Biodiversity of New Caledonia


Biodiversity of New Caledonia

The Biodiversity of New Caledonia is considered to be one of the most important in the world. New Caledonia, a large south Pacific island group about 1,200 km east of Australia, supports high levels of endemism, with many unique plants, insects, reptiles and birds. This biodiversity is threatened by introduced species, logging, fire, agriculture and urban development, and mining (nickel and other valuable minerals). The island has lost several species since the arrival of man, but none are thought to have become extinct since 1500.

Contents

Location and description

New Caledonia sits on the southernmost edge of the tropical zone. Its main island, Grande Terre, hosts a variety of habitats arising from several factors, including precipitation, geology, soils and altitude. The island has been categorised as having two main ecoregions, the majority of the island being New Caledonia rain forests while the New Caledonia dry forests runs along the west coast, although here the original forest has mostly been cleared with only fragments remaining.

Evolution and history

Unlike many of the islands of the South Pacific, New Caledonia is not of volcanic origin, but is instead a fragment of the ancient continent of Gondwana. In the Carboniferous and Permian, New Zealand and New Caledonia were on the periphery of Gondwana (which included Africa, South America, Antarctica, India, New Zealand and Australia). Paleomagnetic data allow us to locate the position of New caledonia, near the south pole. In the Triassic and early Jurassic, the Gondwana moved northward away from the pole, leading to a warming of the eastern margin. The marine fauna of the period, separate from the southwest Pacific was distinguished as "province Maori". In the middle and upper Jurassic, the Gondwana began his fragmentation and the arrival of a benthic invertebrate fauna thétysiens is visible in the fossil deposits. The Cretaceous is marked by the appearance of a marine invertebrate fauna of southern origin. It was then when the angiosperm flora such as Notofagus and Proteaceae have colonized New Zealand and New Caledonia, from South America, along the Antarctic margin of Gondwana. At the beginning of the Tertiary, New Zealand and New Caledonia move north, to more warm climate.

It separated from Australia and New Zealand during the breakup of the super-continent, from Australia at the end of the Cretaceous (65 MYA) and from New Zealand in the mid-Miocene. This has led to a long period of evolution in near complete isolation. New Caledonia’s natural heritage significantly comprises species whose ancestors were ancient and primeval flora and fauna present on New Caledonia when it broke away from Gondwana millions of years ago, not only species but entire genera and even families are unique to the island, and survive nowhere else.

Since the age of the dinosaurs, as the island moved north due to the effects of continental drift, some geologists assert that it was submerged at various intervals. Botanists, however, assert that there must have been some areas that remained above sea-level, serving as refugia for the descendants of the original flora that inhabited the island when it broke away from Gondwana. The isolation of New Caledonia was not absolute, however and some species migration from Australia and other islands into, and out of, the island was facilitated by the rise and fall of sea levels due to the ebb and flow of ice ages, when islands and land bridges formed between New Caledonia and its neighbours, the Solomon Islands, Vanuatu, and Australia. Thus new species came to New Caledonia while species of Gondwanan origin were able to penetrate further eastward into the Pacific Island region.

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 flightless bird known as Sylviornis neocaledoniae.[1] The island also held the large terrestrial turtle Meiolania, unlike any alive today, armed with a clubbed tail and spikes coming out from its head. A terrestrial mekosuchine crocodile, Mekosuchus inexpectatus, also went extinct after the arrival of man. Both Meiolania and Mekosuchus may have arrived after crossing the ocean (via island hopping and/or waif dispersal) from Australia.

Flora

New Caledonia plant communities are veritable living fossils, offering the opportunity to examine species with roots in the age of dinosaurs. Besides their antiquity, the flora of this island nation is exceedingly diverse, and includes a level of endemism, per square kilometre, seen almost nowhere else on earth. Three quarters of native plant species on New Caledonia are endemic, but a quarter of those are "at risk" of decline or extinction.[2]

Unlike many Pacific islands, which are of volcanic Recently, New Caledonia is an ancient fragment of the super Gondwana. New Caledonia and New Zealand were separated by continental drift from Australia 85 million years ago. The islands still retain flora and fauna that originated in Gondwana.

It presents as a peculiarity, which has genera originated in the Antarctic flora, and shares many plant families with the Valdivian forest of South America, New Zealand, Tasmania and Australia, in habitats of cloud forest and temperate rainforest. It was in the Cretaceous that angiosperm flora colonized New Zealand and New Caledonia, from South America, along the Antarctic margin of Gondwana, with species as Nothofagus and Proteaceae.

