Fire

INTRODUCTION

Forest fires have shaped Canada’s forests since the last ice age, and they will continue to be a major agent of change in the future. On average, 9,500 forest fires burn more than 3 million hectares of Canadian forests annually.

Fire is a natural component of the environment and plays an important ecological role. A problem develops when the level of damage reaches a point where it conflicts with people’s values and desires.

The forest setting produces many important products and values for people such as summer homes, scenic vistas, recreation, and economic opportunity. The fear of potential losses moves people to set up to set up systems to protect their economic or emotional investment. The average annual timber losses to forest fires in Canada tops one billion dollars.

The systems for forest protection are also costly. Fire management costs are an average of $384 million per year in Canada. The cost seems understandable when measured against the dramatic destruction that fires can cause. However, understanding the ecological role of fire can help bring some perspective to the issue.

In this article, we will be looking at the characteristics of fire, the role it plays within an ecosystem, forest fire suppression efforts, the effects of fire suppression on ecosystems, and the use of fire as a management tool.

FIRE AND ITS CHARACTERISTICS

The images of mountainsides on fire, rural homes being destroyed and suppression crews facing danger are powerful. These sensational images are backed by equally dramatic facts.

• Forest fires can have flames 50 feet high.
• Forest fires can create their own weather including hurricane force winds, rain and lightening.
• 42% of forest fires are caused by lightning, the rest are caused by people.
• A bolt of lightning can be 5 times hotter than the surface of the sun.
• More than 200 bolts of lightning hit the earth every second.
• Fire can travel faster than you can run.
• Forest fires can melt metal.
• For every 30 cm along a fire front, a large fire produces as much energy per second as three gas-fired home furnaces.
• There are from 1500-3000 forest fires in BC annually.
• The Wisp fire ( near Fort St. John) in 1950 destroyed 1,400,000 hectares of forest.
• The Garnet fire (near Penticton) in 1994 caused the evacuation of 3500 people and the loss of 18 homes.

Fire Behaviour is the manner in which fuel ignites, flame develops and fire spreads as determined by the interaction of fuel, weather and topography. Forest fires can be categorized as ground fires, surface fires and crown fires.

Ground fires

burn the organic matter in the soil beneath the surface litter layer.

Surface fires

burn the leaf litter and fallen branches at the ground level.

Crown fires

burn through the canopy of the trees. They are the most intense fires and the most difficult to control. Crown fires usually burn in conjunction with a surface fire.

In nature, all of these types of fires are by lightning. However, six out of every ten fires in BC are actually started by people’s carelessness. Examples of carelessness include campfires not put out properly, cigarettes flung burning onto the ground or the heat from machinery working in dry forest conditions.

To start a fire requires the presence of fuel, heat (lightning or a cigarette) and oxygen. Once the fire has begun to burn, the intensity of behaviour of the resulting fire is dependent on weather, topography and fuels. A fire hazard rating for an area is based on examining these three factors.

Weather is a key factor in the creating favourable fire conditions. Wind dries fuel (such as branches and debris on the ground), supplies oxygen to the fire and moves the fire front along by transporting cinders and pushing the wall of flame forward. High temperature and low relative humidity also dry the fuels. The rate of this drying can be accelerated by temperature inversions. Wind speed and air temperature can also add to fire intensity.

Topography (the steepness of the land) also affects the speed od a fire. In a fire, wind is created from rising heat (convective heating). Fire travels more rapidly up a slope as convective heating increases with the angle of the slope. Fire travels more quickly in canyons or draws which can funnel the heat and convective currents to a higher speed.

The amount of fuel in a forest is related to how long it has been since the last fire. The greater the amount of dead material on the ground the more fuel for a fire. The quantity, density and distribution of the fuel are important factors in the level of fire hazard. As the moisture level in these fuels drops, the hazard level increases.

Some plants and trees contain flammable resins and oils that promote combustion. As well as the chemical make-up of these branches and litter, the ambient temperature of the fuels is also important. The hotter the weather, the higher the temperature of the fuels and the more susceptible they are to ignition.

When the combination of weather and fuel moisture reach extreme hazard levels a ban on campfires, camping and even on working in the forest will be put in place to try to prevent forest fires. In spite of precautions, if any heat source comes into contact with the fuels in these conditions, a wildfire will likely erupt.

