Gulf Uplands and Mount Isa Inlier: Plants and animals

Sandstone areas

Much of the biota inhabiting the sandstone ranges and stony hills in the Gulf country can be found in other regions of northern Australia. However, of all the environments in the Gulf country the sandstone contains most of the rare and endemic species, as is evident in their common names.

Some of these include:

• carpentarian rock gecko Gehyra Borroloola
• Hosmer's skink Egernia hosmeri
• Carpentarian grass-wren Amytornis dorothea
• Carpentarian sandstone antechinus Pseudantechinus mimulus
• Carpentarian lerista Lerista carpentariae.

The last two species have only recently been recorded on mainland Australia, previously known only from islands in the Gulf of Carpentaria.

Other common species found here are the common rock-rat Zyzomys argurus, euro Macropus robustus, and goannas Varanus acanthurus and Varanus storri.

Vegetation on the sandstone is dominated by spinifex hummock grass (Triodia spp.) with low mallee eucalypts and acacias. The high diversity of plant species seen on the Arnhem Land escarpment in Kakadu does not occur in the Gulf, possibly because of lower rainfall. However, rare species such as the cycad Cycas brunea occur in isolated patches. More botanical surveys of the area are needed to provide a clearer picture of the Gulf region's conservation values.

Riparian and wetland systems

Major river systems are important environments for many species in the Gulf district because of the much lower annual rainfall than the more northern savannas, and the searingly high temperatures experienced during the summer months.

Birds such as the vulnerable purple-crowned fairy-wren Malurus coronatus, also found in the Victoria River District, live in the canegrass fringing the rivers. The endangered gouldian finch Erythrura gouldiae also relies on permanent water of the larger river systems. The riparian forests are usually quite tall and are restricted to the thin strip along the water's edge. They are commonally composed of Eucalyptus papuana , paperbarks Melaleuca leucadendra , Terminalia platyptera and an understorey of Pandanus spiralis , Casuarina cunninghami and freshwater mangrove Barringtonia acutangula . Lawn Hill Gorge is an excellent example of the deep permanent water characteristic of these important refuges.

To see a list of research findings for each species click on the species name.

Rainforest

Rainforests are scattered throughout the inland areas of the Gulf of Carpentaria, occurring in steep gorges and ravines, often close to spring-fed waterholes. They represent significant habitats for the carpentarian rock-rat Zyzomys palatalis, a large rodent restricted to a few patches of rainforests close to the Northern Territory-Queensland border, which is listed as critically endangered. The rainforest itself is home to many rare species of plant such as the vine Tilocora australiana. Many of the rainforest patches are very small, often less than 5 hectares, and are sometimes found clinging to the edge of a rocky slope.

Woodlands

Much of the woodlands environment is dominated by undulating rocky hills where low open eucalypt forests occur, and on the deeper alluvial soils you may find pockets of taller forest interspersed with grassland.

Low open woodland dominated by acacia cambagei occur on alluvial surfaces throughout the Gulf Photo: Tony Griffiths

Melaleuca citrolens, a dwarf paperbark, occurs in thick stands on clay soils between ridges, and contains some rare plants species but these stands generally have relatively few animal species.

Notable species found in the woodlands include

• spectacled hair-wallaby Largochestes conspicillatus
• Australian bustard Ardeotis australis
• grey falcon Falco hypoleucos.

Among the commonly encountered species are the cockatiel Nymphicus hollandicus and the bearded dragon Pogona barbartus. The diversity and abundance of small mammal species in the Gulf woodlands are very low compared with higher rainfall woodland to the north, possibly because of limited availability of daytime refuges among small trees.