Fire Vol 1 No

Tropical Topics A n i n t e r p r e t i v e n e w s l e t t e r f o r t h e t o u r i s m i n d u s t r y Fire Vol 1 No. 15 September 1993 Rainforest invasion Notes from the Recently one of our rangers discovered a dragon on the Cape Tribulation headland. It was not a fire-breathing monster but nonetheless it gave him quite a Editor shock because it was a species, the two-lined dragon (Diporiphora bilineata), It is the fire season again. The which is common in dry areas, particularly around Mt Carbine and Mt Molloy, subject raises considerable but not at Cape Tribulation! Found in a patch of heathland, this little reptile is controversy usually because fire is probably a relict left over from a time when, due to Aboriginal burning, the area seen simply as a destructive force. had more sclerophyll woodland. Well within living memory goats grazed on It is superficially difficult to Cape Tribulation. Areas north of Emmagen Creek are marked on an 1890 distinguish between wildfire and survey map as ‘magnificently grassed flat’. deliberate burning but the effects are very different. It has been estimated that rainforest, in very different reactions to fire. some areas, is expanding at the rate of Rainforest (although it does not At the time of European settlement 1.25m per year. This sounds like good normally burn) cannot survive the environment had been news until we look at some of the repeated fires, whereas sclerophyll influenced by Aboriginal burning habitats it is taking over. Wet plants can tolerate and even require it. practices. Since these have largely sclerophyll forest has similar In a marginal area, therefore, fires will ceased in the Wet Tropics, some requirements to rainforest, particularly kill young rainforest species allowing natural vegetation (outside those with regard to rainfall. It is generally sclerophyll species to remain. areas totally transformed by found on the western margins of European farming practices) has rainforest and in isolated pockets such The Wet Tropics is a diverse area. been changing. At the moment as hill tops but cannot exist on drier While its rainforests are its most hazard-reduction burning is taking areas where dry sclerophyll forest celebrated feature they are by no place to minimise the impact of takes over. Unlike rainforest, however, means the only vegetation wildfires but managers of the Wet trees of the wet sclerophyll, such as communities. Once an area has been Tropics are faced with an important flooded gum (Eucalyptus grandis), taken over by rainforest, however, the decision. Current objectives are to need open well-lit conditions to change is irreversible because it does maintain existing habitat diversity. germinate and develop. Where not burn easily. Therefore, it seems Should they reintroduce the fire rainforest species are moving in and that fire is necessary, in certain regimes of the Aborigines to forming a dense cover, shady circumstances, to limit rainforest in the maintain existing vegetation and to conditions mean that eucalypt Wet Tropics so that diversity can be recover previous environmental seedlings cannot establish maintained. diversity - thus leaving options for themselves. An area where invasion is the future open - or should they in progress is typified allow nature to take its course at the by a canopy of tall risk of permanently reducing eucalypts with an diversity in the area? understorey of rainforest - but no This Tropical Topics presents eucalypt saplings. different approaches to fire So why is this management and focuses on flora happening? and fauna, outside the rainforest, which stands to gain from It is likely that the deliberate, positive use of fire. rainforest margin has, in the past, been controlled by disturbance, primarily fire. Wet sclerophyll and rainforest have Managing fire Aboriginal burning practices Present burning practices The first fire managers in Australia were the dry season to reduce the likelihood Prescribed burning the Aborigines. Early accounts refer of later life-threatening wildfires and This refers to fire deliberately used by a frequently to their skillful use and sometimes fire breaks were created to control of burning. They used it in protect the rainforest or sacred sites. land manager to achieve a specified goal. numerous ways. Fire was an early form There are two main aims. The goal of hazard reduction fires is to pre-empt of stock management, used to promote Employing a sound appreciation of its new growth which would attract animals behaviour, the Aborigines skillfully wildfires by burning off fuel loads (such for hunting or to drive game into an as dead plant matter) under controlled manipulated fire by timing it according conditions at the most appropriate times ambush. Undergrowth was burnt to to vegetation and weather conditions provide easier passage — in some areas and by using their knowledge of for the vegetation involved. Cool, calm (notably Iron Range) corridors of days when soils and fuels are moist create landscape features which would act as slow-moving fires with low flames. These sclerophyll forest mark old Aboriginal natural breaks. The early inhabitants of tracks through the rainforest. Smaller Australia may not have had ploughs cause little damage to trees and give fires were used to fell dead trees for animals a chance to escape. The goal of but in their hands fire was a useful and ecological fires is to manipulate the firewood by burning their bases, to appropriate tool. ‘Firestick farming’ flush out small mammals and reptiles enabled them to lead what has been vegetation structure. These may be of from undergrowth or holes and to clear higher intensity to achieve maximum effect termed an ‘affluent’ hunter gatherers’ on unwanted plants (such as rainforest in areas before digging for edible roots. lifestyle. Small controlled fires were set early in wet sclerophyll), debris, etc. Three fire sites Different sites have different requirements. Below are three examples in the Cairns area. Cairns Hillslopes Eubenangee Swamp Captain Cook Highway north of (fire exclusion) (ecological fires) Cairns (hazard-reduction fires) The rainforests of these hillslopes have Apart from reducing fuel loads, fire in Severe wildfires along the grassy coastal suffered badly since European settlement. melaleuca swamps (M) prevents invasion hills are almost an annual event due largely In the past fires frequently escaped from by non-native plants such as pond apple to arsonists. On the steep slopes these the cane fields or from along the Kuranda bush (Annona glabra). These areas are fires have tended to be of high intensity, railway line when vegetation was burnt off burnt every six to nine years but it has to difficult to control and a threat to buildings to protect the tracks. Although rainforest be done while about 5cm of surface water as well as a pocket of rare lowland does not burn easily it cannot withstand remains. Fire in dry times could result in a rainforest. A plan is being implemented to repeated high intensity fires. Increasingly very destructive burning in the peat layer. control the situation with a series of hazard large tongues of fire-induced grassland, Two areas are burnt in different years. reduction fires. These are lit soon after the composed mainly of tall, highly- wet season when they can be controlled inflammable non-native species such as The grasslands (G) begin to decline after using natural barriers such as rocky gullies guinea and molasses grass, carried fires or greener vegetation. progressively further up the hillsides into G N parts of the Barron Gorge National Park. G G The area has been divided up into zones to be burnt at different times. The aim is to The hillslopes of Cairns are a top tourist produce a mosaic of burnt and unburnt asset so local government is keen to R areas which reduces the chances of promote revegetation. In the Redlynch M subsequent wildfires sweeping through area a 3-5m wide bulldozed buffer strip the whole area. has been constructed 20-200m uphill from and parallel to the railway line and M Since 1991, a community group, Treeforce, the area between is burnt annually to R has been hard at work planting trees on the provide a fuel-free strip. Then, 10m hillslopes above Aeroglen. A small forest above this firebreak, a dense strip of now grows where the first plantings took native trees has been planted. For place and the establishment of an irrigation several years community volunteers took system*, along with fire breaks, is helping part in annual planting days. Fast- more recently planted areas to survive the growing pioneer species were used and about three years without fire. Moderate wildfire season. the result is a dense strip of vegetation to high intensity fires stimulate the revival which not only resists the spread of fire of a number of species that have For more information on Treeforce, call (07) but also shades out the grass. It also ‘disappeared’. Ideally these areas are 4053 7314 or (07) 4054 3304. attracts birds and other animals which do burnt every three years but at times when their bit by spreading the seeds to other adjacent areas are still wet so the fire will degraded areas. These plantings have not spread. Areas are burnt in different become substantially ‘fire-safe’ within six years. years and the scheme has been successful * Funded by DoE,Cairns City Council, in its aim of excluding fire from those Rainforest (R) is not burnt at all but Reef Casino Benefit Trust Fund and Port hillslopes. protected from fire. Authority. Fire on islands Prescribed burning is carried out on many of the national park islands.

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