This zone has plant vicariant species that met the same ecological role, eg in the west coast of North America, New Zealand or Eurasia Tertiary where there was also accompanied by a laurel pine communities in the most extreme climate areas. The role of Nothofagus and Podocarpaceae was occupied by the Taxus and various oaks.

These characterizes that New Caledonia, being much lower than New Zealand and Australia in extent, has the highest rate of endemic plant species in the Pacific and one of the richest rainforests on the planet in an area so isolated. Habitats are lowland or tropical high forest mixed forest, or cloud forest: dense mountain forests of New Caledonia.

The vegetation in the western part of the Big Island is more xerophilous, with low wet areas occupied by various communities of mangroves and rainforest, very degraded. It is very rich in epiphytes and mountain forests are mainly located in mountainous areas in the lee slopes, where communities are evergreen species of laurel forest.

They are typically evergreen and multi-species forests. Evergreen because the mild climate allows for continuous biological activity, and multi-species by the remarkable diversity of tree species in the canopy. Indeed, in the absence of a strong environmental selective pressure, the number of species that share the tree canopy is high. It is precisely this multispecies what they deserve the name of rainforest, in contrast to the "woods", Mediterranean forests, temperate deciduous forests etc, which is monospecific or its canopy is dominated by one or a few species. In this sense, the laurel forest is a formation of transition between temperate forests and rainforests. Many tree species do not coincide in the loss of leaf, at flowering or at the time of fruit ripening, finding all the phases at any time of year. The woody plants including conifers of the families Podocarpaceae, Araucariaceae and the subfamily Callitroideae of Cupressaceae and angiosperms such as families Erythroxylaceae,Epacridaceae, Proteaceae, Griseliniaceae, Cunoniaceae, Atherospermataceae, and Winteraceae, and genus as southern beech (Nothofagus) and fuchsia Fuchsia (Fuchsia). Many other families of flowering plants and ferns, including the tree fern Dicksonia , Cyathea novae-caledoniae,[3] or the more tall in the world, Cyathea intermedia. Remarkably Amborella is of great interest to plant systematists because of last molecular phylogenetic Analyses. Lauraceae genus as Beilschmiedia some exclusive (Adenodaphne). There are many epiphytes and large mossy formations that hang at times, giving a surreal and ghostly jungle. The moisture is abundant, becoming in some areas a limiting factor for less adapted vegetation, to create a hygrophilous moistured environment with great visual appeal, in the form of mists and sprays, ponds and streams that permeate the entire visual field.

Four genera: Araucaria, Libocedrus, Prumnopitys and Retrophyllum have a current distribution subantarctic Pacific, with endemic species in New Caledonia. for example The genus Acmopyle (Podocarpaceae) currently present in New Caledonia and Fiji is a fossil in Patagonia. The tree niaouli (Melaleuca quinquenervia), which also grows in Australia and New Zealand. Other species are: Pine of New Caledonia, Pine colonario, Podocarpaceae, Mangrove, Swietenia macrophylla, Cocos nucifera, Erythroxylum novocaledonicum and so on. It has 21 species of Metrosideros, Metrosideros brevistylis, M. cacuminum ... There are 13 endemic species of araucaria: Araucaria rulei, Araucaria columnaris... and some more that are also on the island of Norfolk, which belongs to Australia and east of New Guinea. Many, if not all current populations are relict. The vegetation in New Caledonia is distinguished by the world's highest rate of endemism: 5 families, 107 genera and 3380 endemic species. Acacia spirorbis, Richea, Dracophyllum, Drosera novae-caledoniae, Grevillea gillivrayi, Cycas circinalis, Neocallitropsis pancheri (Cupressaceae) ; Austrotaxus spicatus (Taxacceae), Parasitaxus ustus (Podocarpaceae)... From the 44 species of Gymnosperm in the archipelago, 43 are endemic. It has the unique parasite Gymnosperm known in the world (Falcatifolium taxoides). The palm trees have 37 endemic species recorded belonging to 16 genus, 15 of them endemic in particular the endangered Pritchardiopsis jennencyi which one only adult tree is known.

The islands form two ecoregions: the umbrófila plants forest or rainforest of New Caledonia in the Loyalty Islands, Isle of Pines and the eastern part of Grande Terre, and the dry tropical forests of New Caledonia, at the West of Grande Terre. The latter was where Europeans settled, leaving the eastern part of the Kanakas. The biome is highly threatened due to the weakness caused by its long evolution with little herbivores or carnivores, deforestation by fire, traditional indigenous inhabitants logging, open pastures, plantations and large farms developed by European immigrants and more recently the opening of resorts and tourism facilities. Some pest problems are caused by introduced species such as insects, mammalians and so on. Although the impact of the use of fire is decreased in humid areas, it is resulting in decreasing in number of different species, and replacement of the original plant species by other made like grass Melinis minutiflora.

