The Nicobar Islands rain forests is a tropical moist broadleaf forest

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

in the Nicobar Islands. The Nicobar Islands are in the Indian Ocean, lying north of Sumatra and south of the Andaman Islands. The islands are politically part of

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, although physically closer to Southeast Asia. Millions of years of isolation from the mainland has given rise to a distinct flora and fauna, including many endemic species.

Geography

The Nicobar Islands consist of 22 islands, of which 13 are inhabited. The islands extend about 260 km from north and south, and form three groups. The northern group is composed of

Car Nicobar Car Nicobar ( in Car language) is the northernmost of the Nicobar Islands. It is also one of three local administrative divisions of the Indian district of Nicobar, part of the Indian union territory of Andaman and Nicobar Islands. Annual ra ...

, the northernmost island, and Batti Malv. The central group includes Nancowry, Katchal, Kamorta, Teressa,

Chowra Chowra is an island in the Andaman and Nicobar islands group of India. It is located to the north of Teressa island and to the south of Battimalv Island in the Indian Ocean. It is also known as Choura, Tatat or Sanenyo. History The island su ...

, Tillangchong, and several smaller islets. The southern group includes

Great Nicobar Great Nicobar is the southernmost and largest of the Nicobar Islands of India, north of Sumatra. History The Nicobar Island has been well known to Indian mariners since the time of the seafaring Cholas https://www.britannica.com/place/Nicoba ...

, Little Nicobar and several smaller islets. Great Nicobar is the largest (), highest (

Mount Thullier Mount Thuillier is a mountain on Great Nicobar Island, located in the Indian Ocean and bordering on the Andaman Sea. At above sea level, it is the highest point on the island and in the Nicobar Islands The Nicobar Islands are an archipelagi ...

, 670 m), and southernmost island. The Andaman Sea lies east of the islands, and the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line betwee ...

to the west. The

Ten Degree Channel The Ten Degree Channel is a channel that separates the Andaman Islands and Nicobar Islands from each other in the Bay of Bengal. The two sets of islands together form the Indian Union Territory (UT) of Andaman and Nicobar Islands. This channel ...

separates the Car Nicobar from the southernmost of the Andaman Islands 150 km north. Sumatra lies 189 miles south of Great Nicobar. The Andaman and Nicobar Islands form an

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alon ...

over 600 km in length, created by the subduction of the

Indian Plate The Indian Plate (or India Plate) is a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian Plate broke away from the other fragments of Gondwana , began ...

under the

Burma Plate The Burma Plate is a minor tectonic plate or microplate located in Southeast Asia, sometimes considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate. This island arc ...

, of which the Nicobar and Andaman islands are part. The subduction zone creates periodic large earthquakes, including the

1881 Nicobar Islands earthquake The 1881 Nicobar Islands earthquake occurred at about 07:49 local time (01:49 UTC) on 31 December, with an epicentre beneath Car Nicobar. It occurred as two separate ruptures, the largest of which had an estimated magnitude of 7.9 on the mome ...

and the 2004 Indian Ocean earthquake. The surface geology of the islands consists of Eocene sedimentary rocks (sandstone, shale, and siltstone) at lower elevations, with intrusions of

ultrabasic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are compos ...

igneous rock.

Serpentinite Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''se ...

and

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...

are found at higher elevations. Only Great Nicobar has perennial streams. The island has five perennial rivers – the Galathea, Jubilee, Amrit Kaur, Dak Aniang, and Dak Tayal – which all originate from Mount Thullier. The Galathea River is the longest, flowing southwards for about 30 km to empty into the sea at Galathea Bay near the southern tip of the island.

Climate

The Nicobar Islands have a tropical rain forest climate. Average temperatures range from 22 to 30 °C. Average annual rainfall ranges from 3,000 to 3,800 mm. Heavier rainfall coincides ith the

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal osci ...

winds, which come from the southwest from May to September, and from the northeast between October and December.

Flora

Plant communities on the islands include mangroves and coastal forests near the shore, and evergreen and deciduous forests in the interiors of the islands. Coastal forests feature widespread Indo-Pacific seashore plants, including the trees ''

Barringtonia ''Barringtonia'' is a genus of flowering plants in the family Lecythidaceae first described as a genus with this name in 1775. It is native to Africa, southern Asia, Australia, and various islands of the Pacific and Indian Oceans. The genus nam ...

