The clues to saving alpine plants from rising temperatures and more frequent bushfires may be hidden away in lake sediments near Kosciuszko.
Climate scientists, biologists, and engineers from the University of New South Wales (UNSW) in Sydney studied a core sample from the bottom of Club Lake that gave them a snapshot of the climate and environment in the area over the past 3500 years.
Grains of pollen at different depths in the sample reveal what sort of plants were growing nearby and how fast changes in vegetation occurred. Small particles of charcoal indicate fire activity.
The study shows that there was a dramatic warming event 1600 years ago stretching across six centuries. Much like today, this was also characterised by an increase in regional fire activity and shift of vegetation to higher altitudes.
Study lead author Dr Zoë Thomas says the insights from the past can help governments, environmental agencies and scientists come up with effective strategies to protect the native plant species of the Australian Alps.
“When the climate suddenly warmed about 1600 years ago, we saw a decline in alpine plants such as herbs and shrubs and an increased abundance of trees, particularly eucalyptus. This also coincided with more fire activity,” said Dr Thomas.
The models predict that today’s temperatures are expected to rise by at least one degree Celsius, while snow cover will substantially diminish over the next two decades.
Dr Thomas said this puts the area on a similar trajectory to 1600 years ago. But this time around, thanks to a century of grazing and in recent times, the impact of tourism, that could lead to the extinction of several alpine plant species.
One such example is a type of snow daisy – Craspedia costiniana – commonly known as ‘Billy-buttons’, which are noticeable for their vibrant yellow rosette of tiny flowers.
“As the temperature warms, tree lines move to higher elevations, shifting the alpine species higher still. But at some point they can go no higher – they’re basically squeezed out of their niche, and it’s not just plants but animals too which are affected.”
By reconstructing the climate, environment and bushfire activity of the last 3500 years, researchers were able to identify the potential fire and vegetation responses that may occur in the future in these vulnerable alpine areas.
“You only need to look at the bushfires that swept through some of these regions a little over a year ago to get a sneak peak of what’s to come,” Dr Thomas says.
Restoration programs over the last half-century have aimed at revitalising the natural vegetation in the Kosciuszko National Park following the effects of grazing – banned in 1967 – and the environmental damage caused by the Snowy River Hydro-Electric Scheme. More recently, the federal government has thrown $3.4m towards recovery from the bushfires.
Dr Thomas says lakes such as Club Lake offer scientists excellent opportunities to study the past with an eye to preparing for the future.
“Lakes are great at recording data because they form a seal over the sediments underneath that are less likely to be disturbed. Lake sediments are used all over the world as indicators of climate and environmental change because the way they trap the material makes it easier to study those sediments.”
Club Lake was so-named because of its resemblance to the club suit in a deck of cards. It is one of four ‘cirque’ lakes on mainland Australia which was created by glaciers as they carved new valleys out of the mountain landscape during the last ice age.
Club Lake might only be small and less than two metres deep, but it turns out the truths it hides go much deeper.