Proceedings of the conference held 8-9 October 1994, Footscray, Melbourne
Biodiversity Series, Paper No. 8
Department of the Environment, Sport and Territories, 1996
21. Fire in flora and fauna management
John T. Fisher
Department of Conservation and Natural Resources, Victoria
Fire is a common broadscale vegetation management tool in Australia but there are significant gaps in our knowledge of its effects on communities and species of flora and fauna. These gaps are becoming increasingly apparent as we attempt to use fire to manage at a specific level – particularly with the management of threatened species.
Implementation of a controlled ecological burn remains a difficult enterprise which can only be achieved within broad parameters especially in heathlands and open forests. The problems in predicting fire behaviour in relation to fuel loads, fuel types, environmental conditions and timing are still difficult to predict and control. Yet these are essential components of the assessment of the potential effect on species and communities.
Fire can be a solution to vegetation management issues in some areas but for us to learn more of its effect burning needs to be implemented with adequate pre-burn and post-burn monitoring. We can then build a better understanding of the complexity of fire behaviour and its effect on vegetation and habitat values.
Key words: fire management, flora management, fauna management, threatened species, controlled ecological burn, Australia
In south western Victoria fire has been investigated as a technique for the ecologically sound management of land that contains threatened flora, fauna or communities. This process of investigation has been hastened by changes to the way vegetation is being managed for objectives such as fire protection and forestry (Wilson 1992; Wouters 1993; Burrows 1985). These changes have meant that large areas of land are having long-term, human induced fire regimes reconsidered (Land Conservation Council 1972). An important part of this reconsideration is an assessment of the impact of fire on the biodiversity of land units. Through this process we are now attempting to define new fire regimes that will achieve improved conservation outcomes and maintain biodiversity.
There is an acceptance that fire of some frequency and intensity is a natural feature of the landscape in Australia (Specht 1981; Gill 1977), but there remains some debate over the exact details of fire regimes for particular vegetation types and particular species (Purdie, 1977; Russel & Parsons, 1978). Caution should be used in defining specific fire requirements without detailed biological evidence of the likely effect. But even with good knowledge of what type of fire is required, there remains the operational difficulty of implementing a particular fire at any specific time. Therefore any opportunity to gain more detailed information on the effect of fire should be fully utilised (Wark et al. 1987).
Despite the scarcity of fire effect information for particular sites or species the need to take some action is often forced upon us by the potential loss of a threatened species or population (Russel & Parsons 1978; Wilson 1992). There are often other demands related to land management needs, to control pest plants or animals or to reduce risks to other public and private assets, which may determine the priority for action.
A number of case studies will be used to demonstrate that the use of fire is a challenging enterprise. Important lessons have been learnt over recent years that highlight the need for detailed planning and a sound methodology in any operation. This will enable the identification of outcomes that can then be measured against the planned objectives for the operation and their direct cause and effect on the particular area or species under active management made more transparent.
21.3 Mellblom's spider orchid Caladenia hastata Nicholls in coastal heathland, Portland (case study 1)
Caladenia hastata was identified as threatened by Willis (1978) and had disappeared from the Point Danger site for some 30 years before being rediscovered in 1973 by local field naturalists. This rediscovery occurred after a wildfire in the area and supports the view that the species is reliant on fire for regeneration in the long term. The Point Danger site is the last known natural occurrence of this species and the site discussed here is some 5 km to the West.
This site represents a population of this threatened species that was transplanted from the nearby coastal site at Point Danger – now the site of the Portland Aluminium smelter. Over two hundred plants were transplanted to the Coastal Reserve in an attempt to create another population (Carr & Kinhill Planners, 1980). The site had been chosen for its similarity to the original heathland and the expectation that similar environmental conditions prevailed. Monitoring over ten years showed the site being slowly invaded by Acacia sophorae (Labill. R.Br.), or coast wattle, and the last flowering of the transplanted population observed at this site was in 1991 (A. Beauglehole 1994 pers comm; G. Carr 1994 pers comm).
