The Australian alps are the highest plateau of
land in Australia, extending from Canberra, through the Snowy Mountains
of New South Wales, and down to the Victorian Alps to the North-East of
Melbourne. They continue through to the highland of eastern Tasmania. In
the NSW area, the Alps peak at over 2000 metres - including the highest
point of the Snowy Mountain Range. Although these heights are not incredible,
with peaks throughout the South American Andes over 6000 metres, and over
8000 throughout the Asian Himalayas, they provide Australia with some variation
to the vast amounts of flat and regular terrain with an average height
of 300 metres.
The strict definition that determines an Alpine
area 'the area above a certain altitude that is treeless due to the inability
of trees to grow at low temperatures', which in Australia is usually above
1400 metres, but is often generalised to include areas under that altitude
such as montane and tableland zones under the alpine and subalpine zones.
Unerlying the upland areas of the Alpine redions are marine sediments deposited throughout the lower Palaeozoic period. These rocks have been intruded by granites and folded and uplifted to many times their current height, then worn down and dissected by different forms of erosion. The land that was uplifted to form the Alps has been greatly flattened by millions of years of erosion, and now the land is a series of plateaus, with sheer cliffs at the edges. Large amounts of erosion by continuous river flows have created a series of 'v' shaped valleys throughout the Victorian Alps. Glacial and periglacial erosion and deposition have left further imprints in the landscape. The geological landscape of the Australian Alpine ranges have an ancient history stemming back hundreds of millions of years. This is evident in various rock types and structures. This is largely contrasted to the Andes and Himalayas which are much more recent formations, as they were formed when continental plates collided, long after the separation of Gondwana.
The soil types found in the Australian Alps are
very diverse, even though the alps cover such a small area. The type of
soil found, largely depends on the gradient of the slope on which it is
located. On the gentle slopes of the subalpine zone, alpine humus loams
are the predominant soil type. In the bottom valleys draining these slopes,
bog peats are formed due to the wetter conditions and the break down of
dense layers of moisture-loving plants.
Located on the higher ridges of the alps are
the sparse sandy lothosols. The plants that occupy these upper regions
of the alps grow slowly because of the cold climate and paucity of nutrients.
Dead biomass decompose slower as bacteria and fungi prefer warmer conditions
and better nutrients in order to act as efficient decomposers.
The bright colours and array of breathtaking plant
life often blinds the unobservant eye of the incredible adaptations that
many alpine plants have had to make in order to survive such harsh conditions.
Although the plant life found at these altitudes resembles those found
in other areas of Australia, the have developed unique characteristics
to allow them to survive. The low temperatures, frost and snow prevent
plant growth throughout most of the year. Most areas of the alpine regions
will produce fairly common plant life that has adapted in order to survive
in those particular conditions. This is common in alpine regions throughout
the world as different plants are only able to survive in certain
areas of the alpine ranges. These communities can be distinguished by differences
in species, heights, growth form and structure. The most obvious change
in plant life occurs at the treeline. This is the altitude at which large
plants and trees are unable to survive, so the only plant life found are
small shrubs and ground hugging herbs.
The evolution of plant life to suit their specific
environment has caused many plants in the alpine region to become endemic.
In fact, ten percent of Australia's alpine plant life are endemic, higher
than that found in most other areas. Several evolutional adaptations have
taken place by a number of plant species. One very helpful adaptation that
most plants have made is the ability to grow rapidly. Because of the low
temperatures, plants are only able to grow during the warmer period from
November - April. Because of this short period given for growth,
the plants that adapted to be able to grow at a rapid rate, flower and
set seed during this short period of tolerable conditions. Many plants
also have the advantage of being small and ground-hugging. This allows
them to survive strong winds, and get warmth from the soil. Tall plants
have flexible stems so that they bend, instead of break, under heavy snow
cover.
These adaptations over millions of years have
given this plant life the ability to survive the harsh conditions found
at these altitudes. It has also given Australia a completely different
area of plant life other than that seen around the rest of the dry, arid
island.
Living on the lower slopes, and on the high open
plateaus of the Alps are more than forty species of native mammals, around
200 native birds, 30 of reptiles, 15 of frogs, 14 kinds of native fish
and various other species of invertebrates.
Most of the mammals are found in the lower areas
of the alpine ranges, amongst the thicker forests. Found her are the larger
browsing and grazing marsupials such as the Common Wombat, Red-necked Wallaby,
the Swamp Wallaby and the Eastern Grey Kangaroo. All are widespread around
the areas of the Alps. Tree-dwelling marsupials include the Brushtail,
Ringtail, Bubock and Eastern Grey Possum, as well as a range of gliding
possum. These, too, are fairly widespread, found in most areas of the lower
Alpine ranges. Higher up in the alps, bats are quite common. Nine species
of tree-dwelling bats can be found in the high country, including the Lesser
Long Eared Bat and the Chocolate Wattle Bat. Few colonies of cave bats
have been recorded, and fruit-eating bats are only found during the summer.
There are three main factors effecting the distribution
of reptiles around the Alps - temperatures, sunshine and basking sites,
and the availability for shelter during harsh weather periods. Some of
the highest densities of lizard communities have been recorded at
the summits of several mountains ranges, where it is not uncommon to find
large number of lizards basking on rocks in the heat of a summer day.
The fauna found at the higher elevations is not diverse compared to that of other ecosystems. Various conditions obvious conditions prohibit the life of many species, and those living there must put up with a harsh climate of low temperatures, high winds, frost and snow, a long with less variations in nutrients and food. However, some animals have developed some means in order to cope with this harsh environment. One strategy is to live entirely under the snow during the winter season. As snow falls and covers the vegetation, there is space between the ground and snow in which small animals can survive. The temperature under the snow stays constant, even though it may change significantly above in the the open areas. Another common method of survival is that of hibernation or torpor. In these cases, the body of the animal shuts down almost completely, reducing metabolism significantly, and thus reducing the need for food. At these times, only the core is kept functional. The main difference between hibernation and torpor is that hibernation is for a long period of time - usually the entire winter season, whereas torpor can be either short or long term. Many animals living in the alpine zone, particularly reptiles and amphibians, make use of these functions. Birds and flying insect are able to escape the harsh conditions completely by means of migration. Studies show that less than half of the bird species actually stay around the summit of the Alpine area during the winter period. The birds that do migrate away from the summit usually move down to the lower altitude areas. This is called altitudinal migration. Some birds actually migrate north to warmer areas of the country. All return to the high country in the summer season in order to feast on the abundant alpine vegetation and flowers that briefly appear and on insects attracted to the flowering alpine plants.
It is clear that the Australian Alpine Ecosystem
is unique in its own right, sporting various forms of life, both animal
and plant, that are endemic to Australia, and giving the continent a small
amount of variation from the huge amounts of flat planes and harsh arid
desert.