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{{Other uses}}
[[Image:Wildfire in California.jpg|thumb|right|upright=2|alt=A daytime fire engulfing large trees|A wildfire in California, USA on 5 September 2008]]

A '''wildfire''' is any uncontrolled [[fire]] in combustible vegetation that occurs in the countryside or a [[wilderness]] area.<ref name="operations1">''Federal Fire and Aviation Operations Action Plan'', 4.</ref><ref name="Cambridge">{{vancite book | title = Cambridge Advanced Learner's Dictionary, Third Edition | publisher = Cambridge University Press <!-- see http://assets.cambridge.org/97805218/58045/frontmatter/9780521858045_frontmatter.pdf page 5 --> | year = 2008  | url = http://dictionary.cambridge.org/define.asp?key=90587&dict=CALD | isbn = 9780521858045 }}</ref> Other names such as '''brush fire''', '''[[bushfire]]''', '''forest fire''', '''grass fire''', '''hill fire''', '''[[Peat#Fires|peat fire]]''', '''vegetation fire''', '''veldfire''' and '''wildland fire''' may be used to describe the same phenomenon depending on the type of vegetation being burned. A wildfire differs from other fires by its extensive size, the speed at which it can spread out from its original source, its potential to change direction unexpectedly, and its ability to jump gaps such as roads, rivers and [[fire break]]s.<ref name = NIFC>{{vancite web | url = http://www.nifc.gov/preved/comm_guide/wildfire/fire_4.html | title = The Science of Wildland fire | publisher = National Interagency Fire Center | accessdate = 2008-11-21}}</ref> Wildfires are characterized in terms of the cause of ignition, their physical properties such as speed of [[wikt:propagation|propagation]], the combustible material present, and the effect of weather on the fire.<ref name=UToronto />

Wildfires occur on every continent except Antarctica. Fossil records and human history contain accounts of wildfires, as wildfires can occur in periodic intervals.<ref name=NOVA>{{vancite web | url = http://www.pbs.org/wgbh/nova/fire/plants.html | title = How Plants Use Fire (And Are Used By It) | author = Stephen J. Pyne | publisher = NOVA online | accessdate = 2009-06-30}}</ref><ref name=Krock>{{vancite web |last=Krock|first=Lexi|title=The World on Fire|publisher=NOVA online - Public Broadcasting System (PBS)|accessdate=2009-07-13|date=June 2002|url=http://www.pbs.org/wgbh/nova/fire/world.html}}</ref> Wildfires can cause extensive damage, both to property and human life, but they also have various beneficial effects on wilderness areas. Some plant species depend on the effects of fire for growth and reproduction,<ref name=NOVA /> although large wildfires may also have negative ecological effects.<ref name=UToronto />

Strategies of wildfire prevention, detection, and suppression have varied over the years, and international wildfire management experts encourage further development of technology and research.<ref>{{vancite web|title=International Experts Study Ways to Fight Wildfires|url=http://www1.voanews.com/english/news/a-13-2009-06-24-voa7-68788387.html|accessdate=2009-07-09|date=2009-06-24|publisher=Voice of America (VOA) News}}</ref> One of the more controversial techniques is ''[[controlled burn]]ing'': permitting or even igniting smaller fires to minimize the amount of flammable material available for a potential wildfire.<ref name=IS>''Interagency Strategy for the Implementation of the Federal Wildland Fire Policy'', entire text</ref><ref>''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'', entire text</ref> While some wildfires burn in remote forested regions, they can cause extensive destruction of homes and other property located in the ''[[wildland-urban interface]]'': a zone of transition between developed areas and undeveloped wilderness.<ref name=IS /><ref>{{vancite web|url=http://www.getprepared.gc.ca/knw/ris/wldf-eng.aspx|title=Wildfires in Canada|accessdate=2009-07-09|date=2009-02-04 |publisher=Government of Canada}}</ref>
{{Wildland Firefighting}}

==Characteristics==
[[Image:2002 african fires nasa.png|thumb|350px|left|upright=1.1|The distribution of wildfires on the African continent during the year 2002.|alt=An artificially colored satellite view of Africa, with red and yellow markers where fires have been detected. A wide red band of markers runs east-west, just south of the Sahara Desert.]]

The name ''[[wikt:wildfire|wildfire]]'' was once a synonym for [[Greek fire]] but now refers to any large or destructive [[conflagration]].<ref name="Cambridge" /> Wildfires differ from other fires in that they take place outdoors in areas of [[grassland]], [[woodland]]s, [[bushland]], [[scrubland]], [[peatland]], and other wooded areas that act as a source of [[fuel]], or combustible material. Buildings may become involved if a wildfire spreads to adjacent communities.  While the causes of wildfires vary and the outcomes are always unique, all wildfires can be characterized in terms of their physical properties, their fuel type, and the effect that weather has on the fire.

Wildfire behavior and severity result from the combination of factors such as available fuels, physical setting, and weather.<ref>Graham, ''et al.'', 12, 36</ref><ref>''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'', 4-6.</ref><ref name = FireBehavior>{{vancite web | url = http://www.nwcg.gov/pms/pubs/410-2/appendixB.pdf |format=PDF| title = National Wildfire Coordinating Group Fireline Handbook, Appendix B: Fire Behavior | accessdate = 2008-12-11 | date = April, 2006 | publisher = National Wildfire Coordinating Group}}</ref> While wildfires can be large, uncontrolled disasters that burn through {{convert|0.4|to|400|km2|acre|sigfig=1|sp=us}} or more, they can also be as small as {{convert|0.0010|km2|acre|sp=us}} or less.<ref>{{vancite web | url = http://www.nifc.gov/fire_info/lg_fires.htm | title = Fire Information - Wildland Fire Statistics | publisher = National Interagency Fire Center | accessdate = 2009-06-26}}</ref><ref name="MapTerms">{{vancite web|url=http://activefiremaps.fs.fed.us/mapterms.htm|title=Definition of Map Terms|publisher=US Forest Service [http://activefiremaps.fs.fed.us/ MODIS Active Fire Mapping Program]|accessdate=2009-07-07}}</ref><ref>''Glossary of Wildland Fire Terminology, 156''</ref> Although smaller events may be included in [[wildfire modeling]], most do not earn press attention.  This can be problematic because public fire policies, which relate to fires of all sizes, are influenced more by the way the media portrays catastrophic wildfires than by small fires.<ref name="Alvarado, et al., 66-68">Alvarado, ''et al''., 66-68</ref><ref>{{vancite web|url=http://web1.msue.msu.edu/emergency/pubs/wildfire_e2882a.pdf|title= Understanding Wildfire Behavior in Michigan|journal=Wildfire Series (in Extension Bulletin)|volume=E2882|date=April 2004|publisher= Michigan State University Extension|accessdate=2009-07-15}}</ref><ref>Olson, ''et al.'', 2-3</ref>

===Causes===
The four major natural causes of wildfire ignitions are [[lightning]], volcanic eruption, sparks from rockfalls, and spontaneous combustion.<ref>{{vancite web | url = http://www.nwcg.gov/pms/docs/wfprevnttrat.pdf |format=PDF| title = Wildfire Prevention Strategies | publisher = National Wildfire Coordinating Group | page = 17 | date = March 1998 | accessdate = 2008-12-03}}</ref><ref name='Scott2000'>{{vancite journal | doi =10.1016/S0031-0182(00)00192-9 | title =The Pre-Quaternary history of fire | year =2000 | author =Scott, A | journal =Palaeogeography Palaeoclimatology Palaeoecology | volume =164 | page =281 }}</ref> The thousands of coal seam fires that are burning around the world, such as those in [[Centralia, Pennsylvania|Centralia]], [[Burning Mountain]], and several [[Coal power in China#Coal mine fires|coal-sustained fires in China]], can also flare up and ignite nearby flammable material.<ref>{{vancite journal|last=Krajick|first=Kevin |url=http://www.smithsonianmag.com/travel/10013541.html|title=Fire in the hole|journal=Smithsonian Magazine |date=May 2005|accessdate=2009-07-30}}</ref> However, many wildfires are attributed to human sources such as [[arson]], discarded cigarettes, sparks from equipment, and power line [[electric arc|arcs]] (as detected by [[arc mapping]]).<ref>{{vancite book|url=http://books.google.com/books?id=yT6bzpUyFIwC&pg=PA56&lpg=PA56&dq=world+start+ignition+wildfire&source=bl&ots=AfiWSW6Q_y&sig=o1Ps1VbwQtHCOC8ZZLNO6Oe32ZY&hl=en&ei=9wpWSsv5EIb8NfeplJ0I&sa=X&oi=book_result&ct=result&resnum=3|title=Introduction to wildland fire|first=Stephen J.|last=Pyne|first2=Patricia L.|last2=Andrews|first3=Richard D.|last3=Laven |author.= | page=65|edition=2nd|year=1996 |publisher=John Wiley and Sons|ISBN=0471549134|isbn13=9780471549130|accessdate=26 January 2010}}</ref><ref>{{vancite web|url=http://www.ucan.org/energy/electricity/sunrise_powerlink/news_8_investigation_sdg_e_could_be_liable_for_power_line_wildfires |title=News 8 Investigation: SDG&E Could Be Liable For Power Line Wildfires|accessdate=2009-07-20|date=2007-11-05|publisher=UCAN News}}</ref> In societies experiencing [[shifting cultivation]] where land is cleared quickly and farmed until the soil loses fertility, [[slash and burn]] clearing is often considered the least expensive way to prepare land for future use.<ref>{{vancite web | url = http://thestar.com.my/news/story.asp?file=/2006/11/16/apworld/20061116114312&sec=apworld | date = 16 November 2006 | title = Orangutans in losing battle with slash-and-burn Indonesian farmers | publisher = TheStar online | author = The Associated Press | accessdate = 2008-12-01}}</ref><ref>Karki, 7.</ref> Forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned [[logging roads]] overgrown by vegetation may act as fire corridors. Annual grassland fires in Southern [[Vietnam]] can be attributed in part to the destruction of forested areas by herbicides, explosives, and mechanical land clearing and burning operations during the [[Vietnam War]].<ref>Karki, 4.</ref>

The most common cause of wildfires varies throughout the world. In the United States, Canada, and Northwest China, for example,  lightning is the major source of ignition.  In other parts of the world, human involvement is a major contributor.  In Mexico, Central America, South America, Africa, Southeast Asia, Fiji, and New Zealand, wildfires can be attributed to human activities such as [[animal husbandry]], agriculture, and land-conversion burning.  Human carelessness is a major cause of wildfires in China and in the [[Mediterranean Basin]].  In Australia, the source of wildfires can be traced to both lightning strikes and human activities such as machinery sparks and cast-away cigarette butts."<ref name=Krock />

===Fuel type===
[[Image:Wildfire3.jpg|thumb|right|upright=1.1|alt=Flat expanse of brown grasses and some green trees with black and some gray smoke and visible flames in the distance.|A surface fire in the western desert of [[Utah]], U.S.]]
[[Image:Forest fire aftermath.jpg|thumb|right|upright=1.1|alt=Mountainous region with blackened soil and trees due to a recent fire.|Charred landscape following a crown fire in the [[Cascade Range|North Cascades]], U.S.]]

