Research by a team of Curtin University plant biologists shows Australian plants have been exposed to fire for 40 million years longer than previously thought.
Led by Banksia expert, Emeritus Professor Byron Lamont, of Curtin’s Department of Environment and Agriculture, the findings reveal Banksias have evolved in the presence of fire for 61 million years, and have developed many adaptations to cope as a result.
Professor Lamont said the significance of the findings contradicted recent claims that fire had only existed in the Australian landscape for 15-20 million years. Previously, it was thought that the 50-100 million-year-old Australian flora was only adapted to drought and poor soil conditions.
“Fossil records indicate that Banksias have been in Australia for at least 60 million years. By tracing back the evolutionary history of Banksia, as revealed by our genetic studies and fossil pollen and cone ages, we discovered that Banksias probably had the ability to retain their seeds in their cones since the very origin of the genus 61 million years ago,” Professor Lamont said.
“We examined features of Banksias that have long been considered examples of adaptations to fire, such as their ability to re-sprout after fire, the retention of seeds in woody cones that are released after fire, and the fact that many species hang onto to their dead flowers.
“If the plant dies from drought it does not release its seeds – they just rot in the cone. Therefore, a fire is essential to melt the resin that keeps the woody fruits closed, in order to release the seeds onto the post-fire seed bed that is now ideal for germination.
“Putting these findings together, we concluded that Banksias must have evolved in the presence of fire right from the time it departed from its rainforest ancestors.”
Professor Lamont said the study also revealed for the first time that many species of Banksia retained their dead leaves indefinitely, helping to provide the necessary heat for fruit opening, with ash providing nutrients for the new seedlings.
“These discoveries mean that biologists must now take seriously the possibility that fire has had a profound effect on the direction of evolution in Australia for more than 60 million years,” he said.
“It is just as important as drought and strong seasonality, high air temperatures and poor soils as limiting factors in the evolution of plants and animals.”
Professor Lamont said the discoveries opened the way for new ideas on the role of fire in shaping many features of plants and animals once they emerged from the rainforests into the typical harsh Australian environment we know today.
“Our research helps us to understand how the plants got to have the traits that they show today. But it does not mean that all species can cope with frequent fire,” he said.
“Research is still required to understand the optimal fire regime for conservation of different species. This can be critical for threatened species but there are many success stories of rare species re-appearing and flourishing after fire, supporting a general adaptation to fire in the Australian flora.”
Professor Lamont said with projected climate change outcomes, some regions of Australia would become more fire-prone and others less.
“Only an understanding of the optimal fire requirements of individual species will assist the most suitable fire management as conditions change,” he said.
Professor Lamont was made a Member of the Order of Australia in 2010 and has studied the fire ecology of Banksias for more than 30 years, making them the best understood plant group in Australia. This study was done in conjunction with two other Curtin researchers, Adjunct Senior Fellow, Dr Tianhua He and Visiting Fellow, Dr Katherine Downes.
Professor Lamont’s study was funded by Curtin’s Office of Research & Development and the Australian Research Council, with support from the Department of Environment and Conservation and Kings Park Botanic Gardens.
The results were recently published in the international plant science journal New Phytologist.
Contacts:
Professor Byron Lamont, Department of Environment and Agriculture, Curtin University
Tel: 08 9266 7784 Email: b.lamont@curtin.edu.au
Andrea Barnard, Public Relations, Curtin University
Tel: 08 9266 4241, Email: andrea.barnard@curtin.edu.au
Web: http://curtin.edu.au
