Dick Williams, Charles Darwin University and James Camac
Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane.
Think of an Australian landscape and you’re unlikely to picture snow-capped mountains or alpine meadows. But that’s what you’ll find atop the peaks of the country’s southeastern corner.
Although relatively small – covering about 11,000 square kilometres or 0.15% of the continent – these alpine and subalpine ecosystems have outstanding natural value and provide billions of dollars’ worth of benefits to the nation each year.
They are in comparatively good health but are facing numerous threats. However, their health in decades and centuries to come will depend largely on how we deal with these threats now.
Australia’s main alpine and subalpine areas are the Snowy Mountains in New South Wales, the Bogong High Plains in Victoria, and central and southwestern Tasmania. They occur above about 1,400-1,500m on the mainland, and 700-1,000m in Tasmania.
Although Australia’s mountains are relatively low by global standards (Mt Kosciuszko, the continent’s highest peak, rises only 2,228m above sea level), there is true treeless, alpine vegetation above the climatic treeline.
Treeless patches may also occur in the high subalpine zone, just below the treeline, typically on rolling high plains where accumulations of cold air or water prevent trees from establishing and growing.
The alpine climate is cold, wet, snowy and windy, with a short growing season. The soils are highly organic and can hold tremendous amounts of water. Alpine plants are short: mostly tussock-forming snow grasses, rosette-forming herbs such as snow daisies, and ground-hugging shrubs.
The dominant plant communities are grasslands, herbfields, heathlands and wetland complexes rich in peat moss (Sphagnum). The animals are mostly invertebrates such as moths, grasshoppers and ants.
The Australian Alps are hugely important for conservation, water production and recreation. Most alpine areas are within national parks and are home to many unique plants and animals.
There are about 700 native alpine plant species on the mainland, while some animal species are extremely rare – there are only about 2,000 mountain pygmy possums in the wild.
Major rivers – such as the Murray, the Murrumbidgee and the Snowy – begin in the Alps. Water from alpine catchments is worth A$9.6 billion a year to the Australian economy.
Millions of people visit every year to camp, walk, ski, ride and take in the scenery. The Alps are one of Tourism Australia’s “National Landscapes” and the local tourism industry is worth hundreds of millions of dollars annually.
The alps also have a rich history of scientific study, dating back to celebrated botanist Sir Ferdinand von Mueller in the 1850s. Pioneers of Australian alpine ecology, Alec Costin and Maisie Carr, established some of the earliest study sites. Research continues to this day and now includes international climate science projects such as the International Tundra Experiment and the Global Research Initiative in Alpine Environments.
These scientific discoveries about alpine flora and fauna, and the factors that affect them, have directly informed land management practices.
We now know that high levels of vegetation cover are needed to protect alpine catchments; that livestock grazing damages alpine ecosystems; how to better implement cost-effective weed control; how to better manage small Mountain Pygmy Possum populations; and that large, infrequent fires do not necessarily cause “ecological disaster”.
Existing and emerging threats
Alas, the alps face multiple threats, including global warming, invasive species, disturbances such as fire, increasing pressure from human recreation, and unsound ideas about how to manage the high country.
The climate has already changed. Since 1979, average temperatures during the growing season on the Bogong High Plains have risen by 0.4℃, while precipitation has decreased by 6%. Since 1954, the depth and duration of the snowpack in the Kosciuszko region have declined.
Rising temperatures are a serious problem because the Australian Alps are relatively low mountains and the alpine species, already at their distributional limits, have nowhere else to go. Woody vegetation may increase – the treeline may rise and shrubs are likely to expand into grasslands and herb fields, which may make the landscape more prone to fire.
Mainland alpine ecosystems can regenerate after large fires. But Tasmania’s alpine vegetation is extremely fire-sensitive, and more frequent fire is likely to be detrimental to all alpine ecosystems.
The threat of livestock grazing to alpine ecosystems has all but ceased. However, feral animals and plants are a clear threat and will become more difficult to manage in the future without concerted action now.
Horse and deer numbers are increasing with alarming speed. These animals are occupying habitats well above the treeline. Many alien plant species have invaded the alps over the past half-century, a trend likely to be exacerbated by climate warming.
We also need to be wary of maladaptive ideas and practices, particularly those concerning the putative benefits to the alps of large non-native grazing animals. We have variously been told that “alpine grazing reduces blazing” (it doesn’t); that grazing combined with burning has “actually prevented soil erosion” (it didn’t); and that a “sustainable, viable” feral horse population can “co-exist” with the alpine environment (surely an oxymoron). There may be strong cultural imperatives behind these propositions, but they have no basis in science.
There is cause for hope, however. The Australian Alps are on the National Heritage List, which is protected by federal law.
There is also still time. The world is acting on climate change. Some species may adapt genetically, while some likely changes to vegetation may happen slowly. Scientists and land managers are working together to anticipate and manage change in the alps.
Change is inevitable, but with enough research, imagination and action, our high country will provide Australians with high-value environmental benefits for generations to come.
Are you a researcher who studies an iconic Australian ecosystem and would like to give it an EcoCheck? Get in touch.
Dick Williams, Adjunct Professorial Fellow, Research Institute for the Environment and Livelihoods, Charles Darwin University and James Camac, Postdoctoral Research Fellow
This article was originally published on The Conversation. Read the original article.