'' sp., '' Pandanus'' sp., and '' Casuarina equisetifolia'', with the shrubs ''

Scaevola frutescens ''Scaevola taccada'', also known as beach cabbage, sea lettuce, or beach naupaka, is a flowering plant in the family Goodeniaceae found in coastal locations in the tropical areas of the Indo-Pacific. It is a common beach shrub throughout the Ara ...

Hibiscus tiliaceus ''Hibiscus tiliaceus'', commonly known as the sea hibiscus or coast cottonwood, is a species of flowering tree in the mallow family, Malvaceae, with a pantropical distribution along coastlines. It has also been introduced to Florida and New Zea ...

'', and '' Clerodendrum inerme''. There are extensive areas of

coconut palm The coconut tree (''Cocos nucifera'') is a member of the palm tree family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or t ...

(''Cocos nucifera'') along the coast, both cultivated and wild.Arora K. (2018) The Nicobarese Tribes and Their Knowledge. In: Indigenous Forest Management In the Andaman and Nicobar Islands, India. Springer, Cham. https://doi.org/10.1007/978-3-030-00033-2_3 The evergreen forests on Great Nicobar, Kamorta, and Katchal are dominated by the trees '' Calophyllum soulattri, Sideroxylon longipetiolatum,

Garcinia xanthochymus ''Garcinia xanthochymus'', the false mangosteen, gamboge, yellow mangosteen, Himalayan Garcinia, or sour mangosteen is a species of mangosteens found from India, southern China, and Japan through Indochina to Peninsular Malaysia at elevations of ...

Pisonia excelsa ''Pisonia'' is a genus of flowering plants in the four o'clock flower family, Nyctaginaceae. It was named for Dutch physician and naturalist Willem Piso (1611–1678). Certain species in this genus are known as catchbirdtrees, birdcatcher tree ...

'', and ''

Mangifera sylvatica ''Mangifera sylvatica'', also known as the Himalayan mango, pickling mango, or Nepal mango, is a species of plant in the family Anacardiaceae. It is found in Bangladesh, Cambodia, China (Yunnan), India (Assam, Darjeeling, Sikkim), Myanmar, Nepal, ...

'', with '' Artocarpus peduncularis, Radermachera lobbi, Symplocos leiostachya'', and '' Bentinckia nicobarica'' also present on Kamorta and Katchal. Species of ''

Macaranga ''Macaranga'' is a large genus of Old World tropical trees of the family Euphorbiaceae and the only genus in the subtribe Macaranginae (tribe Acalypheae). Native to Africa, Australasia, Asia and various islands of the Indian and Pacific Oceans, t ...

Ficus ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extendi ...

'', and '' Terminalia'' are common along the riverbanks of Great Nicobar. The tree canopy averages 30 to 50 metres in height. The climbing bamboo '' Dinochloa andamanica'' climbs the tall trees. Deciduous forests are found at lower elevations on Great Nicobar, and typical trees include '' Terminalia procera'' and ''

Terminalia bialata Terminalia may refer to: * Terminalia (festival), a Roman festival to the god of boundaries Terminus * ''Terminalia'' (plant), a tree genus * Terminalia (insect anatomy), the terminal region of the abdomen in insects * ''Polyscias terminalia ' ...

''. Some of the northern and central islands, including Car Nicobar, Kamorta, Katchall, and Nancowry, have extensive areas of grassland in the interior. The grasslands may be anthropogenic in origin. Typical species include the grasses ''

Imperata cylindrica ''Imperata cylindrica'' (commonly known as cogongrass or kunai grass ) is a species of perennial rhizomatous grass native to tropical and subtropical Asia, Micronesia, Melanesia, Australia, Africa, and southern Europe. It has also been introduc ...

Saccharum spontaneum ''Saccharum spontaneum'' (wild sugarcane, Kans grass) is a grass native to the Indian Subcontinent. It is a perennial grass, growing up to three meters in height, with spreading rhizomatous roots. In the Terai-Duar savanna and grasslands, a l ...

Heteropogon contortus ''Heteropogon contortus'' is a tropical, perennial tussock grass with a native distribution encompassing Southern Africa, southern Asia, Northern Australia, Oceania, and southwestern North America. The species has also become a naturalised weed i ...

