|
Bushfires: - fire"³one of the most paradoxical phenomenons in the nature - 1.:most destroying one of the 4 elements "³ lane of devestation and death - 2.:donate life - autralian outback ("³arid vegetation"³sun): BF=natural phenomeneon Fire climate: - geograph.location+topography of A."³almost all vegetation types"³fire prone"³ few high mountains, no truly alpine regions - only the tropical rainforests of North Queensland"³virtually fire-free - even the normally arid interior of the country"³capable of carrying extensive fires - fire season in diff.regions of A.
"²primarily on latitude - the south-eastern areas of A.+Tasmania along with the south-west corner of Western A. also produce the tallest forests and associated heavy fuel loads"³ these wet forests occasionally dry out+under extreme fire weather, these fuels produce the most intense+devastating bushfires"» so the greatest potential for a bushfire disaster is, where people have built in close proximity to the tall, wet forests of southern A. Bushfires in pre-european times: - historical accounts record that aborigines burnt extensivly+often - although they had little capacity for fire suppression, there seems little doubt that they had a very extensive knowledge about when+where particular areas would burn+the biological consequences of their burning - they burnt some areas early in the fire season, before fires would spread extensivly, to protect them from fires later in the season - when the weather conditions were appropriate, they burnt to promote the flowering+fruiting of certain edible plants After european settlement: - despite the popular view that european settlement increased the frequency of fire in the country, it is clear from the historical evidence that as european settlement increased, fire frequency decreased. As fire frequency decreased, however, the fuels built up+when fires did occur they were more intense than fires under the aboriginal annual burning regime - for a period around 1850 to 1900, there was deliberate firing of the vegetation by europeans associated with minerals prospecting"³ burning was widely used to clear scrub+litter+expose the underlying rocks. Where this was carried out in dry forests carrying substantil regeneration+heavy fuel, build up after the cessation of annual aboriginal burning some years earlier, the fire intensities were dramatically increased - burning was undertaken by grazieres to clear the land of rough shrub+coarse grasses+to produce green pick for cattle on rough bush leases"³ this burning differed from aboriginal burning both in timing+in frequency Legislation and Management: - legislation to specifically limit the lightening+spread of bushfires was established at different times in different states around the 1880¡¦s - the first ordinance ¡¥to diminish the dangers from buchfires¡¦ was established in Western A.
in 1847 followed by the Bushfires Acts in South A.+Tasmania - organised protection from fire was not possible until much later - in the early 1900¡¦s forestry departments were established+advocated complete protection from fire caused by the miners+the graziers - still, legislation lacked until after the disastrous fires of February 1926 when sweeping changes were made in almost every state"³ lightening of fires during the fire season was prohibited, forestry departments were strengthened+the volunteer bushfire brigades were formed to control fires in rural areas Fire ecology: - although wildfire is detrimental to our rural production+the built environment, it should be considered, to be as much a part of the natural enironment of our forests+heath land ecosystems as the sun+the rain - some australian plants are stimulated to flower by the presence of fire or smoke, while othres have seeds which require some heat treatment before they will germinate"³ eucalypts+banksias have adapted to fires, waiting for them to crack their seed pods, stimulating regeneration - there is a suite of specific plants+animals which are associated which each fire regime - other plants have the capacity to produce abundant shoots from stems or lignotubers after fire, so they can withstand frequent+repeated firing at regular intervals - during any fire some animals will perish. However, in the absence of fire, changes in vegetation may cause the decline+disappearance of some species The nature of bushfire disasters ¡V Past and Future: - the most intense conflagrations will occur in those locations where there is the potential for extreme fire weather+the accumulation of heavy fuel loads"³in A., these locations are the tall, wet forests of the temperate zones of Victoria,south western Western A.+southern Tasmania - for a conflagration to be a disaster depends on the vulnerability of the population+their level of preparedness - in 1939, 71 lost their lives, mostly from timber towns in the forest lands of Victoria - in 1974-1975 fires burnt over 117 million hectares or 15% of the total land area of the continent - fires of the intensity of the Ash Wednesday fires, which swept through South A.+Victoria states in 1983 to cause 76 deaths+the loss of many thousands of homes, would occur only every 50 years - however, in each of the recent fire disasters, the major losses have occured when a single fire burnt into a residential area, either major town or on one of the city fringes - the trend for housing intermixed with bushland fuels is incresing in A.
- in addition to living more intimately with the fuels, the people living in these areas have little understanding of bushfires or fire behaviour - a lot of the population is urban-based+don¡¦t understand the role of fire in the natural environment. +there is natural aversion against fire, longstanding in our heritage, being largely european based"³this was quite different from indigenous Australians, who used fire to manage the land - without the experience of regular fires under mild conditions, the residents of these areas can be totally unprepared for the occasional wildfire burning under extreme fire weather conditions "³ fewer precautions will be taken to clear fuels around individual houses+the concentration of house losses is likely to be greater than in the past - the fury of the Sydney fires was so great on Christmas day that they jumped Warragamba Dam, Sydney¡¦s major water supply, as if it wasn¡¦t there
|