The spread of wildfires varies based on the flammable material present and its vertical arrangement.<ref name="Graham, et al., iv">Graham, ''et al''., iv.</ref> For example, fuels uphill from a fire are more readily dried and warmed by the fire than those downhill, yet burning logs can roll downhill from the fire to ignite other fuels.  Fuel arrangement and density is governed in part by [[topography]], as land shape determines factors such as available sunlight and water for plant growth. Overall, fire types can be generally characterized by their fuels as follows:<ref group=note>This section is a composite of several references. Refer to:
* {{vancite web | url = http://www.fs.fed.us/projects/hfi/2003/november/documents/forest-structure-wildfire.pdf | title = Influence of Forest Structure on Wildfire Behavior and the Severity of Its Effects | date = November 2003 | format = PDF | publisher = US Forest Service | accessdate = 2008-11-19}}
* National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, 3.
* {{vancite web | url = http://www.nwcg.gov/pms/pubs/410-2/appendixB.pdf |format=PDF| title = National Wildfire Coordinating Group Fireline Handbook, Appendix B: Fire Behavior | accessdate = 2008-12-11 | date = April, 2006 | publisher = National Wildfire Coordinating Group
}}
* {{vancite journal | url = http://www.treesearch.fs.fed.us/pubs/9521 | format = PDF | title = Standard Fire Behavior Fuel Models: A Comprehensive Set for Use with Rothermel’s Surface Fire Spread Model | first = Joe H. | last = Scott | first2 = Robert E. | last2 = Burgan | author. = | publisher = US Forest Service | date = June 2005 | accessdate = 2009-02-05}}</ref>

* '''Ground''' fires are fed by subterranean roots, [[forest floor|duff]] and other buried [[organic matter]]. This fuel type is especially susceptible to ignition due to spotting. Ground fires typically burn by smoldering, and can burn slowly for days to months, such as [[Peat#Fires|peat fires]] in [[Kalimantan]] and Eastern [[Sumatra]], [[Indonesia]], which resulted from a [[Mega Rice Project (Kalimantan)|riceland creation project]] that unintentionally drained and dried the peat.<ref>Graham, ''et al''., 9, 13</ref><ref>{{vancite web | url = http://news.bbc.co.uk/2/hi/science/nature/4208564.stm | title = Asian peat fires add to warming | publisher = British Broadcasting Corporation (BBC) News | last = Rincon | first = Paul | date = 2005-03-09 | accessdate = 2008-12-09}}</ref>
* '''Crawling''' or '''surface''' fires are fueled by low-lying vegetation such as leaf and timber litter, debris, grass, and low-lying shrubbery.<ref>Graham, ''et al'' ., iv, 10, 14</ref>
* '''Ladder''' fires consume material between low-level vegetation and tree canopies, such as small trees, downed logs, and [[vine]]s. [[Kudzu]], [[Old World climbing fern]], and other [[invasive plant]]s that scale trees may also encourage ladder fires.<ref name = FireInitiative>{{vancite web | url = http://www.tncfire.org/crosscutting_fandi.htm | title = Global Fire Initiative: Fire and Invasives | publisher = The Nature Conservancy | accessdate = 2008-12-03}}</ref>
* '''Crown''', '''canopy''', or '''aerial''' fires burn suspended material at the canopy level, such as tall trees, vines, and mosses. The ignition of a crown fire, termed ''crowning'', is dependent on the density of the suspended material, canopy height, canopy continuity, and sufficient surface and ladder fires in order to reach the tree crowns.<ref>Graham, ''et al''., iv, 8, 11, 15.</ref> For example, ground-clearing fires lit by humans can spread into the [[Amazon rain forest]], damaging ecosystems not particularly suited for heat or arid conditions.<ref>{{vancite web|url=http://e360.yale.edu/content/feature.msp?id=2010|title=Global Commodities Boom Fuels New Assault on Amazon |last=Butler|first=Rhett |publisher=Yale School of Forestry & Environmental Studies|accessdate=2009-07-09|date=2008-06-19}}</ref>

===Physical properties===
{{See also|Combustion|Fire control|Extreme weather|Firestorm}}

Wildfires occur when all of the necessary elements of a [[fire triangle]] come together in a wooded area: an ignition source is brought into contact with a combustible material such as [[vegetation]], that is subjected to sufficient heat and has an adequate supply of oxygen from the ambient air. A high moisture content usually prevents ignition and slows propagation, because higher temperatures are required to evaporate any water within the material and heat the material to its [[fire point]].<ref name = NIFC /><ref name = FireBehavior/> Dense forests usually provide more shade, resulting in lower ambient temperatures and greater humidity, and are therefore less susceptible to wildfires.<ref name="Graham, et al., 12">Graham, ''et al''., 12.</ref> Less dense material such as grasses and leaves are easier to ignite because they contain less water than denser material such as branches and trunks.<ref name="ReferenceA">''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'', 3.</ref> Plants continuously lose water by [[evapotranspiration]], but water loss is usually balanced by water absorbed from the soil, humidity, or rain.<ref>{{vancite web | url = http://www.msnbc.msn.com/id/27148069/ | title = Ashes cover areas hit by Southern Calif. fires | author = Associated Press | publisher = MSNBC | date = 2008-11-15 | accessdate = 2008-12-04}}</ref> When this balance is not maintained, plants dry out and are therefore more flammable, often a consequence of droughts.<ref name = Structure>{{vancite web | url = http://www.fs.fed.us/projects/hfi/2003/november/documents/forest-structure-wildfire.pdf | title = Influence of Forest Structure on Wildfire Behavior and the Severity of Its Effects | date = November 2003 | format = PDF | publisher = US Forest Service | accessdate = 2008-11-19}}</ref><ref>{{vancite web | url = http://www.fema.gov/hazard/wildfire/wf_prepare.shtm | title = Prepare for a Wildfire | publisher = Federal Emergency Management Agency (FEMA) | accessdate = 2008-12-01}}</ref>

[[Image:Northwest Crown Fire Experiment.png|thumb|left|upright=1.1|Experimental fire in Canada|alt=A line of trees completely engulfed in flames. Towers with instrumentation are seen just beyond the fire's reach.]]

A wildfire ''front'' is the portion sustaining continuous flaming combustion, where unburned material meets active flames, or the [[smolder]]ing transition between unburned and burned material.<ref>''Glossary of Wildland Fire Terminology'', 74.</ref> As the front approaches, the fire heats both the surrounding air and woody material through [[convection]] and [[thermal radiation]]. First, wood is dried as water is vaporized at a temperature of {{convert|100|C|F}}. Next, the [[pyrolysis]] of wood at {{convert|230|C|F|sigfig=2}} releases flammable gases. Finally, wood can smolder at {{convert|380|C|F|sigfig=2}} or, when heated sufficiently, ignite at {{convert|590|C|F|sigfig=1}}.<ref>de Sousa Costa and Sandberg, 229-230.</ref><ref>{{vancite web | url =http://web.mit.edu/2.009/www/experiments/deathray/10_ArchimedesResult.html | title = Archimedes Death Ray: Idea Feasibility Testing | date = October 2005 | publisher = Massachusetts Institute of Technology (MIT) | accessdate = 2009-02-01}}</ref> Even before the flames of a wildfire arrive at a particular location, [[heat transfer]] from the wildfire front warms the air to {{convert|800|C|F|sigfig=3}}, which pre-heats and dries flammable materials, causing materials to ignite faster and allowing the fire to spread faster.<ref name="ReferenceA" /><ref name = FireScars>{{vancite web | url = http://www.esa.int/esaCP/SEMNJMV4QWD_Protecting_0.html | title = Satellites are tracing Europe's forest fire scars | publisher = European Space Agency | date = 2004-07-27 | accessdate = 2009-01-12}}</ref> High-temperature and long-duration surface wildfires may encourage [[flashover]] or ''torching'': the drying of [[canopy (ecology)|tree canopies]] and their subsequent ignition from below.<ref>Graham, ''et al''., 10-11.</ref>

Wildfires have a rapid ''forward rate of spread'' (FROS) when burning through dense, uninterrupted fuels.<ref>{{vancite web|url=http://www.flash.org/resources/files/WildfireBrochure.pdf|format=PDF|title=Protecting Your Home From Wildfire Damage|publisher=Florida Alliance for Safe Homes (FLASH)|accessdate=3 March 2010|page=5}}</ref> They can move as fast as {{Convert|10.8|km/h|mph|sp=us}} in forests and {{convert|22|km/h|mph|sp=us}} in grasslands.<ref>Billing, 5-6</ref> Wildfires can advance tangential to the main front to form a ''flanking'' front, or burn in the opposite direction of the main front by ''backing''.<ref>Graham, ''et al''., 12</ref> They may also spread by ''jumping'' or ''spotting'' as winds and vertical [[convection]] columns carry ''[[firebrand]]s'' (hot wood embers) and other burning materials through the air over roads, rivers, and other barriers that may otherwise act as [[firebreak]]s.<ref name = underfire>{{vancite web | url = http://ngm.nationalgeographic.com/2008/07/fire-season/shea-text.html | title = Under Fire | last = Shea | first = Neil | publisher = National Geographic | date = July 2008 | accessdate = 2008-12-08}}</ref><ref>Graham, ''et al''., 16.</ref> Torching and fires in tree canopies encourage spotting, and dry ground fuels that surround a wildfire are especially vulnerable to ignition from firebrands.<ref>Graham, ''et al''., 9, 16.</ref> Spotting can create ''spot fires'' as hot embers and firebrands ignite fuels downwind from the fire. In Australian bushfires, spot fires are known to occur as far as {{convert|10|km|0|sp=us}} from the fire front.<ref>Billing, 5</ref>

