South Western Slopes - biodiversity
In the higher rainfall eastern hill country, woodlands and open woodlands of white box (Eucalyptus albens) are dominant. To the west and north these give way to vegetation communities dominated by grey box (Eucalyptus microcarpa) and white cypress pine (Callitris glaucophylla).
Other tree species characteristic of the bioregion include red stringybark (Eucalyptus macrorhynca) on higher slopes, with black cypress pine (Callitris endlicheri), kurrajong (Brachychiton populneum), red ironbark (Eucalyptus sideroxylon), white gum (Eucalyptus rossi), yellow box (Eucalyptus melliodora) and Blakely's red gum (Eucalyptus blakelyi) occupying the lower slopes.
Valley flats are dominated by rough-barked apple (Angophora floribunda), with river oak (Casuarina cunninghammia) found along eastern streams and river red gum (Eucalyptus camaldulensis) lining the larger central and western streams.
In the western half of the bioregion, where altitude and rainfall are lower, Dwyer's mallee gum (Eucalyptus dwyeri) dominates areas of granite-derived soils and red ironbark communities occupy areas of sandy soils derived from sedimentary rock. Other common trees include hill red gum (Eucalyptus dealbata), white cypress pine and red stringybark in the ranges and grey box woodlands, with yellow box, white cypress pine and belah (Casuarina pauper) occupying lower areas.
Vegetation communities in the northwest are dominated by poplar box (Eucalyptus populnea), kurrajong, wilga (Geijera parviflora) and red box (Eucalyptus intertexta), and limited areas of bull mallee (Eucalyptus behriana), blue mallee (Eucalyptus polybractea), green mallee (Eucalyptus viridis) and congoo mallee (Eucalyptus dumosa) occur in the central west.
Towards the edge of the Riverine Plain, myall (Acacia pendula), rosewood (Heterodendrum oleifolium) and yarran (Acacia homalophylla) associations are found on grey clays. Yellow box, poplar box and belah associations occupy alluvial loams. River red gum grows along all streams, with some black box (Eucalyptus largiflorens), lignum (Muehlenbeckia cunninghamii) and river cooba (Acacia stenophylla) also occurring.
There are 36 threatened flora species listed in the schedules of the TSC Act in the South Western Slopes Bioregion (NSW NPWS 2001). Of these, 13 are endangered, 22 are listed as vulnerable and one species, Euphrasia arguta, is considered extinct in the bioregion.
Sixty-seven species listed in the schedules of the TSC Act are found in the South Western Slopes Bioregion (NSW NPWS 2001). Of these, 13 are listed as endangered and 54 are listed as vulnerable.
As the South Western Slopes Bioregion has been intensively cleared and cultivated what remains is mostly fragmented vegetation, a landscape conducive to decline of bird populations. These woodland fragments are important for species such as the vulnerable superb parrot (Polytelis swainsonii) and the endangered regent honeyeater (Xanthomyza phrygia) as well as non-breeding swift parrots (Lathamus discolor).
A decline in ground-feeding insectivores was recently observed in the bioregion while numbers of temperate forest birds increased (Australian Terrestrial Biodiversity Assessment 2002). Protection and enhancement of woodland fragments is necessary to prevent continued loss of woodland birds.
Three wetlands are identified as being of bioregional significance. The Barmedman/Yiddah Creek Floodplain is considered to be able to support 32,000 waterbirds (Kingsford et al. 1997). The endangered malleefowl (Leipoa ocellata), the vulnerable brolga (Grus rubicundus) and the painted honeyeater (Grantiella picta) have all been recorded in the floodplains (NSW NPWS 2001). The superb parrot has also been sighted. The endangered plant Austrostipa wakoolica has been recorded on this floodplain.
Lake Burrendong Reservoir is described as being in good condition and supported over 32,000 waterbirds in 1985, including the Eurasian coot (Fulica atra), maned duck (Chenonetta jubata) and great cormorant (Phalacrocorax carbo). In 1991, the reservoir supported 10,000 waterbirds including grey teal (Anas gracilis), Pacific black duck (Anas superciliosa) and maned duck (Chenonetta jubata).
Vulnerable species sighted at the reservoir include the glossy black cockatoo (Calyptorhynchus lathami), turquoise parrot (Neophema pulchella) and Gilbert's whistler (Pachycephala inornata). The endangered swift parrot (Lathamus discolor) and regent honeyeater (Xanthomyza phrygia) have also been recorded. The Lake also provides habitat for the endangered plant Swainsona recta (Australian Terrestrial Biodiversity Assessment 2002).
Wiesners Swamp located in Weisners Swamp Nature Reserve is also bioregionally significant, providing habitat for the vulnerable brolga (Grus rubicundus).
The biodiversity of the wetlands of the South Western Slopes Bioregion is affected by a range of threats. These include feral animals, exotic weeds, inappropriate recreational activities, erosion, increased nutrients, sedimentation, altered hydrology, salinity, water extraction and regulation, grazing pressure, pollution from gold mining, lakebed cropping when dry and indiscriminate duck shooting and commercial fishing.
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Page last updated: 27 February 2011