Australian Alps Montane Grasslands

• Category: Grassland, Tundra, and Human Biomes
• Geographic Location: Australia
• Summary: This mountainous ecoregion, which is threatened by periodic bushfires, is home to numerous unique species.

The Australian Alps montane grasslands ecoregion consists of the high-elevation lands in the Australian Alps mountain ranges in southeastern mainland Australia. The highest point in the ecosystem is the peak of Mount Kosciuszko in the Snowy Mountains at 7,310 feet (2,228 meters). The highest mountains in Australia, the Australian Alps are the southeastern section of the continent's Great Dividing Range. This range runs for 373 miles (600 kilometers) from the Brindabella Ranges near Canberra along the borders of the Australian Capital Territory, New South Wales, and Victoria. Ranges in the Australian Alps include the Snowy Mountains in New South Wales, the Victorian Alps in Victoria, and the Brindabella Ranges in the Australian Capital Territory. The higher mountains are especially cold. Kosciuszko is snow-covered most of the year. Outside of Tasmania, the montane region is the only part of Australia where deep snow occurs regularly. The montane grasslands are surrounded by the Australian temperate forests at lower elevations below 3,609 feet (1,100 meters), called the tableland.

Despite the name, the Australian Alps are neither as high nor nearly as steep as the European Alps, and most peaks can be reached on foot without specialized mountaineering or rock-climbing equipment. There are few permanent human settlements in the Alps, apart from the ski resorts and the town of Cabramurra in the Snowy Mountains Scheme. Though the Alps constitute less than one percent of Australia's landmass, they receive about a quarter of the country's rainfall and supply the water for nearly half of the population. The eastern slopes' runoff is diverted into the Murray and Murrumbidgee Rivers through the Snowy Mountains Scheme.

Bushfires

Australia is predominantly hot and dry, and though the Alps are less so, they are still prone to frequent bushfires. Bushfires have almost completely burned the Victorian Alps on several occasions. Several of the fires ae infamous, namely the "Black Thursday" fire of 1851, the "Black Friday" fire of 1939, fires in 2003, 2006 to 2007, 2009's "Black Saturday" fire, and 2019–20 fires referred to as "Black Summer." Studies between 2020 and 2023 show the 2019-20 Black Summer bushfires were particularly devastating for the Alps region, as they burned approximately eighty percent of the Australian Alps National Parks. Research indicated the combination of prolonged drought, higher temperatures, and more frequent extreme weather events led to slower vegetation recovery rates compared to historical patterns. Scientists also documented concerning changes in snow cover duration and depth. The average snow season shortened by about two weeks since the 1950s, affecting both endemic species and the region's crucial role in water supply. However, several eucalypt and banksia species depend on bushfire events to cause their seed pods to open before germination. The fires also encourage the growth of new plants throughout the grasslands.

But the fires were often catastrophic. The 2003 fires destroyed two-thirds of the pasture, forest, and nature parks in the Australian Capital Territory and spread into the suburbs of Canberradestroying 500 homes and killing four people. The Black Saturday bushfires were the deadliest in Australian history, killing 173 people and injuring hundreds more. More than one million acres (404,686 hectares) of land were burned and 12,000 head of livestock killed. More than a million wild animals were estimated to have been killed, and the only known habitat of Leadbeater's possum was burned. A great many surviving animals were seriously injured and may have died later as a resultlarge numbers of kangaroos were burned while traveling through smoldering grasslands.

With the acceleration of global warming, conservationists have posited whether the greater frequency and intensity of bushfires in the region in recent years are in part fueled by the drying effects of various climate change factors. As the toll of such events includes flora, wild fauna, and increasingly human lives and property, action to protect the biological infrastructure of the Australian Alps is a focus. It is noted, for example, that reduction of plant root systems can contribute to looser soil structure and thus exacerbate erosion and intensify flood damage, yet another concern.

Flora

The ecoregion is home to 1,400 higher plant species, sixty-six of which are endemictwenty-six of which are specifically evolved to the subalpine and alpine bands. The ecoregion is a mix of grassland, heath, and bog, divided into montane, subalpine, and alpine bands in ascending order of elevation. Different trees flourish at different elevationsthe mountain ash (Eucalyptus regnans) and alpine ash (E. delegatensis) in the montane band, and the snow gum (E. pauciflora) and black sallee (E. stellulatea) in the subalpine. Above the tree line in the alpine band, the dominant species is a species of snow grass (Poa), growing along with shrubs like orites, Grevillea, Prostanthera, and Hobea.

Alpine vegetation grows no more than three feet (one meter) high, with tall herbs growing in rich humus soil. The only alpine conifer in Australia is the mountain plum pine (Podocarpus lawrencei). Stream beds are populated by sphagnum bog communities. Little light reaches the forest floor, so the understory is sparser than in other montane forests. The alpine plants are well adapted to the cold climate and winter drought. Caltha introloba flowers under the snow, while others form floral buds during the fall and flower as soon as the snow has melted. Few alpine plants produce seeds as germination and taking root is too difficult in the cold, hard soil. Instead, they grow from rhizomes, root nodes, or bulbs.

Fauna

Endemic wildlife in the region includes the mountain pygmy possum (Burramys parvus), the corroboree frog (Pseudophryne corroboree), and the alpine thermocolor grasshopperwhich changes hue like a chameleon. Both the possum and the corroboree frog are two of the very few alpine endemics and are found strictly in the alpine areas. The possum is also the only marsupial to hibernate for long periodsits method of dealing with the long winter.

The Baw Baw Plateau in the Victorian Alps is home to the Baw Baw frog (Philoria frosti), which is found nowhere else. Other notable species in the high elevations include the red cryptic treefrog (Litoria paraewingi), Spencer's treefrog (L. spenceri), dendy toadlet (Pseudophryne dendyi), and Maccoy's elf skink (Nannoscincus maccoyi). In the montane bands, there are red-necked wallabies (Macropus rufogriseus), swamp wallabies (Wallabia bicolor), tiger quolls (Dasyurus maculatus), platypuses (Ornithorhynchus anatinus), and various species of wombats (Vombatus). The montane woodlands support large breeding populations of flame robins and pilotbirds, and have been classified by BirdLife International as an Important Bird and Biodiversity Area (IBA).

Bibliography

Costin, A. B. “The High Mountain Vegetation of Australia.” Australian Journal of Botany, vol. 5, no. 2, 1957.

Gibson, David J. Grasses and Grassland Ecology. Oxford University Press, 2009.

Johnston, Frances M. and Catherine Pickering. “Alien Plants in the Australian Alps.” Mountain Research and Development, vol. 21, no. 3, 2001.

Davis, E., et al. "Ecological Impacts and Management Implications of the 2019-20 Megafires for Australian Alpine Plants." Australian Journal of Botany, vol. 71, no. 1, 2023, pp. 1-15. Accessed 9 Nov. 2024.

Di Virgilio, G., et al. "Climate Change Increases the Potential for Extreme Wildfires." Geophysical Research Letters, vol. 47, no. 17, 2020, pp. 1-9. Accessed 9 Nov. 2024.

Gallagher, R. V., et al. "High Fire Frequency and the Impact of the 2019-2020 Megafires on Australian Plant Diversity." Diversity and Distributions, vol. 27, no. 7, 2021, pp. 1166-79. Accessed 9 Nov. 2024.