Fire environment, fire regimes and the ecological role offire
There have been several different systems used inclassifying fire regimes in the United States (Heinselman 1978; Agee 1993;Morgan et al. 1998; and Frost 1998). Brown and Smith (2000) classified fireregimes based on fire severity. Use of fire severity as the key component indescribing fire regimes is appealing because it relates directly to the effectsof disturbance, especially on survival and structure of the dominant vegetation.Brown and Smith (2000) described fire regimes as follows:
Understory fire (applies to forests and woodlands)–fires are generally non-lethal to the dominant vegetation and do not substantially change the structure of the dominant vegetation. This fire regime typically applies to the 39 million acres of ponderosa pine in the western U.S. where fires historically occurred every 10-15 years as low intensity surface fires. Southern pines in the southeast U.S also belong in this fire regime.
Mixed severity fire (applies to forests and woodlands)–severity of fire either causes selective mortality in dominant vegetation, depending on different tree species’ susceptibility to fire, or varies between understory and stand replacement. Lodgepole pine in the western U.S. fits in this regime because fires can be characterized as both understory surface fires in younger stands and later as stand replacement crown fires in older stands.
Stand replacement fire (applies to forests, woodlands, shrublands and grasslands)–fires kill aboveground parts of the dominant vegetation, changing the aboveground structure substantially. Approximately 80 percent or more of the aboveground dominant vegetation is either consumed or dies as a result of fires. Plant communities in this regime include chaparral in California, sagebrush in the Interior West, grasslands in the Great Plains and spruce-fir forests in the West.
Non-fire regime–little or no occurrence of natural fire. Most plant communities in the U.S. fall into one of the three previous fire regimes. Sitka spruce in Alaska, however, would fall into the non-fire regime class, because fires are rare or absent in this wet environment.
Narrative summary of major wildfire impacts on people,property and natural resources that occurred historically
The Peshtigo, Michigan, Hinckley, Yacoult and Maine firesburned hundreds of thousands of hectares and killed more than 2000 peoplebetween 1871 and 1947. On the same day, October 8, 1871, that fire wiped out thetown of Peshtigo, Wisconsin, the great Chicago fire devastated urban Chicago.Comparative statistics for those two fires highlight the destructive potentialof wildland fires. The Peshtigo fire covered 518,016 hectares and killed 1150people, whereas 860 hectares burned and 300 lives were lost in the Chicago fire.The 1910 wildland fires in northern Idaho and Montana had several commonelements: many uncontrolled fires burning at one time; prolonged drought, hightemperatures and moderate to strong winds; and mixed conifer and hardwood fuelswith slash from logging and land clearing. These large fires occurred primarilyin conifer forests north of the 42nd meridian, or roughly across the northernquarter of the contiguous United States. One critical element, which is not aslikely to occur today as formerly, was the simultaneous presence of manyuncontrolled fires. The effectiveness of modern fire suppression organizationshas been greatly enhanced by their rapid growth and by the air deployment offirefighters and retardants to even the most remote wildland locations.High-velocity winds and more than 1700 individual fires contributed to thespread of the 1910 fires.
Prolonged drought, high winds and flammable fuel types,however, are as significant to the behaviour of high-intensity fires today aspreviously. In 1967 the Sundance fire in northern Idaho burned more than 22,627hectares and killed two firefighters (Anderson 1968). In 1970, other firesburned approximately 40,470 hectares near Wenatchee, Washington. During thedrought-stricken 1977 fire season in California, 21 major fires burned almost150,000 hectares. The largest of these fires, the remote Marble Cone, spreadthrough 70,418 hectares (174,000 acres) of flammable chaparral and mixed forest.The Sycamore fire near Santa Barbara, California, although only 324 hectares insize, destroyed more than 200 homes.