Especially large wildfires may affect air currents in their immediate vicinities by the [[stack effect]]: air rises as it is heated, and large wildfires create powerful [[updraft]]s that will [[advection|draw in]] new, cooler air from surrounding areas in [[thermal column]]s.<ref>''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'', 4.</ref> Great vertical differences in temperature and humidity encourage [[pyrocumulus cloud]]s, strong winds, and [[fire whirl]]s with the force of tornadoes at speeds of more than {{convert|80|km/h|mph|sigfig=1|sp=us}}.<ref>Graham, ''et al''., 16-17.</ref><ref>Olson, ''et al.'', 2</ref><ref>{{vancite web | url = http://www.nwcg.gov/pms/pubs/newshelt72.pdf | format = PDF | title = The New Generation Fire Shelter | page = 19 | publisher = National Wildfire Coordinating Group | date = March 2003 | accessdate = 2009-01-16}}</ref>  Rapid rates of spread, prolific crowning or spotting, the presence of fire whirls, and strong convection columns signify extreme conditions.<ref>''Glossary of Wildland Fire Terminology'', 69.</ref>

===Effect of weather===
[[Heat wave]]s, [[drought]]s, cyclical [[climate change]]s such as [[El Niño]], and regional weather patterns such as high-pressure ridges can increase the risk and alter the behavior of wildfires dramatically.<ref>
{{vancite web | url = http://lwf.ncdc.noaa.gov/oa/reports/billionz.html | title = Chronological List of U.S. Billion Dollar Events | publisher = National Oceanic and Atmospheric Administration (NOAA) Satellite and Information Service | accessdate = 2009-02-04}}</ref><ref>McKenzie, ''et. al.'', 893</ref> Years of precipitation followed by warm periods can encourage more widespread fires and longer fire seasons.<ref>Graham, ''et al''., 2</ref> Since the mid 1980s, earlier snowmelt and associated warming has also been associated with an increase in length and severity of the wildfire season in the [[Western United States]].<ref>{{vancite journal |url=http://www.sciencemag.org/cgi/content/full/313/5789/940 | doi = 10.1126/science.1128834 | year = 2006 | month = Aug | author = Westerling, Al; Hidalgo, Hg; Cayan, Dr; Swetnam, Tw | title = Warming and earlier spring increase western U.S. Forest wildfire activity | volume = 313 | issue = 5789 | pages = 940–3 | issn = 0036-8075 | pmid = 16825536 | journal = Science (New York, N.Y.)}}</ref> However, one individual element does not always cause an increase in wildfire activity.  For example, wildfires will not occur during a drought unless accompanied by other factors, such as lightning (ignition source) and strong winds (mechanism for rapid spread).<ref>McKenzie, ''et. al.'', 894</ref>

Fire intensity also increases during daytime hours. Burn rates of smoldering logs are up to five times greater during the day due to lower humidity, increased temperatures, and increased wind speeds.<ref>de Souza Costa and Sandberg, 228</ref> Sunlight warms the ground during the day which creates air currents that travel uphill.  At night the land cools, creating air currents that travel downhill. Wildfires are fanned by these winds and often follow the air currents over hills and through valleys.<ref>''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'', 5.</ref> Fires in Europe occur frequently during the hours of 12:00 p.m. and 2:00 p.m.<ref>San-Miguel-Ayanz, ''et al.'', 364.</ref> Wildfire suppression operations in the United States revolve around a 24-hour ''fire day'' that begins at 10:00 a.m. due to the predictable increase in intensity resulting from the daytime warmth.<ref>''Glossary of Wildland Fire Terminology'', 73.</ref>

==Ecology==
{{Main|Fire ecology}}
{{See also|Disturbance (ecology)|Forestry}}

[[Image:Global Fires - August and February 2008.jpg|thumb|right|upright=2|alt=Two illustrations of the earth, one above the other.  The seas are dark gray in color and the continents a lighter gray. Both images have red, yellow, and white markers indicating where fires occurred during the months of August (top image) and February (bottom image) of the year 2008.|Global fires during the year 2008 for the months of August (top image) and February (bottom image), as detected by the [[Moderate Resolution Imaging Spectroradiometer]] (MODIS) on NASA's [[Terra satellite]].]]

Wildfires are common in climates that are sufficiently moist to allow the growth of vegetation but feature extended dry, hot periods.<ref name=NOVA /> Such places include the vegetated areas of Australia and [[Southeast Asia]], the [[veld]] in southern Africa, the [[fynbos]] in the Western Cape of South Africa, the forested areas of the United States and Canada, and the [[Mediterranean Basin]]. Fires can be particularly intense during days of strong winds, periods of drought, and during warm summer months.<ref>{{vancite web | url = http://www.ncar.ucar.edu/research/climate/drought.php | title = Drought and Wildland Fires | publisher = National Center for Atmospheric Research | accessdate = 2009-02-03}}</ref><ref>{{vancite web | url = http://www.fire.ca.gov/CDFBOFDB/pdfs/sap4-3_final_synthesis.pdf | title = The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity: Synthesis | author = Schimel, D., ''et al''. |author.= | publisher = The U.S. Climate Change Science Program | format = PDF | accessdate = 2008-12-05 |page=183}}</ref> [[Global warming]] may increase the intensity and frequency of droughts in many areas, creating more intense and frequent wildfires.<ref name=UToronto>{{vancite journal | url = https://www.firelab.utoronto.ca/pubs/2005_flannigan_wotton_etal.pdf |format=PDF| title = Forest Fires and Climate Change in the 21st century | last = Flannigan | first = M.D. | coauthors = B.D. Amiro, K.A. Logan, B.J. Stocks, and B.M. Wotton | journal = Mitigation and Adaptation Strategies for Global Change | doi = 10.1007/s11027-005-9020-7 | year = 2005 | volume = 11 | page = 847 | accessdate = 2009-06-26}}</ref><ref>{{vancite web | url = http://www.tncfire.org/crosscutting_fcc.htm | title = Global Fire Initiative: Fire and Climate Change | publisher = The Nature Conservancy | accessdate = 2008-12-03}}</ref><ref name=climatechangelink>{{vancite web | url = http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/07/07/MNG7JJR8521.DTL&feed=rss.news | title = Climate Change Link Seen in Surge of Western Blazes | publisher = Baltimore Sun | date = 2006-07-07 | accessdate = 2008-12-03}}</ref>

Although some ecosystems rely on naturally occurring fires to regulate growth, many ecosystems suffer from too much fire, such as the [[chaparral]] in [[southern California]] and lower elevation deserts in the American Southwest. The increased fire frequency in these ordinarily fire-dependent areas has upset natural cycles, destroyed native plant communities, and encouraged the growth of fire-intolerant vegetation and non-native weeds.<ref>''Interagency Strategy for the Implementation of the Federal Wildland Fire Policy'', 3, 37.</ref><ref>Graham, ''et al''., 3.</ref><ref>{{vancite journal | url = http://www.werc.usgs.gov/seki/pdfs/Future%20of%20California%20Floristics%20and%20Systematics%20Wildfire%20Th.pdf |format=PDF| title = Future of California floristics and systematics: wildfire threats to the California flora | author = Keeley, J.E. |author.= | publisher =US Geological Survey |journal = Madrono | volume = 42 | pages = 175–179 | year = 1995 | accessdate = 2009-06-26}}</ref><ref>{{vancite conference | last = Zedler | first = P.H. |author.= | title = Fire frequency in southern California shrublands: biological effects and management options | year = 1995 | booktitle = Brushfires in California wildlands: ecology and resource management | editor = Keeley, J.E.; Scott, T., editors | pages = 101–112 | place = Fairfield, WA | publisher = International Association of Wildland Fire}}</ref> [[Invasive species]], such as ''[[Lygodium microphyllum]]'' and ''[[Bromus tectorum]]'', can grow rapidly in areas that were damaged by fires. Because they are highly flammable, they can increase the future risk of fire, creating a [[positive feedback loop]] that increases fire frequency and further destroys native growth.<ref name = FireInitiative/><ref name="van Wagtendonk, 14">van Wagtendonk (2007), 14.</ref>

In the [[Amazon Rainforest]], drought, logging, cattle ranching practices, and [[slash-and-burn]] agriculture damage fire-resistant forests and promote the growth of flammable brush, creating a cycle that encourages more burning.<ref>Nepstad, 4, 8-11</ref> Fires in the rainforest threaten its collection of diverse species and produce large amounts of CO<sub>2</sub>.<ref>{{vancite web |url=http://earthobservatory.nasa.gov/Features/AmazonFireRise/|title=Amazon fires on the rise|publisher=Earth Observatory (NASA)| accessdate=2009-07-09 | date=2008-03-05| last=Lindsey|first=Rebecca}}</ref> Also, fires in the rainforest, along with drought and human involvement, could damage or destroy more than half of the Amazon rainforest by the year 2030.<ref>Nepstad, 4</ref> Wildfires generate ash, destroy available organic nutrients, and cause an increase in water runoff, eroding away other nutrients and creating [[flash flood]] conditions.<ref name="Graham, et al., iv" /><ref>{{vancite web | url = http://www.ewatercrc.com.au/bushfire/background_effects.shtml | title = Bushfire and Catchments: Effects of Fire on Soils and Erosion | publisher = eWater Cooperative Research Center's | accessdate = 2009-01-08}}</ref> A 2003 wildfire in the [[North Yorkshire Moors]] destroyed {{convert|2.5|km2|acre|sigfig=1|sp=us}} of [[Ericaceae|heather]] and the underlying [[peat]] layers. Afterwards, wind erosion stripped the ash and the exposed soil, revealing archaeological remains dating back to 10,000&nbsp;BC.<ref>{{vancite journal|title=Fylingdales Moor a lost landscape rises from the ashes |journal=Current Archaelogy |publisher=Current Publishing |last=Refern |first=Neil |coauthor=Vyner, Blaise |pages=20&ndash;27 |volume=XIX |issue=226 |issn=11-321005}}</ref> Wildfires can also have an effect on climate change, increasing the amount of carbon released into the atmosphere and inhibiting vegetation growth, which affects overall carbon uptake by plants.<ref>{{vancite journal | last = Running | first = S.W. |author.= | title = Ecosystem Disturbance, Carbon and Climate | journal = Science | volume = 321 | pages = 652–653 | year = 2008 | doi = 10.1126/science.1159607 | pmid = 18669853}}</ref>

===Plant adaptation===
[[Image:Boreal pine forest after fire.JPG|thumb|right|upright=2|alt=Two photographs of the same section of a pine forest; both show blackened bark at least halfway up the trees. The first picture is noticeably lacking in surface vegetation, while the second shows small, green grasses on the forest floor.|[[Ecological succession]] after a wildfire in a [[boreal forest|boreal pine forest]] next to Hara Bog, [[Lahemaa National Park]], [[Estonia]]. The pictures were taken one and two years after the fire.]]

