Ecology of Sydney

The ecology of Sydney, located in the state of

It has been calculated that around 98,000 hectares of native vegetation remains in the Sydney metropolitan area, shaping the geography of Sydney, about half of what is likely to have been existing at the time of European arrival.^[12]

Historical descriptions

In 1787,

In 1819, British settler William Wentworth described Sydney's vegetation and landform in great detail:

The colony of New South Wales possesses every variety of soil, from the sandy heath, and the cold hungry clay, to the fertile loam and the deep vegetable mould. For the distance of 5 mi (8.0 km) to 6 mi (9.7 km) from the coast, the land is in general extremely

dwarf underwood

, are the richest productions of the best part of it; while the rest never gives birth to a tree at all, and is only covered with low flowering shrubs, whose infinite diversity, however, and extraordinary beauty, render this wild heath the most interesting part of the country for the botanist, and make even the less scientific beholder forget the nakedness and sterility of the scene.

Beyond this barren waste, which thus forms a girdle to the coast, the country suddenly begins to improve. The soil changes to a thin layer of vegetable mould, resting on a stratum of yellow clay, which is again supported by a deep bed of schistus. The trees of the forest are here of the most stately dimensions. Full sized gums and iron barks, alongside of which the loftiest trees in this country would appear as pigmies, with the beefwood tree, or as it is generally termed, the forest oak, which is of much humbler growth, are the usual timber. The forest is extremely thick, but there is little or no underwood.

At this distance, however, the aspect of the country begins rapidly to improve. The forest is less thick, and the trees in general are of another description; the iron barks,

bleating flocks and lowing herds, at length indicate that you are in regions fit to be inhabited by civilized man. The soil has no longer the stamp of barrenness. A rich loam resting on a substratum of fat red clay, several feet in depth, is found even on the tops of the highest hills, which in general do not yield in fertility to the valleys. The timber, strange as it may appear, is of inferior size, though still of the same nature, i. e. blue gum, box, and stringy bark. There is no underwood, and the number of trees upon an acre do not upon an average exceed thirty. They are, in fact, so thin, that a person may gallop without difficulty in every direction.^[14]

In 1827, Peter Cunningham described the western plains of Sydney as "a fine timbered country, perfectly clear of bush...without any impediment in the shape of rocks, scrubs, or close forest".^[15]