The benefits accrued by decreasing the number ofuncontrolled fire starts have been offset by the tendency of people to live infire-prone areas. For example, some of the fires most potentially damaging tohuman lives and property occur in areas rich in chaparral shrub fuel inCalifornia. Several wildfires in southern California in 1970, fuelled by aprolonged drought and fanned by strong Santa Ana winds, produced 14 deaths,destroyed 885 homes and burned more than 242,820 hectares. Ten years later thesituation recurred over 28,330 hectares in southern California, resulting in thedeaths of 5 persons and loss of more than 400 structures.
Wildland fires that threaten human lives and property arenot exclusively located in southern California, since the exodus to wildlandregions has become a national phenomenon. Fires burned more than 80,940 hectaresin Maine in October 1947, killing 16 people; another 80,940 hectares burned inNew Jersey in 1963. On July 16, 1977, the Pattee Canyon fire in Missoula,Montana, destroyed 6 homes and charred 486 hectares of forests and grasslands inonly a few hours.
The 1985 wildland fire season was one of the most severein this century. The national toll for that year paints a stark picture: 44civilians and firefighters died, 1400 homes and structures were destroyed ordamaged and 1.2 million hectares were burned. On one day in Florida, May 17, afirefighter died, 40,470 hectares burned, 600 homes and other buildings weredestroyed or damaged and more than 1000 residents were safely evacuated. During1986, in three states alone, wildfires forced 13,500 people to evacuate theirhomes.
A human-caused fire, starting on July 9, 1989, nearBoulder, Colorado, raced through residential areas among the trees, destroying44 homes and other structures and burning over 850 hectares. Losses for homesand natural resources were estimated at $10 million and the cost to control thefire was another $1 million. This Black Tiger fire produced the worst firelosses in Colorado’s history. The causes were familiar: lack of rainfall, hightemperatures, strong winds, steep topography, buildup of forest fuels,construction factors affecting the susceptibility of the homes to fire,combustible construction materials, poor access for emergency vehicles and lackof home site maintenance for fire protection. The conditions that led to theBlack Tiger fire are still prevalent in many parts of Colorado as well as inother states.
Narrative summary of major wildfire impacts on people,property and natural resources during 1990-2000
This narrative summary of wildfire impacts was compiledfrom reports maintained by the National Interagency Fire Center in Boise, Idaho.
A wildfire in Arizona in 1990 resulted in the death of sixfirefighters who were overrun as they were attempting to protect a group ofhomes. In late June California experienced extreme fire behaviour on severalfires due to dry conditions and high winds. Over 500 structures and two shoppingmalls were destroyed. Air tankers were in short supply, necessitating theactivation of eight military C-130s equipped with airborne retardant deliverysystems and three airtankers from Canada. In August, dry lightning stormsoccurred in northern California, Oregon, Washington and the Great Basin, callingfor the mobilization of hundreds of firefighters and other firefightingresources. By August 9 all domestic firefighting resources were fully committedand the military was asked to provide personnel to be trained to assist with thefire emergency.
The 1992 fire season was dominated by the El Niño weatherphenomenon. Most El Niño episodes produce a split flow in the upper air patternwest of the Pacific Coast. This produces above normal precipitation over thesouthern United States and drier than normal conditions in the Pacific Northwestand Great Basin. From October 1991 to April 1992, the Pacific Northwest received50 to 70 percent of normal precipitation, while the Desert Southwest and thesouthern states received up to 150 percent of normal precipitation. TheFoothills Fire started near Boise, Idaho, in late August on a Bureau of Landmanagement area and quickly burned into ponderosa pine forests on the BoiseNational Forest. This fire grew to 257, 600 acres before it was controlled,making it the largest wildfire of the year. Where it burned into the overlydense ponderosa pine forest, it burned as a stand replacement crown fire andkilled most of the trees over a 70,000-acre area.