THE ECOLOGICAL ROLE OF FIRE

Forest fire is a natural change agent within ecosystems. In the study of fire ecology, scientists look at the links between wildfires and the living and non-living environment. Fire history, fire dependence and fire regime are key concepts to explore.

Some ecosystems such as prairie or grassland have developed with a history of frequent fires where other types of ecosystems such as temperate rainforests have developed with a lower frequency of fires. Fire history is the frequency with which fires have occurred in an ecosystem.

In areas where fires are frequent, plants have evolved with fire as a critical step in their life cycle. For example, the lodgepole pine forests of northern BC are fire dependent since they actually require intense heat in order for the cones to open. Fire prepares the soil by adding ash and removing competition. These plants also require the increased light intensity that results after a fire has removed the overhead competition.

Forest ecosystems evolve with fire playing a formative role. An ecosystem’s fire regime is the historic range of variability of fire history, fire intensity, seasonality and extent. The variation from area to area is determined by ignition sources, weather, fuel characteristics, wind and topography. A fire regime integrates many natural and cultural influences and will only change if there is a significant shift in climate or fire policies.

Historically, ecosystems like the dry low-elevation interior forests and grasslands experienced frequent low intensity fires every 5 – 20 years. These surface fires consumed fuels such as needles and branches and coarse woody debris. This resulted in low amounts of fuel build-up between fires. As smaller trees were killed, the stand was thinned, producing more room for herb and shrub species on the forest floor.

These plant communities are fire dependent. Lodgepole pine and black spruce need fires to melt the resin that holds the cone scales shut so seeds can be spread. Western larch, ponderosa pine and Douglas fir have developed a thick bark to protect them from surface fires. After a fire, aspen produce sucker shoots from underground buds. Many animals, such as deer, moose and elk, eat the growth of herbs and grasses that result from the openings created by fire and so they are also fire dependent.

Surface fires are a selective force that affect both the appearance and the ecology of such forests. The unevenness of the fires and their varied intensities produce a mosaic of vegetation patterns. Fire affects both the stand and landscape composition and structure. Open patchy, multi-storied stands provide suitable niches for certain plants and animals. In reality, forest fires are evolution in action and are key agents in creating habitat diversity.

Forest ecosystems that have evolved with very infrequent fires have adapted to the lack of fire. Coastal temperate rain forest has a very different fire regime than dry interior forests. This results in different species distribution, plant adaptations and vegetation patterns.

FIRE SUPPRESSION

Human development has introduced urbanization, domestic grazing, forest harvesting, forest roads and recreation into the landscape. People fear the destructive capacity of fire which can cause the loss of timber, the "destruction" of wilderness reserves, the loss of scenic values for recreation areas, damage to private property and loss of life. Limiting the damage from forest fires, or "fire suppression", is a provincial responsibility (except on federal lands) and suppression activities have become a multi-million dollar expenditure.

Total fire suppression is not physically possible, nor economically feasible. Fire policies try to balance suppression costs with the values at risk. More than 93% of Canadian fires receive a full response. The 7% that are judged to be not to pose serious risk to life, property, or resources and are left to burn - account for 64% of the total area burned.

In British Columbia the fire suppression strategies include:

1. Early Detection
2. Inital attack: a swift aggressive response within 24 hours that can include:
   • Firetack: crews using road access
   • Helitack: crews trained in hover exits for remote access fires
   • Rapattack: crews trained in rapelling from helicopters for heavily mountainous of remote areas.
   • Air attack: Airtankers or helicopters that drop retardent or water onto fires.
   • Initial attack controls 85% of reported fires.
3. Expanded attack: After 24 hours if the initial attack crews cannot contain the fire additional crews and equipment are brought in.
   • Fire Crew: 20 person crews. A large fire may have ten or more crews at work.
   • Heavy machinery: Bull dozers, larger pumps, portable water supplies are deployed to build and maintain fire guards Explain what a fire guard is.
   • Overhead Teams: Fire management specialists are brought in
   • Information Teams: media communication specialists
   • The fire may be attacked directly, adjacent to the burning front. Another option is to use a parallel attack, where a fire guard is constructed as close to the fire as possible, thus burning out the fuel between fire and guard. A third option is to an indirect attack, where a control line is located using natural terrain breaks in advance of the fire and the strip is usually back burned.
4. Mop up: Once the fire is controlled the mop up crew concentrates on extinguishing or removing burning material. Cold trailing, a method of determining whether a fire is still burning, uses touch or a hand held infra red scanner to assist mop up crews in detecting remaining heat sources.
5. Patrol and Inspection: These stages may continue for several weeks to ensure complete fire suppression.
6. Site Rehabilitation Measures: Silviculture methods can help to bring the burned site back into production. Rehabilitation measures can include planting and cutting down fire snags where safety is an issue.