Monitoring plots were established at the time of transplantation and have been monitored by Portland Aluminium during spring and summer since re-establishment. Each tuber of the orchid had been pegged and numbered for identification. This allowed ongoing monitoring of each plant through each season. Since transplantation a slow decline of the population appeared to take place resulting in the last flowering being observed in 1991 (J. Hill 1994 pers comm). Coast wattle growth from the south and north of the plot was actively encroaching on the transplant site and had created a full canopy cover over 25 per cent of the plots. The remaining plots were situated amongst dense heathland vegetation which had also covered some plots. This was considered a serious blow to the conservation of the species and some action was essential to revive this population.
Since the last flowering a review of the site indicated that overall canopy coverage had increased and in particular the coast wattle had become dominant and was excluding the heathland community. This was similar to other sites being studied at Dean's Heath (see McMahon et al. 1995). In 1991 the Department of Conservation and Natural Resources had proposed that an ecological burn be conducted at the site but this did not eventuate until autumn 1994. This was mainly due to operational difficulties and a low priority for this site in local burning schedules.
The species had been observed to respond well to burning and had only been rediscovered at Point Danger in 1973 after a wildfire. Therefore it was considered that an autumn burn of the site could promote flowering and achieve two objectives:
- to allow identification of dormant tubers that had survived the transplant but not flowered; and
- to provide a more favourable habitat for the orchid and a seed bed for the recruitment of seed from any induced flowering of dormant tubers.
In preparing for the ecological burn a number of issues were considered important. Many were related to the type of burn required for the orchid but others were operational considerations of burning a coastal heathland in a safe and controlled manner. To a large degree the operational considerations were paramount because the ecological criteria of the burn could only be broad. This allowed a degree of flexibility in planning the burn with the objectives expressed in terms of burn timing and localised fire intensity requirements.
Operational requirements were that the fire breaks be sufficient to prevent an escape and allow access for 4wd tankers. Also that the burn be conducted under a wind speed less than 15km/h and a direction predominantly from the south. This would allow greater control of the back burn before the main burn was initiated and provided for a greater safety margin by increasing the northern break. It was also considered that a southerly wind was predictable and stable and unlikely to change strength or direction during the period of the burn. Private property to the north was to be protected and sufficient resources were to be on hand to control any spotting from the elevated fuels.
Concerns were held that sites where the orchid was located at Point Danger were no longer producing flowering plants and attempts to artificially raise the species had not been successful (Carr & Kinhill Planners 1980). Therefore this transplant site was a vital component for the survival prospects of this species.
The ecological requirements of the species were reasonably known from work conducted for Portland Aluminium, but the requirement for fire was still based on casual observation and historical records of wildfires. The main objective appeared to be that fire intensity was sufficient to remove the canopy that was shading the site and to prevent further invasion it should kill mature plants of coast wattle throughout the site.
A site of some 5 hectares was chosen and mineral earth breaks were prepared on the boundaries. In particular the areas adjoining mature coast wattle in the remainder of the Reserve were made to five metres wide to reduce the chance of escape from the controlled area. Because of the level of disturbance this caused the break was treated along a ridgeline that had been heavily invaded by coast wattle rather than through heathland vegetation. The former coastal road and the current bitumen road were used for the south western and northern boundaries therefore reducing disturbance and cost of firebreak establishment.
The burn was planned for Autumn in 1994 with particular prescriptions developed to produce a hot burn through the transplant site and canopy scorch in areas of mature Coast Wattle. Because of the sensitivity of the coastal cliff vegetation the burn was to be conducted under a prevailing southerly wind. The burn was to commence in late morning when the weather would be predictable and stable.
21.3.2 The burn
The site was burnt in March of 1994. The conditions on the day were: Time: 1000 - 1400 hours; Temperature; 16 - 20°C; Wind; S - SE at 10 - 15 km/h; Relative Humidity: 65 per cent. Fire Danger Index: Moderate.