On 20 October 1992, a devastating fire occurred in thehills above Oakland and Berkeley, California. Burning embers carried by highwinds from the perimeter of a small fire resulted in a major wildland/urbaninterface conflagration that killed 25 people, injured 150 others and destroyednearly 2449 single-family dwellings and 437 apartment and condominium units. Itburned over 648 hectares and did an estimated $1.5 billion in damage.
Although the 1993 fire season was well below average interms of numbers of fires and area burned, strong winds in southern Californiain late October and November contributed to wildfires burning about 200,000acres. Three people died and over 1000 homes were destroyed in multiple fires.
In terms of length and scope of the fire activity, the1994 fire season was the most demanding on record to date. Major firesthroughout the western United States occurred from the end of May untilSeptember. Demand for firefighting resources often exceeded the supply.Thirty-four firefighters lost their lives from one end of the country to theother. Fourteen firefighters lost their lives on a single fire, the Storm Kingfire in Colorado in early July. Also, for the first time in history $1 billionwas spent in fire suppression by all agencies. Seven military battalions weremobilized for firefighting during July and August in the western U.S. Abattalion contains approximately 600 people. At the peak of activity in August,more than 25,000 firefighters, 900 engines, 155 helicopters, 54 air tankers, 31mobile kitchens and 42 shower units were assigned to the fires.
In 1996, record fire activity occurred in Kansas, Oklahomaand Texas with very large areas burned on primarily state and local lands. Bymid-August, there were 48 major fires burning in the West; and 90 IncidentManagement Teams were mobilized to fires. The fire season finally ended in earlyNovember. The following year, 1997, exhibited a low level of fire activitynationwide.
The El Niño weather pattern in 1998 produced extremelydry conditions from New Mexico and Texas all the way east to Florida andsouthern Georgia. Florida and Texas were especially hard hit by wildfires, withmany evacuations and losses of homes in Florida.
Intense drought conditions in the western United States inthe 2000 fire season contributed towards wildfires burning 120,000 hectares onand near one National Forest in Montana, destroying more than 70 homes andforcing the evacuation of nearly 1000 people. In June, the Hanford fire rippedacross 77,700 hectares of southeastern Washington, destroying more than 20 homesand threatening the Hanford Nuclear reservation. Throughout the nation,wildfires burned about 2.5 million hectares of forests and grasslands. More than29,000 firefighters attacked the fires with the assistance of 1200 fire engines,240 helicopters and 50 air tankers. Montana, Idaho and Oregon were declarednational disaster areas. The National Guard, Army and Marines were called toaction, as were firefighting personnel from Australia, Canada, Mexico and NewZealand.
About 80,000 wildfires occurred in the country and mostwere controlled at small size by aggressive initial attack efforts. As isusually the case, about 2 percent of the wildfires caused over 90 percent of thearea burned. The firefighting efforts cost the United States nearly $1 billion,but it was the onset of September rains that quelled the firestorms. It tookappreciable rainfall towards the end of the fire season to overcome the effectsof record heat and drought in the western United States in 2000 (Figure 1).
In May 2000, the National Park Service in New Mexicoignited a prescribed fire. The fire eventually was called a wildfire and threedays later suppression actions contributed to the fire spreading out of theproject area into the town of Los Alamos. The fire in Los Alamos destroyed morethan 200 homes.
Figure 1. Record heat anddrought made 2000 one of the worst wildfire seasons in the West in 50 years.
Fire management organization
All Federal and most State wildland fire organizationsoperate under the National Interagency Incident Management System (NIIMS), whichconsists of five major subsystems providing for an integrated response towildfires and other emergencies. The five subsystems include:
Incident Command System for the on-site management of any emergency.
Training (development and delivery of courses in support of wildfires and prescribed fires).
Qualification and Certification (national standards that include training, experience and physical fitness requirements for all wildland fire agencies).
Publications management (development and control of publications, suppliers and distribution of fire-related materials).