In the habitat of tropical montane laurel forest of New caledonia, which are cloud-covered for much of the year, the moist evergreen forests have a closed canopy of moderately sized trees, up to 20 m at lowland forest and about 3 to 8 m. tall in montane tropical rainforest. The species face threats as destruction by human deforestation. It could cause the extinction of complete genus and orders across the restricted region area, resulting from present distribution. For example, the reproductive structures of primigenia group of Amborella are true flowers, that have a unique in the world embryo sac, and provide an anatomical bridge between the structures seen for cone-bearing and flower-bearing plants. The order with the unique species is found only in rain forests of New Caledonia.

Most of Gymnosperms species are in New Caledonia in rainforest, in montane cloud forest or in extreme environmental conditions, but excluding the drylands. The Gymnosperms are more common on poor acid soils and unbalanced soils by excess of magnesium and others phytotoxic elements, derived from ultramafic rocks, 39 species are found yet and 27 species are considered extinct. The Gymnosperms are more common also on exposed ridges or next to rivers or creeks in floodplains. Their concentration is important on individual stations (exposed ridges, floodplains) which figure lifesaving refugia there, where environmental conditions make it very selective interspecific competition, less severe. Angiosperms also include many groups of archaic characteristics that appear as vestiges of an old Gondwanan floral background.

Several genus belonging to primitive families, are endemic or sub-endemics. Of these, Amborella, monospecific endemic genus of the endemic family Amborellaceae; Hedycarya and Kibaropsis (Monimiaceae) Nemuaron (Atherospermalaceae) Balanops (Balanopaceae). The Winteraceae, of the order Magnoliales, considered the oldest group of angiosperms, is represented by the type Zygogynum with 18 species of a order with fifty genus split of the Moluccas islands to northern Australia. Among the families with conducting vessels absent or imperfect, New Caledonia has next to Atherospermataceae, the Amborellaceae, the Annonaceae and Winteraceae, representatives of families of Chloranthaceae, as the genus Ascarina with two species, Piperaceae family, with twenty species of genus Piper and Peperomia, and Trimeniaceae family with Trimenia neocaledonica. The importance of the families of Gondwanan origin, both in the number of species as the abundance of some of them in different plant communities contrasts with the low representation in the indigenous vegetation of more modern groups such as the Compositae, Gramineae, Labiatae and Melastomataceae.

The groups of Gondwanan origin, that are the most remarkable flora of New Caledonia, including the families of Cunoniaceae, Proteaceae and Myrtaceae. The family of Cunoniaceae comprising a total of 25 genus and some 350 species has six genus in New Caledonia. Two of them, Pancheria and Codia are endemic, while genus Cunonia has 23 endemic species in New Caledonia and one species in South Africa. The other three genus have a distribution Papuan-Australian (Acsmithia), Australian (Geissois), and sub-Antarctic (Weinmannia).

The family Proteaceae with the two main centers of dispersion in Australia and Southern Africa is represented in the archipelago by 43 species. They are divided into six endemic genus: Beaupre, Beaupreopsis, Eucarpha, Garnier, Kermadecia, and Sleumerodendron. Two sub-endemics genus: Virotia and Macadamia. An Australian genus: Grevillea. An Australian-Papuan genus: Stenocarpus.

The family Myrtaceae, although basically Gondwanan in origen, currently has a distribution which includes all the tropical world and also a group has reached the Northern Hemisphere. With 229 species, is the largest family in New Caledonia. It has two genus largely distributed in the rest of the world: Eugenia and Syzygium, but also the endemic genus: Arillastrum, Carpolepis, Cloezia, Pleurocalyptus and Purpurostemon. Purpurostemon, of the subfamily Leptospermoideae is most distribuited in Australia, and from the sub-family Myrtoideae of wide distribution in tropics, Cupheanthus and Myrtastrum. The genus sub endemics: Archirhodomyrtus, Piliocalyx, Uromyrtus. The Australian genus: Baecker, Callistemon, Melaleuca. And the Australian-Papuan genus: Austromyrtus, Rhodomyrtus, Xanthostemon.

The remaining seven genera have distributions mainly in the Pacific, Indomalesia and IndoAustralian. The great biodiversity of native tree species, has prevented that invasive introduced tree species could be a problem, as has happened in other Pacific islands. The government made efforts to create parks and reserves. They are in danger of extinction due to over exploitation as medicinal plants or timber extraction and also for loss of habitat.