Initially the vegetation would not carry a burn and operations were delayed for 1.5 hours.
It was not until 1130 that the cloud cover had lifted and a moderate wind had developed. This represented an increase in the wind speed of only 5 - 7km/h and an increase in temperature of 3°C which demonstrates the difficulty in planning such operations.
The northern boundary of the site was back burnt some ten to 15 metres to remove fuel close to the edge. This backburn was then extended to the south western edge where fuel loads and greater exposure to the wind allowed the fire to be carried into the site for distances of 30 - 50 metres.
With the increased temperature at 1300 hours the southern and eastern boundaries were lit and the fire carried the full width of the site up through a small valley and drainage line. Importantly the transplant site was completely burnt and a large area of 1 ha below the transplant site was cleared of coast wattle canopy.
Fire behaviour was difficult to predict as was expected (Wouters 1993; Billings 1986). There is need for a strong wind to force the fire ahead in a heathland dominated by this species of Acacia but once established the fire can be difficult to control because of the flammability of the fuels and their elevated nature. Flame heights were up to four metres above the canopy and forward rates of spread were variable and directly related to the amount of wind carrying the flames forward into preheated fuels. These rates of spread reached a maximum of 0.28km/h up a slope five degrees at 1330 hours. But earlier at 1100 hours, with temperatures only three degrees lower and 5km/h less wind speed it was not possible to initiate the burn.
The operation involved over 20 staff and required one D4 bulldozer, three 2200 litre 4WD tankers and five small tankers. The total cost was in the region of $3 000.
Between 70 - 80 per cent of the site was burnt and 90 per cent of the coast wattle was killed by direct canopy removal or by a back burn sufficient to girdle the trunk and kill the cambium layer under the thin bark.
The site has been monitored regularly since the burn and at least ten plants of C. hastata have been located and positively identified. Two flowered in October 1994 and both were successfully hand pollinated. The intention is to retrieve the mature seed pods and cryogenically store them while an inoculum of the fungal associate is prepared for five new transplant sites in the coastal heathland.
At least two will be in the current site to attempt to expand this population and to try to maximise the conservation of genetic diversity within this population. It is hoped that the other tubers that produced leaves but did not flower in 1994 will do so in 1995 and provide more seed for natural and artificial recruitment.
The ecological burn was considered an outstanding success in achieving a revival of the plants at the site and encouraging regrowth of plants that had been dormant for some years. Removal of the coast wattle canopy and mature plants had been extensive and particularly in the transplant site. Ongoing monitoring will now concentrate on the regeneration of the heathland (Gill 1977; Siddiqui et al. 1976; Specht 1981) and the fate of the orchids identified that did not flower in 1994. Reseeding into the site is also planned using seed collected in 1994 and using inoculum of the fungal associate according to methods identified in Dixon (1992).
In 1989 an area of Kangaroo Grass Themeda triandra dominated native grassland to the north of the City of Hamilton was fenced out to provide a 100 hectare refuge for the eastern barred bandicoot, Perameles gunnii. This area was a former Water Reserve which was no longer used for that purpose and was managed under a local Committee of Management. Both the Western Basalt Plains Grassland and the eastern barred bandicoot are listed under the provisions of the Flora and Fauna Guarantee Act 1988.
Because of the proximity of the area to the City of Hamilton and community concerns with fire protection there was a need to develop a fire protection strategy for the area. This was complicated by the threatened nature of the Western Basalt Plains Grassland community and the effect of burning on the threatened population of eastern barred bandicoots. Burning could only occur if some means of avoiding killing individual eastern barred bandicoots in the process could be implemented. Any strategy should attempt to protect and enhance these assets as well as providing protection for the residents of the northern boundary of Hamilton.