The National Interagency Fire Center in Boise, Idaho,coordinates wildfire response activities for all five national resourcemanagement agencies; and assists the State fire services as well. In addition,the National Weather Service issues two fire-weather forecasts daily during thefire season to all agencies and prepares spot weather forecasts on request forprescribed fires.
The fire management organization is backed by a strong anddiversified fire research programme in the United States. Fire research isconducted at two fire research laboratories in California and Montana and atother locations throughout the country. Long duration fire research programmeshave been instrumental in providing fire managers with fire behaviour models,fire effects information, a fire danger rating system, fire retardantinformation, smoke management protocols and numerous other advances. TechnologyDevelopment Centers in California and Montana have provided essential support interms of physical fitness standards, personal protective equipment andfirefighting equipment specifications.
The following wildfire data were summarized from thecomputerized records maintained by the National Interagency Fire Center locatedin Boise, Idaho.
Table 1. Wildfire Database forthe United States, 1990-1999
Total No. of Fires on Forest, Other Wooded Land, & Other Land
Note:Total number of fires and total area burned by human or natural causes onFederal, State and Private land.
Use of prescribed fire to achieve resource managementobjectives
Prescribed fire, the intentional ignition of grass, shrub,or forest fuels for specific purposes according to predetermined conditions, isa recognized land management practice. Objectives of such burning vary: toreduce fire hazards after logging, expose mineral soil for seedbeds, regulateinsects and diseases, perpetuate natural ecosystems and improve range forage andwildlife habitat.
How widespread is the use of prescribed fire, firesdesigned to produce beneficial results, in the United States today? A survey(Ward and others 1993) indicated that over five million acres are treatedannually by prescribed fire in the United States. Over 70 percent of all prescribed burning, or about 3.5 million acres,was in the Southeast. Purposes for using prescribed fire included hazard reduction,silviculture, wildlife habitat improvement, range improvement, vegetationmanagement, and other reasons. Thesurvey lumped such prescribed burning reasons as watershed management, pestcontrol, disease control, and research in the category called “other”.
Resource management agencies and private timber companiescooperate with State Air Quality Bureaus to prescribe burn in a way that reducesadverse effects on human health and visibility. This survey demonstrates that prescribed burning practices areconcentrated in the southeastern states. Also,although 5 million acres burned annually appears to be a large number, peopleare projecting a much greater need for prescribed fire in the future tomaintain, or restore, the health of fire-adapted ecosystems.
For example, the new Federal Fire Policy (USDI/USDA1995)states that: Managing for landscape health requires expansion ofcooperative interagency prescribed fire programs. Agencies must make acommitment with highly qualified people, from leader to practitioner, andprovide funding mechanisms to conduct the programme. Recent fire fatalitieshave focused attention on the need to reduce hazardous fuel concentrations. Many areas need immediate treatment of live and dead vegetation toprevent large, life-threatening, high intensity wildfires (Mutch 1994). Fueltreatment alternatives include mechanical, chemical, biological, and manualmethods, in addition to the use of fire.
In some areas managed by the National Park Service, USDAForest Service and Bureau of Land Management, naturally ignited fires may beallowed to burn according to approved prescriptions (Kilgore and Heinselman1990). Fire management areas have been established in national parks andwildernesses from the Florida Everglades to the Sierra Nevada in California.Visitors are increasingly aware that wildland fires can provide an importantenvironment for the enjoyment of park and wilderness experiences.
Fires are not simply allowed to burn. Their spread ismonitored to ensure that they remain in designated areas. Suppression measures,backed by modern fire control technology, are employed to protect human life andproperty and to contain fires within the management unit.
