The Biodiversity of New Caledonia, a large Pacific island group, is considered to be one of the most important in the region. The island supports high levels of endemism, with many unique plants, insects reptiles and birds. The island has no native land mammals except for bats, and no native amphibians. New Caledonia 's biodiversity is threatened by introduced species, logging and nickel mining, it has lost several species since the arrival of man on the island, but none are thought to have become extinct since 1500.

Evolution of New Caledonian Biodiversity

Unlike many of the islands of the South Pacific, New Caledonia is not of volcanic origin, instead it is a fragment of the ancient continent of Gondwana. It separated from Australia and New Zealand during the break up of the super-continent, from Australia at he end of the Cretaceous (65 MYA) and from New Zealand in the mid-Miocene. This has led to a long period of evolution and means that New Caledonia’s fauna and flora comprise both dispersed species from Australia and other islands, and species whose ancestors were present on New Caledonia when it broke away from Gondwana. In many cases this long isolation has led to the evolution of not only species, but genera and even families that are unique to the island, or in some cases simply survive nowhere else. As the island moved north geologists assert that it was submerged at some times, botanists assert that there must have been some areas that acted as refugia for the plants that bear floral affinities with Gondwana. The rise and fall of sea levels caused by ice ages has led to islands being formed between New Caledonia and its neighbours, the Solomon Islands, Vanuatu, and Australia, this has helped species reach New Caledonia, and species of Gondwanan origin reach further into the Pacific.

Elements of New Caledonian Biodiversity

New Caledonia sits on the southernmost edge of tropical zone. Its main island, Grande Terre, hosts a variety of habitats caused by several factors, geology, soils and altitude.

Floral Biodiversity

The three main types of vegetation found on New Caledonia are moist evergreen forest, sclerophyllous forest and heath_like maquis scrub. New Caledonia has about 4000 species of angiosperms, of which about 76.4% are endemic to the island. 14% of the genera are endemic, and five families, the Amborellaceae, Oncothecaceae, Paracryphiaceae, Phellinaceae and Strasburgiaceae, are restricted to the island. The only islands in the world with a higher level of plant endemism are Hawaii, New Zealand and Madagascar. The islands also boasts 44 species of gymnosperms (conifers), of which 43 are endemic. The three main types of vegetation found on New Caledonia are moist evergreen forest, sclerophyllous forest and heath-like maquis scrub. Of these, the moist forests hold the highest diversity of species.

Faunal Biodiversity

New Caledonia's faunal diversity is similar to that of many islands, particularly New Zealand. It lacks land mammals (other than bats) instead having a vertebrate fauna dominated by reptiles and birds. Prior to the arrival of man some large species had evolved on the island that have become extinct, fossils found in cave deposits show the island once had a species of barn owl (Tyto letocarti) two extinct hawks, a megapode and a large extinct megapode known as Sylviornis neocaledoniae. The island also held a large terrestrial turtle unlike any today, armed with a clubbed tail and spikes coming out from it's head. A terrestrial mekosuchine crocodile, Mekosuchus inexpectatus was a component of the ancient Gondwanan fauna that also went extinct after the arrival of man.

Today the island has 21 endemic species of birds, including one endemic family, the Rhynochetidae, represented by one living species, the Kagu. The island is also home to the unusual tool using New Caledonian Crow.

The island's reptile fauna shares most of its affinities with Australia. 62 of the 69 species are endemic to the island. Two species of snake are found on the island. It is the home to the world’s largest gecko, and a large number of skinks and geckos. No crocodiles or terrestrial turtles remain on the island.

Threats to New Caledonian Biodiversity

New Caledonia's biodiversity is threatened by a number of factors. Like many island biotas, its species were poorly equipped to deal with introduced species like the rat, cat, dog and pig. These have taken a toll on species like the ground living Kagu. Hunting is still a problem in remote areas, as is habitat loss caused by deforestation and mining (one of the island's principal industries).

Although no species are known to have become extinct since 1500, two species, the New Caledonian Rail and the New Caledonian Lorikeet have not been seen for over a hundred years and are considered to be critically endangered if not actually extinct. A similar fate was thought to have befallen the New Caledonian Owlet-nightjar, but a recent survey reported finding them in remote parts of the island.

New Caledonia is considered a conservation priority by many organizations, and work is underway to preserve the islands unique ecosystems.

External links

• Birdlife International: New Caledonia (http://www.birdlife.net/datazone/search/ebas_search.html?action=EbaHTMDetails.asp&sid=201&m=0)
• Conservation International : Biodiversity Hotspots (http://www.biodiversityhotspots.org/xp/Hotspots/new_caledonia/?showpage=Biodiversity)
• Missouri Botanical Garden : New Caledonia's Flora (http://www.mobot.org/MOBOT/research/newcaledonia/caledonia.html)