Biodiversity of the Southwest

Biodiversity is life; the variety of all living things. It is genetic diversity, species diversity and ecosystem diversity, which together make up the complexity of life on Earth. It is essential for our existence, but also intrinsically valuable in its own right.

The South West region of Western Australia is one of Conservation International's 34 'International Biodiversity Hotspots', the only one on the Australian continent. These biodiversity hotspots contain at least 1,500 species of vascular plants, as endemic species; species that are found nowhere else on Earth.

Each hotspot faces extreme threats and has already lost at least seventy percent of its original natural vegetation. These hotspots are described as 'the richest and most threatened reservoirs of plant and animal life on Earth.'

Impressive plant endemism in south west Australia is attributed to millions of years of isolation from the rest of Australia by the country's vast central deserts. Extreme climate shifts, poor soils and frequent fire also promoted specialisation of the region's flora. Iconic tree species includes three eucalyptus; the jarrah, marri and karri. Karri trees may grow as high as eighty metres, making this endemic species one of the tallest trees on earth.

Living on and in this diverse plant life and in the soil and leaf litter of the forest floor, there is an amazing array of invertebrate life. These animals clean, control, regulate and recycle, maintaining a healthy forest environment and filtration of water through to the caves below.

In the waters of Lake Cave and deep within the Jewel Cave system, exists a 'micro-ecosystem' in danger of being lost. Animals that live permanently in underground water are called 'stygofauna'. Stygofauna are ancient species; many of them are relics from an age before the great mass of land known as 'Gondwana' broke apart to form the continents as we know them today. However their habitats are under threat as water levels in the caves are declining fast. In 2000 there were twenty three species of stygofauna found in Lake Cave; this means it had the highest species diversity of any of the caves in the Leeuwin-Naturaliste Ridge. In 2010 only six species remain; a loss of seventy four percent of species richness in just ten years. It is essential that we act now to protect these unique micro-ecosystems before we lose them forever.

Donkey orchid

Stygofauna species

Karri forest