Our Ecoregion

Jewel of the Australian continent

The Southwest Australia Ecoregion (SWAE) is a vast, triangular-shaped swathe of land stretching roughly from Shark Bay on Western Australia’s northern coast to Esperance on the southeast coast, and then along a narrow strip towards the South Australian border. It covers approximately 493,000km2 of some of the most biologically diverse areas on earth (1) , and is unique, even within the bounds of Australia’s huge array of weird and wonderful wildlife.

The region’s global significance is based on high levels of natural diversity, particularly for plants, coupled with high levels of threat to that diversity. It is one of the world’s 34 official biodiversity hotspots as recognised by Conservation International. To qualify as a hotspot, a region must meet two strict criteria: it must contain at least 1,500 species of vascular (higher order) plants as endemics, and it has to have lost at least 70% of its original habitat. In addition, the Southwest Australia Ecoregion is globally recognised as:

•    One of only five Mediterranean-type ecosystems to be listed as globally significant;
•    A Centre of Plant Diversity as defined by WWF and the International Union for Conservation of Nature and Natural Resources (IUCN). If protected, Centres of Plant Diversity would safeguard most of Earth’s plant diversity;
•    A WWF Global 200 Ecoregion due to significant wetland systems;
•    An Endemic Bird Area by Birdlife International; and
•    Containing five of the 15 national biodiversity hotspots nominated by the Australian Government.

What is an Ecoregion?

An ecoregion is a large area of land containing a geographically distinct array of species, natural communities, dynamics and environmental conditions. Working at the ecoregion scale offers several advantages for conservation planning and action.

Defined in biological terms, an ecoregion focuses attention on the biodiversity at stake, in a bid to think, plan and act in relation to a single ecological unit, regardless of man-made boundaries. Because ecoregions are identified as far as possible to be biologically coherent, it is feasible to set more meaningful and strategic biodiversity conservation goals – focusing on populations, processes and ecological phenomena and serious threats to the region.

Ecoregion conservation is visionary, encouraging us to plan for the long term.

The power of flowers – a floristic capital of the world

Western Australia, and in particular the southwest, is recognised nationally and internationally for its magnificent displays of wildflowers. The Southwest Australia Ecoregion is characterised by a highly diverse flora that has evolved to cope with the ancient and nutrient deficient soils. Its major vegetation types are woody and include the temperate forests of the deep southwest; woodlands, the Eucalyptus-dominated mallee and shrublands of the temperate and semi-arid zones; Kwongan heathlands; and other habitats such as naturally saline wetlands and granite outcrops.

Mallee is an Aboriginal term and refers to any short tree with a large underground stem fused with the main root, called a lignotuber. All eucalyptus trees with this growth pattern are referred to as mallees. So, too, is any plant cover that is dominated by mallee trees and shrubs (2).

Kwongan is a term adapted from the Aboriginal Noongar language to cover the various types of shrub-land comparable with the maquis, chaparral and fynbos of Mediterranean-type systems in other countries (3). The principal structural types of Kwongan are thicket, scrub-heath, and heath, which together comprise about 30 percent of the original vegetation (4).

The ten largest families in the Southwest Australia Ecoregion (including the Myrtaceae with 785 species, of which 92 percent are endemic, and Proteaceae with 684 species, 96 percent endemic) comprise 61 percent of the flora (5). The Banksia plants of the family Proteaceae are among the most distinctive found in this biodiversity hotspot. These brilliant flowering plants range from trees to small prostrate plants, one of which even has underground stems (6).

Inside the Southwest Australia Ecoregion, 341 species of flora have been declared “Rare Flora - Extant” (taxa which have been adequately searched for, and are deemed to be in the wild either rare, in danger of extinction, or otherwise in need of special protection) under the Wildlife Conservation Act of Western Australia (7).  Within the Southwest Botanical Province (covering an area of 309,840km2), more than 5,710 native plant species have been identified with 3,000 of these found nowhere else in the world (a 52.5 per cent level of endemism) (8).

Tourism in the ecoregion is partly dependent on the wildflowers for which Western Australia is famous. The better known of these include Western Australia’s state emblem, the Kangaroo Paw (Anigozanthos manglesii), and the Scarlet Banksia (Banksia coccinea), an iconic south coast species. Another drawcard are the magnificent karri (E. diversicolor) forests, with trees reaching up to 80 meters in height, ranking this endemic species as one of the tallest trees on earth (9). The Jarrah-Karri Forests and Shrublands within the ecoregion extend along the Indian Ocean coastline of Southwest Australia (10). This ‘hotspot within a hotspot’ is considered the most important centre of endemism for conservative, high-rainfall vascular plants in Western Australia (11).