Plants in wildfire-prone [[ecosystems]] often survive through adaptations to their local [[fire regime]]. Such adaptations include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and may eliminate [[competition]]. For example, plants of the genus ''[[Eucalyptus]]'' contain flammable oils that encourage fire and hard [[sclerophyll]] leaves to resist heat and drought, ensuring their dominance over less fire-tolerant species.<ref>{{vancite web | url=http://library.csustan.edu/bsantos/section3.htm | title=Section Three: Problems, Cares, Economics, and Species | work=The Eucalyptus of California | first=Robert L. | last=Santos |author.= | publisher=California State University | year=1997 | accessdate=2009-06-26}}</ref><ref>''Fire. The Australian Experience'', 5.</ref> Dense bark, shedding lower branches, and high water content in external structures may also protect trees from rising temperatures.<ref name=NOVA /> Fire-resistant seeds and reserve [[shoot]]s that sprout after a fire encourage species preservation, as embodied by [[pioneer species]]. Smoke, charred wood, and heat can stimulate the germination of seeds in a process called ''[[serotiny]]''.<ref>{{vancite journal | url = http://www.werc.usgs.gov/seki/pdfs/emissions.pdf |format=PDF| title = Trace gas emission in smoke-induced germination | author = Keeley, J.E. and C.J. Fotheringham | publisher =Science | volume = 276 | pages = 1248–1250 | year = 1997 | accessdate = 2009-06-26}}</ref> Exposure to smoke from burning plants promotes [[germination]] in other types of plants by inducing the production of the orange [[butenolide]].<ref name = flematti>{{vancite journal | author = Flematti GR, Ghisalberti EL, Dixon KW, Trengove RD | year = 2004 | title = A compound from smoke that promotes seed germination | journal = Science | volume = 305 | issue = 5686 | page = 977 | doi = 10.1126/science.1099944 | pmid = 15247439}}</ref>

Grasslands in Western [[Sabah]], Malaysian [[pine]] forests, and Indonesian ''[[Casuarina]]'' forests are believed to have resulted from previous periods of fire.<ref>Karki, 3.</ref> [[Chamise]] deadwood litter is low in water content and flammable, and the shrub quickly sprouts after a fire.<ref name=NOVA /> [[Sequoia sempervirens|Sequoia]] rely on periodic fires to reduce competition, release seeds from their [[conifer cone|cone]]s, and clear the soil and canopy for new growth.<ref>{{vancite web |url=http://www.nps.gov/archive/seki/fire/segi.htm |title=Giant Sequoias and Fire|accessdate=2009-06-30 |publisher=US National Park Service}}</ref> [[Caribbean Pine]] in [[Bahamian pineyards]] have adapted to and rely on low-intensity, surface fires for survival and growth. An optimum fire frequency for growth is every 3 to 10 years. Too frequent fires favor [[herbaceous plant]]s, and infrequent fires favor species typical of [[Bahamian dry forests]].<ref>{{vancite web |url=http://www.nature.org/initiatives/fire/files/bahamas_assessment.pdf |title=Fire Management Assessment of the  Caribbean Pine (''Pinus caribea'') Forest Ecosystems on Andros and Abaco Islands, Bahamas |work=TNC Global Fire Initiative |publisher=[[The Nature Conservancy]] |month=September |year=2004 |accessdate=2009-08-27}}</ref>

===Atmospheric effects===
{{See also|Air pollution|Atmospheric chemistry|Haze|1997 Southeast Asian haze|2005 Malaysian haze|2006 Southeast Asian haze}}
[[Image:Wildfire in Yellowstone NP produces Pyrocumulus cloud.jpg|right|upright=1.1|alt=A paved road with trees and grasses on the side with a large, white and dark gray smoke cloud rising in the distance.|A [[Pyrocumulus cloud]] produced by a wildfire in [[Yellowstone National Park]]|thumb]]

Most of the Earth's weather and air pollution reside in the [[troposphere]], the part of the atmosphere that extends from the surface of the planet to a height of about {{convert|10|km|mi|sigfig=1|sp=us}}. The vertical lift of a severe thunderstorm or [[pyrocumulonimbus]] can be enhanced in the area of a large wildfire, which can propel smoke, soot, and other [[particulate matter]] as high as the lower [[stratosphere]].<ref>{{vancite web | first = P.K. | last = Wang |author.= | contribution = The physical mechanism of injecting biomass burning materials into the stratosphere during fire-induced thunderstorms | title = American Geophysical Union fall meeting | year = 2003 | place = San Francisco, California}}</ref> Previously, prevailing scientific theory held that most particles in the stratosphere came from [[volcano]]es, but smoke and other wildfire emissions have been detected from the lower stratosphere.<ref>{{vancite conference | url = http://adsabs.harvard.edu/abs/2006AGUFM.U14A..04F | title = Smoke in the Stratosphere: What Wildfires have Taught Us About Nuclear Winter; abstract #U14A-04 | author = Fromm, M.; Stocks, B.; Servranckx, R.; Lindsey, D. |author.= | place = American Geophysical Union, Fall Meeting 2006 | accessdate = 2009-02-04}}</ref> Pyrocumulus clouds can reach {{convert|6100|m|ft|sp=us}} over wildfires.<ref>Graham, ''et al''., 17</ref> Increased fire byproducts in the stratosphere can increase ozone concentration beyond safe levels.<ref>{{vancite web | url = http://www.innovations-report.de/html/berichte/geowissenschaften/wildfires_ozone_pollution_violate_health_standards_120086.html | title = Wildfires Cause Ozone Pollution to Violate Health Standards | publisher = Geophysical Research Letters | date = 13 October 2008 | accessdate = 2009-02-04 | author = National Center for Atmospheric Research}}</ref> Satellite observation of smoke plumes from wildfires revealed that the plumes could be traced intact for distances exceeding {{convert|1600|km|mi|sigfig=1|sp=us}}.<ref>{{vancite web | url = http://ams.confex.com/ams/pdfpapers/68737.pdf | format = PDF | title = Meteorological Conditions Associated with the Rapid Transport of Canadian Wildfire Products into the Northeast during 5–8 July 2002 | author = John R. Scala, ''et al''. |author.= | date = | publisher = American Meteorological Society | accessdate = 2009-02-04}}</ref> Computer-aided models such as [[CALPUFF]] may help predict the size and direction of wildfire-generated smoke plumes by using [[atmospheric dispersion modeling]].<ref>{{vancite web | url = http://www.fs.fed.us/pnw/pubs/pnw_gtr379.pdf | format = PDF | title = User Assessment of Smoke-Dispersion Models for Wildland Biomass Burning | publisher = US Forest Service | first = Steve | last = Breyfogle | first2 = Ferguson | last2 = Sue A.
 | date = December 1996 | accessdate = 2009-02-06}}</ref>

Wildfires can affect climate and weather and have major impacts on atmospheric pollution.<ref>
{{vancite journal | last = Bravo | first = A.H. | coauthors = E. R. Sosa, A. P. Sánchez, P. M. Jaimes and R. M. I. Saavedra | title = Impact of wildfires on the air quality of Mexico City, 1992-1999 | journal = Environmental Pollution | volume = 117 | issue = 2 | pages = 243–253 | year = 2002 | doi = 10.1016/S0269-7491(01)00277-9
}}</ref> [[Wildland fire emissions|Wildfire emissions]] contain fine [[particulate matter]] which can cause cardiovascular and respiratory problems.<ref>{{vancite web | first = R. | last = Douglass |author.= | title = Quantification of the health impacts associated with fine particulate matter due to wildfires. MS Thesis. | publisher = Nicholas School of the Environment and Earth Sciences of Duke University | year = 2008|url=http://dukespace.lib.duke.edu/dspace/bitstream/10161/495/1/MP_rld10_a_052008.pdf}}</ref> Forest fires in Indonesia in 1997 were estimated to have released between 0.81 and 2.57 giga[[tonne]]s (0.89 and 2.83 billion [[short ton]]s) of CO<sub>2</sub> into the atmosphere, which is between 13%–40% of the annual carbon dioxide emissions from burning fossil fuels.<ref>{{vancite journal | first = Susan E. | last = Page | coauthors = Florian Siegert, John O. Rieley, Hans-Dieter V. Boehm, Adi Jaya and Suwido Limin | title = The amount of carbon released from peat and forest fires in Indonesia during 1997 | journal= Nature | doi=10.1038/nature01131 | volume=420 | pages=61–65 | date=2002-07-11}}</ref><ref>{{vancite web | url = http://www.cifor.cgiar.org/publications/pdf_files/OccPapers/OP-038.pdf |format=PDF| publisher = Center for International Forestry Research | title = Fires in Indonesia: Causes, Costs, and Policy Implications (CIFOR Occasional Paper No. 38) | last = Tacconi | first = Luca | issn = 0854-9818 | date = February 2003 | place = Bogor, Indonesia | accessdate = 2009-02-06}}</ref> Atmospheric models suggest that these concentrations of sooty particles could increase absorption of incoming [[solar radiation]] during winter months by as much as 15%.<ref>{{vancite conference | author = Baumgardner, D. ''et al''. |author.= | title = Warming of the Arctic lower stratosphere by light absorbing particles | booktitle = American Geophysical Union fall meeting | year = 2003 | place = San Francisco, California}}</ref>

{{wide image|Fire activity swifts creek 2007 edit.jpg|933px|Smoke trail from a fire seen while looking towards [[Dargo, Victoria|Dargo]] from [[Swifts Creek, Victoria]], Australia, 11 January 2007|alt=Panorama of a hilly expanse featuring a large smoke trail covering more than half of the visible sky.}}

==History==
{{See|Fossil record of fire}}
In the [[Welsh Borders]], the first evidence of wildfire is [[Rhyniophyta|rhyniophytoid]] plant fossils preserved as [[charcoal]], dating to the [[Silurian]] period (about {{ma|420}}).  Smoldering surface fires started to occur sometime before the Early [[Devonian]] period {{ma|405}}. Low atmospheric oxygen during the Middle and Late Devonian was accompanied by a decrease in charcoal abundance.<ref name= "Glasspool">{{cite doi|10.1130/G20363.1}}</ref><ref>{{cite jstor|3515846}}</ref> Additional charcoal evidence suggests that fires continued through the [[Carboniferous]] period. Later, the overall increase of atmospheric oxygen from 13% in the Late Devonian to 30-31% by the [[Late Permian]] was accompanied by a more widespread distribution of wildfires.<ref name=Scott2006>{{cite pmc|1544139}}</ref> Later, a decrease in wildfire-related charcoal deposits from the late Permian to the [[Triassic]] periods is explained by a decrease in oxygen levels.<ref name="Pausas 594">Pausas and Keeley, 594</ref>

