Original distribution area of Melaleuca quinquenervia or NiaouliNothofagus 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 14,600 square kilometers (5,600sqmi).
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, 1,200km east of Australia and 1,500km 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 1,500mm yearly on the Loyalty Islands, 2,000mm at low elevations on eastern Grand Terre, and 2,000-4,000mm 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.
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.[6] 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).[7] Again, of the 35 known species of Araucaria, 13 are endemic to New Caledonia.[8]
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.[9]
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.[7]
Cloud forest formerly covered much of the tropical mountain and coastal areas of the world. The laurel forests are found in the islands of the Oceans, some tropical mountains and locally on favourable wet climate microenvironments of the coast and coastal mountains of the mainland, but the forests have been much reduced in extent by logging, clearance for agriculture and grazing, and the invasion of exotic species. The decline of much of the endemic fauna and flora is largely due to deforestation to accommodate agricultural expansion. This is accompanied by displacement of native flora by invasive alien weeds and crop plants. The most famous laurisilva forests remain on Madeira, where they are found between 300m and 1400m altitude on the northern slope, and 700m to 1600m on the southern slope, and cover 149,5km2.
New Caledonia was an ancient fragment of the supercontinentGondwana. 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 60–85million years ago,[11] 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 fossilizedforest 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.[12]
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.[13]
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
The New Caledonia rain forests are made up of three predominant forest types. The lowland rain forests cover the Loyalty Islands, and the Iles des Pines and the lower elevations of Grand Terre. Montane forests cover the higher elevations of Grand Terre. The wet maquis forests of Grand Terre are low shrub forests found on rocky soils derived from ultramafic rocks.
The predominant flora of New Caledonia rain forests is derived from the Antarctic flora of ancient southern Gondwana. Like the Australian rainforests and the temperate forests of New Zealand, conifers of the Southern Hemisphere families Araucariaceae and Podocarpaceae are mixed with angiosperm trees, including the Southern Hemisphere genus Nothofagus and trees and shrubs of families Myrtaceae and Proteaceae.
The Montane rain forests are also mixed-species, predominantly the conifers Araucaria, Agathis, Podocarpus, Dacrydium, Libocedrus, and Acmopyle, and the angiosperms Metrosideros, Pterophylla, Quintinia, and Nothofagus.
The Maquis forests hold a great variety of species, with many endemics. The ultramafic rocks, which formed in the deep ocean, are rich in metals, including nickel, magnesium, chromium, and manganese, which are toxic to many plants. The predominant trees are stunted Araucarias.
Fauna
New Caledonia has one of the most enigmatic birds of the world, the endangered kagu. It is related to the cranes and it lives very hidden. It is also the heraldic bird of the island. Another endemic bird is the New Caledonian rail. This critically endangered bird could be extinct but many believe that it still persists. Both the New Caledonian owlet-nightjar and the New Caledonian lorikeet are believed to persist under similar circumstances. There are also another twenty or so endemic birds on the island, including the tool-using New Caledonian crow. See Endemic birds of New Caledonia for more details. The seashells from New Caledonia are in great demand by collectors.
Conservation
A 2017 assessment found that 7,872km2, or 56%, of the ecoregion is in protected areas.[1] Protected areas include Parc de la Côte Oubliée (1222.59km2), Blue River Provincial Park (220.72km2), Parc de la Haute Dumbéa (91.71km2), and Parc des Grandes Fougères (45.45km2). Parc de la Zone Côtière Ouest (2552.68km2) is partly in the New Caledonia dry forests ecoregion.[14]
The geography of New Caledonia (Nouvelle-Calédonie), an overseas collectivity of France located in the subregion of Melanesia, makes the continental island group unique in the southwest Pacific. Among other things, the island chain has played a role in preserving unique biological lineages from the Mesozoic. It served as a waystation in the expansion of the predecessors of the Polynesians, the Lapita culture. Under the Free French it was a vital naval base for Allied Forces during the War in the Pacific.
