This bioregion is characterised by spectacular high relief ranges and foothills, of diverse geology (mostly sedimentary rocks in the Amadeus Basin and crystalline metamorphic rocks in the Arunta Block). These ranges enclose some broad plains and watercourses. Soils are generally skeletal or shallow sands on the rocky hills, with earthy sands and deep loamy alluvium on the lowlands. The dominant vegetation types are spinifex hummock grassland, sparse Acacia shrublands and woodlands along watercourses. The bioregion includes 3 subregions.
The MacDonnell Ranges Bioregion is one of the most important refugial areas in arid Australia, supporting many endemic plant taxa and isolated occurrences of plants more typically associated with higher rainfall areas (often referred to as relictual plants). It also supports resident populations of some plant and animal species that are significant at the Northern Territory and national level, including a number of invertebrate land snails which are currently listed as threatened in the Northern Territory. From a national perspective, there are a number of invertebrate species which are endemic to the bioregion along with 25 plant taxa, including Acacia undoolyana, Actinotus schwarzii, Livistonia mariae subsp. mariae, Olearia macdonnellensis, Ricinocarpos gloria-medii and Wrixonia schultzii, all of which are listed as vulnerable both nationally and in the Northern Territory. Many ecosystems and species are highly localised, typically to the most fire-protected, topographically complex sites (such as gorges and escarpments), and/or to places with unusually persistent moisture availability.
Summary of overall condition and trend
The bioregion is generally in good condition, but this is being eroded by continuing increases in the extent, incidence or abundance of weeds, exotic animals (especially rabbits, foxes, cats, house mice), livestock and broad-scale changes in fire regime. There are localised areas of heavy impact associated with the urban area of Alice Springs and with tourism.
Subregions of the MacDonnell Ranges Bioregion are scored a continental stress class of 4 (MAC3) and 5 (MAC1, MAC2).
Summary of priority management/conservation priorities
The bioregion is generally well reserved (approximately 14% of bioregional extent), with particularly good representation of the rugged mountain and hill environments. A recent addition of some areas in the more fertile lowlands has to some extent enhanced the comprehensiveness of the reserve system in the bioregion. Wetlands
Nationally important wetlands
- This bioregion includes the small (10 ha) but nationally significant wetland of the Finke River headwater gorge system (NT002: wetland type B1), an important set of perennial waterholes within the rugged ranges. Most of this system is within the West MacDonnnell National Park, and is in good condition. Tourism may be having minor local effects.
Other wetlands of subregional significance
- There are many other waterhole and gorge systems within the mountain systems of this bioregion which are of local and regional significance in this arid system. The ranges form the headwaters of many ephemeral or intermittent river systems. There are also floodout and swamp areas, including Ilparpa Swamp near Alice Springs. Well-protected moist areas are especially significant as refuge areas, with the most notable of these being Palm Valley.
For more information on arid wetlands of the NT refer to our arid wetlands page.
Major river systems arising in this bioregion include the Finke, Todd, Hugh and Hale Rivers. Riparian condition is variable. The lowland sections of many riparian areas are subject to substantial invasion by weeds (particularly buffel grass), and trampling and other damage by livestock or feral animals. Within the mostly reserved ranges, the upper reaches of most river systems are well protected and in good condition.
Ecosystems at risk
No ecosystem in this bioregion has formally been listed as threatened, but there has been some decline in some environments, particularly fire-sensitive habitats (e.g. some mulga woodlands) and those that are vulnerable to the impacts of exotic plants (buffel grass and couch grass) and feral animals (e.g. wetlands, riparian areas).
Species at risk
Many species have been lost from this bioregion over the last 150 years. Of those that persist, 48 species are currently listed as threatened at National and/or Territory level including 14 plants, 1 fish (finke goby Chalmydogobius japalpa) and 21 invertebrates (land snails and the desert sand skipper Croitana aestiva), many of which occur as highly localised populations.