Wildfires during the Paleozoic and Mesozoic periods followed patterns similar to fires that occur in modern times. Surface fires driven by dry seasons are evident in Devonian and Carboniferous [[progymnosperm]] forests.  [[Lepidodendron]] forests dating to the Carboniferous period have charred peaks, evidence of crown fires. In Jurassic [[gymnosperm]] forests, there is evidence of high frequency, light surface fires.<ref name="Pausas 594" /> The increase of fire activity in the late [[Tertiary]]<ref name="cenozoic-division">Historically, the [[Cenozoic]] has been divided up into the [[Quaternary]] and [[Tertiary]] sub-eras, as well as the [[Neogene]] and [[Paleogene]] periods. The [http://www.stratigraphy.org/upload/ISChart2009.pdf 2009 version of the ICS time chart] recognizes a slightly extended Quaternary as well as the Paleogene and a truncated Neogene, the Tertiary having been demoted to informal status (Taken from {{Tl|Geologic time scale}}).</ref> is possibly due to the increase of [[C4 carbon fixation|C<sub>4</sub>]]-type grasses.  As these grasses shifted to more [[mesic habitat]]s, their high flammability increased fire frequency, promoting grasslands over woodlands.<ref>Pausas and Keeley, 595</ref> However, fire-prone habitats may have contributed to the prominence of trees such as those of the genus ''Pinus'', which have thick bark to withstand fires and employ serotiny.<ref>Pausas and Keeley, 596</ref>

===Human involvement===
{{See also|Control of fire by early humans|Deforestation#Historical causes|Environmental history|History of firefighting|List of wildfires}}

The human use of fire for agricultural and hunting purposes during the [[Paleolithic]] and [[Mesolithic]] ages altered the preexisting landscapes and fire regimes. Woodlands were gradually replaced by smaller vegetation that facilitated travel, hunting, seed-gathering and planting.<ref>Pausas and Keeley, 597</ref> In recorded human history, minor allusions to wildfires were mentioned in the [[Bible]] and by classical writers such as [[Homer]]. However, while ancient Hebrew, Greek, and Roman writers were aware of fires, they were not very interested in the uncultivated lands where wildfires occurred.<ref name=RackhamFire>{{vancite journal| url=http://ag.arizona.edu/OALS/ALN/aln54/rackham.html#hist|title=Fire in the European Mediterranean: History |last=Rackham|first=Oliver |accessdate=2009-07-17|journal=AridLands Newsletter|volume=54|date=November/December 2003|publisher=University of Arizona College of Agriculture & Life Sciences}}</ref><ref name=RackhamHist>Rackham, 229-230</ref> Wildfires were used in battles throughout human history as [[early thermal weapons]]. From the [[Middle ages]], accounts were written of [[occupational burning]] as well as customs and laws that governed the use of fire. In Germany, regular burning was documented in 1290 in the [[Odenwald]] and in 1344 in the [[Black Forest]].<ref name="Goldammer" /> In the 14th century [[Sardinia]], firebreaks were used for wildfire protection. In Spain during the 1550s, [[sheep husbandry]] was discouraged in certain provinces by [[Philip II of Spain|Philip II]] due to the harmful effects of fires used in [[transhumance]].<ref name=RackhamFire/><ref name=RackhamHist/> As early as the 17th century, Native Americans were observed [[Native American use of fire|using fire]] for many purposes including cultivation, [[Smoke signal|signaling]], and warfare. Scottish botanist [[David Douglas]] noted the native use of fire for tobacco cultivation, to encourage deer into smaller areas for hunting purposes, and to improve foraging for honey and grasshoppers. Charcoal found in sedimentary deposits off the Pacific coast of Central America suggests that more burning occurred in the 50 years before the [[Spanish colonization of the Americas]] than after the colonization.<ref>* {{vancite journal| title=Wildland fire - An American legacy||pages=4, 5, 9, 11|journal=Fire Management Today|publisher=USDA Forest Service|volume=60|issue=3|date=Summer 2000|url=http://www.fs.fed.us/fire/fmt/fmt_pdfs/fmn60-3.pdf|accessdate=2009-07-31}}</ref> In the post-World War II [[Baltic region]], socio-economic changes led more stringent air quality standards and bans on fires that eliminated traditional burning practices.<ref name="Goldammer">{{vancite conference|url=http://www.fire.uni-freiburg.de/programmes/natcon/natcon_1.htm |title= History of Fire in Land-Use Systems of the Baltic Region: Implications on the Use of Prescribed Fire in Forestry, Nature Conservation and Landscape Management|first=Johann G.|last=Goldammer | booktitle = First Baltic Conference on Forest Fires | date=5–9 May 1998| place = Radom-Katowice, Poland | publisher = Global Fire Monitoring Center (GFMC)}}</ref>

Wildfires typically occurred during periods of increased temperature and drought. An increase in fire-related [[debris flow]] in [[alluvial fan]]s of northeastern [[Yellowstone National Park]] was linked to the period between AD 1050 and 1200, coinciding with the [[Medieval Warm Period]].<ref>{{vancite journal |url=http://www.co2science.org/data/mwp/studies/l3_yellowstone.php |last=Meyer |first=G.A. |last2=Wells |first2=S.G.|last3=Jull|first3=A.J.T.|author.=|year=1995|title=Fire and alluvial chronology in Yellowstone National Park: Climatic and intrinsic controls on Holocene geomorphic processes|journal=GSA Bulletin|issue=107|pages=1211–1230}}</ref> However, human influence caused an increase in fire frequency. [[Dendrochronological]] fire scar data and charcoal layer data in [[Finland]] suggests that, while many fires occurred during severe drought conditions, an increase in the number of fires during 850 BC and 1660 AD can be attributed to human influence.<ref>Pitkänen, ''et. al.'', 15-16 and 27-30</ref> Charcoal evidence from the Americas suggested a general decrease in wildfires between 1 AD and 1750 compared to previous years. However, a period of increased fire frequency between 1750 and 1870 was suggested by charcoal data from North America and Asia, attributed to human population growth and influences such as land clearing practices. This period was followed by an overall decrease in burning in the 20th century, linked to the expansion of agriculture, increased livestock grazing, and fire prevention efforts.<ref>{{vancite journal|url=http://www.nature.com/ngeo/journal/v1/n10/full/ngeo313.html |title=Climate and human influences on global biomass burning over the past two millennia | authors=J. R. Marlon, P. J. Bartlein, C. Carcaillet, D. G. Gavin, S. P. Harrison, P. E. Higuera, F. Joos, M. J. Power, I. C. Prentice |journal =Nature Geoscience |volume=1 |pages=697–702 |year=2008 |doi=10.1038/ngeo313}} [http://pmr.uoregon.edu/science-and-innovation/uo-research-news/research-news-2008/september-2008/climate-change-human-activity-and-wildfires-1/ University of Oregon Summary, accessed 2 Feb 2010]</ref>

==Prevention==
{{See also|Fire protection|}}
[[Image:Smokey3.jpg|thumb|right|upright=1.1|alt=Drawing of a grizzly bear with human features. He is wearing blue jeans with a belt and a brimmed hat with the name "Smokey" on the cap, and has a shovel in his left hand. He is pointing to the viewer while the text "Only You" is seen below him.|1985 [[Smokey Bear]] poster with part of his admonition, "Only you can prevent forest fires".]]

Wildfire prevention refers to the preemptive methods of reducing the risk of fires as well as lessening its severity and spread.<ref>Karki, 6.</ref> Effective prevention techniques allow supervising agencies to manage air quality, maintain ecological balances, protect resources,<ref name="van Wagtendonk, 14"/> and to limit the effects of future uncontrolled fires.<ref>van Wagtendonk (1996), 1156.</ref> North American firefighting policies may permit naturally caused fires to burn to maintain their ecological role, so long as the risks of escape into high-value areas are mitigated.<ref>''Interagency Strategy for the Implementation of the Federal Wildland Fire Policy'', 42.</ref> However, prevention policies must consider the role that humans play in wildfires, since, for example, 95% of forest fires in Europe are related to human involvement.<ref>San-Miguel-Ayanz, ''et al.'', 361.</ref> Sources of human-caused fire may include arson, accidental ignition, or the uncontrolled use of fire in land-clearing and agriculture such as the slash-and-burn farming in Southeast Asia.<ref>Karki, 7, 11-19.</ref>

In the mid-19th century, explorers from the [[HMS Beagle]] observed [[Australian Aborigines]] using fire for ground clearing, hunting, and regeneration of plant food in a method later named [[fire-stick farming]].<ref>''Fire. The Australian Experience'', 7.</ref> Such careful use of fire has been employed for centuries in the lands protected by [[Kakadu National Park]] to encourage biodiversity.<ref>Karki, 27.</ref> In 1937, U.S. President [[Franklin D. Roosevelt]] initiated a nationwide fire prevention campaign, highlighting the role of human carelessness in forest fires. Later posters of the program featured [[Uncle Sam]], leaders of the [[Axis powers of World War II]], characters from the Disney movie ''[[Bambi]]'', and the official mascot of the [[U.S. Forest Service]], [[Smokey Bear]].<ref>{{vancite web | url=http://www.smokeybear.com/vault/default.asp?js=1 | title=Smokey's Journey | publisher = Smokeybear.com | accessdate = 26 January 2010}}</ref>

[[Image:Image-DSCF0013.JPG|thumb|left|upright=1.1|alt=A small fire on the slope of a hill. The hill features small, green shubbery and some trees. A person in light-colored clothing in seen in the background, some distance from the flames.|A prescribed burn in a ''[[Pinus nigra]]'' stand in [[Portugal]]]]

Wildfires are caused by a combination of natural factors such as topography, fuels, and weather. Other than reducing human infractions, only fuels may be altered to affect future fire risk and behavior.<ref name="Graham, et al., iv">Graham, ''et al''., iv.</ref> Wildfire prevention programs around the world may employ techniques such as ''wildland fire use'' and ''prescribed or [[controlled burn]]s''.<ref name="operations1" /><ref>{{vancite web|url=http://encarta.msn.com/dictionary_561501139/backburn.html|title=Backburn|publisher=MSN Encarta|accessdate=2009-07-09}}</ref><ref>{{vancite journal|url=http://www.fire.uni-freiburg.de/iffn/country/gb/gb_1.htm |title=UK: The Role of Fire in the Ecology of Heathland in Southern Britain |journal=International Forest Fire News|volume=18|date=January 1998|pages=80–81}}</ref> ''Wildland fire use'' refers to any fire of natural causes that is monitored but allowed to burn. ''Controlled burns'' are fires ignited by government agencies under less dangerous weather conditions.<ref>{{vancite web | url = http://www.smokeybear.com/prescribed-fires.asp | title = Prescribed Fires | publisher = SmokeyBear.com | accessdate = 2008-11-21}}</ref> 

