Ecological systems

As described in Section 1.1. 1.1, the Sydney Basin bioregion aligns closely, but not exactly, with the Sydney Basin bioregion of the Interim Biogeographic Regionalisation for Australia (IBRA) classification (SEWPaC, 2012) – it also includes parts of the NSW South Western Slopes and South Eastern Highlands IBRA bioregions. The main IBRA subregions that occur within the Sydney Basin bioregion (as defined for use in the Sydney Basin Bioregional Assessment) are Wollemi, Yengo, Cumberland, Burragorang, Ettrema, Sydney Cataract, Jervis, Pittwater, Illawarra and Moss Vale; these account for nearly 92% of the bioregion. The Capertee Valley and Capertee Uplands IBRA subregions account for a further 7.1% of the bioregion. The vegetation characteristics of key IBRA subregions are described in detail in Table 21 (see also Figure 6 in Section 1.1.1 .1) based on Morgan (2001); details of geology, landforms and soils can be found in Table 7 in Section .1.

The Sydney Basin bioregion is one of the most species diverse in Australia largely as a result of the variety of rock types, topography and climates in the bioregion. It includes lagoons, estuaries and coastal lake systems. It contains large areas of World Heritage and wilderness-listed national parks and includes a variety of vegetation types such as rainforest, wet and dry sclerophyll forest, and hanging swamps.

Table 21 Characteristic vegetation of the main Interim Biogeographic Regionalisation for Australia subregions in the Sydney Basin bioregion

IBRAa subregion



Heath, shrubland and woodland with black ash, hard-leaved scribbly gum, Sydney peppermint and red bloodwood on sandstone similar to other parts of the Basin. Deane's gum, turpentine, blue-leaved stringybark immediately below escarpment passing to grey gum, narrow-leaved ironbark and thin-leaved stringybark on bouldery slopes. River oak along main streams below the plateaux.

Capertee Uplands

Woodlands support rough-barked apple, red stringybark, red box, yellow box, Blakely's red gum with shrubby understorey and wallaby grass in open valleys. Scribbly gum, red stringybark, red box and broad-leaved ironbark on talus slopes. Black ash and Sydney peppermint on sandstone peaks. Dwarf casuarina, tea tree, and sedge on pagoda margins.


Red bloodwood and black ash woodland with abundant shrubs on sandstone with extensive gahnia, banksia in hanging swamps. Coastal dune sequence of tea-tree, coast wattle, smooth-barked apple, blackbutt and swamp mahogany on barrier system. Mangroves and salt marsh on Towra Point and up the Georges River estuary.


Grey box, forest red gum, narrow-leaved ironbark woodland with some spotted gum on the shale hills. Hard-leaved scribbly gum, rough-barked apple and old man banksia on alluvial sands and gravels. Broad-leaved apple, cabbage gum and forest red gum with abundant swamp oak on river flats. Tall spike rush, and juncus with Parramatta red gum in lagoons and swamps.


Very prominent ‘contour’ vegetation pattern. Lichens, mosses and low heath patches on rock, woodlands with dwarfed red bloodwood, black ash, tall heath and sedgeland on soil benches. Better soils have messmate and brown barrel. Gullies support rainforest elements with turpentine plumwood, coachwood, lilly pilly and mountain pepper.


Mixed warm temperate and subtropical rainforest complexes on rich shale soils and alluvium under the escarpment. Coachwood, native tamarind, cabbage tree palm, Port Jackson fig, cheese tree, with soft tree fern and rough tree fern understorey. Adjacent tall forests; Sydney peppermint, brown barrel, yellow stringybark coastal white box. Coastal dunes; coast wattle, tea-tree, banksia, and blackbutt. Common reed in fresh swamps and lakes, mangroves and limited saltmarsh in estuaries.


Coastal forests on shale dominated by spotted gum, blackbutt, black ash, and bangalay. Rainforest elements on trachyte, watergum along streams. Open understorey with macrozamia. Sand dunes have barrier sequence of tea-tree, banksia, wattles merging to protected forests and scrubs with smooth-barked apple, red bloodwood, forest oak, bangalay and blackbutt. Gahnia sedgelands with black wattle in steep wet gullies. Common reed swamps and sedgeland in wide valleys on shale and behind dunes. Swamp oak, salt marsh and mangrove sequence in estuaries.

Moss Vale

Tall forest of narrow-leaved peppermint, Sydney peppermint, monkey gum, black ash, messmate, coastal white box, and brown barrel on shale and basalts. Extensive sedgelands and hanging swamps on sandstone. Wingecarribee raised sphagnum bog. Sydney peppermint, narrow-leaved peppermint, and gully ash on trachyte domes.


Shale caps support tall forest of Sydney blue gum and blackbutt or turpentine and grey ironbark. Sandstone plateau; Sydney peppermint, smooth-barked apple, scribbly gum, red bloodwood, yellow bloodwood, with diverse shrubs and patches of heath. Blackbutt, turpentine, coachwood and water gum in deep sheltered gullies. Spotted gum, Deane's gum, bangalow palm, and forest oak on Narrabeen sandstone lower slopes. Banksia, tea-tree heath on dunes. Bangalay, swamp mahogany, cabbage tree palm, swamp oak, common reed and cumbungi in fresh swamps. Mangrove and saltmarsh communities in calm estuaries.


Red bloodwood, yellow bloodwood, rough-barked apple, smooth-barked apple, hard-leaved scribbly gum, and grey gum with diverse shrubs and heaths on plateau. Smooth-barked apple, Sydney peppermint, blue-leaved stringybark, and turpentine and gully rainforests in gullies and canyon heads. Ribbon gum and Blaxland’s stringybark on basalt. River oak along main streams.


Red bloodwood, yellow bloodwood, rough-barked apple, smooth-barked apple, hard-leaved scribbly gum, and grey gum with diverse shrubs and heaths on plateau. Smooth-barked apple, Sydney peppermint, blue-leaved stringybark, and turpentine with rainforest species in gullies. Hard-leaved scribbly gum, rough-barked apple and Parramatta red gum with sedge swamps on Mellong Range sand. River mangrove and grey mangrove along margins of upper Hawkesbury estuary, freshwater reed swamps with sedges and paperbarks.

aInterim Biogeographic Regionalisation for Australia (IBRA; Environment Australia, 2000)

Data: NSW National Parks and Wildlife Service (2003)

Last updated:
21 January 2019
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