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Fire ecology is a scientific discipline concerned with natural processes involving
fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...
in an
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
and the ecological effects, the interactions between fire and the abiotic and biotic components of an ecosystem, and the role as an ecosystem process. Many ecosystems, particularly
prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
, savanna,
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...
and coniferous forests, have evolved with fire as an essential contributor to
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 ...
vitality and renewal. Many plant species in fire-affected environments require fire to germinate, establish, or to reproduce.
Wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated ...
not only eliminates these species, but also the animals that depend upon them. Campaigns in the United States have historically molded public opinion to believe that
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 are always harmful to nature. This view is based on the outdated beliefs that ecosystems progress toward an equilibrium and that any disturbance, such as fire, disrupts the harmony of nature. More recent ecological research has shown, however, that fire is an integral component in the function and
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity' ...
of many natural habitats, and that the organisms within these communities have adapted to withstand, and even to exploit, natural wildfire. More generally, fire is now regarded as a 'natural disturbance', similar to
flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...
ing, windstorms, and
landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, ...
s, that has driven the evolution of species and controls the characteristics of ecosystems. Fire suppression, in combination with other human-caused environmental changes, may have resulted in unforeseen consequences for natural ecosystems. Some large wildfires in the United States have been blamed on years of fire suppression and the continuing expansion of people into fire-adapted ecosystems, but
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
is more likely responsible. Land managers are faced with tough questions regarding how to restore a natural
fire regime A fire regime is the pattern, frequency, and intensity of the bushfires and wildfires that prevail in an area over long periods of time. It is an integral part of fire ecology, and renewal for certain types of ecosystems. A fire regime describes t ...
, but allowing wildfires to burn is the least expensive and likely most effective method.


Fire components

A
fire regime A fire regime is the pattern, frequency, and intensity of the bushfires and wildfires that prevail in an area over long periods of time. It is an integral part of fire ecology, and renewal for certain types of ecosystems. A fire regime describes t ...
describes the characteristics of fire and how it interacts with a particular ecosystem. Its "severity" is a term that ecologists use to refer to the impact that a fire has on an ecosystem. It is usually studied using tools such as remote sensing which can detect burned area estimates, severity and fire risk associated with an area. Ecologists can define this in many ways, but one way is through an estimate of plant mortality. Fire can burn at three levels. Ground fires will burn through soil that is rich in organic matter. Surface fires will burn through dead plant material that is lying on the ground. Crown fires will burn in the tops of shrubs and trees. Ecosystems generally experience a mix of all three. Fires will often break out during a dry season, but in some areas wildfires may also commonly occur during a time of year when lightning is prevalent. The frequency over a span of years at which fire will occur at a particular location is a measure of how common wildfires are in a given ecosystem. It is either defined as the average interval between fires at a given site, or the average interval between fires in an equivalent specified area.Bond and Keeley 2005 Defined as the energy released per unit length of fireline (kW m−1), wildfire intensity can be estimated either as * the product of **the linear spread rate (m s−1), ** the low heat of combustion (kJ kg−1), ** and the combusted fuel mass per unit area, *or it can be estimated from the flame length.Byram, 1959


Abiotic responses

Fires can affect soils through heating and combustion processes. Depending on the temperatures of the soils caused by the combustion processes, different effects will happen- from evaporation of water at the lower temperature ranges, to the combustion of
soil organic matter Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous ...
and formation of pyrogenic organic matter, otherwise known as charcoal. Fires can cause changes in soil nutrients through a variety of mechanisms, which include oxidation, volatilization, erosion, and leaching by water, but the event must usually be of high temperatures for significant loss of nutrients to occur. However, quantity of nutrients available in soils are usually increased due to the ash that is generated, and this is made quickly available, as opposed to the slow release of nutrients by decomposition. Rock spalling (or thermal exfoliation) accelerates weathering of rock and potentially the release of some nutrients. Increase in the pH of the soil following a fire is commonly observed, most likely due to the formation of calcium carbonate, and the subsequent decomposition of this calcium carbonate to calcium oxide when temperatures get even higher. It could also be due to the increased cation content in the soil due to the ash, which temporarily increases
soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the n ...
. Microbial activity in the soil might also increase due to the heating of soil and increased nutrient content in the soil, though studies have also found complete loss of microbes on the top layer of soil after a fire. Overall, soils become more
basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
(higher pH) following fires because of acid combustion. By driving novel chemical reactions at high temperatures, fire can even alter the texture and structure of soils by affecting the clay content and the soil's porosity. Removal of vegetation following a fire can cause several effects on the soil, such as increasing the temperatures of the soil during the day due to increased solar radiation on the soil surface, and greater cooling due to loss of radiative heat at night. Fewer leaves to intercept rain will also cause more rain to reach the soil surface, and with fewer plants to absorb the water, the amount of water content in the soils might increase. However, it might be seen that ash can be water repellent when dry, and therefore water content and availability might not actually increase.