Vegetation may be burned periodically to maintain high species diversity, and frequent burning of surface fuels limits fuel accumulation, thereby reducing the risk of crown fires.<ref>''Fire. The Australian Experience'', 5-6.</ref><ref>Graham, ''et al''., 15.</ref> Using strategic cuts of trees, fuels may also be removed by [[handcrew]]s in order to clean and clear the forest, prevent fuel build-up, and create access into forested areas.<ref>Peuch, 3.</ref> Chain saws and large equipment can be used to thin out ladder fuels and shred trees and vegetation to a [[mulch]].<ref>{{vancite web |url = http://www.fs.fed.us/r6/umpqua/publications/pyrolysis-biomass-briefing-paper.pdf | title = Forest biomass utilization decreases wildfire risk and dependence on foreign oil | date = October 2008 | accessdate = 2009-02-03 | format = PDF | publisher = US Forest Service}}</ref> Multiple fuel treatments are often needed to influence future fire risks, and wildfire models may be used to predict and compare the benefits of different fuel treatments on future wildfire spread.<ref name="Graham, et al., iv" /> 

However, controlled burns are reportedly "the most effective treatment for reducing a fire’s rate of spread, fireline intensity, flame length, and heat per unit of area" according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station.<ref>van Wagtendonk (1996), 1164</ref> Additionally, while fuel treatments are typically limited to smaller areas, effective fire management requires the administration of fuels across large landscapes in order to reduce future fire size and severity.<ref>Graham, ''et. al.'', 32-33.</ref>

Building codes in fire-prone areas typically require that structures be built of flame-resistant materials and a [[defensible space (fire control)|defensible space]] be maintained by clearing flammable materials within a prescribed distance from the structure.<ref>{{vancite web | url = http://www.fire.ca.gov/fire_prevention/downloads/FHSZBSR_Backgrounder.pdf | format = PDF | title = California’s Fire Hazard Severity Zone Update and Building Standards Revision | publisher = CAL FIRE | date = May 2007 | accessdate = 2008-12-18}}</ref><ref>{{vancite web | url = http://www.leginfo.ca.gov/pub/07-08/bill/sen/sb_1551-1600/sb_1595_bill_20080927_chaptered.pdf | format = PDF | title = California Senate Bill No. 1595, Chapter 366 | publisher = State of California | date = 2008-09-27 | accessdate = 2008-12-18}}</ref> Communities in the [[Philippines]] also maintain [[fire line]]s {{convert|5|to|10|m|ft|sp=us}} wide between the forest and their village, and patrol these lines during summer months or seasons of dry weather.<ref>Karki, 14.</ref> Fuel buildup can result in costly, devastating fires as new homes, ranches, and other development are built [[wildland-urban interface|adjacent to wilderness areas]]. Continued growth in fire-prone areas and rebuilding structures destroyed by fires has been met with criticism.<ref name=Trial2>{{vancite web | url = http://www.onearth.org/article/our-trial-by-fire?page=2 | title = Our Trial by Fire | authorlast = Manning | authorfirst = Richard | publisher = onearth.org | date = 2007-12-01 | accessdate = 2009-01-07}}</ref> 

However, the population growth along the wildland-urban interface discourages the use of current fuel management techniques. Smoke is an irritant and attempts to thin out the fuel load is met with opposition due to desirability of forested areas, in addition to other wilderness goals such as endangered species protection and habitat preservation.<ref>''Are Big Fires Inevitable? A Report on the National Bushfire Forum'', 15.</ref> The ecological benefits of fire are often overridden by the economic and safety benefits of protecting structures and human life.<ref name = NOAA>{{vancite web | url = http://www.economics.noaa.gov/?goal=ecosystems&file=events/fire/ | title = Extreme Events: Wild & Forest Fire | publisher = National Oceanic and Atmospheric Administration (NOAA) | accessdate = 2009-01-07}}</ref>  For example, while fuel treatments decrease the risk of crown fires, these techniques destroy the habitats of various plant and animal species.<ref>McKenzie, ''et al.'', 899</ref> Additionally, government policies that cover the wilderness usually differ from local and state policies that govern urban lands.<ref name="van Wagtendonk, 14"/><ref>''Interagency Strategy for the Implementation of the Federal Wildland Fire Policy'', 38-40.</ref>

{{Wide image|Forest Development in Bitterroot.jpg|900px|A [[ponderosa pine]] stand in the [[Bitterroot National Forest]] in [[Montana]] in 1909, 1948, and 1989. The increase in vegetation density was attributed to fire prevention efforts since 1895.{{#tag:ref|Graham, ''et al.'', page 4}}|alt=Three photos of the same forest region. The first features a central tree with other trees in the distance. A man and two mounted horses are seen at varying distances behind the central tree. The forest floor features low-lying vegetation such as grasses. The second and third photos feature the same central tree but with increasing amounts of trees in the mid- and foregrounds. The central tree is almost completely blocked from view in the third picture.}}

==Detection==
{{See also|Remote sensing}}
[[Image:Drymountainlookout1930.jpg|thumb|upright=1.1|alt=A four-legged tower with a small enclosure at the top, next to two one-story buildings. The tower is four stories tall. Trees are at either side, and in the foreground there are rocks, some vegetation, and a rough trail.|Dry Mountain Fire Lookout in the [[Ochoco National Forest]], [[Oregon]], circa 1930]]

Fast and effective detection is a key factor in wildfire fighting.<ref>San-Miguel-Ayanz, ''et al.'', 362.</ref> Early detection efforts were focused on early response, accurate results in both daytime and nighttime, and the ability to prioritize fire danger.<ref name = Integration>{{vancite journal | url = http://www.westerndisastercenter.org/DOCUMENTS/PERS_PAPER.pdf | publisher = Western Disaster Center | format = PDF | title = An Integration of Remote Sensing, GIS, and Information Distribution for Wildfire Detection and Management | journal = Photogrammetric Engineering and Remote Sensing | volume = 64 | issue = 10 | date = October 1998 | pages = 977–985 | accessdate = 2009-06-26}}</ref> [[Fire lookout tower]]s were used in the United States in the early 20th century and fires were reported using telephones, [[carrier pigeon]]s, and [[heliograph]]s.<ref>{{vancite web | url = http://archives.cbc.ca/version_print.asp?page=1&IDLan=1&IDClip=4917&IDDossier=849&IDCat=346&IDCatPa=261 | title = Radio communication keeps rangers in touch | publisher = Canadian Broadcasting Corporation (CBC) Digital Archives | date = 21 August 1957 | accessdate = 2009-02-06}}</ref> Aerial and land photography using [[instant camera]]s were used in the 1950s until [[infrared photography|infrared scanning]] was developed for fire detection in the 1960s. However, information analysis and delivery was often delayed by limitations in communication technology. Early satellite-derived fire analyses were hand-drawn on maps at a remote site and sent via overnight mail to the [[incident commander|fire manager]]. During the [[Yellowstone fires of 1988]], a data station was established in [[West Yellowstone]], permitting the delivery of satellite-based fire information in approximately four hours.<ref name = Integration/>

Currently, public hotlines, [[fire lookout]]s in towers, and ground and aerial patrols can be used as a means of early detection of forest fires. However, accurate human observation may be limited by [[asthenopia|operator fatigue]], time of day, time of year, and geographic location. Electronic systems have gained popularity in recent years as a possible resolution to human operator error. These systems may be semi- or fully-automated and employ systems based on the risk area and degree of human presence, as suggested by [[Geographic information system|GIS]] data analyses. An integrated approach of multiple systems can be used to merge satellite data, aerial imagery, and personnel position via [[Global Positioning System]] (GPS) into a collective whole for near-realtime use by wireless [[Incident Command System|Incident Command Centers]].<ref>{{vancite web | url = http://www.forestry.state.al.us/WildfireControl.aspx?bv=1&s=0 | title = Wildfire Detection and Control | publisher = Alabama Forestry Commission | accessdate = 2009-01-12}}</ref><ref>"Evaluation of three wildfire smoke detection systems", 4</ref>

A small, high risk area that features thick vegetation, a strong human presence, or is close to a critical urban area can be monitored using a local [[sensor network]]. Detection systems may include [[wireless sensor network]]s that act as automated weather systems: detecting temperature, humidity, and smoke.<ref>{{vancite web | url = http://cse.seas.wustl.edu/techreportfiles/getreport.asp?399 | archiveurl = http://web.archive.org/web/20070103233730/http://cse.seas.wustl.edu/techreportfiles/getreport.asp?399 | archivedate = 2007-01-03 | format = PDF | title = Mobile Agent Middleware for Sensor Networks: An Application Case Study | date = 2004-11-29 | last = Fok | first = Chien-Liang | coauthors = Roman, Gruia-Catalin; and Lu, Chenyang | publisher = Washington University in St. Louis | accessdate = 2009-01-15}}</ref><ref>{{vancite journal | url = http://ieeexplore.ieee.org/search/wrapper.jsp?arnumber=1488955 | title = Wireless Sensor Network Based System for Fire Endangered Areas | date = July, 2005 | last = Chaczko | first = Z. | coauthors = Ahmad, F. |author.= | journal = Third International Conference on Information Technology and Applications | volume = 2 | issue = 4-7 | pages = 203–207 | accessdate = 2009-01-15 | doi = 10.1109/ICITA.2005.313}}</ref><ref>{{vancite web | url = http://firecenter.umt.edu/index.php/project/Wireless-Weather-Sensor-Networks-for-Fire-Management/ID/461d72ad/fuseaction/whatWeDo.projectDetail.htm | title = Wireless Weather Sensor Networks for Fire Management | publisher = University of Montana - Missoula | accessdate = 2009-01-19}}</ref><ref>{{vancite web |url= http://www.libelium.com/libeliumworld/articles/101031032811  |title=Detecting Forest Fires using Wireless Sensor Networks with Waspmote|publisher=Libelium Comunicaciones Distribuidas S.L. |first=Javier |last=Solobera |date=9 April 2010}}</ref> These may be battery-powered, solar-powered, or ''tree-rechargeable'': able to recharge their battery systems using the small electrical currents in plant material.<ref>{{vancite web | url = http://web.mit.edu/newsoffice/2008/trees-0923.html | title = Preventing forest fires with tree power | date = 2008-09-23 | accessdate = 2009-01-15 | last = Thomson | first = Elizabeth A. |author.= | publisher = Massachusetts Institute of Technology (MIT) News}}</ref> Larger, medium-risk areas can be monitored by scanning towers that incorporate fixed cameras and sensors to detect smoke or additional factors such as the infrared signature of carbon dioxide produced by fires. Additional capabilities such as [[night vision]], brightness detection, and color change detection may also be incorporated into sensor arrays.<ref>"Evaluation of three wildfire smoke detection systems", 6</ref><ref>{{vancite web | url = http://advancement.sdsu.edu/marcomm/news/releases/spring2005/pr062305.html | archiveurl = http://web.archive.org/web/20060901120511/http://advancement.sdsu.edu/marcomm/news/releases/spring2005/pr062305.html | archivedate = 2006-09-01 | title = SDSU Tests New Wildfire-Detection Technology | date = 2005-06-23 | place = San Diego, CA | publisher = San Diego State University | accessdate = 2009-01-12}}</ref><ref>San-Miguel-Ayanz, ''et al.'', 366-369, 373-375.</ref>