, Chloris barbata,

Chrysopogon aciculatus ''Chrysopogon aciculatus'' (syn. ''Andropogon aciculatus'') is a species of grass native to the tropics of Asia, Polynesia, and Australia at low elevations. Common names include ''amorseco'' (Spanish, "dry love") (not to be confused with the ''am ...

'', and '' Scleria cochinchinensis'', together with herbs and shrubs. There are 580 species of flowering plants on the islands. Approximately 14% are endemic to the islands. The flora of the islands shares more affinities with Sumatra and the Malay Peninsula than with the Andamans or Myanmar; only 28% of flowering plant species are shared with the Andamans.Manohara, T.N., Linto, E.L. & Renuka, C. Diversity and conservation of palms in Andaman & Nicobar archipelago. Biodivers Conserv 19, 3655–3666 (2010). https://doi.org/10.1007/s10531-010-9918-6 The palms '' Bentinckia nicobarica, Rhopaloblaste augusta, Calamus dilaceratus'', and '' Calamus nicobaricus'' are endemic to the Nicobar Islands. ''

Areca triandra ''Areca triandra'', the wild areca palm, is a palm which is often used as ornamental plant. It is native to India, Bangladesh, Cambodia, Laos, Burma, Thailand, Vietnam, Malaysia, Indonesia, and the Philippines. It is also reportedly naturalized i ...

, Calamus andamanicus,

Caryota mitis ''Caryota mitis'', known as the clustering fishtail palm or fishtail palm, is a species of palm native to Tropical Asia from India to Java to southern China, now sparingly naturalized in southern Florida and in parts of Africa and Latin America. ...

, Korthalsia laciniosa, Licuala peltata'', and '' Pinanga manii'' are more widespread species native to the islands.

Fauna

There are 25 native mammal species on the islands, principally bats and rats. Large mammals include the

wild boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...

(''Sus scrofa'') and Nicobar macaque (''Macaca fascicularis umbrosa''). Four species are endemic to the islands – the

Nicobar shrew The Nicobar shrew or Nicobar white-tailed shrew (''Crocidura nicobarica'') is a critically endangered species of mammal in the family Soricidae. It is endemic to Great Nicobar Island in India India, officially the Republic of India (Hin ...

(''Crocidura nicobarica'') on Great Nicobar, the Nicobar treeshrew (''Tupaia nicobarica'') on Great Nicobar and Little Nicobar, the Palm rat (''Rattus palmarum'') on Car Nicobar and Great Nicobar, and the

Nicobar flying fox The Nicobar flying fox (''Pteropus faunulus'') is a species of flying fox in the family Pteropodidae. It is endemic to India. Its natural habitats are subtropical or tropical moist lowland forest and subtropical or tropical swamps. It is thre ...

(''Pteropus faunulus'') throughout the islands. 82 species of birds are native to the islands. These include eight species of heron, seven hawk species, six kingfisher species, and six species of

pigeon Columbidae () is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with short necks and short slender bills that in some species feature fleshy ceres. They primarily ...

. Five species are endemic, including the Nicobar serpent-eagle (''Spilornis minimus''),

Nicobar sparrowhawk The Nicobar sparrowhawk (''Accipiter butleri'') is a species of bird of prey in the family Accipitridae. It is endemic to the Nicobar Islands of India. There are two subspecies, the nominate race which is found on Car Nicobar in the north of the ...

(''Accipiter butleri''),

Nicobar parakeet The Nicobar parakeet (''Psittacula caniceps''), also known as the Blyth's parakeet, is a parrot in the genus ''Psittacula'', endemic to the Nicobar Islands of the Indian Ocean. It is one of the largest parakeets, measuring 56 to 60 cm from ...

(''Psittacula caniceps''), and

Nicobar bulbul The Nicobar bulbul (''Ixos nicobariensis'') is a songbird species in the bulbul family, Pycnonotidae. It is endemic to the Nicobar Islands. Taxonomy and systematics The Nicobar bulbul was originally described in the genus '' Hypsipetes'' and m ...

