Tanami
Bioregional Description
The Tanami bioregion comprises mainly red Quaternary sandplains overlying Permian and Proterozoic strata which are exposed locally as hills and ranges. The sandplains support mixed shrub steppes of Hakea suberea, desert bloodwoods, acacias and grevilleas over Triodia pungens hummock grasslands. Acacia shrublands over hummock grass communities occur on the ranges. Alluvial and lacustrine calcareous deposits occur throughout. In the north they are associated with Sturt Creek drainage, and support Chrysopogon and Iseilema short-grasslands often as savannas with River Gum. The climate is arid tropical with summer rain. The Tanami bioregion is divided into three subregions.
Special values
The Tanami bioregion comprises large areas of desert communities little affected by intensive development and at least superficially largely in good condition. The sandplains support threatened species including bilby, marsupial mole and mulgara. There are also impermanent but significant wetland systems.
- Summary of overall condition and trend
Most of the bioregion is generally in good condition, with little intensive use. However, feral predators (foxes, cats) and other factors have caused the regional extinction of 13 mammal species (including central rock-rat and mala), and the decline of many other mammals. Fire regimes have changed substantially over the last century, following less intricate Aboriginal management over large areas, leading to broad-scale detriment in many vegetation communities. Some weeds are also increasing, with at least localised impacts of buffel grass and Parkinsonia. The three subregions are all rated as continental stress class 5. - Summary of priority management/conservation priorities
There are three main priorities for natural resource management in the Tanami: (1) remedial actions (e.g. exclosure fencing) in some pastoral lands largely on the periphery of the region (most notably in the wetland system of Sturt Creek); (2) resources and capacity building for Aboriginal land owners to become more effective managers of NRM (mostly fire, weeds and ferals) problems over the extensive areas of Aboriginal lands; and (3) development and ongoing support for IPAs or other cooperatively managed conservation areas. - Wetlands
- Nationally important wetlands
The bioregion includes two nationally significant wetlands: Lake Surprise (Yinapaka) (NT019: wetland type A6) and the Lake Gregory system (WA096: wetland types B7, B8 and B2). Parts of the Lake Gregory system have been degraded by livestock, but management may be expected to improve as the area has recently been included within the large (4,346 km2) Paruku IPA.
- Other wetlands of subregional significance
The bioregion also contains many smaller ephemeral wetlands and watercourses, which are intermittently of at least regional significance.
- Nationally important wetlands
- Riparian zones
The largest river system in the bioregion is Sturt Creek (which flows into Lake Gregory). Other ephemeral watercourses include the Lander and Hanson Rivers and Winnecke Creek. Condition is generally good, although there are at least localised impacts from feral animals and livestock, and from weeds. - Ecosystems at risk
There has been no formal assessment of the conservation status of ecosystems across most of the bioregion. At least parts of some wetland communities (e.g. Lake Wilson, Lake Gregory) have been degraded by livestock and/or feral animals. Changed fire regimes have led to floristic changes and/or demographic changes for some plant species in many communities across much of the bioregion. - Species at risk
10 species still occurring in this bioregion are listed as threatened at federal or State/Territory level.
Number of taxa in the Tanami bioregion listed as threatened at national and/or NT/WA 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 | 1 |
| reptiles | 0 | 1 | 0 | 1 |
| birds | 0 | 3 | 0 | 3 |
| mammals | 1 | 3 | 0 | 4 |
- Other flora values for eucalypts and acacias
- Endemism
There are no endemic eucalypt species and three endemic acacia species in this bioregion: Acacia abbreviata, A. crassifructa and A. sp. (Tanami A91044), all from subregion 1. There is little information about the status of these species, but all are likely to have been detrimentally affected by changed fire regimes
- Richness
Tanami 1 subregion is rich for Acacia (76 species), and moderately rich for Eucalyptus (33 species). Reflecting their smaller size and less intensive collecting, the two other subregions have low to moderate richness of Acacia (26 and 31 species) and Eucalyptus (19 and 19 species).
- Endemism
- Birds
Although there were relatively few records in the two Atlas periods, there was some evidence for increase of waterfowl and some granivorous and nectarivorous species. This trend may simply reflect better rainfall conditions during the second Atlas period. Over a longer term, the night parrot has probably become regionally extinct, or at least declined substantially. - Mammals
The mammal fauna of the Tanami bioregion has been substantially reduced: of 50 species reported, 13 are regionally extinct, 1 has severely declined, 6 have declined and 30 are stable.
Management Responses
- Reserve consolidation
Notwithstanding the important recent establishment of an IPA around Lake Gregory, the existing reserve system in this bioregion is meagre and far from comprehensive. Enhancement of this system is a priority, especially in the far eastern part (subregion 3) and in the central Tanami Desert itself. - Off park conservation for species and ecosystem recovery
There is little existing NRM specifically for threatened species or ecosystem recovery. Notable exceptions are some exclosure fencing to allow recovery of riparian/wetland areas (Birrindudu and Lake Gregory area), and a long-running but now defunct enclosure and protective management for mala at Sangsters Bore in the Tanami Desert. Enhancement of the IPA system and agreements on pastoral stations may provide scope for additional similar intensive management actions for threatened species and susceptible ecosystems. - Integrated NRM
The major NRM issues in the bioregion relate to pervasive insidious threatening processes (weeds, feral animals, changed fire regimes), whose management requires additional resources and support, capacity building among landowners, and better integration across tenures and jurisdictions. There has been some improvement in this management in recent years, through the Central Land Council's land management units, the development of the IPA process and broad-scale monitoring and management of fire by the Bushfires Council (in the NT), however the resources currently available are insufficient to check these processes across this vast and poorly accessed region.
Further Information and Gaps
- Major data gaps and research priorities for bioregion
Most of the large NT portion of subregion 1 has been sampled comprehensively for vertebrates, although this work is now more than 15 years old. There has been far less systematic sampling for fauna in the WA portion of in the two other subregions, and very little systematic floristic sampling.
Management would also benefit from more detailed environmental mapping, in particular vegetation mapping at the scale of 1:250,000 or better.
Currently in this bioregion, there is no substantial monitoring program which includes as a major goal the assessment of trends in biodiversity conservation, or in the extent and impacts of threatening processes (with the exception of some mapping of fire regimes and irregular aerial surveys of feral animals). Such a program should be a management priority. - Other information