[[Image:Wildfires Balkans July 2007-NASA.jpg|thumb|right|upright=1.1|alt=A satellite view of the Balkans and Greece. Clouds and smoke trails are seen above the Balkans and trailing south into the Ionian Sea.|Wildfires across the [[Balkans]] in late July 2007 ([[MODIS]] image)]]

Satellite and aerial monitoring can provide a wider view and may be sufficient to monitor very large, low risk areas. These more sophisticated systems employ GPS and aircraft-mounted infrared or high-resolution visible cameras to identify and target wildfires.<ref>{{vancite web | author = Rochester Institute of Technology | url = http://www.sciencedaily.com/releases/2003/04/030410072055.htm | title = New Wildfire-detection Research Will Pinpoint Small Fires From 10,000&nbsp;feet | publisher = ScienceDaily | date = 2003-10-04 | accessdate = 2009-01-12}}</ref><ref>{{vancite web | url = http://www.esa.int/esaLP/SEMEAE0CYTE_index_0.html | title = Airborne campaign tests new instrumentation for wildfire detection | date = 2006-10-11 | publisher = European Space Agency | accessdate = 2009-01-12}}</ref> Satellite-mounted sensors such as [[Envisat]]'s [[AATSR|Advanced Along Track Scanning Radiometer]] and [[European Remote-Sensing Satellite]]'s Along-Track Scanning Radiometer can measure infrared radiation emitted by fires, identifying hot spots greater than {{convert|39|C|F}}.<ref>{{vancite web | url = http://www.esa.int/esaCP/SEMRBH9ATME_Protecting_0.html | title = World fire maps now available online in near-real time | publisher = European Space Agency | date = 2006-05-24 | accessdate = 2009-01-12}}</ref><ref>{{vancite web | url = http://www.esa.int/esaEO/SEMEKMZBYTE_index_0.html | title = Earth from Space: California’s ‘Esperanza’ fire | date = 2006-03-11 | publisher = European Space Agency | accessdate = 2009-01-12}}</ref> The [[National Oceanic and Atmospheric Administration]]'s [[Hazard Mapping System]] combines remote-sensing data from satellite sources such as [[Geostationary Operational Environmental Satellite]] (GOES), [[Moderate-Resolution Imaging Spectroradiometer]] (MODIS), and [[Advanced Very High Resolution Radiometer]] (AVHRR) for detection of fire and smoke plume locations.<ref>{{vancite web | url = http://www.ssd.noaa.gov/PS/FIRE/hms.html | publisher = National Oceanic and Atmospheric Administration (NOAA) Satellite and Information Service | title = Hazard Mapping System Fire and Smoke Product | accessdate = 2009-01-15}}</ref><ref name = Swarm>{{vancite journal | url = http://www3.interscience.wiley.com/journal/119817008/abstract | title = A probabilistic zonal approach for swarm-inspired wildfire detection using sensor networks | last = Ramachandran | first = Chandrasekar | coauthors = Misra, Sudip and Obaidat, Mohammad S. |author.= | journal = Int. J. Commun. Syst. |journal.= | volume = 21 | issue = 10 | pages = 1047–1073 | date = 2008-06-09 | doi = 10.1002/dac.937}}</ref> However, satellite detection is prone to offset errors, anywhere from {{convert|2|to|3|km|mi|sigfig=1|sp=us}} for MODIS and AVHRR data and up to {{convert|12|km|mi|sp=us}} for GOES data.<ref>{{vancite web | url = http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050180316_2005176776.pdf | format = PDF | title = Automated Wildfire Detection Through Artificial Neural Networks | last = Miller | first = Jerry | coauthors = Borne, Kirk; Thomas, Brian; Huang Zhenping; and Chi, Yuechen | publisher = NASA | accessdate = 2009-01-15}}</ref> Satellites in geostationary orbits may become disabled, and satellites in polar orbits are often limited by their short window of observation time. Cloud cover and image resolution and may also limit the effectiveness of satellite imagery.<ref>{{vancite journal | url = http://www.springerlink.com/content/l67347334n258772/fulltext.pdf?page=1 | title = Forest fire detection system based on a ZigBee wireless sensor network | date = September, 2008 | doi = 10.1007/s11461-008-0054-3 | pages = 369–374 | volume = 3 | issue = 3 | journal = Frontiers of Forestry in China | publisher = Higher Education Press, co-published with Springer-Verlag GmbH | last = Zhang | first = Junguo | coauthors = Li, Wenbin, Han, Ning, and Kan, Jiangming | accessdate = 2009-06-26}}</ref>

==Suppression==
{{Main|Wildfire suppression}}
{{See also|Firefighting}}

[[Image:10tanker-N450AX-061215-04-8.jpg|thumb|right|upright=1.1|alt=A three-engine red-and-white cargo plane in-flight, releasing a large quantity of water from its undercarriage storage tanks. The water trails behind the aircraft in a continuous, fan-shaped drop pattern.|[[Tanker 910]] during a drop demonstration in December, 2006]]

Wildfire suppression depends on the technologies available in the area in which the wildfire occurs. In less developed nations such as [[Thailand]], the techniques used can be as simple as throwing sand or beating the fire with sticks or palm fronds.<ref>Karki, 16</ref> In more advanced nations, the suppression methods vary due to increased technological capacity. [[Silver iodide]] can be used to encourage snow fall,<ref>{{vancite web|url=http://origin.foxnews.com/story/0,2933,195969,00.html |title=China Makes Snow to Extinguish Forest Fire |publisher=FOXNews.com |accessdate=2009-07-10|date=2006-05-18}}</ref> while [[fire retardant]]s and water can be dropped onto fires by [[unmanned aerial vehicle]]s, [[airtanker|planes]], and [[helitack|helicopters]].<ref>{{vancite web|url=http://geo.arc.nasa.gov/sge/WRAP//projects/docs/ISRSE_PAPER_2003.PDF |format=PDF |accessdate=2009-07-21| title=Disaster Management Applications – Fire| first=Vincent G. |last=Ambrosia |author.= |publisher=NASA-Ames Research Center|date=2003}}</ref><ref>Plucinski, ''et al.'', 6</ref> Complete fire suppression is no longer an expectation, but the majority of wildfires are often extinguished before they grow out of control. While more than 99% of the 10,000 new wildfires each year are contained, escaped wildfires can cause extensive damage. Worldwide damage from wildfires is in the billions of euros annually.<ref>Automatic remote surveillance system for the prevention of forest fires, 2</ref> Wildfires in Canada and the US burn an average of {{convert|54500|km2|acre|sigfig=2|sp=us}} per year.<ref>{{vancite web | url = http://www.cbc.ca/canada/story/2009/06/17/f-forest-fires.html | title = Fighting fire in the forest | publisher = CBS News | date = 2009-06-17 | accessdate = 2009-06-26}}</ref><ref>{{vancite web | url = http://www.ncdc.noaa.gov/sotc/?report=fire&year=2008&month=13 | title = Climate of 2008 Wildfire Season Summary | publisher = National Climatic Data Center | date = 2008-12-11 | accessdate = 2009-01-07}}</ref>

Above all, fighting wildfires can become deadly. A wildfire's burning front may also change direction unexpectedly and jump across fire breaks. Intense heat and smoke can lead to disorientation and loss of appreciation of the direction of the fire, which can make fires particularly dangerous.  For example, during the 1949 [[Mann Gulch fire]] in [[Montana]], USA, thirteen [[smokejumper]]s died when they lost their communication links, became disorientated, and were overtaken by the fire.<ref>{{vancite web |url=http://www.fs.fed.us/rm/pubs_int/int_gtr299/ | title = General Technical Report INT-GTR-299 - Mann Gulch Fire: A Race That Couldn't Be Won | publisher = United States Department of Agriculture, Forest Service, Intermountain Research Station | date = May 1993 | author-last = Rothermel | author-first = Richard C. | accessdate = 2009-06-26}}</ref> In the Australian [[February 2009 Victorian bushfires]], at least 173 people died and over 2,029 homes and 3,500 structures were lost when they became engulfed by wildfire.<ref name="homeslost">{{vancite web |url=http://www.parliament.nsw.gov.au/prod/PARLMENT/hansart.nsf/V3Key/LA20090313005|title=Victorian Bushfires|date=13 March 2009 |published=New South Wales Government|work=Parliament of New South Wales|accessdate=26 January 2010}}</ref>

===Modeling===
{{Main|Wildfire modeling}}

[[Image:Propagation model wildfire.png|right|thumb|upright=1.1|alt=A dark region shaped like a shield with a pointed bottom. An arrow and the text "propagation axis (wind)" indicates a bottom-to-top direction up the body of the shield shape. The shape's pointed bottom is labeled "fire start". Around the shield shape's top and thinning towards its sides, a yellow-orange region is labeled "left front", "right front", and (at the top) "head of the fire".|Fire Propagation Model]]

Wildfire modeling is concerned with [[numerical simulation]] of wildfires in order to comprehend and predict fire behavior.<ref>{{vancite web | url = http://firegrowthmodel.ca/  | title = PROMETHEUS | publisher =  Tymstra, C.; Bryce, R.W.; Wotton, B.M.; Armitage, O.B. 2009. Development and structure of Prometheus: the Canadian wildland fire growth simulation Model.  Inf. Rep. NOR-X-417. Nat. Resour. Can., Can. For. Serv., North. For. Cent., Edmonton, AB. | accessdate = 2009-01-01}}</ref><ref>{{vancite web | url = http://www.firemodels.org/content/view/112/143/ | archiveurl = http://web.archive.org/web/20080215083312/http://www.firemodels.org/content/view/112/143/ | archivedate = 2008-02-15 | title = FARSITE | publisher = FireModels.org - Fire Behavior and Danger Software, Missoula Fire Sciences Laboratory | accessdate = 2009-07-01}}</ref> Wildfire modeling can ultimately aid wildfire suppression, increase the safety of firefighters and the public, and minimize damage. Using [[computational science]], wildfire modeling involves the statistical analysis of past fire events to predict spotting risks and front behavior. Various wildfire propagation models have been proposed in the past, including simple ellipses and egg- and fan-shaped models. Early attempts to determine wildfire behavior assumed terrain and vegetation uniformity. However, the exact behavior of a wildfire's front is dependent on a variety of factors, including windspeed and slope steepness. Modern growth models utilize a combination of past ellipsoidal descriptions and [[Huygens' Principle]] to simulate fire growth as a continuously expanding polygon.<ref>G.D. Richards, “An Elliptical Growth Model of Forest Fire Fronts and Its Numerical Solution”, Int. J. Numer. Meth. Eng.,. 30:1163-1179, 1990.</ref><ref>Finney, 1-3.</ref> [[Extreme value theory]] may also be used to predict the size of large wildfires. However, large fires that exceed suppression capabilities are often regarded as statistical outliers in standard analyses, even though fire policies are more influenced by catastrophic wildfires than by small fires.<ref name="Alvarado, et al., 66-68" />

