or Niaouli '' is a plant genus that illustrates Gondwanan distribution, having descended from the supercontinent and existing in current day Australia, New Zealand, New Caledonia and Chile. Fossils have also recently been found in Antarctica. The ecoregion covers the
windward eastern side of Grand Terre, New Caledonia's mountainous main island, as well as the smaller
Loyalty Islands to the east and the
Isle of Pines to the south of Grand Terre. The ecoregion covers an area of . Grand Terre is a long island that runs approximately north–south, with a mountain range down the center with five peaks that exceed 1500 meters elevation. The Loyalty Islands and Ile des Pins are much lower. New Caledonia lies astride the
Tropic of Capricorn, between 19° and 23° south
latitude, 1,200 km east of Australia and 1,500 km northeast of New Zealand. The climate of the islands is
tropical, and
rainfall is highly seasonal, brought by
trade winds that usually come from the east. Rainfall averages about 1,500 mm yearly on the Loyalty Islands, 2,000 mm at low elevations on eastern Grand Terre, and 2,000-4,000 mm at high elevations on Grand Terre. The western slopes of Grand Terre, which are in the
rain shadow of the central mountain range, are much drier, and are home to the
New Caledonia dry forests ecoregion. New Caledonia is an ancient fragment of
Gondwana, the southern supercontinent. It separated from
Australia 85 million years ago, and remained attached to
New Zealand until 55 million years ago. It has been isolated from other land masses since then, although a number of plants and animals have been able to cross the straits separating New Caledonia from neighboring islands. The forests are made up of laurel-leaved
evergreen hardwood trees, reaching up to 40 m in height. Many of the
species are
endemic to the islands, and harbour and rich
biota of
understorey plants,
invertebrates, and
birds and
bats. New Caledonia's fauna and flora derive from ancestral species isolated in the region when it broke away from Gondwana many tens of millions of years ago. Not only endemic species have evolved here, but entire genera and even families are unique to the islands. More tropical
Gymnosperm species are endemic to New Caledonia than to any similar region on Earth. Of the 44 indigenous species of gymnosperms, 43 are endemic, including the only known parasitic Gymnosperm (
Parasitaxus usta). Again, of the 35 known species of
Araucaria, 13 are endemic to New Caledonia. The world's largest extant species of
fern,
Sphaeropteris intermedia, also is endemic to New Caledonia. It is very common on acid ground, and grows about one metre per year on the east coast, usually on fallow ground or in forest clearings. There also are other species of
Cyathea, notably
Sphaeropteris novae-caledoniae. The islands soils derived largely from
ultramafic rocks, and have been a refuge for many native flora species that have adapted to their composition a long time ago; such flora can survive on acid soils with unfavourable compositions of nutrient elements. On New Caledonia examples of such soils commonly have an excess of magnesium, plus unusually high concentrations of
phytotoxic compounds of heavy metals such as nickel. Not many invader species can compete successfully with plants adapted to such challenging soils. New Caledonia also is one of five regions on the planet where species of
Nothofagus are indigenous; five species are known to occur here. New Caledonia was an ancient fragment of the
supercontinent Gondwana. Unlike many of the Pacific Islands, which are of relatively recent volcanic origin, New Caledonia is part of
Zealandia, a fragment of the ancient
Gondwana super-continent. Zealandia separated from Australia 60–85 million years ago, and the ridge linking New Caledonia to New Zealand has been deeply submerged for millions of years. This isolated New Caledonia from the rest of the world's landmasses, preserving a snapshot of Gondwanan forests. New Caledonia and New Zealand are separated by
continental drift of Australia 85 million years ago. The islands still shelters an extraordinary diversity of
endemic plants and animals of Gondwanan origin have spread to the southern continents later. The laurel forest of Australia,
New Caledonia (
Adenodaphne), and New Zealand have a number of other related species of the Valdivian laurel forest, through the connection of the
Antarctic flora of gymnosperms like the podocarpus and deciduous Nothofagus. New Caledonia lies at the northern end of the ancient continent
Zealandia, while New Zealand rises at the plate boundary that bisects it. These land masses are two outposts of the
Antarctic flora, including
Araucarias and
Podocarps. At
Curio Bay, logs of a
fossilized
forest closely related to modern
kauri and
Norfolk pine can be seen that grew on Zealandia about 180 million years ago during the
Jurassic period, before it split from Gondwana. During glacial periods more of Zealandia becomes a
terrestrial rather than a marine environment. Zealandia was originally thought to have no native land
mammal fauna, but a recent discovery in 2006 of a fossil mammal jaw from the Miocene in the Otago region shows otherwise. New Guinea and Northern Australia ecoregion are closely related. Over time Australia and New Caledonia drifted north. New Caledonia protected by the ocean remained unchanged preserving their species and Australia became drier; the humid
Antarctic flora from Gondwana retreated to the east coast and Tasmania, while the rest of Australia became dominated by
Acacia,
Eucalyptus, and
Casuarina, as well as xeric shrubs and grasses.
Humans arrived in Australia 50–60,000 years ago, and used fire to reshape the vegetation of the continent; as a result, the Antarctic flora, also known as the
rainforest flora in Australia, retreated to a few isolated areas composing less than 2% of Australia's land area. ==Flora==