Environment

Vegetation

New South Wales has very diverse types of native vegetation. There are rainforests and deserts, wetlands, heathlands, grasslands, alpine herbfields, and eucalypt forests and woodlands.

Diversity of Native Vegetation

New South Wales has very diverse types of native vegetation. There are rainforests and deserts, wetlands, heathlands, grasslands, alpine herbfields, and eucalypt forests and woodlands. Few other regions of the world rival such a variety of vegetation within a comparable area.

The character and composition of NSW native vegetation is a result of its origins on the supercontinent of Gondwana, its evolution in isolation over tens of millions of years, changes associated with uplift of the Great Dividing Range, widespread infertility of soils, variability in climatic conditions including wet and dry phases and recurring fires, floods and storms, as well as recent impacts from human activities.

Classification of Vegetation

We use a hierarchical system of classification to help describe the diversity of vegetation. The most localised classification is the plant community, an assemblage of species occurring together in the same place at the same time. Vegetation classes are groups of communities that share similar species. Plant communities and classes may be assigned to formations, which are defined by their structural properties, such as the growth forms of plants, the form and size of their leaves, and the vertical arrangement and density (or cover) of plants. Formations are used for broad generalisations about the character and distribution of different vegetation types. Sixteen structural formations and subformations of native vegetation are currently recognised in NSW and are shown on accompanying maps.

Distribution of Native Plant Species

There is trend of decreasing numbers of plant species from east to west. Highest numbers of plant species occur in the Sydney Basin, NSW North Coast and South-east Queensland. These are known as areas of high biodiversity, and include the World Heritage-listed Gondwana Rainforests of Australia (north-east NSW and south-east Queensland) and the greater Blue Mountains. Plants are less diverse where conditions are more extreme e.g. the dry north-west or western slopes and plains. The distribution of plants is also influenced by modification of large areas of the landscape for agriculture and infrastructure. This mapped distribution also reflects current knowledge – inland areas are less well known and may have more species than are shown here.

Threatened Species of Plants

The highest proportions of threatened plants are found in the Sydney Basin bioregion and along the coast. This is no coincidence – these are the areas with most people. Principle threats in this region include development of areas for houses, roads and businesses involving clearing native vegetation and building of infrastructure. Loss of habitat and reduced connection between patches of remaining vegetation or along rivers are major threats to biodiversity. The Murray Darling Depression (far-western NSW) bioregion also has a high percentage of threatened plants. The major threats here are alteration of rivers and wetlands, grazing pressure and burning regimes.

One of the key threatening processes to animals is modification to major vegetation groups. Since European settlement, approximately 40% of native vegetation in NSW has been cleared and replaced by crops, introduced pastures or urban and industrial landscapes. Eucalypt woodlands, eucalypt open forest, and mallee woodlands and shrublands, in particular, have been extensively cleared, mostly for agriculture, and in some regions are retained only as remnants in relatively small patches. In the sheep-wheat belt of NSW (the Brigalow Belt South and NSW South-west Slopes bioregions), clearing has reduced native vegetation to small, fragmented areas, covering less than 40% in these bioregions. This has had, and continues to have, a major impact on all native species, especially mammals and woodland birds.

Exotic Species of Plants

Competition from invasive species is one of the most frequently noted threats in formal documentation for national listing and recovery of threatened species and communities.

Nationally, of the 27,000 alien plant species that have been introduced into Australia, approximately 2,800 have naturalised. The rate of naturalisation is estimated at about 10 species per year. Many of these species compete successfully with Australian native plants and have become abundant and widely distributed.

Highest proportions of exotic plants are found in and around urban areas of the Sydney Basin, and in the agricultural regions of Nandewar, NSW South Western Slopes and the Riverina. Introducing plants for gardens or agriculture provides plants that can become weeds, human activities then move plants around the landscape, and disturbing native vegetation communities allows weeds to establish.

Department of Environment, Climate Change and Water

Alpine Complex

includes a suite of treeless, cold-resistant plant communities dominated by shrubs, herbs, grasses and sedges. It is restricted to the Snowy Mountains alpine zone, generally above 1,830 m elevation, where temperatures are too low for trees to grow. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 1.72 Mb image.