Biotic responses and adaptations


Plants

Plants have evolved many adaptations to cope with fire. Of these adaptations, one of the best-known is likely ''
pyriscence Serotiny in botany simply means 'following' or 'later'. In the case of serotinous flowers, it means flowers which grow following the growth of leaves, or even more simply, flowering later in the season than is customary with allied species. Havi ...
'', where maturation and release of seeds is triggered, in whole or in part, by fire or smoke; this behaviour is often erroneously called '' serotiny'', although this term truly denotes the much broader category of seed release activated by any stimulus. All pyriscent plants are serotinous, but not all serotinous plants are pyriscent (some are necriscent, hygriscent, xeriscent, soliscent, or some combination thereof). On the other hand,
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, ...
of seed activated by trigger is not to be confused with pyriscence; it is known as ''physiological dormancy''. In
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...
communities in Southern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
, for example, some plants have leaves coated in flammable oils that encourage an intense fire. This heat causes their fire-activated seeds to germinate (an example of dormancy) and the young plants can then capitalize on the lack of
competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, ind ...
in a burnt landscape. Other plants have smoke-activated seeds, or fire-activated buds. The cones of the
Lodgepole pine ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalp ...
(''Pinus contorta'') are, conversely, pyriscent: they are sealed with a resin that a fire melts away, releasing the seeds.USDA Forest Service Many plant species, including the shade-intolerant
giant sequoia ''Sequoiadendron giganteum'' (giant sequoia; also known as giant redwood, Sierra redwood, Sierran redwood, California big tree, Wellingtonia or simply big treea nickname also used by John Muir) is the sole living species in the genus ''Sequoiade ...
(''Sequoiadendron giganteum''), require fire to make gaps in the vegetation canopy that will let in light, allowing their seedlings to compete with the more shade-tolerant seedlings of other species, and so establish themselves.US National Park Service Because their stationary nature precludes any fire avoidance, plant species may only be fire-intolerant, fire-tolerant or fire-resistant.Kramp ''et al.'' 1986


Fire intolerance

Fire-intolerant plant species tend to be highly flammable and are destroyed completely by fire. Some of these plants and their seeds may simply fade from the community after a fire and not return; others have adapted to ensure that their offspring survives into the next generation. "Obligate seeders" are plants with large, fire-activated seed banks that germinate, grow, and mature rapidly following a fire, in order to reproduce and renew the seed bank before the next fire.Knox and Clarke 2005 Seeds may contain the receptor protein KAI2, that is activated by the growth hormones karrikin released by the fire.


Fire tolerance

Fire-tolerant species are able to withstand a degree of burning and continue growing despite damage from fire. These plants are sometimes referred to as " resprouters". Ecologists have shown that some species of resprouters store extra energy in their roots to aid recovery and re-growth following a fire. For example, after an Australian bushfire, the
Mountain Grey Gum ''Eucalyptus cypellocarpa'', commonly known as mountain grey gum, mountain gum, monkey gum or spotted mountain grey gum, is a species of straight, smooth-barked forest tree that is endemic to southeastern Australia. It has relatively large, lanc ...
tree (''Eucalyptus cypellocarpa'') starts producing a mass of shoots of leaves from the base of the tree all the way up the trunk towards the top, making it look like a black stick completely covered with young, green leaves.


Fire resistance

Fire-resistant plants suffer little damage during a characteristic fire regime. These include large trees whose flammable parts are high above surface fires. Mature
ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is t ...
(''Pinus ponderosa'') is an example of a tree species that suffers virtually no crown damage under a naturally mild fire regime, because it sheds its lower, vulnerable branches as it matures.Pyne 2002


