Brigalow Belt South - biodiversity
The sandstone areas of the bioregion support various forests and woodlands. Woodlands dominated by blue-leaved ironbark (Eucalyptus fibrosa), scribbly gum (Eucalyptus rossii), black cypress pine (Callitris endlicheri), whitewood (Atalaya hemiglauca) and rough-barked apple (Angophora floribunda) are found on stony sandstone plateau and streams.
Silver-leaved ironbark (Eucalyptus melanophloia), spotted gum (Eucalyptus maculata) and smooth-barked apple (Angophora costata) occur on stony hills in the north of the bioregion. Narrow-leaved red ironbark (Eucalyptus creba), white cypress pine (Callitris glaucophylla), red stringybark (Eucalyptus macrorhynca), patches of mallee (Eucalyptus sp.) and broom heath (Melaleuca uncinata) occur on gentler sandstone slopes.
Pilliga box (Eucalyptus pilligaensis), with grey box (Eucalyptus moluccanna), poplar box (Eucalyptus populnea), fuzzy box (Eucalyptus conica), bull oak (Casuarina luemhannii), rosewood (Heterodendrum oleifolium), whitewood, wilga (Geijera parviflora), belah (Casuarina cristata), yarran (Acacia homalophylla) and budda (Eremophila mitchellii) occur on heavier alluvial soils in the west and north of the bioregion.
Poplar box, pilliga box, Blakely's red gum (Eucalyptus blakelyi), white cypress pine and red ironbark (Eucalyptus sideroxylon) occur on coarser soils with occasional silver-leaved ironbark, white box (Eucalyptus albens) and fuzzy box in run-on sites. River red gum (Eucalyptus camaldulensis) lines all streams.
In the southern end of the bioregion the vegetation comprises narrow-leaved ironbark, white cypress pine and white box on hills and slopes. Patches of black cypress pine, hill red gum (Eucalyptus dealbata), the occasional kurrajong (Brachychiton populneum) and scrubby acacia species are present in rocky outcrops. Grey box (Eucalyptus microcarpa), yellow box (Eucalyptus melliodora) and rough-barked apple occur on valley floors, while river red gum lines larger streams and river oak (Casuarina cunninghamiana) the tributaries.
The vegetation on the northern basalts includes brigalow, belah, whitewood, wilga, budda and poplar box on the hills, with river red gum, belah, myall (Acacia pendula) and poplar box on the flats. White box with silver-leaved ironbark, white wood, bull oak and brigalow are present on alluvial clays. River red gum occurs on all streams.
Diverse grasslands dominate the Liverpool Plains. Common species include plains grass (Stipa sp.), panic grass (Panicum sp.), windmill grass (Chloris sp.) and blue grass (Dicanthium sp.) on black earths, with the occasional white box, yellow box, poplar box and wilga. On the high (colder) ridge crests, silvertop stringybark (Eucalyptus laevopinea), manna gum (Eucalyptus viminalis) and mountain gum (Eucalyptus dalrympleana) are found with snow gum (Eucalyptus pauciflora) in cold air drainage hollows.
Tallow wood (Eucalyptus microcorys), blackbutt (Eucalyptus pilularis) and blue gum (Eucalyptus saligna) occur on eastern slopes with small areas of vine forest. On northern slopes, white box with rough-barked apple occur with belah in the creeks. Yellow box and Blakely's red gum are found on slopes with a southerly aspect.
There are 3 endangered ecological communities within the bioregion listed under Schedule 1 of the TSC Act. These are the semi-evergreen vine thicket Cadellia pentastylis (poline or scrub myrtle) and carbeen open forest communities. The bioregion is important for the long-term viability of these vegetation communities which are predominantly found here, with a small area lying in the Nandewar Bioregion. The carbeen open forest communities are now restricted to the Brigalow Belt South Bioregion and very limited areas of the Darling Riverine Plains Bioregion.
Benson (1999) notes brigalow, box woodlands and plains grasses as the most threatened plant communities in the bioregion.
The grassy white box woodland community also occurs in this bioregion. It is nationally endangered and protected under the EPBC Act 1999.
At a species level there are 4 endangered and 12 vulnerable species listed in the schedules of the TSC Act. Records within the bioregion tend to be concentrated in the major reserves and forests of the bioregion such as Goonoo State Forest, the Warrumbungles, Mt Kaputar and the Pilliga.
Although few systematic surveys have been conducted in the bioregion, records from a variety of surveys can be used to illustrate the vertebrate fauna of the bioregion, which consists of 18 amphibian species, 68 reptiles, 281 birds and 82 mammal species.
Many of these species are considered threatened, including the endangered malleefowl (Leipoa ocellata), for which the bioregion contains important habitat, and the vulnerable koala (Phascolarctos cinereus) which has important populations in the Warrumbungles, the Pilliga and the area around Gunnedah (NSW NPWS 2000a). In this bioregion the tree species often selected by koalas include Blakely's red gum, river red gum and white box, while pilliga box, poplar box, narrow-leaved ironbark and rough-barked apple are occasionally used for food (NSW NPWS 2000a).
Another significant mammal species in the bioregion is the vulnerable eastern pygmy possum (Cercartetus nanus) which has a very patchy distribution, with more than 10 records of the species known from each of only 5 locations in NSW, the Pilliga State Forest being one of them (NSW NPWS 2000a).
As its name suggests, the Pilliga mouse (Pseudomys pilligaensis) is known only from the Pilliga State Forest, although its preferred habitat has not yet been established. It is thought to prefer mixed eucalypt forest with a shrubby understorey with logs and litter and may face threat from disturbance of ground storey vegetation. (NSW NPWS 2000a).
A species of hopping mouse (Notomys) is thought to be present in the remnant forests of the bioregion. It is known only from hairs and footprints and is yet to be found in the Brigalow Belt South.
The birds of the bioregion are highly diverse, mainly consisting of tropical woodland species and comprising the largest number of Australian resident species of any bioregion. There are no major populations of rare or threatened birds in the bioregion and although many birds within the bioregion have restricted ranges, none is endemic. Exotic species are low in numbers and those present are located mainly around towns.
Although bird species diversity is high relative to other NSW bioregions, the Brigalow Belt South Bioregion has experienced major declines in ground-nesting, ground-feeding insectivorous and grassland birds, a trend common to many parts of Australia. An increased reporting rate in the bioregion's rainforest and temperate forest taxa may reflect greater survey effort in these habitats. Reduction of bird diversity in habitat fragments and the continued loss of woodland and freshwater birds seem to be the prediction for the future. However, there was an increase in the numbers of mallard (Anas platyrhynchos), cattle egret (Bubulcus ibis) and the common myna (Acridotheres tristis).
Conservation of habitat is crucial to the survival of small grassland and woodland birds. This should include protecting a substantial and representative proportion of the woodland and grassland landscapes of the bioregion, as well as maintaining and increasing the connectivity between seasonally variable food sources. Ideally, these would be in blocks large enough to discourage invasion by exotic species or fragment specialists such as noisy miners.
Lake Goran is considered to be significant as it provides an important refuge for waterbirds and other species during times of drought (ANCA 1996). When inundated, it is an important waterbird habitat for species such as the red-necked stint (Calidris ruficollis), a migratory wader. Despite its significance, the lake's condition is considered to be degraded and tending towards further decline due mainly to salinity, increased flooding and pollution caused by runoff from surrounding agricultural lands.
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Page last updated: 27 February 2011