From fire

In the 1930s the forest services introduced the first mobile fire units and expanded their detection systems, a well-known innovation being the tree-top lookouts in the Western Australian karri forests which were used effectively for about 40 years. The use of fire to reduce fuel in forests also became more common, particularly in Western Australia, but the requirements to achieve this in a controlled manner were incompletely understood, with some unfortunate results.

In 1939 disastrous and widespread fires in south-eastern Australia brought about a close review of fire protection legislation, methods and organization, as well as the relocation of sawmills to sites outside the forest area. Somewhat fortuitously the Second World War made an important contribution to establishing improved protection methods as it hastened the development and increased the availability of much of the technology that was required; in particular, four-wheel drive vehicles, bulldozers, mobile radios, pumps, tankers and aircraft.

Since the Second World War fire protection technology has developed in three main areas -fuel reduction burning, early warning and the fire-fighting operation itself -much of it stemming from research programs started by the Forestry and Timber Bureau and CSIRO in the 1950s. Based on investigation of fire variables and field trials the conditions required for safe and successful fuel reduction burning were established by McArthur[30} and the operation then became known as prescribed burning. As this required the lighting of many small fires in a grid pattern it was slow and labour intensive when ground-based methods were used. Moreover, because weather conditions had to be suitable and large areas of forest had to be treated, it was desirable to develop a rapid means of carrying it out. After disastrous fires in 1961 the WA Forests Department set out to do this in co-operation with the CSIRO Division of Applied Chemistry and this led to the development of an aerial ignition system, using a fixed-wing aircraft flying a grid pattern and dropping special incendiary devices at predetermined points. The incendiary devices were small polystyrene tubes containing solid potassium permanganate into which ethylene glycol was injected mechanically just before dropping. The system, developed by Packham and Peet[31] was a world first and in 1966 it enabled 85 000 ha of forest to be ignited in 18 days with highly satisfactory results. Since then it has been further improved and widely used throughout Australia, not only for fuel reduction but also for back-burning and to promote regeneration in forests where ground-based treatments would be impracticable or costly.

Australian Academy of Technological Sciences and Engineering