Animals, birds and microbes

Like plants, animals display a range of abilities to cope with fire, but they differ from most plants in that they must avoid the actual fire to survive. Although
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s may be vulnerable when nesting, they are generally able to escape a fire; indeed they often profit from being able to take prey fleeing from a fire and to recolonize burned areas quickly afterwards. In fact, many wildlife species globally are dependent on recurring fires in fire-dependent ecosystems to create and maintain habitat. Some anthropological and ethno-ornithological evidence suggests that certain species of fire-foraging raptors may engage in intentional fire propagation to flush out prey. Mammals are often capable of fleeing a fire, or seeking cover if they can burrow. Amphibians and reptiles may avoid flames by burrowing into the ground or using the burrows of other animals. Amphibians in particular are able to take refuge in water or very wet mud. Some
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s also take shelter during a fire, although the heat and smoke may actually attract some of them, to their peril.DeBano ''et al.'' 1998 Microbial organisms in the soil vary in their heat tolerance but are more likely to be able to survive a fire the deeper they are in the soil. A low fire intensity, a quick passing of the flames and a dry soil will also help. An increase in available nutrients after the fire has passed may result in larger microbial communities than before the fire.Hart ''et al.'' 2005 The generally greater heat tolerance of bacteria relative to fungi makes it possible for soil microbial population diversity to change following a fire, depending on the severity of the fire, the depth of the microbes in the soil, and the presence of plant cover. Certain species of fungi, such as ''Cylindrocarpon destructans'' appear to be unaffected by combustion contaminants, which can inhibit re-population of burnt soil by other microorganisms, and therefore have a higher chance of surviving fire disturbance and then recolonizing and out-competing other fungal species afterwards.


Fire and ecological succession

Fire behavior is different in every ecosystem and the organisms in those ecosystems have adapted accordingly. One sweeping generality is that in all ecosystems, fire creates a mosaic of different
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 ...
patches, with areas ranging from those having just been burned to those that have been untouched by fire for many years. This is a form of ecological succession in which a freshly burned site will progress through continuous and directional phases of colonization following the destruction caused by the fire.Begon ''et al.'' 1996, pg. 692 Ecologists usually characterize succession through the changes in vegetation that successively arise. After a fire, the first species to re-colonize will be those with seeds are already present in the soil, or those with seeds are able to travel into the burned area quickly. These are generally fast-growing
herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition ...
plants that require light and are intolerant of shading. As time passes, more slowly growing, shade-tolerant woody species will suppress some of the herbaceous plants.Begon ''et al.'' 1996, pg 700 Conifers are often early successional species, while broad leaf trees frequently replace them in the absence of fire. Hence, many conifer forests are themselves dependent upon recurring fire.Keddy 2007, Chapter 6 Both natural and human fires affect all ecosystems from peatlands to shrublands to forests and tropical landscapes. This impacts the way that the ecosystem is structured and functions. Though there have always been wildfires naturally, the frequency of wildfires has increased at a rapid rate in recent years. This is largely due to decreases in precipitation, increases in temperature, and increases in human ignitions. Different species of plants, animals, and microbes specialize in exploiting different stages in this process of succession, and by creating these different types of patches, fire allows a greater number of species to exist within a landscape. Soil characteristics will be a factor in determining the specific nature of a fire-adapted ecosystem, as will climate and topography. Different frequencies of fire also result in different successional pathways; short intervals between fires often eliminate tree species due to the time required to rebuild a seed bank, resulting in replacement by lighter seeded species like grasses and forbs https://www.ipcc.ch/report/ar6/wg3/


