Australia's ecoregions

Wilsons Promontory National Park, Victoria | John Baker

Australia's eight ecoregions

There are 14 ecoregions found across the globe. Ecoregions contain geographically distinct groups of plants and animals that have evolved in relative isolation, separated by features such as oceans or high mountain ranges.

This classification system was developed by the conservation organisation, WWF, as a more comprehensive conservation tool than simply looking at ecosystem types, or biomes, based on climate and vegetation. Each ecoregion contains several biomes and biomes may transcend ecoregion borders.

Map right: Australia's eight ecoregions
Source: Department of Sustainability, Environment, Water, Populations and Communities (adapted from WWF) Download Australia's ecoregions map (PDF - 1.66 MB)

The main characteristics of the eight ecoregions in Australia are described in the following table:

Ecoregion Description and ecoregions

Tropical and subtropical moist broadleaf forests

These forests are generally found in large, discontinuous patches on the equatorial belt and between the Tropics of Cancer and Capricorn. Characterised by low variability in annual temperature and high levels of rainfall (>200 centimetres annually) these forests' composition is dominated by semi-evergreen and evergreen deciduous tree species.

Australia has a small and scattered areas of this type of forest in Queensland and they are believed to be residual fragments of the forests that once covered most of Australia and Antarctica, approximately 15 million years ago. These forests are of particular interest for their southern location and the high degree of endemism of their plant (many with ancient lineages) and animal species. There is also subtropical moist forests with high levels of plant and bird endemism on Lord Howe Island and Norfolk Island.

Temperate broadleaf and mixed forests

Temperate forests experience a wide range of variability in temperature and precipitation. In regions where rainfall is broadly distributed throughout the year, deciduous trees mix with species of evergreens. Species such as Eucalyptus and Acacia typify the composition of the temperate broadleaf and mixed forests in Australia.

In Australia, the temperate forests stretching from southeast Queensland to south Australia enjoy a moderate climate and high rainfall that give rise to unique eucalyptus forests and open woodlands. The temperate rain forests of Tasmania are extraordinarily complex and contain species from the time when the island was part of the super-continent Gondwana.

This biome in Australia has served as a refuge for numerous plant and animal species when drier conditions prevailed over most of the continent. That has resulted in a remarkably diverse spectrum of organisms with high levels of regional and local endemism.

Tropical and subtropical grassland, savannas and shrublands

Large expanses of land in the tropics do not receive enough rainfall to support extensive tree cover. The tropical and subtropical grasslands, savannas, and shrublands are characterised by rainfall levels between 90-150 centimetres per year.

While much of Australia is covered by grassland, savannah ecosystems are far more restricted - these ecosystems are limited to moister areas along the coast with the Kimberley, Top End, and Cape York savannas offering the best examples. Patches of dry rainforest with high species diversity also occur throughout the ecoregion.

Temperate grasslands, savannas and shrublands

This ecoregion differs largely from tropical grasslands due to the cooler and wider annual temperatures as well as the types of species found here. Generally speaking, these regions are devoid of trees, except for riparian or gallery forests associated with streams and rivers. Positioned between temperate forests and the arid interior of Australia, the southeast Australian temperate savannas span a broad north-south swatch across Queensland, New South Wales and Victoria. Unfortunately, most of this ecoregion has been converted to sheep rearing and wheat cropping and only small fragments of the original eucalypt vegetation remains.

Montane grasslands and shrublands

This ecoregion includes high elevation (montane and alpine) grasslands and shrublands.

In Australia montane grassland and shrublands are restricted to the montane regions of south-eastern Australia above 1300 metres. This region occupies less than three per cent of the Australian landmass and straddles the borders of the Australian Capital Territory, Victoria and New South Wales on the Australian mainland, as well as a significant element in Tasmania.

Mediterranean forests, woodlands and shrubs

Mediterranean ecoregions are characterised by hot and dry summers, while winters tend to be cool and moist.

Only five regions in the world experience these conditions and whilst the habitat is globally rare, it features extraordinary biodiversity of uniquely adapted animal and plant species and the five areas collectively harbour well over 10 per cent of the Earth's plant species. Most plants are fire adapted, and dependent on this disturbance for their persistence.

The Fynbos and southwest Australia shrublands have floras that are significantly more diverse than the other Mediterranean ecoregions. More than 5,500 species of plants have adapted to the forests and scrub of southwestern Australia, with nearly 70 percent being endemic.

Deserts and xeric shrublands

This ecoregion varies greatly in the amount of annual rainfall they receive; generally, however, evaporation exceeds rainfall in these ecoregions.

Temperature extremes are a characteristic of most deserts. Searing daytime heat gives way to cold nights because there is no insulation provided by humidity and cloud cover. Not surprisingly, the diversity of climatic conditions - though quite harsh - supports a rich array of habitats. Many of these habitats are ephemeral in nature - reflecting the paucity and seasonality of available water. The Great Sandy-Tanami deserts are the richest deserts in Australia and exhibit high levels of local endemism including the richest lizard communities in the world.

Tundra

The tundra is a treeless polar desert found in the high latitudes in the polar regions such as the sub-Antarctic islands - Macquarie, Heard and McDonald.

Structurally, the tundra is a treeless expanse that supports communities of sedges and heaths as well as dwarf shrubs. Most precipitation falls in the form of snow during the winter while soils tend to be acidic and saturated with water where not frozen.