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia.
The Queensland tropical rain forests ecoregion covers a portion of the coast of Queensland in northeastern Australia and belongs to the Australasian realm. The forest contains the world's best living record of the major stages in the evolutionary history of the world's land plants, including most of the world's relict species of plants from the ancient supercontinent of Gondwana. The history of the evolution of marsupials and songbirds is also well represented.
Araucariaceae – also known as araucarians – is a family of coniferous trees, with three living genera, Araucaria, Agathis, and Wollemia. While the family was distributed globally during the Jurassic and Cretaceous periods, they are now largely confined to the Southern Hemisphere, except for a few species of Agathis in Southeast Asia.
Araucaria is a genus of evergreen coniferous trees in the family Araucariaceae. While today they are largely confined to the Southern Hemisphere, during the Jurassic and Cretaceous they were distributed globally. There are 20 extant species in New Caledonia, Norfolk Island, eastern Australia, New Guinea, Argentina, Brazil and Chile.
Nothofagus, also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America and east and southeast Australia, New Zealand, New Guinea, and New Caledonia. The species are ecological dominants in many temperate forests in these regions. Some species are reportedly naturalised in Germany and Great Britain. The genus has a rich fossil record of leaves, cupules, and pollen, with fossils extending into the late Cretaceous period and occurring in Australia, New Zealand, Antarctica, and South America.
The Valdivian temperate forests (NT0404) is an ecoregion on the west coast of southern South America, in Chile and Argentina. It is part of the Neotropical realm. The forests are named after the city of Valdivia. The Valdivian temperate rainforests are characterized by their dense understories of bamboos, ferns, and for being mostly dominated by evergreen angiosperm trees with some deciduous specimens, though conifer trees are also common.
Antarctic flora are a distinct community of vascular plants which evolved millions of years ago on the supercontinent of Gondwana. Presently, species of Antarctica flora reside on several now separated areas of the Southern Hemisphere, including southern South America, southernmost Africa, New Zealand, Australia, and New Caledonia. Joseph Dalton Hooker was the first to notice similarities in the flora and speculated that Antarctica had served as either a source or a transitional point, and that land masses now separated might formerly have been adjacent.
Laurel forest, also called laurisilva or laurissilva, is a type of subtropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glossy and elongated leaves, known as "laurophyll" or "lauroid". Plants from the laurel family (Lauraceae) may or may not be present, depending on the location.
The biodiversity of New Caledonia is of exceptional biological and paleoecological interest. It is frequently referred to as a biodiversity hotspot. The country is a large South Pacific archipelago with a total land area of more than 18,000 square kilometres (6,900 sq mi). The terrain includes a variety of reefs, atolls, small islands, and a variety of topographical and edaphic regions on the largest island, all of which promote the development of unusually concentrated biodiversity. The region's climate is oceanic and tropical.
The biodiversity of New Zealand, a large island country located in the south-western Pacific Ocean, is varied and distinctive. The species of New Zealand accumulated over many millions of years as lineages evolved in the local circumstances. New Zealand's pre-human biodiversity exhibited high levels of species endemism, but has experienced episodes of biological turnover. Global extinction approximately 65 Ma resulted in the loss of fauna such as non-avian dinosaurs, pterosaurs and marine reptiles e.g. mosasaurs, elasmosaurs and plesiosaurs. The ancient fauna is not well known, but at least one species of terrestrial mammal existed in New Zealand around 19 Ma. For at least several million years before the arrival of human and commensal species, the islands had no terrestrial mammals except for bats and seals, the main component of the terrestrial fauna being insects and birds. As recently as the 14th century a component has been introduced by humans, including many terrestrial mammals.
Neozealandia is a biogeographic province of the Antarctic Realm according to the classification developed by Miklos Udvardy in 1975.