Fauna

The Kagu represents not only an endemic species but also New Caledonia's only endemic bird family, the Rhynochetidae.

New Caledonia's faunal diversity is similar to that of many islands, particularly New Zealand. The island has no native mammals except for bats, and no native amphibians, instead having a vertebrate fauna dominated by reptiles and birds. Today the island has 21 endemic species of birds, including one endemic family, the Rhynochetidae, represented by one living species, the Kagu.[4] The island is also home to the unusual tool-using New Caledonian Crow. See Endemic birds of New Caledonia for a full list. It is the separation of the islands of Gondwana block before the mammals expansion that could allow the radiation of flightless birds (Moa, Kiwi, Sylviornis, cagous) and Mesozoic reptilian forms such as the Tuatara of New Zealand.

The island's reptile fauna shares most of its affinities with Australia. Species endemic to the island comprise 62 of 69 total. Two species of snake are found in the Territory. Only one is found on Grand Terre; the other is native to the nearby Loyalty Islands which are part of New Caledonia. It is the home to the world’s largest gecko, and a large number of skinks and other geckos. No crocodiles or terrestrial turtles remain on the island.

The world's highest biodiversity of Volutomitridae is in waters off New Caledonia.[5]

The tropical invertebrates make up the bulk of the endemic fauna, they are a lot of species well represented in New Caledonia: freshwater sponges, annelid worms, and molluscs terrestrial and freshwater, arachnids, scorpions and mygales of this many vicariant to the mygales of Queensland. There are fourteen endemic species of decapod crustaceans in rivers and lakes. Mites, Pauropodes, Isopoda, Collembola, insects, among them: Diptera, Lepidoptera, Psocoptera, Odonata, Ephemeroptera, Trichoptera, Dermaptera, and several families of Coleoptera and Homoptera. Giant Coconut Grasshopper (Pseudophyllanax Montrouzier imperialis), only of Lepidopter there are 521 species, with 197 endemic species (38%), giant butterfly Montrouzier (Papilio montrouzieri Boisduval).

There are twenty two endemic species of terrestrial birds, three endemic genera and one family. Caledonian Raven (Corvus moneduloides),know by the studies done on their intelligence. The laurel forest pigeon (Columba vitiensis hyponochroa), giant wood pigeon notou (Ducula goliath), two genera endemic Drepanoptila (the green pigeon), and Eunymphicus (the chest nut parakeet and Ouvea parakeet). The best known animal species is the Rhynochetos jubatus or cagou endangered by the introduction of dogs, rats and other predators. It is a bird of the size of a chicken almost unable to fly, with a long crest and a funny cackling own of leafy forest mountain. The other terrestrial birds endemics are (Accipiter haplochrous), (Philemon diemenensis), (Erythrura psittacea), (Zosterops xanthochroa), (Phylidonyris undulata), (Pachycephala caledonica), (Aplonis striatus), (Gymnomyza aubryana), (Eopsaltria flaviventris), (Coracina analis), (Myzomela caledonica), (Megalurulus mariei). It is considered, in relation to the size of the territory of New Caledonia, the island of Grande Terre is the place of planet Earth with a greater variety of reptiles, giant gecko, (Rhacodactylus leachianusis), giant skink (Phoboscincus bocourti), emphasizing the giant monitor lizards. Sea snakes laticaudinae have venom ten times as strong as rattlesnake venom.

Before the arrival of Europeans, the only mammals in the island was the six endemic species of bats, Rousettus bat, a large fruit bat, is consumed by local people. Numerous species were wiped out before the arrival of Europeans, including a large flightless bird Sylviornis neocaledoniae .[6] a species of owl, two species of hawks, a megapode (Pile-builder Megapode), a species of giant tortoise Meiolania , a giant bat, two species of terrestrial crocodiles, descendants of terrestrial Gondwana, Mekosuchinae crocodiles, (Mekosuchus inexpectatus), arthropods, etc..

New Caledonia dry forests

The west coast of New Caledonia has a drier climate and different habitat from the rain forests that cover most of the island. Although not as rich as the rainforest the plant life of the coast does consist of nearly 400 species including a number of endemic species such as the unique Captaincookia margaretae, and Oryza neocaledonica, a wild rice that is in danger of disappearing. This coast is traditionally home to a number of New Caledonia's endangered animals including the New Caledonia Wattled Bat (Chalinolobus neocaledonicus) and the Ornate Flying Fox. Dry forests are always vulnerable to forest fires and human intervention and the original vegetation of this coast has been cleared for farming, especially cattle ranching, with only two percent of natural dry forest remaining in isolated patches, none of them in protected areas.[7] Urban areas on the west coast include New Caledonia's cosmopolitan capital Nouméa, while there are farms and farming communities all along the coast.