FIRE SUPPRESSION: Technology

Science and technology have helped to develop new approaches to fire management and new tools for fire fighting.

Lightning locators are monitoring devices that track lightning strikes and pin point where the strike occurred. This data capturing system detects and records all cloud to ground lightning strikes in BC. A network of these "direct finders" transmit lightning data instantaneously to a computer which pinpoints the location of the strike.

Protection Information System is a computer system designed to provide information on weather. It includes real time lightning locations and predicts where fires will start and how they will behave. This information helps the fire manager decide how to position resources effectively.

Satellite Technology called REMSAT, for Real Time Emergency Management via Satellite, provides real time fire scenarios. The satellite maps show weather conditions, information on dwellings and other vital information.

Resource Management System or RMS permits electronic tracking of equipment and personnel anywhere in the province. This helps speed up preparations and maximizes the use of equipment and staff.

Weather Information is essential in fire management. Satellite weather monitoring, regional weather technicians, and automatic weather stations all feed data into information and communication systems.

Canadian Fire Weather Index (FWI) provides numeric ratings of the relative fire potential in standard fuel types. FWI is used extensively by forest industry in BC. Most companies have their own automated weather stations that record the various parameters to determine the index. The index considers the moisture levels of various forest fuels, the rate of spread, the amount of available fuels and the fire intensity.

Technological improvements in aircraft, fire retardant, crew safety equipment and communications abilities all help to make today’s fire fighting efforts more efficient. However, in spite of technological advances, the best fire fighters are still rain, lack of wind and cooler weather. Without nature’s cooperation, all the skills, tools and technology are often no match for the fury and intensity of a wildfire. That is why it is important to find fires fast, before they get out of control, and put resources into prevention. Prevention focuses on stopping those 60% of forest fires that are caused by human carelessness.

The responsibilities of a forest company includes clearly identifying fuel management activities, fire preparedness strategies and prescribed burning plans for the forest development plan area. The Fire Management guidebook details aspects of these key responsibilities. For example, once the fire hazard reaches a certain level, companies must institute ground and air patrols and have workers go on early shift (work in the cooler early morning hours).

The goals of fire suppression are to protect timber values, water quality, recreational opportunities, visual resources, property value and human lives. However, these suppression efforts themselves are changing forest ecosystems in dramatic ways.

ECOLOGICAL RESULTS OF SUPPRESSION

Just as fire is a significant factor shaping ecosystems, fire suppression has an equally significant effect. Fire suppression in dry interior forests has reduced the fire frequency from historical levels of a fire every 7 to 20 years to today’s situation of some areas having had no fires for 30 to 90 years. This is not frequent enough to maintain the fire-dependent ecosystem in an optimum state of health and diversity. Excluding fire has caused:

• an increase in tree density
• more shade tolerant species are favoured
• less diversity in the shrub herb vegetation
• increased tree mortality due to bark beetles and defoliating insects
• increased mortality of trees from root rot
• slower nutrient cycling
• fuel build up so fires are likely to be larger and more intense
• greater canopy closure
• more homogenous landscapes
• encroachment of forest on grasslands
• decrease in forage for wildlife species

So as suppression continues, the structure and diversity of the forest changes, and the fuel build-up continues, increasing the risk for intense large fires.

Without the thinning effect of fires some forests become crowded creating prime conditions for insect and disease outbreaks. The mortality from these outbreaks adds to the fuel loading and increases the chance of further insect outbreaks and extreme fire hazards.