On the hop - fauna of the Southwest Australia Ecoregion

The Southwest Australia Ecoregion has a rich and varied fauna, including twelve species of mammals, 10 species of birds, 27 species of reptiles and 22 species of frogs that are found only in this region (12). Invertebrates are relatively poorly known but it is likely that high numbers of endemic species are also present, particularly for some groups such as spiders in the Wheatbelt, where many are long-lived and move only very short distances over their lifetime. Freshwater ecosystems harbor a number of Gondwanan relicts, including endemic freshwater worms from the family Phreodrilidae, and freshwater crayfish from the genera Cherax and Engaewa (13). The Perth metropolitan region alone is known for a diverse herpetofauna, including 16 frogs, two freshwater turtles, 51 lizards, and 24 snakes (14).

The Numbat (Myrmecobius fasciatus), now effectively a Southwest Australia Ecoregion endemic due to massive range retraction, is the mammal emblem for Western Australia and the only member of the family Myrmecobiidae (15). Other endemic species include the:

  • Honey Possum – weighing just 7–12 grams and giving birth to the smallest live young of any mammal (less than 5 milligrams (16) ), it is dependent on the nectar and pollen of native flowering plants such as banksias;
  • Yinnietharra rock dragon -  an understudied lizard species that is apparently specialized to two granitic rock outcrops in the region and does not inhabit outcrops of different origins (17);
  • Quokka – a member of the kangaroo family which was once widespread but is now restricted to the island of Rottnest near Perth, Bald Island and a number of restricted mainland locations;
  • Western Whipbird – this endangered bird lives in mallee habitat, with estimates of only 500 of these endemic birds left (18);
  • Lake Cronin snake – whose very limited range includes unprotected private lands (19);
  • Noisy Scrub-bird – which earned its name because of the loud vocalizations of its males, was long presumed to be extinct until it was discovered in unburnt thickets and gullies in Two Peoples Bay near Albany 1961 (20);
  • Western Swamp Tortoise – Australia’s smallest and rarest turtle which hibernates for nearly eight months of the year. This species may in fact be the most threatened freshwater turtle species in the world (21);
  • Salamanderfish – the only member of the hotspot’s single endemic family (Lepidogalaxiidae) (22); and
  • Sunset Frog – discovered in 1994 and appears to be an ancient species more than 30 million years old.

A rich cultural heritage

Beyond its global and national significance for biodiversity, the Ecoregion has a unique and important cultural heritage. Its landscapes have been peopled for at least 50,000 years. Aboriginal culture and relationships between groups and families are rich and complex. Although broadly, much of the southwest has been the homeland for the Noongar (Nyoongar or Nyungar) people, for the Yamadji people in the northwest of the region, and the Wongai people in the east, Southwest Australia is a mosaic of linguistic and cultural diversity.

European settlement has a relatively recent history within the Ecoregion, dating back to 1826, but many people depend on the natural resources of the Southwest Australia Ecoregion for their livelihoods. Outside the main population centres, where service industries, manufacturing and commerce are the main sources of income, most income is derived from agriculture, pastoralism, forestry and mining.

References

  1. National Geographic - http://wwf.panda.org/about_our_earth/ecoregions/swaustralia_forests_scrub.cfm
  2. World Wildlife Fun - Esperance mallee (AA1202) Wild World
  3. Conservation International (http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth)
  4. Conservation International (http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth)
  5. Conservation International (http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth)
  6. Conservation International (http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth)
  7. Flora Base - http://florabase.calm.wa.gov.au/search/advanced?family=&genus=&species=&infrasp=&author=&constat=R&current=&alien=&ms=&common=&id=&reference=&photo=&colour=&fltime=&habitat=&habit=&soiltype=&northern=&eremaean=&southwst=*
  8. Beard, J.S., Chapman, A.R. and Gioia, P. (2000). Species richness and endemism in the Western Australian flora. Journal of Biogeography 27, 1257-1268.
  9. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  10. World Wildlife Fund – Jarrah-Karri forest and shrublands (AA1204) Wild World
  11. Hopper et al. 1992 in Wardell-Johnson and Horwitz 1996
  12. Conservation International - http://www.conservation.org/explore/priority_areas/hotspots/asia-pacific/Southwest-Australia/Pages/biodiversity.aspx
  13. Wardell-Johnson and Horwitz 1996
  14. Hopper, S. D., M. S. Harvey, J. A. Chappill, A. R. Main, and B. Y. Main. 1996. The western Australian biota as Gondwanan heritage – a review. Pages 1-46 in S. D. Hopper, J. A. Chappill, M. S. Harvey, and A. S. George, editors. Gondwanan
    Heritage: past, present, and future of the western Australian biota. Surrey Beatty & Sons, Chipping Norton, Australia.
  15. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  16. World Wildlife Fund - Kwongan heathlands (AA1205) Wild World
  17. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  18. World Wildlife Fund – Esperance mallee (AA1202) Wild World
  19. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  20. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  21. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  22. Conservation International - http://www.biodiversityhotspots.org/xp/hotspots/australia/Pages/conservation.aspx#indepth
  • Map
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The Southwest Australia Ecoregion Initiative is a consortium project - find out more about how we're achieving conservation through collaboration.

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A large number of agencies, organisations, individuals and community groups are conducting a wide variety of projects aimed at conserving the rich biodiversity of the SouthWest Australia Ecoregion...

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