from moderate-intensity fires in older stands however, climate change is causing more frequent high intensity fires in North America.^[23] Controlled burns can manage the fire cycle and the intensity of regenerate fires in forests with pyriscent species like the boreal forest in Canada.

Eucalyptus regnans or mountain ash of Australia also shows a unique evolution with fire, quickly replacing damaged buds or stems in the case of danger^{[citation needed]}. They also carry their seeds in capsules which can be deposited at any time of the year ^{[citation needed]}. During a wildfire, 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, like-aged eucalyptus forest grows.^[24] Other tree species like poplar can easily regenerate after a fire into a like-aged stand from a vast root system that is protected from fires because it is underground.^[25]

Grassland restoration

Native grassland species in North America and Australia are adapted to survive occasional low intensity fires.^[26] Controlled burns in prairie ecosystems mimic low intensity fires that shift the composition of plants from non-native species to native species.^[6] These controlled burns occur during the early spring before native plants begin actively growing, when soil moisture is higher and when the fuel load on the ground is low^[27] to ensure that the controlled burn remains low intensity.

Wildfire management

Controlled burns reduce the amount of understory fuel so when a wildfire enters the area, a controlled burn site can reduce the intensity of the fire or prevent the fire from crossing the area entirely.^[28] A controlled burn prior to the wildfire season can protect infrastructure and communities or mitigate risks associated with many dead standing trees such as after a pest infestation when forest fuels are high.^[29]

Agriculture

In the developing world, the use of controlled burns in agriculture is often referred to as slash and burn. In industrialized nations, it is seen as one component of shifting cultivation, 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.^[31]

Prescribed fires are broadly used in the context of woody plant encroachment, with the aim of improving the balance of woody plants and grasses in shrublands and grasslands.^{[32][33][34][35]}

In Northern-India, especially, In Punjab, Haryana, and Uttar Pradesh, unregulated burning of agricultural waste is a major problem. Smoke from these fires leads to degradation in environmental quality in these states and the surrounded area.^[36]

In East Africa, bird densities increased months after controlled burning had occurred.^[37]

Greenhouse gas abatement

Controlled burns on Australian savannas can result in a long-term cumulative reduction in greenhouse gas emissions. One working example is the West Arnhem Fire Management Agreement, started to bring "strategic fire management across 28,000 square kilometres (11,000 sq mi) 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;^[38][39] it is also known as "patch burning".

Ground ignition

Back burning or a back fire 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. Controlled burns utilize back burning during planned fire events to create a "black line" where fire cannot burn through. Back burning or backfiring is also done to stop a wildfire that is already in progress. Firebreaks are also used as an anchor point to start a line of fires along natural or man-made features such as a river, road or a bulldozed clearing.^[42]

Head fires, that burn with the prevailing wind, are used between two firebreaks because head fires will burn more intensely and move faster than a back burn. Head fires are used when a back burn would move too slowly through the fuel either because the fuel moisture is high or the wind speed is low.^[40] Another method to increase the speed of a back burn is to use a flank fire which is lit at right angles to the prevailing wind and spreads in the same direction.^[40]

Aerial ignition

Aerial ignition is a type of controlled burn where incendiary devices are released from aircraft.^[46]

North America

The use of controlled burns in North America ended in the early 20th century, when federal fire policies were enacted with the goal of suppressing all fires.^[50] Since 1995, the US Forest Service has slowly incorporated burning practices into its forest management policies.^[10]

Fire suppression has changed the composition and ecology of North American habitats, including highly fire-dependent ecosystems such as oak savannas^[54][55] and canebrakes,^[56][57] which are now critically endangered habitats on the brink of extinction. In the Eastern United States, fire-sensitive trees such as the red maple are increasing in number, at the expense of fire-tolerant species like oaks.^[58]

Europe

In the European Union, burning crop stubble after harvest is used by farmers for plant health reasons under several restrictions in cross-compliance regulations.^[74]

In the north of Great Britain, 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 (heather) of different ages which allows very large populations of red grouse to be reared for shooting.^[75] The peat-lands are some of the largest carbon sinks in the UK, providing an immensely important ecological service. The governments has restricted burning to the area but hunters have been continuing to set the moors ablaze, releasing a large amount of carbon into the atmosphere and destroying native habitat.^[76]

Africa

The Maasai ethnic group conduct traditional burning in savanna ecosystems before the rainy season to provide varied grazing land for livestock and to prevent larger fires when the grass is drier and the weather is hotter. In the past few decades, the practice of burning savanna has decreased because rain has become inadequate and unpredictable, there are more frequent occurrences of large accidental fires and Tanzanian government policies prevent burning savanna.^[77]