Public policies affecting wildfires and fire management
Recent tragedies in the West focused attention on the needto reduce hazardous fuel accumulations. In the summer of 1994, 34 firefighterslost their lives. The events of that season created a renewed awareness andconcern among federal land management agencies and their constituents aboutwildfire impacts. Federal agencies conducted a combined review of their firepolicies and programmes. The result was the enactment of a new interagencyfederal wildland fire management policy, which provided a common approach towildland fire among all five federal land management agencies (USDI/USDA 1995).The new policy also called for close cooperation with tribal, state and otherjurisdictions. Nine major issues were addressed in the new fire policy:
1. The challenge of managing wildland fire is increasing in complexity andmagnitude. Public and private values are seriously at risk and severe ecologicaldeterioration is possible from catastrophic wildfire. The new Federal wildlandfire policies are critical and help to strengthen cooperative relationships:
2. Firefighter and public safety remains the first priority in wildland firemanagement. Protection of natural and cultural resources and property are thesecond priority.
3. Wildland fire, as a critical natural process, must be reintroduced intothe ecosystem, accomplished across agency boundaries and based on the bestavailable science.
4. Where wildland fire cannot be safely reintroduced because of hazardousfuel accumulations, pretreatment must be considered, particularly in thewildland/urban interface.
5. Wildland fire management decisions and resource management decisions areconnected and based on approved plans. Agencies must have the ability to choosefrom the full spectrum of actions–from prompt suppression to allowing fire tohave an ecological function.
6. All aspects of wildland fire management will involve all partners andhave compatible programmes, activities and processes.
7. The role of federal agencies in the wildland/urban interface includesfirefighting, hazard fuel reduction, cooperative prevention and education andtechnical assistance. Ultimately, the primary responsibility, rests at the Stateand local levels.
8. Structural fire protection in the wildland/urban interface is theresponsibility of tribal, state and local governments.
9. Federal agencies must better educate internal and external audiencesabout how and why we use and manage wildland fire.
Sustainable land use practices used to reduce wildfirehazards and wildfire risks
Numerous ecosystem indicators from the Southeast to theWest are highlighting alarming examples of declining forest health. Attemptedfire exclusion practices, prolonged drought and epidemic levels of insects anddiseases have coincided to increase wildland fuels, produce extensive forestmortality and cause major changes in forest density and species composition.
Quigley and Cole (1997) reported that fire severity andfrequency in the Columbia River Basin have changed across the landscape. Beforethe settlement of America by Europeans, most fires in the Basin at low to midelevations were low intensity fires. Forest and rangelands benefited from thesefrequent surface fires, which thinned vegetation and favored growth offire-tolerant trees. In recent times, the area in the Columbia Basin with highintensity, stand replacement fire regimes has more than doubled. This poses asignificant threat to ecological integrity, water quality, species recovery andhomes in wildland areas.
Gray (1992) called attention to a forest health emergencyin parts of the western United States where trees have been killed across alarge area in eastern Oregon and Washington. He indicated that similar problemsextend over a much larger area south into Utah, Nevada and California and eastinto Idaho. Denser stands and unnatural fuel accumulations are also causing highintensity crown fires in Montana, Colorado, Arizona, New Mexico and Nebraska.Historically fires in these long-needled pine forests were more frequent lowintensity surface fires.
Since the 1980s, large wildfires in dead and dying westernforests have accelerated the rate of forest mortality, threatening people,property and natural resources (Mutch 1994).
The solution to this problem lies in managing thesefire-dependent forests in a more sustainable manner, recognizing that fire is animportant ecosystem process vital to forest health (Mutch 1993). The managementstrategy begins with thinning and harvesting the dense understory of fir; andretaining old growth ponderosa pine, larch and Douglas-fir in the overstory as aseed source. Where large quantities of standing dead trees are present, salvagelogging is encouraged to remove large accumulations of fuel. Prescribed fire iscarried out on a large scale to reduce the fuel hazard, re-cycle nutrients andstimulate the regeneration and growth of fire-adapted vegetation. This strategyreduces the density of fir in the stands and abates the future insectinfestations and large-scale wildfires. Over the long term, silviculturalpartial-cutting and underburning favour retention of more open stands that havea lesser fire hazard.