Examples of fire in different ecosystems


Forests

ImageSize = width:460 height:400 PlotArea = right:50 top:10 left:50 bottom:10 DateFormat = yyyy TimeAxis = orientation:vertical order:reverse Period = from:1600 till:2020 AlignBars = early ScaleMajor = unit:year increment:100 start:1600 Colors = id:canvas value:rgb(1,1,0.85) id:forest value:rgb(0.85,1,0.85) id:range value:rgb(1,0.85,0.85) id:bush value:rgb(0.85,1,1) BackgroundColors = canvas:canvas PlotData = width:15 color:white bar:test from:1600 till:1860 # Pre European PlotData = width:15 color:yellow bar:test from:1860 till:1874 # Gold Rush PlotData = width:15 color:bush bar:test from:1874 till:1912 # Bush Fire Act PlotData = width:15 color:forest bar:test from:1912 till:2020 # Forest Act PlotData = at:1600 shift:(20,0) text: Year of fire at:1600 shift:(160,0) text: Percent of sample plots with fire evidence at:1610 shift:(70,-5) text: 70 60 50 40 30 20 10 0 at:1619 shift:(10,-5) text: 1619 CE 2/8 bar:test at:1619 mark:(line,red) at:1630 shift:(10,-5) text: 1630 CE 2/9 bar:test at:1630 mark:(line,red) at:1661 shift:(10,-5) text: 1661 CE 3/12 bar:test at:1661 mark:(line,red) at:1679 shift:(10,-5) text: 1679 CE 3/16 bar:test at:1679 mark:(line,red) at:1695 shift:(10,-4) text: 1695 CE 3/17 bar:test at:1695 mark:(line,red) at:1704 shift:(10,-5) text: 1704 CE 3/19 bar:test at:1704 mark:(line,red) at:1718 shift:(10,-5) text: 1718 CE 3/20 bar:test at:1718 mark:(line,red) at:1730 shift:(10,-5) text: 1730 CE 8/24 bar:test at:1730 mark:(line,red) at:1748 shift:(10,-5) text: 1748 CE 2/25 bar:test at:1748 mark:(line,red) at:1758 shift:(10,-5) text: 1758 CE 6/27 bar:test at:1758 mark:(line,red) at:1767 shift:(10,-5) text: 1767 CE 3/27 bar:test at:1767 mark:(line,red) at:1773 shift:(10,-10) text: 1773 CE 1/27 bar:test at:1773 mark:(line,red) at:1790 shift:(10,-5) text: 1790 CE 19/28 bar:test at:1790 mark:(line,red) at:1804 shift:(10,-5) text: 1804 CE 6/30 bar:test at:1804 mark:(line,red) at:1818 shift:(10,-5) text: 1818 CE 14/30 bar:test at:1818 mark:(line,red) at:1832 shift:(10,-4) text: 1832 CE 13/33 bar:test at:1832 mark:(line,red) at:1842 shift:(10,-5) text: 1842 CE 16/33 bar:test at:1842 mark:(line,red) at:1863 shift:(10,-5) text: 1863 CE 24/35 bar:test at:1863 mark:(line,red) at:1877 shift:(10,-5) text: 1877 CE 1/35 bar:test at:1877 mark:(line,red) at:1895 shift:(10,-5) text: 1895 CE 1/35 bar:test at:1895 mark:(line,red) at:1905 shift:(10,-5) text: 1905 CE 13/35 bar:test at:1905 mark:(line,red) at:1929 shift:(10,-5) text: 1929 CE 2/35 bar:test at:1929 mark:(line,red) at:1944 shift:(10,-5) text: 1944 CE 2/35 bar:test at:1944 mark:(line,red) at:1861 shift:(-60,-5) fontsize:XS text: Gold Rush bar:test at:1861 mark:(line,black) at:1874 shift:(-60,-5) fontsize:XS text: Bush Fires at:1884 shift:(-60,-5) fontsize:XS text: Act bar:test at:1874 mark:(line,black) at:1912 shift:(-60,-5) fontsize:XS text: Forest Act bar:test at:1912 mark:(line,black) at:1960 shift:(30,-5) fontsize:XS text: Area studied escaped subsequent much larger adjacent forest fires at:1970 shift:(30,-5) fontsize:XS text: Brooks W. et al. A Disrupted Historical Fire Regime in Central British Columbia at:1980 shift:(30,-5) fontsize:XS text: Front. Ecol. Evol., 28 June 2021 at:1990 shift:(30,-5) fontsize:XS tex

at:2010 shift:(30,-3) fontsize:XS text:KEY: % Fire exposed Estimated upper bound sampling error LineData = at:2010 frompos:110 tillpos:150 color:red width:2 at:2010 frompos:210 tillpos:250 color:range width:2 at:1619 frompos:346 tillpos:460 color:range width:2 at:1619 frompos:430 tillpos:460 color:red width:2 at:1630 frompos:358 tillpos:460 color:range width:2 at:1630 frompos:430 tillpos:460 color:red width:2 at:1661 frompos:346 tillpos:460 color:range width:2 at:1661 frompos:422 tillpos:460 color:red width:2 at:1679 frompos:374 tillpos:460 color:range width:2 at:1679 frompos:422 tillpos:460 color:red width:2 at:1695 frompos:379 tillpos:460 color:range width:2 at:1695 frompos:422 tillpos:460 color:red width:2 at:1704 frompos:387 tillpos:460 color:range width:2 at:1704 frompos:422 tillpos:460 color:red width:2 at:1718 frompos:391 tillpos:460 color:range width:2 at:1718 frompos:422 tillpos:460 color:red width:2 at:1730 frompos:307 tillpos:460 color:range width:2 at:1730 frompos:360 tillpos:460 color:red width:2 at:1748 frompos:423 tillpos:460 color:range width:2 at:1748 frompos:430 tillpos:460 color:red width:2 at:1758 frompos:358 tillpos:460 color:range width:2 at:1758 frompos:386 tillpos:460 color:red width:2 at:1767 frompos:409 tillpos:460 color:range width:2 at:1767 frompos:422 tillpos:460 color:red width:2 at:1773 frompos:442 tillpos:460 color:range width:2 at:1773 frompos:445 tillpos:460 color:red width:2 at:1790 frompos:149 tillpos:460 color:range width:2 at:1790 frompos:208 tillpos:460 color:red width:2 at:1804 frompos:369 tillpos:460 color:range width:2 at:1804 frompos:386 tillpos:460 color:red width:2 at:1818 frompos:247 tillpos:460 color:range width:2 at:1818 frompos:280 tillpos:460 color:red width:2 at:1832 frompos:279 tillpos:460 color:range width:2 at:1832 frompos:294 tillpos:460 color:red width:2 at:1842 frompos:238 tillpos:460 color:range width:2 at:1842 frompos:252 tillpos:460 color:red width:2 at:1863 frompos:140 tillpos:460 color:red width:2 at:1877 frompos:445 tillpos:460 color:red width:2 at:1895 frompos:445 tillpos:460 color:red width:2 at:1905 frompos:294 tillpos:460 color:red width:2 at:1929 frompos:430 tillpos:460 color:red width:2 at:1944 frompos:430 tillpos:460 color:red width:2
Mild to moderate fires burn in the
forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
understory In forestry and ecology, understory (American English), or understorey (Commonwealth English The use of the English language in current and former member countries of the Commonwealth of Nations was largely inherited from British co ...
, removing small trees and herbaceous groundcover. High-severity fires will burn into the crowns of the trees and kill most of the dominant vegetation. Crown fires may require support from ground fuels to maintain the fire in the forest canopy (passive crown fires), or the fire may burn in the canopy independently of any ground fuel support (an active crown fire). High-severity fire creates complex early seral forest habitat, or
snag forest Complex early seral forests, or snag forests, are ecosystems that occupy potentially forested sites after a stand-replacement disturbance and before re-establishment of a closed forest canopy. They are generated by natural disturbances such as w ...
with high levels of biodiversity. When a forest burns frequently and thus has less plant litter build-up, below-ground soil temperatures rise only slightly and will not be lethal to roots that lie deep in the soil. Although other characteristics of a forest will influence the impact of fire upon it, factors such as
climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologica ...
and
topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary s ...
play an important role in determining fire severity and fire extent.Beaty and Taylor (2001) Fires spread most widely during drought years, are most severe on upper slopes and are influenced by the type of vegetation that is growing.


