Australian Native Vegetation Assessment 2001
Maria Cofinas, Colin Creighton
National Land and Water Resources Audit, 2001
ISBN 0 642 37128 8
Major vegetation groups and their status in each State & Territory
Northern Territory
Mulga distribution patterns south of Alice Springs, NT
Photo: Murray Fagg
Key features
The Northern Territory has a diversity of vegetation that is maintained by its variety of climate and soils (Parks and Wildlife Commission, no date):
- the climate gradually moves from seasonally wet tropical in the north to arid in the south; and
- areas of rocky escarpment and plateau break a low relief landscape in the north while the south contains rocky ranges.
In the north, the vegetation is typically tropical savanna (eucalypt woodland and eucalypt open woodland with a grassy understorey). This landscape experiences dramatic seasonal changes with intense growth in the wet season (summer) and widespread fires in the dry season (winter). Famous worldwide for the tropical wetlands and rugged sandstone escarpments of Kakadu National Park the wetlands are of importance for conservation, providing breeding areas, habitat and refuge for important wildlife populations (Parks and Wildlife Commission, no date) (Figure 24, Table 19).
From the north a transition area moves from eucalypt woodlands into areas of melaleuca and acacia forests and woodlands and south into the spinifex (hummock grasslands), Mitchell grass (tussock grasslands) and acacia woodlands and shrublands. The vegetation increases in diversity around Alice Springs with areas of mulga, mallee, chenopods, hummock grasslands, small pockets of eucalypt woodlands and salt lakes.
The Northern Territory is the only area in Australia that does not have conspicuous temperate flora.
Bioregions in Northern Territory
Tiwi-Cobourg
This bioregion has gently sloping terrain and includes the mainland Cobourg Peninsula and the Tiwi Islands. It is within the tropical monsoonal north of Australia, with a distinct wet dry season and high temperatures throughout the year.
- Dominated by eucalypt open forests and smaller areas of tropical eucalypt woodlands/grasslands and mangroves.
- Patches of rainforest and vine thickets, acacia shrublands, samphire shrublands, melaleuca forests and woodlands and grasslands occur.
Major land uses are traditional Indigenous uses and nature conservation.
Arnhem Coast
This bioregion has gently undulating plains and low plateaus and is within the tropical monsoonal north of Australia, with distinct wet and dry seasons, and high temperatures throughout the year. It includes the northern Arnhem coast and Groote Eylandt.
- Dominated by eucalypt open forests and tropical eucalypt woodlands/grasslands.
- Patches of mangroves, melaleuca forests and woodlands and the grasslands group occur.
The major land use is traditional Indigenous use.
Darwin Coastal
This bioregion has gently undulating plains and is within the tropical monsoonal north of Australia, with a distinct wet dry season and high temperatures throughout the year. It includes the city of Darwin.
- Dominant vegetation is eucalypt open forests, tropical eucalypt woodlands/grasslands, melaleuca forests and woodlands and grasslands group on the floodplains.
- Patches of the mangroves group and other shrublands are present.
Major land uses are traditional Indigenous uses, nature conservation (including parts of Kakadu National Park and World Heritage Area and Litchfield National Park), urban and other intensive uses and grazing. Approximately 85,000 hectares have been cleared.
Pine Creek
This bioregion consists of hilly to rugged terrain and is within the tropical monsoonal belt of northern Australia.
- Dominant vegetation is tropical eucalypt woodlands/grasslands with some eucalypt open forests, melaleuca forests and woodlands and rainforest and vine thickets.
The region has undergone some localised clearing and the major land uses are grazing, nature conservation (including parts of Kakadu National Park and World Heritage Area and Litchfield National Park), traditional Indigenous uses and other intensive uses including horticulture.
Arnhem Plateau
This bioregion consists of rugged dissected terrain and plateaus and is within the tropical monsoonal belt of northern Australia.
- Dominant vegetation is eucalypt woodlands and open woodlands (spinifex understorey) with some eucalypt open forests and rainforest and vine thickets.
Major land uses are traditional Indigenous uses and nature conservation (including parts of Kakadu National Park and World Heritage Area).
Central Arnhem
This bioregion consists of gently sloping terrain and low hills and is within the tropical monsoonal belt of northern Australia.
- Dominant vegetation is tropical eucalypt woodlands/grasslands and eucalypt open forests.