A strategy was developed by the Department of Conservation and Natural Resources that divided the Parkland into seven sections (Department of Conservation and Environment 1990). One central strip was to be burnt each year to provide a strategic fire break for the City of Hamilton. One area was to be retained as a wetland around the former catchment dams, and was not to be burnt. The remaining five areas were to be burnt in autumn in rotation on a five year program that was seen as an optimum burning regime for this grassland community (Stuwe 1984). During burning small areas within the block were to be left unburnt to act as refugia for animals that may be trapped by the strip burning process.
The strategy incorporated a need to address community concerns regarding fire protection while also protecting the area from wildfire which might have been catastrophic to the fauna component of the Parklands. By sacrificing one central area it was considered that the rest of the grassland could be managed for conservation purposes. This strategy has been implemented successfully since 1989 but a number of issues have developed that highlight the need for a review of the strategy to improve the conservation values for the native grassland.
The annual burning of native grasslands leads to a dominance of annuals and a dominant sward of Kangaroo Grass. This has been shown on roadsides in the Western District (Stuwe 1984) where local Country Fire Authority brigades burn roadsides for fire protection purposes.
In the parklands the occurrence of pasture species in some areas was not considered in the development of the strategy. As burning in autumn has proceeded the distribution and dominance of these introduced species has been observed to increase (D. Frood 1993 pers comm). This is particularly so in the area that is burnt annually and represents a threat to the other grassland areas that are being managed for conservation purposes (Carr et al. 1992).
A survey in 1993 indicated that introduced grasses were actively invading the Parklands and appeared to be more prominent in the annually burnt fire break. There was a need to review both the timing of the burning regime and a consideration of an integrated weed management program to reduce these species. The continued invasion would be a threat to the integrity to the native grassland community and eventually the biodiversity of the reserve.
Research is currently investigating the use of fire in spring to remove flowering plants and seed from the area and allow control of the species while still maintaining a fire break in the Parklands.
The Strategy may need to be reviewed to reflect a much more dynamic management regime incorporating the following components:
- the use of spring burns and cool patch burning in areas that have revegetated with trees and contain hard shelter;
- the active control of invasive plant species as is done with feral predators;
- the more dynamic location of the strategic fire break utilising the proposed and recent ecological burns and less extensive areas of annual burns;
- the mapping of faunal usage of zones to promote habitat values for the eastern barred bandicoot;
- an annual monitoring program to evaluate the strategy against both fire protection and conservation objectives.
Fire management strategies that are developed without reference to ecological concerns are as incomplete as ecological burning strategies developed without reference to operational requirements. Because of the difficulty and risk in using fire as a management tool, ecological strategies can develop unattainable objectives or objectives that are so restrictive that they are operationally impossible to implement.
Any proposal to use fire for ecological purposes should firstly develop a plan that has both clearly stated and measurable objectives which can be used to develop a fire management strategy. Familiarity with operational requirements and fire management techniques will ensure the plan is implementable and the objectives achievable. Just as importantly there is the need for the development of an ongoing monitoring program that has both pre-burn and post-burn components; this will ensure information is recovered from the project that can be incorporated into future proposals. A fire regime needs to reflect changes in vegetation and habitat characteristics of the area and be used as an active management tool.
The future holds a challenge for ecologists to become more actively involved in the planning, conduct and assessment of burning programs. If major fuel reduction burning becomes more widespread then a sound ecological basis for these burns is essential. If such burning becomes less widespread but more strategic then the remaining communities will need to be more actively managed to implement a fire regime that is appropriate to the community components and ensures biodiversity maintenance and enhancement.
Billings, P. 1986, 'Portland fires 6 & 7, 12 January 1986', Division of Forest Protection Report, Forests Commission of Victoria.
Burrows, N.D. 1985, 'Planning fire regimes for nature conservation forests in South Western Australia', in Fire Ecology and Management of Western Australian Ecosystems, ed. J.R. Ford, Western Australian Institute of Technology.