Forests in British Columbia

In
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...
, forests cover about 10% of the land area and yet harbor 70% of the country’s bird and terrestrial mammal species. Natural fire regimes are important in maintaining a diverse assemblage of
vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...
species in up to twelve different
forest types A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
in
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...
.Bunnell (1995) Different species have adapted to exploit the different stages of succession, regrowth and habitat change that occurs following an episode of burning, such as downed trees and debris. The characteristics of the initial fire, such as its size and intensity, cause the habitat to evolve differentially afterwards and influence how vertebrate species are able to use the burned areas. The change in forest fire intensity over time has been studied for the period since 1600 in an area of central British Columbia and is consistent with
fire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated a ...
since regulation was introduced.


Shrublands

Shrub fires typically concentrate in the canopy and spread continuously if the shrubs are close enough together.
Shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It ...
s are typically dry and are prone to accumulations of highly volatile fuels, especially on hillsides. Fires will follow the path of least moisture and the greatest amount of dead fuel material. Surface and below-ground soil temperatures during a burn are generally higher than those of forest fires because the centers of combustion lie closer to the ground, although this can vary greatly. Common plants in shrubland or chaparral include manzanita, chamise and coyote brush.


California shrublands

California shrubland, commonly known as
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...
, is a widespread plant community of low growing species, typically on arid sloping areas of the California Coast Ranges or western foothills of the
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
. There are a number of common shrubs and tree shrub forms in this association, including salal, toyon, coffeeberry and Western poison oak. Regeneration following a fire is usually a major factor in the association of these species.


South African Fynbos shrublands

Fynbos shrublands occur in a small belt across
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...
. The plant species in this ecosystem are highly diverse, yet the majority of these species are obligate seeders, that is, a fire will cause germination of the seeds and the plants will begin a new life-cycle because of it. These plants may have coevolved into obligate seeders as a response to fire and nutrient-poor soils.Wisheu ''et al.'' (2000) Because fire is common in this ecosystem and the soil has limited nutrients, it is most efficient for plants to produce many seeds and then die in the next fire. Investing a lot of energy in roots to survive the next fire when those roots will be able to extract little extra benefit from the nutrient-poor soil would be less efficient. It is possible that the rapid generation time that these obligate seeders display has led to more rapid
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
and
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution withi ...
in this ecosystem, resulting in its highly diverse plant community.


Grasslands

Grasslands burn more readily than forest and shrub ecosystems, with the fire moving through the stems and leaves of herbaceous plants and only lightly heating the underlying soil, even in cases of high intensity. In most grassland ecosystems, fire is the primary mode of
decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is ...
, making it crucial in the recycling of nutrients. In some grassland systems, fire only became the primary mode of decomposition after the disappearance of large migratory herds of browsing or grazing megafauna driven by predator pressure. In the absence of functional communities of large migratory herds of herbivorous megafauna and attendant predators, overuse of fire to maintain grassland ecosystems may lead to excessive oxidation, loss of carbon, and desertification in susceptible climates. Some grassland ecosystems respond poorly to fire.