- Smaller patches of eucalypt woodlands, melaleuca forests and woodlands and samphire shrublands on the coast are present.
The major land use is traditional Indigenous use.
Near Adelaide River, NT
Photo: Murray Fagg
Daly Basin
This bioregion consists of gently undulating plains and scattered low plateau remnants and has a tropical monsoonal climate with distinct wet and dry seasons and high temperatures throughout the year.
- Dominant vegetation is tropical eucalypt woodlands/grasslands and eucalypt open forests.
- Smaller patches of eucalypt woodlands and melaleuca forests and woodlands are present.
The major land use is grazing on native pastures and traditional Indigenous uses with some horticulture, grazing on modified pastures and nature conservation. The region has undergone some clearing (approximately 167,000 ha) for these developments.
Victoria Bonaparte
This region extends into Western Australia and consists of a number of basins and the interior is dominated by the Victoria River Plateau, a large highly dissected plateau up to about 350 m above sea level. It has a dry winter, warm monsoon climate.
- Dominant vegetation is tropical eucalypt woodlands/grasslands, eucalypt open woodlands, tussock grasslands, eucalypt woodlands and melaleuca forests and woodlands.
- Small patches of eucalypt open forests and samphire shrublands on the coast occur.
The major land use is grazing on native pastures, traditional Indigenous uses and nature conservation.
Ord-Victoria Plains
This bioregion extends into Western Australia and consists of level to gently undulating plains with scattered hills and a climate that is dry, hot and tropical with summer rainfall.
- Dominant vegetation is eucalypt and open woodlands, hummock and tussock grasslands, other forests and woodlands (Terminalia and Lysiphyllum spp.) and small areas of acacia shrublands.
Major land uses are cattle grazing and some nature conservation (e.g. Gregory National Park).
Sturt Plateau
This bioregion consists of gently undulating plains with a hot, summer rainfall climate.
- Dominated by eucalypt woodlands, acacia forests and woodlands (including lancewood-Acacia shirleyi), hummock grasslands, eucalypt open woodlands.
- Small patches of melaleuca forests and woodlands, other forests and woodlands, acacia shrublands and tussock grasslands occur.
Major land uses are traditional Indigenous uses and cattle grazing.
Gulf Fall Uplands
This bioregion falls mainly in the Northern Territory with a very small part in Queensland. It consists of undulating terrain with scattered low steep hills and a dry, hot, summer rainfall climate.
- Dominant vegetation is eucalypt woodlands in the north and eucalypt open woodlands in the south with small pockets of melaleuca and acacia and other forests and woodlands.
Major land uses are cattle grazing and traditional Indigenous uses.
Mitchell Grass Downs
This bioregion extends into Queensland and consists of undulating plains with deep heavy clay soils and a hot arid climate.
- Dominant vegetation is tussock grasslands and eucalypt open woodlands in the north with small areas of chenopod shrublands, hummock grasslands, acacia open woodlands and low closed forests and woodlands.
Major land uses are cattle grazing (with much of the region dependent on the underlying Great Artesian Basin for water) and some nature conservation.
Davenport Murchison Ranges
The bioregion is characterised by a chain of rocky ranges and a hot and dry climate.
- Dominant vegetation is eucalypt open woodlands and mallee woodlands and shrublands, with acacia open woodlands, acacia shrublands and hummock grasslands in the south.
Major land uses are grazing, traditional Indigenous uses, minimal use (vacant crown land) and some nature conservation.
Tanami Desert
This bioregion extends into Western Australia and consists of hills and ranges with sand plains and a hot arid climate with summer rain.
- Dominant vegetation is hummock grasslands (Triodia spp.) with small areas of eucalypt open woodlands, tussock grasslands, low closed forests and closed shrublands, salt lakes, acacia shrublands and mallee communities.
Major land uses are traditional Indigenous uses, grazing and some minimal use and nature conservation (Puurta Co-Management Area).
Great Sandy Desert
This bioregion extends into Western Australia and includes extensive sand plains, dune fields, lakes and remnant rocky outcrops with a hot, arid climate. The monoliths Uluru and Kata Tjuta are in the very south-east of the bioregion.
- Dominated by hummock grasslands with small areas of acacia shrublands, low closed forest and closed shrublands, lakes (Lake Neale and Lake Amadeus), eucalypt open woodlands and chenopod shrublands.
Major land uses are traditional Indigenous uses, grazing and nature conservation (including the Uluru-Kata Tjuta National Park and World Heritage Area).