The U.S. Government Accounting Office (1999) recommendedthat the Secretary of Agriculture direct the Chief of the Forest Service todevelop, and formally communicate to Congress, a cohesive strategy for reducingand maintaining accumulated fuels on national forests at acceptable levels.
Community involvement in fire management activities
The problems of living in a fire environment are no longerunique to southern California, as was thought when these wildland/urbaninterface fires gained national attention in the 1950s and 1960s. In recentyears wildland/urban fire disasters have occurred from coast to coast. As morepeople move out of cities and into wildlands, these tragedies will recur.Following the recent disastrous fires in several states, recommendations formitigating the impact of fires in the wildland/urban interface have beendeveloped. The combined efforts of fire protection services, legislators,planners, developers and homeowners will be required to prevent the tragic lossof lives and homes in the wildlands. In other words, community involvement byresidents in conducting fire safe measures around their homes is absolutelyessential in community protection.
The homeowner has the ultimate responsibility to take thenecessary measures to ensure that a home can survive a wildfire. If the properprecautions are taken, a house can survive a wildfire even when the fireservices are not able to respond. However, to this day a large number ofhomeowners throughout the country have not responded in fireproofing propertywell in advance of the inevitable fires.
Recommendations to reduce the loss of life and property inthe wildland/urban interface will be useless unless all stakeholders implementthem at the grassroots level. An excellent example of a community-basedprogramme is one implemented at Incline Village and Crystal Bay in the LakeTahoe basin. The objective of this programme was to reduce the potential fornatural resource, property and human life losses due to wildfire by empoweringthe residents with the knowledge to address the hazard. The three majorcomponents of this defensible-space programme included neighbourhood leaders,creation of survivable space and agency coordination. The key to protecting lifeand property in the wildland/urban interface is the property owners’ realizationthat they have a serious problem and that their actions embody a significantpart of the solution. In the Incline Village/Crystal Bay Plan, neighbourhoodleaders are trained in survivable-space techniques. They are expected to teachthese techniques to their neighbours and to coordinate neighbourhood efforts.Such concerted community action will minimize the threats from fires in theinterface.
It is also wise to have sensible land developmentpractices, since tragedies arise not only from ignorance of fuels and firebehaviour, but also from a greater concern for the aesthetics of a homesite thanfor fire safety. Several aspects of development detract from fire safety in thewildland/urban interface:
Lack of access to adequate water sources.
Firewood stacked next to houses.
Slash (that is, branches, stumps, logs and other vegetative residues)piled on homesites or along access roads.
Structures built on slopes with unenclosed stilt foundations.
Trees and shrubs growing next to structures, under eaves and among stiltfoundations.
Roads that are steep, narrow, winding, unmapped, unsigned, unnamed andbordered by slash or dense vegetation that make them impossible to drive onduring a fire.
Subdivisions on sites without two or more access roads for simultaneousingress and egress.
Roads and bridges without the grade, design and width to permitsimultaneous evacuation by residents and access by firefighters, emergencymedical personnel and equipment.
Excessive slopes, heavy fuels, structures built in box canyons and otherhazardous situations.
Living fuels that have not been modified by thinning, landscaping, orother methods to reduce vegetation and litter that contribute to fire intensity.
Homes constructed with flammable building materials (wooden shakes,shingles).
Resource management agencies, regulatory agencies andsociety have failed to implement programmes in the past to sustain the health offire-adapted ecosystems to benefit people, property and natural resources.Today, however, many decades of research results have provided the basis formanaging ecosystems more in harmony with disturbance factors to foster thehealth, resilience and productivity of wildland ecosystems. The principles ofecosystem management can guide society and managers in developing strategies toachieve a range of desired future conditions that will sustain or restoreecosystem health. It has taken 6 or 7 decades to produce today’s decline in manyforested ecosystems in the United States. It will take an equally long time toreverse this trend. Fortunately many resource management agencies are commencingecosystem restoration programmes at this time.
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