North American grasslands

In North America fire-adapted invasive grasses such as '' Bromus tectorum'' contribute to increased fire frequency which exerts selective pressure against native species. This is a concern for grasslands in the
Western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the Wes ...
. In less arid grassland presettlement fires worked in concert with grazing to create a healthy grassland ecosystem as indicated by the accumulation of
soil organic matter Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous ...
significantly altered by fire. The tallgrass prairie ecosystem in the Flint Hills of eastern Kansas and Oklahoma is responding positively to the current use of fire in combination with grazing.


South African savanna

In the savanna of
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...
, recently burned areas have new growth that provides palatable and nutritious forage compared to older, tougher grasses. This new forage attracts large herbivores from areas of unburned and grazed grassland that has been kept short by constant grazing. On these unburned "lawns", only those plant species adapted to heavy grazing are able to persist; but the distraction provided by the newly burned areas allows grazing-intolerant grasses to grow back into the lawns that have been temporarily abandoned, so allowing these species to persist within that ecosystem.Archibald et al. 2005


Longleaf pine savannas

Much of the southeastern United States was once open
longleaf pine The longleaf pine (''Pinus palustris'') is a pine species native to the Southeastern United States, found along the coastal plain from East Texas to southern Virginia, extending into northern and central Florida. In this area it is also known as ...
forest with a rich understory of grasses, sedges, carnivorous plants and orchids. These ecosystems had the highest fire frequency of any habitat, once per decade or less. Without fire, deciduous forest trees invade, and their shade eliminates both the pines and the understory. Some of the typical plants associated with fire include yellow pitcher plant and
rose pogonia ''Pogonia ophioglossoides'', the snakemouth orchid or rose pogonia, is a species of orchid occurring from central Canada to the east-central and eastern United States. It is the type species of the genus '' Pogonia''. It is pollinated by bees. ...
. The abundance and diversity of such plants is closely related to fire frequency. Rare animals such as gopher tortoises and indigo snakes also depend upon these open grasslands and flatwoods. Hence, the restoration of fire is a priority to maintain species composition and biological diversity.


Fire in wetlands

Many kinds of wetlands are also influenced by fire. This usually occurs during periods of drought. In landscapes with peat soils, such as bogs, the peat substrate itself may burn, leaving holes that refill with water as new ponds. Fires that are less intense will remove accumulated litter and allow other wetland plants to regenerate from buried seeds, or from rhizomes. Wetlands that are influenced by fire include coastal marshes, wet prairies, peat bogs,
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
s, prairie marshes and flatwoods.Keddy 2010, p. 114-120. Since wetlands can store large amounts of carbon in peat, the fire frequency of vast northern peatlands is linked to processes controlling the carbon dioxide levels of the atmosphere, and to the phenomenon of global warming.Vitt et al. 2005 Dissolved organic carbon (DOC) is abundant in wetlands and plays a critical role in their ecology. In the Florida Everglades, a significant portion of the DOC is "dissolved charcoal" indicating that fire can play a critical role in wetland ecosystems.


Fire suppression

Fire serves many important functions within fire-adapted ecosystems. Fire plays an important role in nutrient cycling, diversity maintenance and habitat structure. The suppression of fire can lead to unforeseen changes in ecosystems that often adversely affect the plants, animals and humans that depend upon that habitat. Wildfires that deviate from a historical fire regime because of fire suppression are called "uncharacteristic fires".


Chaparral communities

In 2003, southern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
witnessed powerful
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...
wildfires. Hundreds of homes and hundreds of thousands of acres of land went up in flames. Extreme fire weather (low humidity, low fuel moisture and high winds) and the accumulation of dead plant material from eight years of drought, contributed to a catastrophic outcome. Although some have maintained that fire suppression contributed to an unnatural buildup of fuel loads,Minnich 1983 a detailed analysis of historical fire data has showed that this may not have been the case.Keeley ''et al.'' 1999 Fire suppression activities had failed to exclude fire from the southern California chaparral. Research showing differences in fire size and frequency between southern California and Baja has been used to imply that the larger fires north of the border are the result of fire suppression, but this opinion has been challenged by numerous investigators and is no longer supported by the majority of fire ecologists. One consequence of the fires in 2003 has been the increased density of
invasive Invasive may refer to: *Invasive (medical) procedure *Invasive species *Invasive observation, especially in reference to surveillance *Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...
and non-native plant species that have quickly colonized burned areas, especially those that had already been burned in the previous 15 years. Because shrubs in these communities are adapted to a particular historical fire regime, altered fire regimes may change the
selective pressure Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of ...
s on plants and favor invasive and non-native species that are better able to exploit the novel post-fire conditions.Keeley ''et al.'' 2005


