Davenport Murchison Range

Bioregional Description

The Davenport-Murchison Ranges bioregion comprises low but rugged rocky hills, formed from folded volcanics and sandstone, siltstone and conglomerates, which contrast starkly with the generally flat sandplain surrounds of the Tanami bioregion. Soils are generally shallow lithosols, but deep fine-grained alluvial soils occur in the valleys and surrounding plains. Vegetation includes hummock grasslands and low open woodlands dominated by eucalypt and Acacia species. This bioregion includes three subregions.

Special values

The rocky ranges which dominate this bioregion are recognised as a significant refugial area, and contain some relatively restricted species. The biodiversity value is not especially high, as the ranges are far less extensive and topographically complex than those to the north (e.g. western Arnhem Land massif) or south (e.g. MacDonnell Ranges). But their contrast to their surrounding sandplains of the Tanami is substantial, and they form (or formed) the northern outlier for some species typically associated with the rocky ranges of central Australia (e.g. the plant Rhamphicarpa australiensis, central rock-rat Zyzomys pedunculatus and pebble-mound mouse Pseudomys johnsoni), and as a southern outlier for some northern species. An important feature of the bioregion is the relative diversity of aquatic and semi-aquatic plants, associated with the large number of permanent or semi-permanent waterholes within the ranges.

• Summary of overall condition and trend
   
  The bioregion is generally in reasonably good condition, although changed fire regimes, feral animals, weeds and livestock are causing broad-scale detriment to some biodiversity values. There are also some local impacts associated with mining. All subregions are scored as continental stress class 5.
• Summary of priority management/conservation priorities
   
  A recently declared moderately large National Park provides good representation of the environments associated with the most rugged and least fertile areas. However a comprehensive reserve system for the bioregion would require that this be augmented by some complementary representation of the more fertile lowland communities.
  
  In addition to enhanced reservation, priorities for management are the broad-scale mitigation of fire, feral animals and weed impacts, and the establishment of some conservation agreements on pastoral lands.
• Wetlands
  • Nationally important wetlands
    
    None.
     
  • Other wetlands of subregional significance
    
    There are some permanent waterholes in the ranges which have allowed the persistence of a biogeographically significant fish fauna. A series of watercourses flow intermittently, and provide contrasting habitat to the dominant environmental matrix. Kurundi Creek, Gosse River, Frew River and its associated floodout swamps, and the upper Elkedra River, are the most important of these (irregular) wetland areas.
     
• Riparian zones
  
  Parts of the Gosse, Frew and Elkedra River systems flow through this bioregion. Riparian areas are in fair to good condition, but are being adversely affected by feral animals (especially donkeys), weeds, altered fire regimes, and generally unrestricted access by livestock.
• Ecosystems at risk
  
  No ecosystems in this bioregion have been formally listed as threatened. The highest risk is probably associated with the region's wetlands (rockholes, riparian areas and flood-outs), because of degradation by livestock and feral animals.
• Species at risk
  
  This bioregion supports seven species listed as threatened at the Territory or national scale. Little is known of their population size or trends in this bioregion. the tally includes several mammal species which would together benefit from broad-scale control of feral predators.
  
  Number of taxa in the Davenport-Murchison 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
plants	0	0	0	2
reptiles	0	1	0	1
birds	0	0	0	1
mammals	0	3	0	3

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 acacias or eucalypts known from this bioregion.
      
  2. Richness
     
     The subregions of the Davenport-Murchison Ranges have only low to moderate diversity of Eucalyptus (20-31 species) and Acacia (32-42 species).
• Birds
  
  Survey effort in this bioregion was relatively low in both Bird Atlases, rendering analysis and explanation of trends effectively impossible. There was some evidence of decline across many bird guilds between the two Atlas periods, and increase in the abundance of one feral bird species.
• Mammals
  
  As with other central Australian bioregions, the mammal fauna of the Davenport-Murchison Range has suffered substantial losses. Of 36 mammal species recorded, 9 have become extinct, 3 have declined and 24 remain stable. The regionally extinct species appear to include the central rock-rat, which has persisted in rocky ranges to the south.

Management Responses

• Reserve consolidation
  
  The moderately large Davenport Range NP and small Devil's Marbles NP provide reasonable representation of the Range environments, but do not sample the flood-out areas and valley floors, which are largely included within pastoral land use. A more comprehensive reserve system should include some representation of these more fertile lowland environments.
• Off park conservation for species and ecosystem recovery
  
  The Plans of Management for Devil's Marbles and Davenport-Murchison parks include some consideration of management for threatened species, however such management response is currently fairly limited.
• Integrated NRM
  
  

  Conservation in this bioregion may be best served by broad-scale integrated management of feral pests (principally including foxes, cats and donkeys), weeds, and fire. Fire management should aim to reduce the incidence and extent of destructive hot fires, possibly through a program of early fine-scale burns.
  
  There is also some scope for conservation agreements on pastoral lands, through exclosure fencing of important wetland areas, and retention of water-remote lightly-grazed areas of environments otherwise favoured by livestock.

Further Information and Gaps

• Major data gaps and research priorities for bioregion
  
  

  There has been some limited wildlife survey of parts of the ranges, but no systematic and comprehensive wildlife survey of the bioregion. Such inventory and resultant conservation planning is needed. There also needs to be some study of the impacts of threatening processes, and the response of biodiversity to mechanisms for the management of these processes. Except for some limited pastoral monitoring and mapping of fire timing and extent, there is no existing substantial monitoring of biodiversity or threatening processes.
  
  Management would also benefit from more detailed environmental mapping, in particular vegetation mapping at the scale of 1:250,000 or better.

• Other information

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