FIRE AND FOREST MANAGEMENT

Fire management aims to minimize the destructive elements of fire as well as maximize its ecological benefits. Fire management includes:

" the activities concerned with the protection of people, property and forest areas from wildfire and the use of prescribed burning for the attainment of forest management and other land use objectives, all conducted in a manner that considers environmental, social and economic criteria" Ministry of Forests Web Glossary.

Looking beyond the immediate needs for suppression, fire management takes a long-term, systems approach to the issues. It seeks balance between the positive and negative effects of fire. Faced with the fuel build up and ecological changes brought about by suppression, what options are available to forest managers?

1. Continue to suppress fires: Forests will continue to change to a less diverse, more dense and stagnant shade-tolerant mix with increasing risk of intense fires. Fire suppression expenditures will increase. Suppression produces benefits such as timber, water quality, visual resources, recreational opportunities and the protection of people’s property and lives. However, these benefits are temporary as the forest will eventually burn, it is just a question of when and how severely.
2. Use prescribed fire: This decreases the risk of future intense fires. There is less risk of losing water quality, property values and human lives to a wildfire. Prescribed burning may improve forest health, diversity and forage, but may damage the overstory and create point for disease entry. Air quality issues may emerge and such fires may burn outside intended boundaries.
3. Use mechanical treatments such as brushing and thinning: These have similar advantages and disadvantages as number 2. Thinnings may produce some revenue to offset the cost. Plants and animals that depend on fire to cycle nutrients or germinate seeds will not benefit and the fire hazard will be increased due to increased dry fuel on site.
4. Use a combination of these treatments: Fire managers determine suitable treatments and set priorities based on variables such as fuel load, aspect, insect and disease problems, high property values and smoke sensitivities.

Using prescribed burning, can provide ecological and fire prevention effects . Burning areas on purpose to attain specified objectives requires careful planning. The design of the fire plan aims to keep the fire under control and limit smoke emissions to populated areas. The results include less fuel for future wildfires and more of the open habitat conditions required by fire-dependent plants and animals.

Prescribed fire is used to:

• Reduce wildfire hazards
• Removal of undesirable plants
• Improve domestic range
• Controlling forest pests
• Enhancing wildlife habitat removal of undergrowth to promote browse species
• Improving planting by decreasing slash loading
• Addition of nutrients (ash)
• Maintaining diversity in ecosystems and re-introducing fire into fire dependent ecosystems.

The benefits of prescribed burning must be balanced by the risk of escape and damage. If not done to standards, prescribed fires can damage soil (by burning off duff layer), causing a loss of nutrients, and removing the cover needed by seedlings. If conditions change, prescribed fires can get out of control and burn areas outside the prescription. Smoke pollution is always a factor especially in forests near communities.

Because of the inherent risk, prescribed fires are subject to meticulous planning. The fire is ignited based on a detailed plan or prescription that defines exactly the required conditions and the specific actions. Acceptable fuel, weather conditions, humidity, temperature, winds are all part of the equation.

Using fire as a tool has many advantages, however, the public often has a negative attitude towards this new view of fire.

SUMMARY

The effect of forest fires both wreaks havoc and renews. The immediate threat to property, scenic value and human lives can be extreme. However, fire also plays an essential role in creating habitats and controlling pests and disease.

Fire fighting or fire suppression is still an important emergency function. Suppression is also a part of a longer-term, multi-faceted view of fire that is now encompassed in fire management. The effects of both fire and fire suppression result in changes to the ecosystem which must be considered from environmental, economic and social viewpoints.

The Fire Research Network, within the Canadian Forest Service, is focusing research efforts on fire behaviour, fire ecology, fire management systems, fire and global change and the role of fire in Canadian forests.

References:

• Bombardier Aerospace. Initial Attack.
• Bombardier website
• Canadian Forest Service
• Canadian Forest Service

Fire in the Dry Interior Forests of British Columbia. Daigle,Patrick. 1996. BC Ministry of Forests, Research Branch Extension Note 08.

• Ministry of Forests.
• WildFire website

Landscape ecology and Natural Disturbances. Parminter, John. 1997. BC Ministry of Forests Research Branch. Extension Note 10

US Government:

• Fire Effects Information System
• Forest Health Protection