Fish impacts

The Boise National Forest is a US national forest located north and east of the city of
Boise, Idaho Boise (, , ) is the capital and most populous city of the U.S. state of Idaho and is the county seat of Ada County. On the Boise River in southwestern Idaho, it is east of the Oregon border and north of the Nevada border. The downtown ...
. Following several uncharacteristically large wildfires, an immediately negative impact on fish populations was observed, posing particular danger to small and isolated fish populations.Burton (2005) In the long term, however, fire appears to rejuvenate fish habitats by causing hydraulic changes that increase flooding and lead to
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel wh ...
removal and the deposition of a favorable habitat substrate. This leads to larger post-fire populations of the fish that are able to recolonize these improved areas. But although fire generally appears favorable for fish populations in these ecosystems, the more intense effects of uncharacteristic wildfires, in combination with the fragmentation of populations by human barriers to dispersal such as weirs and dams, ''will'' pose a threat to fish populations.


Fire as a management tool

Restoration ecology is the name given to an attempt to reverse or mitigate some of the changes that humans have caused to an ecosystem.
Controlled burn 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, prairie restoration or greenhouse gas abatement. A contro ...
ing is one tool that is currently receiving considerable attention as a means of restoration and management. Applying fire to an ecosystem may create habitats for species that have been negatively impacted by fire suppression, or fire may be used as a way of controlling invasive species without resorting to herbicides or pesticides. However, there is debate as to what state managers should aim to restore their ecosystems to, especially as to whether "natural" means pre-human or pre-European. Native American use of fire, not natural fires, historically maintained the diversity of the savannas of North America. When, how, and where managers should use fire as a management tool is a subject of debate.


The Great Plains shortgrass prairie

A combination of heavy livestock grazing and fire-suppression has drastically altered the structure, composition, and diversity of the shortgrass prairie ecosystem on the Great Plains, allowing woody species to dominate many areas and promoting fire-intolerant invasive species. In semi-arid ecosystems where the decomposition of woody material is slow, fire is crucial for returning nutrients to the soil and allowing the grasslands to maintain their high productivity. Although fire can occur during the growing or the dormant seasons, managed fire during the dormant season is most effective at increasing the grass and forb cover,
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity' ...
and plant nutrient uptake in shortgrass prairies.Brockway et al. 2002 Managers must also take into account, however, how invasive and non-native species respond to fire if they want to restore the integrity of a native ecosystem. For example, fire can only control the invasive spotted knapweed (''Centaurea maculosa'') on the Michigan tallgrass prairie in the summer, because this is the time in the knapweed's life cycle that is most important to its reproductive growth.


Mixed conifer forests in the US Sierra Nevada

Mixed
conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ex ...
forests in the United States
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
used to have fire return intervals that ranged from 5 years up to 300 years, depending on the local climate. Lower elevations had more frequent fire return intervals, whilst higher and wetter elevations saw much longer intervals between fires. Native Americans tended to set fires during fall and winter, and land at a higher elevation was generally occupied by Native Americans only during the summer.


Finnish boreal forests

The decline of habitat area and quality has caused many species populations to be red-listed by the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natur ...
. According to a study on forest management of Finnish boreal forests, improving the habitat quality of areas outside reserves can help in conservation efforts of endangered deadwood-dependent beetles. These beetles and various types of fungi both need dead trees in order to survive. Old growth forests can provide this particular habitat. However, most Fennoscandian boreal forested areas are used for timber and therefore are unprotected. The use of controlled burning and tree retention of a forested area with deadwood was studied and its effect on the endangered beetles. The study found that after the first year of management the number of species increased in abundance and richness compared to pre-fire treatment. The abundance of beetles continued to increase the following year in sites where tree retention was high and deadwood was abundant. The correlation between forest fire management and increased beetle populations shows a key to conserving these red-listed species.


Australian eucalypt forests

Much of the old growth
eucalypt Eucalypt is a descriptive name for woody plants with capsule fruiting bodies belonging to seven closely related genera (of the tribe Eucalypteae) found across Australasia: ''Eucalyptus'', '' Corymbia'', '' Angophora'', '' Stockwellia'', '' Allo ...
forest in Australia is designated for conservation. Management of these forests is important because species like ''Eucalyptus grandis'' rely on fire to survive. There are a few eucalypt species that do not have a lignotuber, a root swelling structure that contains buds where new shoots can then sprout. During a fire a lignotuber is helpful in the reestablishment of the plant. Because some eucalypts do not have this particular mechanism, forest fire management can be helpful by creating rich soil, killing competitors, and allowing seeds to be released.


