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wildfires
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- 1wildfires are a natural process in many ecosystems and can even be what ?beneficial process
- 2fires can be major events, occurring on a large scale and causing widespread destruction, killing much wildlife - surface fires do what ?spread rapidly over the ground, consuming plant litter, grasses, scorching trees
- 3it is possible for ground temperatures to rise to over what degrees ?1000 degrees
- 4at higher levels there are what ?canopy fires that spread through the canopy of trees
- 5the nature of the fire will depend on what ?the types of plants involved, strength of winds, topography of area in question and the behaviour of the fire itself
- 6once the vegetation has dried out, the nature of the fire will depend largely upon what ?the wind
- 7the largest fires occur in what conditions ?dry windy weather with low humidity
- 8wind drives the fire forwards and burning embers that ignite more vegetation are more easily spread in windy weather - the key factors therefore in any fire are what ?the climate and the nature of the plants involved
- 9for wildfires to spread there are two things that are needed ?- an ignition source
- fuel - 10IGNITION SOURCE: NATURAL: in the case of natural fires what is by far the main cause ?lightning
climate will affect the frequency of electrical storms, particularly one which there is hardly any rainfall - 11IGNITION SOURCE: HUMAN: increasingly fires are the result of what ?human intervention such as :
- fires started by falling power lines
- discarded fags
- children playing with matches
- camp fires
- agricultural fires which can get out of hand - 12FUEL: the fuel has to be of sufficient quantity and dry enough to burn - climate affects the frequency and duration of droughts during which vegetation and litter has an opportunity to do what ?dry out and accumulate
- 13DISTRIBUTION : wildfires are essentially a rural hazard and can occur in most environments, although with continued expansion of human habitation, wildfires now occur within the boundaries of what?substantial settlements
- 14DISTRIBUTION : areas that are most susceptible are those with a combination of what ?dry vegetation and lightning strikes
- 15DISTRIBUTION : areas with a dry season are most likely to be affected as those are regions of the world with semi-arid climate and susceptible drought - name some parts of the world like this- parts of Australia
- USA and Canada
- Southern Europe - southern france, italy etc - 16fires and natural ecosystems are often closely linked, particularly in what climate regionsmediterranean climate regions and savannah grasslands
- 17what is pyrophytic vegetation?plants adapted to tolerate fire - methods of survival include thick bark, tissue with high moisture content and underground storage structures
- 18fire can clear vegetation and aid what ?new seed germination, stimulate growth of certain plants and rid an area of insects and some parasites
- 19some species are pyrophytic in that they can withstand fire through some mechanism, such as resistant bark - in Australia, what plant needs fire ?banksia need fire for their woody fruit to open and thus regenerate
- 20fire has not been areal hazard of a tropical rainforest due to the humid climate, but recent burning for forest clearance has often got out of hand, resulting in what ?widespread fires that have burned out of control for long periods
- 21what areas of tropical rainforest have suffered from such fires in recent years ?Amazon Basin - brazil
South-east asia - indonesia - 22what is a good example of an area with a continuing problem ?the los angeles basin in california - wildfires that occur here often get a great deal of media coverage as it is likely that a wildfire event could threaten the homes of famous film and TV personalities
- 23why does wildfires in the los angeles area pose a serious threat ?- much of the area is covered by drought-resistant chaparral which is a scrub vegetation as the area is too dry for much tree growth - this vegetation after summer drought can be tinder dry
- dry win called santa ana that descends from the local mountains increases the dryness of the vegetation
- area outside of LA consists of
low-density building where the natural vegetation has been allowed to remain between properties - 24EFFECTS : DIRECT EFFECTS : what are the direct effects of wildfires ?- loss of crops, timber and livestock = huge impact on timber producing areas can lead to economic loss
- loss of life = fires move fast so ppl can get trapped
- loss of property = with urban expansion, the fringes are now susceptible = the cost of the damage can run into hundreds of millions
- release of toxic gases and particulates = the southeast asia 'haze' is fire-related large-scale air pollution that occurs regularly and is still present in parts of the region - pollution spread across a no. of countries = govs of countries have demanded indonesia take actions against companies responsible for illegal forest fires
- loss of wildlife = habitats destroyed
- damage to soil structure and nutrient content = intense heat generated at ground level they can destroy nutrients and lead to alteration of soils structure - 25EFFECTS : what are the secondary effects ?- evacuation = ppl may flee from area - not allowed back into affected area for long period of time or forever = emergency shelters have to be found
- increased flood risk - in certain environments where rain comes in heavy bursts the loss of so much vegetation and the consequent decrease in interception can lead to increased flooding - 26MANAGEMENT : RESPONSES: what are some preparation techniques ?- modelling = involves studying the ways in which fires behave with computer simulations in order to comprehend and predict fire behaviour
- Education - in areas susceptible to wildfires make people aware with regard to home safety
- Managing the vegetation - controlled burning to get rid of much of the litter and by creating firebreaks in the vegetation in advance rather than during the event
- being well insured - in HICs residents are urged to take out insurance against fire damage - 27MANAGEMENT : RESPONSES: what are some ways of preventing ?- warning systems = can be put in place by establishing lookout towers and even air patrols - in tourist areas notice boards at strategic locations could carry warnings of the fire hazards = to prevent deaths Education - in areas susceptible to wildfires make people aware with regard to
- 28MANAGEMENT : RESPONSES: what are some ways of mitigating ?- managing the built environment = increasing gap between houses and vegetation and by incorporating fire-resistant methods in construction - use more brick and stone
- community action - residents develop their own survival techniques such as local warning systems, ensuring that buffer zones were maintained, conducting brush and street cleanups, running equipment training sessions - 29MANAGEMENT : RESPONSES: what does dealing with the event as it happens involve ?fighting the fires as they happen, can be v dangerous operation and it is not unknown fore firefighters to suffer fatalities when they are involved in this action.
firefights can be on the ground beating out flames and bulldozing large breaks in vegetation preventing fires from jumping in certain directions - 30MANAGEMENT : RESPONSES: what can be used to put fires out ?water and chemicals - spraying them from both from the ground and from the air
retardants can be used to slow down the pace of the wildfire - often used on fires in areas which are fairly inaccessible or when human safety / structures are endangered - 31what are retardants ?chemicals sprayed on to fires in order to slow them down - composed of nitrates, ammonia, phosphates, sulphates and thickening agents
- 32ADDRESSING THE EFFECTS : LONG TERM RESPONSE: what are the long term actions taken to prepare for the next fire1. replant trees - particularly in commercial forestry areas in order to improve the economy of areas devastated by fire
2. replant trees - after vegetation has been removed by fire there is a greater danger of flash flooding and mud slides - planting trees should stabilise slopes
3. preparedness = making sure that people are better prepared for the next fire by having emergency supplies ready along with survival kits
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- A level (hazards) Geography - physical Fichas sobre wildfires, creado por niamh bergin el 24/05/2018.
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- niamh bergin
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