(''Hypsipetes nicobariensis''). The Nicobar scrubfowl (''Megapodius nicobariensis'') once inhabited the Andaman islands as well, but is now extinct there and found only on the Nicobar Islands. Four species, the Andaman wood-pigeon (''Columba palumboides''),

Andaman cuckoo-dove The Andaman cuckoo-dove (''Macropygia rufipennis'') is a species of bird in the family Columbidae. It is endemic to the Andaman and Nicobar Islands. It is becoming rare due to habitat loss Habitat destruction (also termed habitat loss and ...

(''Macropygia rufipennis''), Andaman boobook (''Ninox affinis''), and

white-headed starling The white-headed starling (''Sturnia erythropygia''), also known as the Andaman white-headed starling, is a species of starling in the family Sturnidae. It is found in wooded habitats of the Andaman and Nicobar Islands The Andaman and Nic ...

(''Sturnus erythropygius''), are limited to the Andaman and Nicobar Islands. The ecoregion constitutes the Nicobar Islands endemic bird area. There are 43 reptile species on the islands, of which eleven are endemic. There are eleven species of amphibians, all frogs and toads, including two endemic species, the Nicobar tree frog (''Polypedates insularis'') and Nicobar cricket-frog (''Minervarya nicobariensis'').

People

The islands have been inhabited for centuries. The

Nicobarese people The Nicobarese people are an Austroasiatic-speaking people of the Nicobar Islands, a chain of islands in the Bay of Bengal north of Sumatra, forming part of the union territory of Andaman and Nicobar Islands, India. Only 12 of the 19 islands ...

live on twelve of the islands. Most Nicobarese live in villages, and grow a variety of tree, root, and vegetable crops for food, fiber, and building materials, including coconut, areca palm, papaya, banana, breadfruit, jackfruit, and yams. Pigs and chickens are kept for food, and wild fruits, roots, tubers, and fibers are gathered from the forests. Larger plantations of coconut have been established near the coast, and tapioca, sweet potato, sugarcane, and cashew are grown in the interior of the more populated islands. The 2011 census recorded 36,842 people on the islands. Starting in the late 1960s the Indian government encouraged people from mainland India to settle on the islands, and by the late 1990s mainlanders constituted over a third of the population. The islands, together with the Andaman Islands, constitute the

Andaman and Nicobar Islands The Andaman and Nicobar Islands is a union territory of India consisting of 572 islands, of which 37 are inhabited, at the junction of the Bay of Bengal and the Andaman Sea. The territory is about north of Aceh in Indonesia and separated f ...

union territory of India. The Nicobar Islands are administered as a separate

district A district is a type of administrative division that, in some countries, is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or county, counties, several municipality, municipa ...

. Malacca on Car Nicobar is the district's administrative headquarters.

Conservation and threats

57% of the islands' land area is in protected areas. A 1997 assessment found that only 14% of the islands' forests had been removed. A 2017 assessment found that 18% of the islands' unprotected area is still covered in primary forest.

Protected areas

17% of the ecoregion is in protected areas. Protected areas include Campbell Bay National Park and

Galathea National Park Galathea National Park is a national park located in the Union Territory of Andaman and Nicobar Islands, India. It is located on the island of Great Nicobar in the Nicobar Islands, which lie in the eastern Indian Ocean (Bay of Bengal). The tot ...

on Great Nicobar. The

Great Nicobar Biosphere Reserve The Great Nicobar Biosphere Reserve encompasses a large part (some 85%) of the island of Great Nicobar, the largest of the Nicobar Islands in the Indian Union Territory of Andaman and Nicobar Islands. The Nicobars lie in the Bay of Bengal, easte ...

was designated on Great Nicobar by

UNESCO The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...

in 2013. The reserve has a total area of 103,870 ha. The core area of 53,623 ha comprises Cambell Bay and Galathea National parks. A buffer area of 34,877 includes lands adjacent to and between the two parks. There is also a transitional area of 10,070 ha, including 5,300 marine hectares."Great Nicobar". Man and Biosphere Programme, United Nations Educational, Scientific, and Cultural Organization (UNESCO). Accessed 5 August 2021. http://www.unesco.org/new/en/natural-sciences/environment/ecological-sciences/biosphere-reserves/asia-and-the-pacific/india/great-nicobar

External links

*
Nicobar Islands endemic bird area (Birdlife International)

Nicobar Islands rain forests (DOPA Explorer)

References

{{reflist Indomalayan ecoregions Ecoregions of India Tropical and subtropical moist broadleaf forests Nicobar Islands Endemic Bird Areas