Management policies


United States

Fire
policy Policy is a deliberate system of guidelines to guide decisions and achieve rational outcomes. A policy is a statement of intent and is implemented as a procedure or protocol. Policies are generally adopted by a governance body within an orga ...
in the United States involves the federal government, individual state governments, tribal governments, interest groups, and the general public. The new federal outlook on fire policy parallels advances in ecology and is moving towards the view that many ecosystems depend on disturbance for their diversity and for the proper maintenance of their natural processes. Although human safety is still the number one priority in fire management, new US government objectives include a long-term view of ecosystems. The newest policy allows managers to gauge the relative values of private property and resources in particular situations and to set their priorities accordingly. One of the primary goals in fire management is to improve public education in order to suppress the " Smokey Bear" fire-suppression mentality and introduce the public to the benefits of regular natural fires.


See also

* Crown sprouting * Evolutionary history of plants * Fire history *
Peat bog fire Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficient c ...
* Pyrophyte * Keystone species reintroduction: (sufficient) native keystone grazing species in grasslands will promote tree growth, reducing wildfire likelihoodThe Serengeti Rules documentary: example Serengeti/gnu


References


Bibliography

*Archibald, S., W.J. Bond, W.D. Stock and D.H.K. Fairbanks.2005. Shaping the landscape: fire-grazer interactions in an African Savanna. Ecological Applications 15:96–109. * * Begon, M., J.L. Harper and C.R. Townsend. 1996. '' Ecology: individuals, populations, and communities'', Third Edition. Blackwell Science Ltd., Cambridge, Massachusetts, USA. * * * * DeBano, L.F., D.G. Neary, P.F. Ffolliot. 1998. ''Fire’s Effects on Ecosystems''. John Wiley & Sons, Inc., New York, New York, USA. * * * * * Keddy, P.A. 2007.
Plants and Vegetation: Origins, Processes, Consequences
'. Cambridge University Press, Cambridge, UK. 666 p. * Keddy, P.A. 2010.
Wetland Ecology: Principles and Conservation
' (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. * * * Keeley J.E., Bond W.J., Bradstock R.A., Pausas J.G. & Rundel P.W. 2012. ''Fire in Mediterranean Ecosystems: Ecology, Evolution and Management''. Cambridge University Pres

* * Kramp, B.A., D.R. Patton, and W.W. Brady. 1986. Run wild: wildlife/habitat relationships. U.S. Forest Service, Southwestern Region. * * * * * Pyne, S.J. "How Plants Use Fire (And Are Used By It)." 2002. PBS NOVA Online. 1 January 2006. https://www.pbs.org/wgbh/nova/fire/plants.html. * *Allan Savory; Jody Butterfield (10 November 2016). Holistic Management, Third Edition: A Commonsense Revolution to Restore Our Environment. Island Press. . * * United States Department of Fish and Agriculture (USDA) Forest Service. www.fs.fed.us. :Federal Wildland Fire Management Policy and Program Review (FWFMP). :http://www.fs.fed.us/land/wdfire.htm. * United States National Park Service (USNPS). www.nps.gov. :Sequoia and King’s Canyon National Parks. 13 February 2006. "Giant Sequoias and Fire." :https://www.nps.gov/seki/learn/nature/fic_segi.htm * Vitt, D.H., L.A. Halsey and B.J. Nicholson. 2005. The Mackenzie River basin. pp. 166–202 in L.H. Fraser and P.A. Keddy (eds.). The World’s Largest Wetlands: Ecology and Conservation. Cambridge University Press, Cambridge, UK. 488 p. * Whitlock, C., Higuera, P. E., McWethy, D. B., & Briles, C. E. 2010. Paleoecological perspectives on fire ecology: revisiting the fire-regime concept. Open Ecology Journal 3: 6-23. * Wisheu, I.C., M.L. Rosenzweig, L. Olsvig-Whittaker, A. Shmida. 2000. What makes nutrient-poor Mediterranean heathlands so rich in plant diversity? Evolutionary Ecology Research 2: 935-955.


External links


The Nature Conservancy's web site for fire practitioners- Fire EcologyThe Nature Conservancy: Why We Work with FireThe ''International Journal of Wildland Fire''''Fire Ecology'' JournalFire and Environmental Research ApplicationsWord Spy - pyrogeography
{{DEFAULTSORT:Fire Ecology Forest ecology Ecological succession Ecology terminology Fire Wildfires Wildfire suppression Wildfire prevention Environmental terminology Habitat