Sturt Plateau

Bioregional Description

The Sturt Plateau bioregion mostly comprises a gently undulating plain on lateritised Cretaceous sandstones. Soils are predominantly neutral sandy red and yellow earths. The most extensive vegetation is eucalypt woodland (dominated by variable-barked bloodwood Eucalyptus dichromophloia) with spinifex understorey, but there are also large areas of lancewood (Acacia shirleyi) thickets, bullwaddy (Macropteranthes keckwickii) woodlands, Acacia shrublands on deep sands, and eucalypt open forests (dominated by a range of species including Darwin stringybark Eucalyptus tetrodonta) over tussock grass understorey. The bioregion is divided into 3 subregions.

Special values

The Sturt Plateau bioregion includes the most extensive areas of the distinctive lancewood-bullwaddy vegetation associations, with associated fauna including spectacled hare-wallaby. There are a range of small wetlands associated with sinkholes and minor depressions in the generally flat landscape.

• Summary of overall condition and trend
   
  Most of the bioregion is generally in moderate to good condition, due at least in part to the lack of intensive development. There are pervasive, but generally minor impacts associated with weeds, feral animals, pastoralism and changed fire regimes. All 3 subregions are rated as continental stress class 5.
• Summary of priority management/conservation priorities
   
  Notwithstanding the recent establishment of a conservation reserve selected to include lancewood-bullwaddy associations, the existing reserve system is meagre and does not include representation of the range of environments within the bioregion. Additional reservation could greatly enhance this system.
  
  At least as important is the enhancement of integrated management of weeds, feral animals, and fire. The bioregion is targetted for intensification of development, including subdivision of existing pastoral properties, horticultural development, and more widespread planting of exotic pasture grasses. The biodiversity costs of such intensification may need to be balanced by increased protection of undeveloped areas and conservation management planning on pastoral lands.
• Wetlands
  • Nationally important wetlands
    
    The nationally significant Lake Woods wetlands (NT013: wetland types B6, B13, B14, B10 and B1) occurs on the border of this bioregion and the Mitchell Grass Downs bioregion. It is in generally good condition, albeit affected adversely by weeds (principally Parkinsonia), and grazing by livestock and feral animals.
    
    Mataranka thermal pools (NT003: wetland type B17) occurs on the border of this bioregion and the Gulf Falls and Uplands bioregion. It is in generally good condition, although somewhat affected by tourist developments and feral animals.
     
  • Other wetlands of subregional significance
    
    There are a number of small wetlands associated with the intermittent, land-locked drainage systems in the south of the bioregion.
     
• Riparian zones
  
  There are no large perennial watercourses in the bioregion. The major drainage system is the Newcastle Creek system in the south, although the bioregion also includes smaller headwater areas of the larger Roper, Daly and Victoria River systems. Riparian zones are generally in fair to good condition, affected mostly by access by livestock and feral animals and weeds.
• Ecosystems at risk
  
  No ecosystems in this bioregion have been assessed formally for risk category. However, riparian areas and wetlands are probably at risk. The current fire regime may be disadvantageous to lancewood-bullwaddy associations, but the extent of this risk has not been assessed.
• Species at risk
  
  6 species occurring in the bioregion are listed as threatened at national or Territory level. Of these species, the bioregion is probably a significant stronghold for the northern shrike-tit, and possibly also for the bilby (because foxes are relatively uncommon so far north).
  
  Number of taxa in the Sturt Plateau bioregion listed as threatened at national and/or NT level (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).

taxa	National		Northern Territory
	endangered	vulnerable	endangered	vulnerable
birds	1	2	1	4
mammals	0	1	0	1

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
  1. Endemism
     
     There are no endemic acacia species and one endemic eucalypt in this bioregion: Eucalyptus (Killarney D138706) from STU3.
      
  2. Richness
     
     Richness The Sturt Plateau subregions have low to moderate richness of Acacia (3-35 species) and Eucalyptus (10-40 species).
     
• Birds
  
  There were insufficient records from this bioregion to confidently ascribe trends to any bird species or guilds for the period between the two bird Atlases.
• Mammals
  
  Of 39 mammal species recorded from this bioregion, 1 is regionally extinct, 1 has declined severely, 1 has declined and 36 are stable.

Management Responses

• Reserve consolidation
  
  The existing reserve system is neither comprehensive nor adequate, and appreciable enhancement is needed to achieve these goals. Such addition may be especially needed if land use intensification proceeds.
• Off park conservation for species and ecosystem recovery
  
  There is some conservation management occurring on some pastoral properties in the bioregion, principally through exclosure fencing of wetland and riparian areas. There is also potential for formal agreements to maintain water-remote lightly-grazed areas in environments otherwise favoured for grazing.
• Integrated NRM
  
  

  A priority for the region is the enhanced integrated management of feral animals, fire and weeds.
  
  There is also a need to be more accountable for the deliberate introduction of exotic pasture grasses (particularly buffel grass) to achieve higher stocking rates. Such introductions cause long-term detriment to the conservation values of those properties and, often, to neighbouring lands.

Further Information and Gaps

• Major data gaps and research priorities for bioregion
  
  A conservation plan for the Sturt Plateau bioregion is currently being prepared. This included a comprehensive survey of the bioregion's fauna and flora, and an assessment of conservation values. A gap to be filled in this project is the availability of environmental mapping at appropriate scale.
  
  Currently in this bioregion, there is no substantial monitoring program which includes as a major goal the assessment of trends in biodiversity conservation, and in threatening processes and their management. Such a program should be a management priority.
• Other information

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