Brigalow Belt

The Brigalow Belt is a wide band of acacia-wooded grassland that runs between tropical rainforest of the coast and the semi-arid interior of Queensland and northern New South Wales, Australia. The Interim Biogeographic Regionalisation for Australia (IBRA) divides the Brigalow Belt into two IBRA regions, or bioregions, Brigalow Belt North (BBN) and Brigalow Belt South (BBS). The North and South Brigalow Belt are two of the 85 bioregions across Australia and the 15 bioregions in Queensland. Together they form most of the Brigalow tropical savanna ecoregion.

Location and description

The Northern Brigalow Belt covers just over and runs from just north of Townsville to Emerald and Rockhampton on the Tropic of Capricorn, while the Southern Brigalow Belt runs from there down to the Queensland/New South Wales border and a little beyond, until the habitat becomes the eucalyptus dominated Eastern Australian temperate forests.

This large, complex strip of countryside covers an area of undulating to rugged slopes, consisting of ranges as well as plains of ancient sand and clay deposits, basalt and alluvium. The Northern Brigalow Belt includes the coal producing Bowen Basin, with the nearby Drummond Basin and the fertile Peak Downs areas. The southern belt, which begins with the sandstone gorges of the Carnarvon Range of the Great Dividing Range, runs into the huge Great Artesian Basin. The south-west side includes the farming area of Darling Downs.

A number of important rivers drain the Brigalow Belt. The large Fitzroy River system and the Belyando and Burdekin rivers near the tropics all drain eastwards, while the south-western areas drain westwards into the Murray–Darling basin via the Maranoa, Warrego and Condamine Rivers.

In the north, there are tropical summer rains and warm weather all year round, while in the south the winter is slightly cooler and there is more rainfall outside of the summer months. Throughout the belt, the interior, with less than 500 mm of rainfall per year, is drier than the coast, which may have 750 mm or more.

Flora

File:Brigalow tree.jpg

Brigalow tree, coastal central Queensland.

The characteristic plant communities are woodlands of highly water stress tolerant brigalow (Acacia harpophylla), a slender acacia tree which thrives on the clay soil and once covered much of the area especially the fertile lowlands. Most of the brigalow has been cleared to make agricultural land, but the Queensland Bottle Tree is often left uncleared due to its leaves being fodder for cattle. Eucalypt woodlands of silver-leaved and narrow-leaved ironbarks, poplar box and other boxes, blackbutt and coolibah are also intact primarily on the higher slopes.

Dichanthium grasslands are another typical habitat of the area while pockets of thicker woodland of brigalow mixed with Casuarina cristata and ooline occur in moister valleys and vine thickets, wetlands, and softwood scrubs are sometimes found although in their undeveloped state, these specialised micro-habitats are rare today. There is a particularly rich variety of habitats in areas such as Isla Gorge and Blackdown Tableland in the sandstone belt of the Carnarvon Range. The Northern Brigalow Belt is one of fifteen national biodiversity hotspots in Australia.

Fauna

The region is home to the unadorned rock-wallaby and the black-striped wallaby, which lives in the areas of vine thicket along with a wingless dung beetle (Onthophagus apterus). Two endangered mammals are found in the Brigalow Belt; the bridled nail-tail wallaby in Taunton and Idalia National Parks, and the burrowing northern hairy-nosed wombat in the grassland and eucalyptus of Epping Forest National Park. There are also populations of dunnart, wallaby, bat and koala. Birds found here include black-throated finch and russet-tailed thrush, while endemic reptiles include the Fitzroy River turtle.

A variety of spiders and insects are found there, including Euoplos dignitas, an armoured trapdoor spider discovered in 2023.

Already extinct fauna include the white-footed rabbit-rat and the Darling Downs hopping mouse.

Threats and preservation

Together with the Mulga Lands, the Brigalow Belt are where most of Queensland's land clearing is occurring. Much of the brigalow woodland has been cleared or radically reduced to the extent that some wildlife, failing to thrive in the altered environment, has become extinct here with a number of the remaining communities threatened or endangered. The clearance of brigalow and poplar box is ongoing as there are a number of nature reserves of which do protect the various types of habitat found in the Belt including brigalow and eucalyptus woodland, grassland, vine thicket, high peaks, sandstone gorges and wetlands however these tend to be located on the sandstone uplands rather than the fertile lowlands, where the brigalow woodlands are still vulnerable to clearance and are often limited to small areas of parkland. The grasslands of the region are also under threat from introduced pasture grasses such as buffelgrass and weeds such as Congress weed. One particular threat comes from alterations to natural flow patterns caused by the addition of dams and weirs which impact the riverine and floodplain plant and animal species.

Protected areas

A little more than two per cent of the Brigalow Belt lies within national parks and other protected areas. The largest national parks in the Brigalow Belt are: Taunton (the largest at 115 km²); Epping Forest, Dipperu, Bowling Green Bay, Goodedulla National Park, Chesterton Range National Park, Homevale National Park, Blackdown Tableland National Park, Expedition National Park, and Carnarvon National Park.

Subregions

IBRA subregions of the Brigalow Belt North include Townsville Plains, Bogie River Hills, Cape River Hills, Beucazon Hills, Wyarra Hills, Northern Bowen Basin, Belyando Downs, Upper Belyando Floodout, Anakie Inlier, Basalt Downs, Isaac–Comet Downs, Nebo–Connors Ranges, South Drummond Basin and Marlborough Plains.

IBRA regions and subregions: IBRA7
IBRA region / subregion	IBRA code	Area	States	Location in Australia
Brigalow Belt North	BBN		Qld	File:IBRA 6.1 Brigalow Belt North.png
Townsville Plains	BBN01
Bogie River Hills	BBN02
Cape River Hills	BBN03
Beucazon Hills	BBN04
Wyarra Hills	BBN05
Northern Bowen Basin	BBN06
Belyando Downs	BBN07
Upper Belyando Floodout	BBN08
Anakie Inlier	BBN09
Basalt Downs	BBN10
Isaac-Comet Downs	BBN11
Nebo-Connors Ranges	BBN12
South Drummond Basin	BBN13
Marlborough Plains	BBN14

IBRA regions and subregions: IBRA7
IBRA region / subregion	IBRA code	Area	States	Location in Australia
Brigalow Belt South	BBS		Qld / NSW	File:IBRA 6.1 Brigalow Belt South.png
Claude River Downs	BBS01
Woorabinda	BBS02
Boomer Range	BBS03
Mount Morgan Ranges	BBS04
Callide Creek Downs	BBS05
Arcadia	BBS06
Dawson River Downs	BBS07
Banana-Auburn Ranges	BBS08
Buckland Basalts	BBS09
Carnarvon Ranges	BBS10
Taroom Downs	BBS11
Southern Downs	BBS12
Barakula	BBS13
Dulacca Downs	BBS14
Weribone High	BBS15
Tara Downs	BBS16
Eastern Darling Downs	BBS17
Inglewood Sandstones	BBS18
Moonie-Commoron Floodout	BBS19
Moonie-Barwon Interfluve	BBS20
Northern Basalts	BBS21
Northern Outwash	BBS22
Pilliga Outwash	BBS23
Pilliga	BBS24
Liverpool Plains	BBS25
Liverpool Range	BBS26
Talbragar Valley	BBS27
Narrandool	BBS28

References

• Sattler, P. S. and R. D. Williams (1999) (eds) The Conservation Status of Queensland’s Bioregional ecosystems. Environmental Protection Agency, Brisbane
• IBRA Version 6.1 data. (Search in "Title" for "IBRA").