Biomes

Biomes

Towra Point

A swamp oak forest near Prospect Creek

A river-flat eucalyptus forest in Georges River

• Rainforests
  • North Coast Warm Temperate Rainforests – Dominated by
    Acmena smithii, it is scarcely present in the RNP and Hacking River valley in around Sutherland in southern Sydney, and predominant in the Ku-ring-gai Chase National Park and Turramurra in Northern Sydney, near Hornsby.^[16]
  • Dry Rainforests or Western Sydney Dry Rainforest – It is very thinly distributed across the dry areas to the south of Blue Mountains and in small portions in Calmsley Hill Farm in Western Sydney Parklands, near Abbotsbury, New South Wales, and as well as in the Camden area, but in fragments. They have Alectryon subcinereus as one of the tree covers and Clerodendrum tomentosum as shrubby covers.^[17]
  • Littoral Rainforests – Dominated by
    Bundeena and in Towra Point Nature Reserve in Sutherland Shire), and also in one diminutive area in Northern Beaches Council (Mona Vale) in the Northern Suburbs to Newcastle.^[18]
• Wet scleropyhll forests
  • North Coast Wet Sclerophyll Forests – Dominated by tall
    Pennant Hills and Castle Hill in the north, and in the Illawara region, with small portions in Ryde, North Parramatta and Pittwater.^[19][20][21]
    • The
      northern parts of Sydney, it is a wet sclerophyll forest where the annual rainfall is over 1100 mm (43 in), with its trees between 20 and 40 metres tall.^[22]
  • Northern Hinterland Wet Sclerophyll Forests – Dominated by
    Baulkham Hills and Blacktown to the north of Sydney, with small outliers in Menai, Bankstown and Auburn in the southwest.^[23][24]
    • Sydney turpentine ironbark forest – Characterized by thick shrubs and dominated by Syncarpia glomulifera, it is a tall open forest with trees as high as 30 metres and is found on shale and shale-meliorated soils found in small pockets at Campbelltown, Heathcote and Menai.^[25][26]
  • Southern Lowland Wet Sclerophyll Forests – Containing Corymbia maculata, it is found in upper Narrabeen, Pittwater, Woronora and Illawara, as well as on the foreshores of Hacking, Parramatta and Georges Rivers.^[27]
• Grassy Woodlands/Savannas
  • twiners, herbs and small trees in a grassy understorey.^[30] It has a number of sub-regions: Moist Shale Woodlands, Western Sydney dry rainforest, and Shale sandstone transition forest, among others.^[31]
• Dry sclerophyll forests
  • Sydney Coastal Dry Sclerophyll Forests – Predominant on the northeast parts of the
    Sydney Harbour and extends to both sides of the Hawkesbury River in Northern Beaches and Hornsby LGA's and Pennant Hills.^[32][33]
  • Sydney Hinterland Dry Sclerophyll Forests – Found in the drier parts (less than 950 mm) of the Woronora Plateau, also in
    sedges.^[34][35]
    • Bankstown and Liverpool, it is an ironbark shrub-grass forest located in western Sydney that sit on gravelly-clay soils and is made up of a moderately tall open eucalyptus forest or woodland to a low compact brush of paperbarks with nascent eucalypts. Broad-leaved ironbark (Eucalyptus fibrosa) is the most commonly spotted tree.^[23][36]
  • Sydney Sand Flats Dry Sclerophyll Forests – Present in northern Holsworthy with smaller examples at Rookwood and Villawood and is dominated by Eucalyptus sclerophylla.^[37]
  • Coastal Dune Dry Sclerophyll Forests – Examples are found at Bundeena, Kurnell and La Perouse in southern Sydney containing a collection of sclerophyllous shrub and heath species and a ferny ground cover.^[38]
• Heathlands
  • Wallum Sand Heaths – Present in
    sedges and forbs.^[39]
  • Sydney Coastal Heaths – Found extensively in the Sydney metropolitan area and in the eastern parts of the Woronora and Hornsby plateaus particularly in Royal and Ku-ring-gai national parks with prominence of Eucalyptus luehmanniana.^[40] Heaths on coastal headlands are found in and around Garie Beach on the outskirts of southern Sydney, near Royal NP.^[41]
• Scrublands/Shrublands
  • Elderslie Banksia Scrub Forest – A critically endangered scrubby woodland community situated in southwestern Sydney that features a variety of stunted forest or woodland found on sandy substrates associated with deep Tertiary sand deposits. It has been reduced in extent of at least 90% of its original pre-European extent.^[42]
  • western Sydney with vegetation comprising low woodlands with sclerophyllous shrubs and an uneven ground layer of graminoids and forbs.^[43]
  • sandstone soils, with regular wildfires, and moderate rainfall.^[44][45]
• Freshwater Wetlands
  • Castlereagh swamp woodland – A swampy sclerophyll forest affiliated with sporadically flooded soils containing
    Voyager Point, and is made up of moderate to heavy cover of paperbark trees.^[40]
  • Coastal Heath Swamps – Common in Holsworthy defense area, Woronora catchment area and the Hornsby plateau including Garigal and Ku-ring-gai Chase national parks.^[46]
  • Coastal Freshwater Lagoons – Occurs on poorly drained
    alluvial flats and sand depressions and may be surrounded by broad-leaved cumbungi (Typha orientalis).^[47]
• Forested wetlands
  • Estuarine swamp oak forest – Found on the floodplains in most parts of metropolitan Sydney near streamlines, where Casuarina glauca (swamp oak) is the dominant species.^[48]
  • alluvial flats, drainage lines and river terraces associated with coastal floodplains.^[49][30]
  • Coastal Swamp Forests – Occupies the low-lying coastal river flats,
    Wheeler Heights, Narrabeen and Dee Why in the Northern Beaches.^[50]
  • Coastal Floodplain Wetlands – They cover a series of eucalypt and casuarina dominated communities found on low-lying coastal alluvial soils, such as in Georges River and its tributaries in northern Woronora and the lowlands of Blue Mountains. They are dominated by Microlaena stipoides.^[51]
  • Eastern Riverine Forests – Many
    riparian scrubs are found on rocky creeks that are enclosed with coarse sandy alluvial deposits with common vegetation being Tristaniopsis laurina.^[52]
• Saline Wetlands
  • Mangrove Swamps – Found in Towra, they are a basic community dominated by either Avicennia marina or Aegiceras corniculatum.^[53]
  • Saltmarshes – Usually located on estuarine
    alluvial soils, small tracts also exist on headlands exposed to prevailing sea spray.^[54]
  • Seagrass Meadows – Occurring on sandy nether of coastal estuaries and bays, they include a number of subaqueous aquatic species, such as
    sea grass (Posidonia australis).^[55]