Lessons on Fire: From the Ashes of the Worst Blaze to Hit the Australian Alps since 1939, Scientists Have Seized a Rare Opportunity to Study the Nature of Fire in the High Country. Their Work Is Revealing New Understanding about Management Interventions Needed to Ensure the Continued Survival and Functioning of These Rare and Specialised Alpine Communities
Pyper, Wendy, Ecos
SOME 1.73 MILLION hectares of sub-alpine and alpine landscapes, across Victoria, New South Wales and the Australian Capital Territory, were severely burnt in January 2003 after hot, windy weather, prolonged drought and a string of lightening strikes combined to set the Alps ablaze.
Immediately after the fires, and now, as the winter snow melts, Dr Dick Williams of CSIRO Sustainable Ecosystems, Dr Henrik Wahren of the Research Centre for Applied Alpine Ecology at La Trobe University, and colleagues from Parks Victoria and the Department of Sustainability and Environment, are documenting burning patterns and intensities, and plant responses in the Victorian Alpine National Park. Similar studies are underway across the Alps, including Kosciuszko National Park (NSW) and Namadgi National Park (ACT).
'We're trying to piece together the patterns of burning, the severity of burning and the patterns of regeneration in the main treeless plant communities--the grasslands, herb fields, heathlands and bogs,' Williams says.
To document burning patterns, the group is overlaying high-resolution aerial photographs of the burnt areas with topographic and vegetation maps. Fire severity in different areas of heathland is being determined by various means, including measuring the minimum twig diameter of burnt shrubs. The smaller the minimum diameter of the burnt end of the twigs, the less severe the fire.
Patterns of regeneration are monitored by documenting how various species re-establish post-fire (whether vegetatively, or by seed, or a combination of both), and by measuring the cover and height of key species. These measurements commenced immediately post-fire, at permanently marked reference areas, and will continue for many years.
By documenting these observations, scientists will have a valuable reference tool for the future management of alpine communities, which are under pressure from a range of man-made threats including skiing, bushwalking, grazing by cattle, deer and horses, and climate change.
The work follows a long history of research in the Alps, looking at the effects of grazing by sheep and cattle, and prescribed burning (to provide green feed for livestock and reduce fuel loads). Stone 50 years of study by scientists such as Dr Alec Costin and Mr Dane Wimbush, formerly of CSIRO Plant Industry, and the late Mrs Maisie Carr and Professor John Turner of The University of Melbourne, showed that the combination of grazing and burning in alpine regions caused changes to the composition of plant communities, land degradation, and a subsequent reduction in nature conservation values, water production and water quality.
In the few years following 1958, the combined interests of the Snowy Mountains Hydroelectric Scheme and nature conservation saw a gradual end to grazing in Kosciuszko National Park. But grazing continues in other parts of the Alps, including parts of the Bogong High Plains in Victoria, where Williams and his colleagues are working.
There is continued pressure in some quarters, however, to reintroduce grazing in Kosciuszko, based on the belief that 'alpine grazing reduces blazing'. In other words, grazing reduces fuels more or less evenly across the whole of the landscape, such that in the event of fire, fire intensity is reduced. However, there is a growing body of evidence to the contrary.
Grazing and fire
Studies of other alpine fires, and fire behaviour in general, have shown that the most flammable part of the alpine landscape is the dense, closed heath communities that are dominated by unpalatable shrubs such as Prostanthem, Phebalium and Orites. These communities are usually avoided by cattle, which prefer open grassy communities where there is abundant, palatable fodder that is significantly less flammable than the shrubs.
Across the Bogong High Plains, the Victorian researchers now have the perfect natural experiment through which they can compare burning patterns and fire intensity in grazed and ungrazed areas. …