Arid Shrublands

are dominated by wattles (acacias) or saltbushes, bluebushes and copperburrs (chenopods). They comprise a mixture of drought-tolerant plants, including shrubs and hummock grasses such as spinifex, with herbs and tussock grasses. They are widespread in the driest parts of western NSW, where average annual rainfall is less than 400 mm, and may be as low as 200 mm. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 1.36 Mb image.

Dry Sclerophyll Forests

are dominated by a range of eucalypts usually with short trunks (including ash, stringybarks, ironbarks, scribbly gums and bloodwoods), and have an understorey of hard-leaved shrubs, ferns, herbs and grasses or reed-like plants called sedges. They are divided into ‘shrubby’ and ‘grassy’ types based on the character of the understorey. They are found on coastal hills and lowlands, the escarpment, tablelands and western slopes of the Great Dividing Range, on fertile soils in regions receiving high to moderate rainfall. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 2.11 Mb image.

Forested Wetlands

are dominated by trees including eucalypts, paperbarks and casuarinas, with an understorey of water-loving herbs, sedges and rushes. They are restricted to floodplains and riverine corridors on coastal lowlands and along inland watercourses. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 1.82 Mb image.

Freshwater Wetlands

include treeless shrublands, sedgelands, reedlands and open-water wetlands. They occur in areas that are waterlogged or flooded from time to time, on coastal lowlands, elevated tablelands and floodplains of inland river systems. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 2.19 Mb image.

Grasslands

are plant communities dominated by perennial tussock grasses with herbs, and lack trees and woody shrubs. They occur on fertile clay soils from the coast to the semi-arid zone, covering an average rainfall range of 400mm to more than 1,200mm per year. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 3.16 Mb image.

Grassy Woodlands

have an open layer of trees (typically box and red gum eucalypts), with scattered shrubs, and abundant grasses and herbs in the understorey. They occur on flat to rolling hills with fertile soils and moderate average rainfall (around 500 – 1,000 mm a year) in coastal valleys, on the tablelands extending to the upper limit of tree growth or ‘treeline’, and on the western slopes of the Great Dividing Range. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 2.71 Mb image.

Heathlands

contain a dense to open layer of shrubs with small, hard leaves and sedges, sometimes with isolated trees. They occur in high rainfall regions of the coast and tablelands on infertile soils, often in exposed places such as coastal headlands. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 3.06 Mb image.

Interim Biogeographic Regionalisation for Australia (IBRA v6.1)

View: 0.35 Mb image.

Kunzea rupestris - vulnerable

Kunzea rupestris is a listed ‘Vulnerable’ shrub. It occurs in a small number of populations in the Central Coast region. Photo: J Plaza, Botanic Gardens Trust Sydney. View: 0.69 Mb image.

Native and exotic vegetation

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Rainforests

have a closed tree canopy composed of relatively soft, horizontally held leaves. Eucalypts are scarce and/or emergent above the canopy. There are many vines and ferns; palms and epiphytes may also be present. Rainforests are found mainly on coastal lowlands and along escarpments in reliably moist, mostly fire-free habitats on soils of moderate to high fertility, though some communities extend inland to the north-west slopes of the Great Dividing Range. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 1.72 Mb image.

Saline Wetlands

include a variety of communities composed of plant species that tolerate high levels of salt. Most saline wetlands, including mangrove forests, saltmarshes and seagrass meadows, occur within coastal estuaries, although some are associated with salt lakes in arid inland regions. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 2.38 Mb image.

Semi-arid Woodlands

are dominated by drought-tolerant eucalypts, wattles or casuarinas. Grassy woodlands typically occur on heavy soils deposited by rivers, while shrubby woodlands are found on sandy or rocky soils. Semi-arid woodlands are widespread across the western plains of NSW, where annual rainfall is less than 500mm. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 3.24 Mb image.

Vegetation Formations

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Wet Sclerophyll Forests

are dominated by eucalypts with long straight trunks (usually species of blue gum or ash), and have an understorey of soft-leaved shrubs, ferns, herbs and grasses. They are divided into ‘shrubby’ and ‘grassy’ types based on the understorey. They are found on coastal hills, the escarpment of the Great Diving Range, the eastern part of the tablelands and sometimes westward, on relatively fertile soils where rainfall exceeds 900 mm a year. Photo: M. Fagg, Department of Sustainability, Environment, Water, Population and Communities. View: 1.63 Mb image.