==See also==
{{Portal box|Disasters|Fire}}
{{Columns-list|2|
* [[Deforestation]]
* [[Flood]]s and [[landslide]]s after wildfires
* [[Keetch-Byram Drought Index]]
* [[National Fire Danger Rating System]]
* [[Remote Automated Weather Station]]
* [[Weather forecasting]] :
** [[Forest fire weather index]]
** [[Haines Index]]
*[[Women in firefighting]]
}}

{{Clear}}

==Notes==
<references group=note/>

==References==
{{Reflist|2}}

==Bibliography==
<!-- Please be careful when changing these templates, as the author last names or titles are used in the references section -->
{{Columns-list|2|
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*{{vcite journal |last1=McKenzie |first1=D |last2=Gedalof |first2=Z |last3=Peterson |first3=D L |last4=Mote |first4=P |title=Climatic change, wildfire, and conservation |journal=Conservation Biology |volume=18 |issue=4 |date=2004 |pages=890–902 |doi=10.1111/j.1523-1739.2004.00492.x |url=http://www2.for.nau.edu/courses/pzf/FireEcolMgt/McKenzie_ConBio2004.pdf |format=PDF }}
* {{vancite web | url = http://www.nifc.gov/preved/comm_guide/wildfire/FILES/PDF%20%20FILES/Linked%20PDFs/2%20Wildland%20fire%20overview.PDF | format = PDF | title = National Wildfire Coordinating Group Communicator's Guide for Wildland Fire Management: Fire Education, Prevention, and Mitigation Practices, Wildland Fire Overview | publisher = National Wildfire Coordinating Group | accessdate = 2008-12-11
}}
* {{vancite web |last=Nepstad|first=Daniel C |url=http://www.worldwildlife.org/climate/Publications/WWFBinaryitem7658.pdf |format=PDF |title=The Amazon’s Vicious Cycles: Drought and Fire in the Greenhouse |publisher=World Wide Fund for Nature (WWF International)| year=2007|accessdate=2009-07-09
}}
* {{vancite journal |last=Olson |first=Richard Stuart |last2=Gawronski |first2=Vincent T |title=The 2003 Southern California Wildfires: Constructing Their Cause(s)|accessdate=2009-07-15|journal=Quick Response Research Report|volume=173 |year=2005|publisher=University of Colorado at Boulder Natural Hazards Center|url=http://www.colorado.edu/hazards/research/qr/qr173/qr173.pdf|format=PDF
}} ([http://www.colorado.edu/hazards/research/qr/qr173/qr173.html HTML version])
* {{vancite journal |last=Pausas |first=Juli G |first2=Jon E |last2=Keeley |title=A Burning Story: The Role of Fire in the History of Life |journal=BioScience |volume=59 |pages=593–601 |issn=0006-3568 |publisher=American Institute of Biological Sciences |doi=10.1525/bio.2009.59.7.10 |url=http://www.werc.usgs.gov/seki/pdfs/K2009_Pausas_Burning%20Story.pdf |format=PDF |date=July/August 2009
}}
* {{vancite conference | first = Eric | last = Peuch | editor = Butler, B W; Alexander, M E, editors | contribution = Firefighting Safety in France | contribution-url = http://www.iawfonline.org/summit/2005%20Presentations/2005_pdf/Peuch.pdf | format = PDF | title = Eighth International Wildland Firefighter Safety Summit - Human Factors - 10 Years Later | date = 26–28 April 2005 | pages = | place = Missoula, Montana | publisher = The International Association of Wildland Fire, Hot Springs, South Dakota | url = http://www.iawfonline.org/summit/2005%20Presentations/2005_pdf/Peuch.pdf| doi = | id =
}}
* {{vancite journal |last=Pitkänen |first=Aki |last2=Huttunen |first2=Pertti |last3=Jungner |first3=Högne |last4=Meriläinen |first4=Jouko |last5=Tolonen |first5=Kimmo |title=Holocene fire history of middle boreal pine forest sites in eastern Finland|url=http://www.sekj.org/PDF/anbf40/anbf40-015.pdf|format=PDF |journal=Annales Botanici Fennici| pages=15–33|volume=40|issn=0003-3847|date=2003-02-28
}}
* {{vancite report |first= M |last= Plucinski |first2= J |last2= Gould |first3= G |last3= McCarthy |first4= J |last4= Hollis | date= June 2007 |title = The Effectiveness and Efficiency of Aerial Firefighting in Australia: Part 1 |url = http://www.bushfirecrc.com/research/downloads/Aerial-Suppression-Report-Final-web.pdf |format= PDF | publisher = Bushfire Cooperative Research Centre |isbn= 0-643-06534-2 |accessdate= 2009-03-04
}}
* {{vancite journal |first= Jesus |last= San-Miguel-Ayanz |first2= Nicolas |last2= Ravail |first3= Vaino |last3= Kelha |first4= Anibal |last4= Ollero |title= Active Fire Detection for Fire Emergency Management: Potential and Limitations for the Operational Use of Remote Sensing |url= http://grvc.us.es/publica/revistas/documentos/R-050.05ActiveFire.pdf |format= PDF |journal= Natural Hazards |year= 2005 |volume= 35 |pages= 361–376 |doi= 10.1007/s11069-004-1797-2 |publisher= Springer |accessdate= 2009-03-05
}}
* {{vancite journal | last=van Wagtendonk | first = Jan W | year = 1996 | title = Use of a Deterministic Fire Growth Model to Test Fuel Treatments | url = http://www.werc.usgs.gov/yosemite/vii_c43.pdf | format = PDF | journal = Sierra Nevada Ecosystem Project: Final report to Congress, vol. II, Assessments and scientific basis for management options | publisher = Davis: University of California, Centers for Water and Wildland Resources | pages = 1155–1166 | accessdate = 2009-02-05
}}
* {{vancite journal | last=van Wagtendonk | first=Jan W | year=2007 | title=The History and Evolution of Wildland Fire Use | format = PDF | journal=Fire Ecology | publisher=Association for Fire Ecology | volume=3 | issue=2 | pages=3–17 | url=http://www.fireecology.net/Journal/pdf/Volume03/Issue02/003.pdf | accessdate=2008-08-24
}} (U.S. Government public domain material published in Association journal. See [http://www.werc.usgs.gov/news/apr2008.html ''WERC Highlights &ndash; April 2008''])
}}

==External links==
{{Commons}}
{{Wikibooks|Applied Ecology/Case Studies/Asian Rainforest Politics}}
* [http://www.extinciondeincendios.es Ballistic System for Fighting Forest Fire]
* [http://www.bushfirecrc.com/ Bushfire Cooperative Research Centre]
* [http://www.libelium.com/libeliumworld/articles/101031032811 Detecting Forest Fires using Wireless Sensor Networks with Waspmote]
* [http://www.fire.uni-freiburg.de/ Global Fire Monitoring Center]
* [http://www.iawfonline.org/ International Association of Wildland Fire]
* [http://www.fire.uni-freiburg.de/iffn/iffn.htm International Forest Fire News]
* NASA [http://geo.arc.nasa.gov/sge/WRAP// Wildfire Research and Applications Partnership (WRAP)]
* National Interagency Fire Center: [http://www.nifc.gov/preved/comm_guide/wildfire/index.htm ''National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management'' Table of Contents]
* National Oceanic and Atmospheric Administration (NOAA): [http://www.economics.noaa.gov/?goal=weather&file=events/fire/ Economic Costs of Wildfires]
* University of Toronto Fire Management Systems Laboratory [https://www.firelab.utoronto.ca/publications/recent_pubs.html Recent Publications]
* US BLM [http://www.blm.gov/nifc/st/en/prog/fire.html Fire and Aviation]
* USFS: [http://www.fs.fed.us/fire/ Fire and Aviation Management]
* USFS: [http://www.fs.fed.us/pnw/fera/ Fire and Environmental Research Applications Team] [http://www.fs.fed.us/pnw/fera/publications/publications-all.shtml Products & Publications]
* USFS: [http://firelab.fire.org/ Fire, Fuel, and Smoke Science Program]
* Wildlandfire.com [http://www.wildlandfire.com/pics/wall/wall.htm Wildfire photographs]
* Wildland Fire Operations Research Group (WFORG): [http://fire.feric.ca/36152002/WorkshopPresentation.htm Detection Workshop Presentations]

{{Fire fighting}}

{{Good article}}

{{Natural disasters}}

[[Category:Wildfires| Wildfire]]
[[Category:Natural hazards]]
[[Category:Climate forcing agents]]
[[Category:Wildland fire suppression]]
[[Category:Ecological succession]]
[[Category:Occupational safety and health]]

[[bs:Šumski požar]]
[[bg:Горски пожар]]
[[ca:Incendi forestal]]
[[da:Skovbrand]]
[[de:Waldbrand]]
[[es:Incendio forestal]]
[[eo:Arbara incendio]]
[[eu:Basoko sute]]
[[fr:Feu de forêt]]
[[gl:Incendio forestal]]
[[ko:산불]]
[[hi:दावानल]]
[[hr:Šumski požar]]
[[id:Kebakaran liar]]
[[kn:ಕಾಳ್ಗಿಚ್ಚು]]
[[lt:Miško gaisras]]
[[nl:Natuurbrand]]
[[ja:山火事]]
[[no:Skogbrann]]
[[oc:Encendi de bòsc]]
[[pl:Pożary lasów]]
[[pt:Incêndio florestal]]
[[ru:Лесной пожар]]
[[sh:Šumski požar]]
[[fi:Metsäpalo]]
[[sv:Skogsbrand]]
[[tl:Sunog sa gubat]]
[[te:దావానలం]]
[[th:ไฟไหม้ป่า]]
[[tr:Orman yangını]]
[[uk:Лісова пожежа]]
[[ur:جنگلی آگ]]
[[vi:Cháy rừng]]
[[yi:וואלד פייער]]
[[zh-yue:山火]]
[[zh:山火]]
[[Category:2Fix]]