Carr, G.W. & Kinhill Planners Pty. Ltd. 1980, 'Alcoa Portland Aluminium Smelter. Environmental design report No. 4. Mellblom's Spider-orchid Conservation. Part A. Status and conservation', Kinhill Planners Pty Ltd, Melbourne, pp. 1-38.
Carr, G., Jugovich, J.V. & Robinson, K.E. 1992, Environmental Weed Invasions in Victoria. Conservation and Management Implications. Department of Conservation & Environment and Ecological Horticulture Pty. Ltd.
Department of Conservation and Environment 1990, 'A fire management strategy for the Hamilton Community Parklands', Department of Conservation and Environment, Portand Region. (unpub.)
Dixon, K. 1992, 'A report of the propagation of Caladenia hastata', Report to Portland Aluminium. (Unpub.) Kings Park Botanical Gardens, Perth.
Cheney, N.P. 1981, 'Fire Behaviour', in Fire and the Australian Biota, eds. A.M. Gill, R.H. Groves & I.R. Noble, Australian Academy of Science, Canberra.
Gill, A.M. 1977, 'Management of fire prone vegetation for plant species conservation in Australia', Search vol. 8, no. 12.
Land Conservation Council. 1972, 'Study Report: South-western Area, District 1 – Review', Land Conservation Council, Victoria.
McMahon, A.R.G.; Carr, G.W.; Bedggood, S.E.; Hill, R.J. & Pritchard, A.M. 1996, `Prescribed fire and control of coast wattle (Acacia sophorae (Labill.) R.Br.) invasion in coastal heath southwest Victoria', in Fire and Biodiversity, Biodiversity Series Paper No. 8, Biodiversity Unit, Department of the Environment, Sport and Territories, Canberra.
McMahon, A.R.G. & Purdie, R.W. 1977, 'Early stages of regeneration after burning in dry sclerophyll vegetation. I. Regeneration of the understorey by vegetative means', Australian Journal of Botany, vol. 25, pp. 21-34.
Russell, R.P. & Parsons, R.F. 1978, 'Effects of time since fire on heath floristics at Wilson's Promontory, southern Australia', Australian Journal of Botany, vol. 26, pp. 53-61.
Siddiqui, M.Y., Carolin, R.C. & Myerscough, P.J. 1976, 'Studies in the ecology of coastal heath in New South Wales. III. Regrowth after fire', Proceedings of the Linnean Society of New South Wales vol. 101, pp. 53-63.
Specht, R.L. 1981, 'Responses to fires in heathlands and related shrublands', in Fire and the Australian Biota, eds. A.M. Gill, R.H. Groves & I.R. Noble, Australian Academy of Science, Canberra.
Stuwe, J. 1984, 'An assessment of basalt plains grassland sites in western Victoria', ARIER Technical report. Flora Branch. Department of Conservation, Forests and Lands.
Warcup, J.H. 1971, 'Specificity of mycorrhizal association in Australian terrestrial orchids', New Phytologist vol. 70, pp. 41-46.
Wark, M.C., White, M.D., Robertson, D.J. & Marriot, P.F. 1987, 'Regeneration of heath and heath woodland in the north western Otway Ranges following the wildfire of February 1983', Proceedings of the Royal Society of Victoria, vol. 99, pp. 51-88.
Willis, J.H. 1978, '507 species of indigenous Victorian plants which are variously rare, very localised and/or endangered', Forests Commission, Victoria. (unpub)
Wilson A.A.G. 1992, 'Assessing fire hazard on public land in Victoria: fire management needs and practical research objectives', Fire Protection Branch, Fire Research Report No. 31, Dept. Conservation & Environment, Victoria.
Wouters, M.A. 1993, 'Wildfire behaviour in heath and other elevated fuels: a case study of the 1991 Heywood fire', Fire Management Branch Research Report No. 36, Department of Conservation & Environment, Victoria.