The Paleotropical Kingdom (Paleotropis) is a floristic kingdom composed of the tropical areas of Africa, Asia and Oceania, as proposed by Ronald Good and Armen Takhtajan. Part of its flora is inherited from the ancient supercontinent of Gondwana or exchanged later. These Gondwanan lineages are related to those in the Neotropical Kingdom, composed of the tropical areas of Central and South America. Flora from the Paleotropical Kingdom influenced the tropical flora of the Australian Kingdom. The kingdom is subdivided into five floristic subkingdoms according to Takhtajan and about 13 floristic regions. In this article the floristic subkingdoms and regions are given as delineated by Takhtajan.
The natural history of New Zealand began when the landmass Zealandia broke away from the supercontinent Gondwana in the Cretaceous period. Before this time, Zealandia shared its past with Australia and Antarctica. Since this separation, the New Zealand landscape has evolved in physical isolation, although much of its current biota has more recent connections with species on other landmasses. The exclusively natural history of the country ended in about 1300 AD, when humans first settled, and the country's environmental history began. The period from 1300 AD to today coincides with the extinction of many of New Zealand's unique species that had evolved there.
Zealandia, also known as Te Riu-a-Māui (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust in Oceania that subsided after breaking away from Gondwana 83–79 million years ago. It has been described variously as a submerged continent, continental fragment, and microcontinent. The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995, and satellite imagery shows it to be almost the size of Australia. A 2021 study suggests Zealandia is 1 billion years old, about twice as old as geologists previously thought.
The Central Range montane rain forests is a tropical moist forest ecoregion on the island of New Guinea. The ecoregion covers the Central Range of the New Guinea Highlands, which extends along the spine of the island. The montane rain forests of the ecoregion are distinct from the surrounding lowland forests, and are home to many endemic plants and animals.
The biodiversity of Tasmania is of exceptional biological and paleoecological interest. A state of Australia, it is a large South Pacific archipelago of one large main island and a range of smaller islands. The terrain includes a variety of reefs, atolls, many small islands, and a variety of topographical and edaphic regions on the largest island, all of which promote the development of unusually concentrated biodiversity. During long periods geographically and genetically isolated, it is known for its unique flora and fauna. The region's climate is oceanic.
The Vogelkop montane rain forests is a tropical moist forest ecoregion in western New Guinea. The ecoregion covers the mountains of western New Guinea's Bird's Head and Bomberai peninsulas.
The New Britain–New Ireland montane rain forests is a tropical moist forest ecoregion in Papua New Guinea. The ecoregion includes the mountain rain forests on the islands of New Britain and New Ireland, which lie northeast of New Guinea.
References
1 2 Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b.
↑ Li, H.M.; Zhou, Z.K. (2007). "Fossil nothofagaceous leaves from the Eocene of western Antarctica and their bearing on the origin, dispersal and systematics of Nothofagus". Science in China. 50 (10): 1525–1535.
↑ Collins, Alan S.; Pisarevsky, Sergei A. (2005). "Amalgamating eastern Gondwana: The evolution of the Circum-Indian Orogens". Earth-Science Reviews. 71 (3–4): 229–270. doi:10.1016/j.earscirev.2005.02.004.
↑ Fujiwara, Kazue and Elgene O. Box (1999)."Evergreen Broad-Leaved Forests in Japan and Eastern North America: Vegetation Shift under Climatic Warming" in Conference on Recent Shifts in Vegetation Boundaries of Deciduous Forests F. Klötzli, G.-R. Walther, eds. Birkhauser, Basel. doi=10.1007/978-3-0348-8722-9_16
↑ Keith Lewis; Scott D. Nodder; Lionel Carter (11 January 2007). "Zealandia: the New Zealand continent". Te Ara— the Encyclopedia of New Zealand. Retrieved 22 February 2007.
↑ Campbell, Hamish; Gerard Hutching (2007). In Search of Ancient New Zealand. North Shore, New Zealand: Penguin Books. pp.183–184. ISBN978-0-14-302088-2.
Flannery, Tim (1994). The Future Eaters. Grove Press, New York.
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