Brigalow Belt Explained

Brigalow Belt
Brigalow tropical savanna
Map:IBRA 6.1 Brigalow Belt South.png
Biogeographic Realm:Australasian
Biome:tropical and subtropical grasslands, savannas, and shrublands
Border1:Eastern Australia mulga shrublands
Border2:Eastern Australia temperate forests
Border3:Einasleigh Uplands savanna
Border4:Mitchell Grass Downs
Border5:Queensland tropical rain forests
Border6:Southeast Australia temperate savanna
Area:408,242
Country:Australia
State1:Queensland
State2:New South Wales
Conservation:Critical/endangered
Protected:17,891 km² (4
Protected Ref:)[1]

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 135000km2 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

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.[2] [3] [4] [5] [6] [7]

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.[8]

A variety of spiders and insects are found there, including Euoplos dignitas, an armoured trapdoor spider discovered in 2023.[9]

Already extinct fauna include the white-footed rabbit-rat and the Darling Downs hopping mouse.[10]

Threats and preservation

Together with the Mulga Lands, the Brigalow Belt are where most of Queensland's land clearing is occurring.[11] 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.[12]

Protected areas

A little more than two per cent of the Brigalow Belt lies within national parks and other protected areas.[13] 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 / subregionIBRA codeAreaLocation in Australia
Brigalow Belt North BBN
BBN01 763495ha
BBN02 1054392ha
BBN03 747393ha
BBN04 95821ha
BBN05 397935ha
BBN06 1316957ha
BBN07 1772127ha
BBN08 466275ha
BBN09 382284ha
BBN10 1274731ha
BBN11 2693397ha
BBN12 449269ha
BBN13 1009244ha
BBN14 1250611ha
IBRA regions and subregions: IBRA7
IBRA region / subregionIBRA codeAreaLocation in Australia
Brigalow Belt South BBS Qld / NSW
BBS01 1026214ha
BBS02 749785ha
BBS03 220541ha
BBS04 1275970ha
BBS05 30133ha
BBS06 715288ha
BBS07 982807ha
BBS08 1547555ha
BBS09 281306ha
BBS10 2263686ha
BBS11 652005ha
BBS12 4264666ha
Barakula BBS13 1301712ha
BBS14 162442ha
BBS15 966510ha
Tara Downs BBS16 511339ha
BBS17 1697945ha
BBS18 1219008ha
BBS19 750661ha
BBS20 765231ha
BBS21 624671ha
BBS22 700241ha
BBS23 535392ha
BBS24 1732137ha
BBS25 941752ha
BBS26 521960ha
BBS27 203894ha
BBS28 303754ha

References

-21.9833°N 155°W

Notes and References

  1. Eric . Dinerstein . David . Olson . etal . 2017 . An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm . BioScience . 67 . 6 . June 2017 . 534–545 . 10.1093/biosci/bix014. 28608869 . 5451287 . free . Supplemental material 2 table S1b.
  2. Fensham . R.J. . McCosker . J.C. . Cox . M.J. . 1998 . Estimating clearance of Acacia-dominated ecosystems in central Queensland using land-system mapping data . Australian Journal of Botany . 46 . 2 . 305–319 . 10.1071/bt96129.
  3. Young, P.A.R., B.A. Wilson, J.C. McCosker, R.J. Fensham, G. Morgan, and P. M. Taylor. 1999. Brigalow Belt. Pages 11/1-11/81 in P. Sattler and R. Williams, editors. The Conservation Status of Queensland's Bioregional Ecosystems. Environmental Protection Agency, Brisbane, Australia
  4. Thackway, R., and I.D. Creswell. 1995. An Interim Biogeographic Regionalisation for Australia: A framework for establishing a national system of reserves, Version 4. Australian Nature Conservation Agency, Canberra, Australia.
  5. Arnold . S. . Thornton . C. . Baumgartl . T. . 2012 . Ecohydrological feedback as a land restoration tool in the semi-arid Brigalow Belt, QLD, Australia . Agriculture, Ecosystems and Environment . 163. 61–71. 10.1016/j.agee.2012.05.020 .
  6. Arnold, S., P. Audet, D. Doley, and T. Baumgartl. 2013. Hydropedology and ecohydrology of the Brigalow Belt, Australia: opportunities for ecosystem rehabilitation in semi-arid environments. Vadose Zone Journal, https://www.soils.org/publications/vzj/articles/12/4/vzj2013.03.0052?highlight=&search-result=1)
  7. Arnold, S., Y. Kailichova, and T. Baumgartl. 2014. Germination of Acacia harpophylla (Brigalow) seeds in relation to soil water potential: implications for rehabilitation of a threatened ecosystem. PeerJ, https://peerj.com/articles/268/
  8. Ponce Reyes, Rocio; Firn, Jennifer; Nicol, Sam; Chades, Iadine; Martin, Tara; Stratford, Danial; Whitten, Stuart; Carwardine, Josie. Priority threat management for imperilled species of the Queensland Brigalow Belt. CSIRO: CSIRO; 2016. https://doi.org/10.4225/08/58542c54413ee
  9. Web site: Super-size trapdoor spider discovered in Australia . . Antonio . Planas . 21 March 2023 . 23 March 2023 . 23 March 2023 . https://web.archive.org/web/20230323001703/https://www.nbcnews.com/news/world/super-sized-trapdoor-spider-discovered-australia-rcna75955 . live .
  10. Ponce Reyes, Rocio; Firn, Jennifer; Nicol, Sam; Chades, Iadine; Martin, Tara; Stratford, Danial; Whitten, Stuart; Carwardine, Josie. Priority threat management for imperilled species of the Queensland Brigalow Belt. CSIRO: CSIRO; 2016. https://doi.org/10.4225/08/58542c54413ee
  11. News: Morris . Nathan . 10 April 2022 . Beef industry could struggle to achieve net zero by 2030 if Queensland keeps clearing land . . . 9 August 2023.
  12. Ponce Reyes, Rocio; Firn, Jennifer; Nicol, Sam; Chades, Iadine; Martin, Tara; Stratford, Danial; Whitten, Stuart; Carwardine, Josie. Priority threat management for imperilled species of the Queensland Brigalow Belt. CSIRO: CSIRO; 2016. https://doi.org/10.4225/08/58542c54413ee
  13. Web site: Expedition National Park: Nature, culture and history . 19 October 2009 . Department of National Parks, Recreation, Sport and Racing . 9 July 2013 .