Australasia - Ecological Geography

Ecological Geography

From an ecological perspective the Australasia ecozone is a distinct region with a common geologic and evolutionary history and a great many unique flora and fauna. In this context, Australasia is limited to Australia, New Guinea, New Zealand, New Caledonia, and neighbouring islands, including the Indonesian islands from Lombok and Sulawesi eastward. The biological dividing line from the Indomalaya ecozone of tropical Asia is the Wallace Line – Borneo and Bali lie on the western, Asian side.

Australia, New Zealand and New Caledonia are all fragments of the ancient supercontinent Gondwana, the marks of which are still visible in the Christmas Island Seamount Province and other geophysical entities. These three land masses have been separated from other continents, and from one another, for millions of years. All of Australasia shares the Antarctic flora, although the northern, tropical islands also share many plants with Southeast Asia.

Australia, New Guinea, and Tasmania are separated from one another by shallow continental shelves, and were linked together when the sea level was lower during the Ice Ages. They share a similar fauna which includes marsupial and monotreme mammals and ratite birds. Eucalypts are the predominant trees in much of Australia and New Guinea. New Zealand has no native land mammals, but also had ratite birds, including the kiwi and the extinct moa. The Australasia ecozone includes some nearby island groups, like Wallacea, the Bismarck Archipelago, Solomon Islands, and Vanuatu, which were not formerly part of Gondwana, but which share many characteristic plants and animals with Australasia.