Burt Plain
This bioregion consists of plains and low rocky ranges with an arid climate.
- Dominant vegetation is acacia shrublands and open woodlands, and mallee woodlands and shrublands.
- Small areas of eucalypt open woodlands occur in drainage depressions.
The major land use is cattle grazing with some traditional Indigenous uses.
Channel Country
This bioregion extends largely into Queensland and South Australia with a small area in New South Wales. It is characterised by low hills and braided river systems with an arid climate that has very dry, hot summers and short, dry winters.
- Dominated by acacia open woodlands with some acacia shrublands, mallee communities, hummock grasslands and eucalypt open woodlands in the drainage depressions.
The major land use is cattle grazing.
Simpson-Strzelecki Desert
This bioregion extends into South Australia with small areas in Queensland and New South Wales. It consists of arid dune fields and sand plains.
- Dominant vegetation is hummock grasslands with mallee woodlands and shrublands, chenopod shrublands, acacia open woodlands and eucalypt open woodlands in the north.
Major land uses are grazing, minimal use (vacant crown land) and traditional Indigenous uses.
Finke
This bioregion extends into South Australia and consists of arid sand plains, dissected uplands and valleys with a hot arid climate.
- Dominated by hummock grasslands, chenopod shrublands and acacia shrublands.
- Small areas of acacia open woodlands and eucalypt open woodlands occur.
The major land use is cattle grazing.
MacDonnell Ranges
This bioregion consists of high relief and foothills with an arid climate modified by the presence of the mountain ranges.
- Dominated by hummock grasslands and acacia shrublands with small areas of acacia open woodlands and eucalypt open woodlands.
Major land uses are traditional Indigenous uses, nature conservation (including the Finke Gorge and West MacDonnell National Parks) and cattle grazing.
Central Ranges
This bioregion extends into Western Australia and South Australia and consists of ranges and sand plains and has an arid climate.
- Dominated by hummock grasslands, chenopod shrublands, acacia shrublands and mallee woodlands and shrublands.
The major land use is traditional Indigenous uses.
| Major vegetation group | Present | Pre-European |
|---|---|---|
| Hummock grasslands | 490,232 | 490,363 |
| Eucalypt open woodlands | 175,775 | 175,842 |
| Eucalypt woodlands | 123,078 | 123,992 |
| Tropical eucalypt woodlands/grasslands | 107,254 | 109,430 |
| Acacia shrublands | 86,035 | 86,272 |
| Tussock grasslands | 83,613 | 83,678 |
| Eucalypt open forests | 58,471 | 59,346 |
| Acacia open woodlands | 48,703 | 48,814 |
| Mallee woodlands and shrublands | 35,450 | 35,450 |
| Chenopod shrubs, samphire shrubs and forblands | 33,753 | 33,757 |
| Acacia forests and woodlands | 29,866 | 30,442 |
| Other forests and woodlands | 29,497 | 29,508 |
| Melaleuca forests and woodlands | 19,244 | 19,402 |
| Other grasslands, herblands, sedgelands and rushlands | 7,633 | 7,666 |
| Mangroves, tidal mudflats, samphires and bare areas, claypans, sand, rock, salt lakes, lagoons, lakes | 5,410 | 5,551 |
| Other shrublands | 5,294 | 5,473 |
| Rainforest and vine thickets | 977 | 978 |
| Eucalypt low open forests | 70 | 70 |
| Note: * in order of greatest to smallest area. | ||
Vegetation change
The Northern Territory has the most intact native vegetation of all States and Territories. It has not been significantly affected by intense land use pressure. Approximately 0.60 million hectares of native vegetation has been removed, but this is limited to a few areas, mainly associated with the Daly Basin, Darwin Coastal, Pine Creek and Sturt Plateau bioregions in the north and the MacDonnell Ranges bioregion in the south. Major vegetation groups affected are the tropical eucalypt woodlands/grasslands, eucalypt open forests and other eucalypt woodlands and acacia forests and woodlands.
Agricultural expansion is proposed or underway in some regions and a large proportion of the Territory is grazed. Careful land use planning will ensure that many values of the existing vegetation are conserved and that land uses are sustainable.
An assessment of landscape health in the Northern Territory including factors of clearing, grazing, feral animals and weeds provides a summary on a subregional basis of the landscape stresses (NLWRA 2001c).
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