by Laura Kent
The Australian alpine area is the only region in Australia where snow falls annually. It includes the Snowy Mountains in south-east NSW and the Victorian Alps in north-east Victoria. The Alps include Australia’s highest mountain, Mt Kosciuszko and support many unique and endemic species that are being threatened by climate change.
The alpine area is split into different zones based on the distribution of vegetation. The alpine zone is at the highest elevation and is separated from the subalpine zone by the tree line. The tree line is the highest elevation that sustains tree growth and is around 1,800 metres high in Australia. The tree line is mainly defined by the gradual disappearance of snow gums which are a type of native Eucalyptus that can withstand the severe cold and dry conditions of the mountains.
ANU has a long history of pioneering research into alpine trees. The Australian alpine zone is easier to study and is unique as the plants must withstand a greater variation in temperature. In the 1970s Professor Ralph Slatyer investigated the ecology and distribution of alpine trees in the Snowy Mountains. Slatyer showed how the snow gums were adapted to the cold climates and showed that plants at different elevations grew at different optimal temperatures. He also illustrated how the rate of photosynthesis changed depending on the temperature not the altitude suggesting temperature was an important factor for the distribution of alpine trees. The work at ANU was used to show that the tree line was defined by temperature, not altitude, which explains why Australia has a lower tree line than most other countries.
Recently Adrienne Nicotra and her team have continued the work began by Professor Slatyer by studying the effects of climate change on alpine plants. Alpine areas are vulnerable to climate change which threatens biodiversity and the abundance and distribution of alpine plants and it is important to study whether these plants can adapt to a changing environment.