Threatened species include slater’s skink, central rock-rat and southern marsupial mole (Endangered at the Federal level); Acacia undoolyana, Actinotus schwarzii, Eremophila sp. Rainbow Valley (T.S. Henshall 1181), Livistonia mariae subsp. mariae, Macrozamia macdonnellii, Minuria tridens, Olearia macdonnellensis, Ricinocarpos gloria-medii, Thryptomene hexandra, Wrixonia schultzii, red goshawk, princess parrot, mulgara and black-footed rock-wallaby (Vulnerable at the Federal level); Baumea arthrophylla, Bolboschoenus caldwellii and common brushtail possum (Endangered at the NT level); and Adiantum capillus-veneris, Eleocharis papillosa, bustard, emu, painted snipe, long-tailed dunnart and finke goby (Vulnerable at the NT level).
Amongst these threatened species, predation is probably an important threat for the bustard, central rock-rat, mulgara, southern marsupial mole, black-footed rock-wallaby and common brushtail possum; changed fire regimes for Acacia undoolyana, Livistonia mariae subsp. mariae, Minuria tridens, Olearia macdonnellensis, Ricinocarpos gloria-medii, Wrixonia schultzii, bustard, emu, princess parrot, slater’s skink, central rock-rat, mulgara, common brushtail possum and long-tailed dunnart; grazing impacts by livestock and/or feral animals for the bustard, emu, princess parrot, slater’s skink, central rock-rat, mulgara, common brushtail possum, long-tailed dunnart and black-footed rock-wallaby; weed infestation for Livistonia mariae subsp. mariae, Eleocharis papillosa, Minuria tridens, Thryptomene hexandra, slater’s skink and long-tailed dunnart; and changes in wetlands across its entire range for the painted snipe.
Number of taxa in the MacDonnell Ranges Bioregion currently listed as threatened at national and/or Northern Territory level (excluding invertebrates and fish) (nb this table includes only species definitely recorded from the bioregion (rather than putative occurrences based on modelling) and presumed to be still extant in the bioregion).
There is also some evidence that there is broad scale decline affecting at least some groups of mammals and birds in this bioregion, in addition to those species currently listed as threatened.
Other flora values for eucalypts and acacias
- At a national level, the subregions of the MacDonnell Ranges Bioregion contain no endemic eucalypts and three endemic acacias: Acacia dolichophylla from MAC1, Acacia sp. Krichauff Range (A. Soos 241) from MAC2, and Acacia undoolyana from MAC3. Of these taxa, high frequency and intensity of fire is thought to pose a major threat to A. undoolyana and A. sp. Krichauff Range (A. Soos 241).
- The subregions contain moderate richness of Acacia (30-47 species) and Eucalyptus (21-36 species).
The most noticeable trends in status over the period of the two bird Atlases was the increase of several exotic birds (barbary dove, spotted turtle-dove, rock dove) around Alice Springs, with some expansion away from the town fringes. There was also some increase in abundance for native granivorous birds, probably because of relatively good seasons during the second Atlas period. There are longer-term indications of regional loss of some native bird species (such as night parrot) and declines for several others.
The MacDonnell Ranges Bioregion has suffered substantial losses of its mammal fauna. Of 53 native mammal species recorded, at least 16 are extinct or no longer occur in the bioregion, while several others have suffered population declines.
The proportion of land reserved in this bioregion is relatively high, but the system could be enhanced by more equitable representation of the valley areas.
Off park conservation for species and ecosystem recovery
Some off-reserve initiatives (e.g. exclosure fencing of natural waterholes and wetland areas) are possible on pastoral lands. Many of the threatened species present in the bioregion are affected by the same processes, such that control of these (principally weeds, feral animals and fire) will benefit many species simultaneously.
The most important NRM priorities are for integrated (cross-tenure) control of weeds and feral animals, and alteration of the prevailing fire regime to decrease the incidence of extensive hot fires.
Further Information and Gaps
Major data gaps and research priorities for bioregion
There are some unusually detailed biodiversity data sets available for this region, including very fine-scale environmental mapping of reserved areas. However, bioregional conservation management would also benefit from more detailed vegetation mapping beyond reserved areas, at the scale of 1:100,000 or better.
There has been some biodiversity monitoring in this bioregion, especially in relation to threatened species on reserves (e.g. Acacia undoolyana, Livistona mariae subsp. mariae, central rock-rat, black-footed rock-wallaby), the occurrence of fire, and the distribution and abundance of some feral animals and weeds across the broader landscape. These programs could be enhanced.