Threats and preservation

New Caledonia's biodiversity is threatened by a number of factors.[8] Like many island biotas, its species were poorly equipped to deal with the destructive effects of the introduced rat, cat, dog and pig, which have taken a toll on native species like the ground-living Kagu. Hunting is still a problem in remote areas, but substantially greater concern arises from dramatic habitat-loss caused by deforestation due to logging, mining (one of the island's principal industries), uncontrolled fires (responsible for substantial destruction of large areas), agriculture (largely responsible for reducing the dry-sclerophyll habitat to a small fraction of its original area), and urban development.

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.[9] The New Caledonian Crested Gecko was thought to have been extinct until it was rediscovered in 1994.

New Caledonia is considered a conservation priority by many international organizations, which have lobbied and sought to work with the country's government to preserve the islands' unique ecosystems. Although their efforts have recently led to a few limited successes, to date they have failed to achieve definitive protection for New Caledonia's remaining natural areas. For instance, given the global importance of these living-fossil ecosystems, attempts have been made to recognize their significance by granting them UNESCO World Heritage Site-status protection. To date, no such attempted initiative has succeeded, due to opposition by regional governments, which are heavily influenced by mining and development interests (see below). Present-day mining operations continue, and are in fact being initiated, in localities of extreme ecological importance. Worldwide public pressure has forced mining companies to recently begin voluntary, minimal post-mining rehabilitation. However, even when taking such rehabilitation efforts into account, mining activity still results in devastation of the extremely high biodiversity that had existed at the exploited site prior to the mining operation. Imposition of World Heritage Site-status would severely impact the pursuit of unrestricted mining activity in areas of ecological importance. However, this, in turn, could affect the economic well-being of the entire country, making a balanced, thoughtful approach essential to national interests.

Conservation efforts at the local, grass-roots level have been, at best, tentative, and have invariably failed when in direct conflict with mining (and other development) projects, due to the above-referenced importance of such projects to the country's comparative prosperity and stability. Recent, local political efforts to increase governmental priority for protection of the country's globally recognized natural environment, met with strong official opposition, and violence against the proponents. Notably, Bruno Van Peteghem, recipient of the 2001 Goldman Environmental Prize, used the local court system to force government leaders to obey laws protecting the country's coral reefs. Despite his short-term victories in the courts, however, his home was firebombed, and his family and himself were repeatedly threatened.[10] Ultimately, the head of government at the time, Jacques Lafleur, succeeded in silencing Bruno Van Peteghem's opposition, forcing him into de facto exile by arranging the termination of his employment with the national airline.

References

  1. ^ Steadman D, (2006). Extinction and Biogeography in Tropical Pacific Birds, University of Chicago Press. ISBN 978-0-226-77142-7
  2. ^ Jaffre, T.; Bouchet, P.; Veillon, J. M. (1997). Biodiversity and Conservation 7: 109. doi:10.1023/A:1008815930865.  edit
  3. ^ Dossier > La flore de Nouvelle-Calédonie - Deuxième partie
  4. ^ Hunt, Gavin R. (1996): Family Rhynochetidae (Kagu). In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (editors): Handbook of Birds of the World, Volume 3 (Hoatzin to Auks): 218-225, plate 20. Lynx Edicions, Barcelona. ISBN 84-87334-20-2
  5. ^ Bouchet, P. & Kantor, Y. I. (2003) "New Caledonia: the major centre of biodiversity for volutomitrid molluscs (Mollusca: Neogastropoda: Volutomitridae)". Systematics and Biodiversity 1(4): 467–502. doi:10.1017/S1477200003001282
  6. ^ Extinction and Biogeography in Tropical Pacific Birds,University of Chicago Press. ISBN 978-0-226-77142-7
  7. ^ John Lamoreux. "New Caledonia dry forests (AA0202)". World Wildlife Fund. http://www.worldwildlife.org/wildworld/profiles/terrestrial/aa/aa0202_full.html. Retrieved 10 August 2011. 
  8. ^ Pascal, M; De Forges, B;, Le Guyader, H & D Simberloff (2008) "Mining and Other Threats to the New Caledonia Biodiversity Hotspot" Conservation Biology 22 (2) , 498–499 doi:10.1111/j.1523-1739.2008.00889.x
  9. ^ Birdlife International (2006) "New Caledonia's most wanted Accessed 21 April 2008.
  10. ^ Tolmé, P. (2002 ) ""Little Scum" Takes On Big Mining" National Wildlife 40 (4)

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