Australasian realm

The Australasia Ecozone

The Australasian realm is a biogeographic realm that is coincident, but not synonymous (by some definitions), with the geographical region of Australasia. The realm includes Australia, the island of New Guinea (including Papua New Guinea and the Indonesian province of Papua), and the eastern part of the Indonesian archipelago, including the island of Sulawesi, the Moluccan islands (the Indonesian provinces of Maluku and North Maluku) and islands of Lombok, Sumbawa, Sumba, Flores, and Timor, often known as the Lesser Sundas.

The Australasian realm also includes several Pacific island groups, including the Bismarck Archipelago, Vanuatu, the Solomon Islands, and New Caledonia. New Zealand and its surrounding islands are a distinctive sub-region of the Australasian realm. The rest of Indonesia is part of the Indomalayan realm.

Geography

From an ecological perspective the Australasian realm is a distinct region with a common geologic and evolutionary history and a great many unique plants and animals. 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 Indomalayan realm of tropical Asia is the Wallace Line: Borneo and Bali lie on the western, Asian side.

Geology

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 tens 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 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 moa. The Australasian realm 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.

Ecology

Note that this zonation is based on flora; animals do not necessarily follow the same biogeographic boundaries. In the present case, many birds occur in both "Indomalayan" and "Australasian" regions, but not across the whole of either. On the other hand, there are few faunistic commonalities shared only by Australia and New Zealand, except some birds. Meanwhile, Australia, Melanesia and the Wallacea are united by a large share of similar animals, but few of these occur farther into the Pacific. On the other hand, much of the Polynesian fauna is related to that of Melanesia. Moreover, Australia generally features eucalyptus, acia and casuarina trees, whereas New Zealand would lack those and instead would mostly consist of conifers and beeches, among other tree species (see List of trees native to New Zealand).

Vegetation list

Australasian temperate broadleaf and mixed forests ecoregions
Chatham Islands temperate forests	New Zealand
Eastern Australian temperate forests	Australia
Fiordland temperate forests	New Zealand
Nelson Coast temperate forests	New Zealand
North Island temperate forests	New Zealand
Northland temperate kauri forests	New Zealand
Stewart Island / Rakiura temperate forests	New Zealand
Richmond temperate forests	New Zealand
Southeast Australia temperate forests	Australia
Southland temperate forests	New Zealand
Tasmanian Central Highland forests	Australia
Tasmanian temperate forests	Australia
Tasmanian temperate rain forests	Australia
Westland temperate forests	New Zealand

See also

• Australasia
• Oceania

External links

• Panda.org: Map of the Ecozones