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Indomalayan realm

Coordinates: 7°00′N 97°00′E / 7.000°N 97.000°E / 7.000; 97.000
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The Indomalayan realm

The Indomalayan realm is one of the eight biogeographic realms.[1] It extends across most of South and Southeast Asia and into the southern parts of East Asia.

Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indian subcontinent and Southeast Asia to lowland southern China, and through Indonesia as far as Sumatra, Java, Bali, and Borneo, east of which lies the Wallace line, the realm boundary named after Alfred Russel Wallace which separates Indomalaya from Australasia. Indomalaya also includes the Philippines, lowland Taiwan, and Japan's Ryukyu Islands.

Most of Indomalaya was originally covered by forest, and includes tropical and subtropical moist broadleaf forests, with tropical and subtropical dry broadleaf forests predominant in much of India and parts of Southeast Asia. The tropical forests of Indomalaya are highly variable and diverse, with economically important trees, especially in the families Dipterocarpaceae and Fabaceae.

Major ecological regions


The World Wildlife Fund (WWF) divides Indomalayan realm into three bio-regions, which it defines as "geographic clusters of eco-regions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)".

Indian subcontinent


The Indian subcontinent bioregion covers most of India, Bangladesh, Nepal, Bhutan, and Sri Lanka and eastern parts of Pakistan. The Hindu Kush, Karakoram, Himalaya, and Patkai ranges bound the bioregion on the northwest, north, and northeast; these ranges were formed by the collision of the northward-drifting Indian subcontinent with Asia beginning 45 million years ago. The Hindu Kush, Karakoram, and Himalaya are a major biogeographic boundary between the subtropical and tropical flora and fauna of the Indian subcontinent and the temperate-climate Palearctic realm.



The Indochina bioregion includes most of mainland Southeast Asia, including Myanmar, Thailand, Laos, Vietnam, and Cambodia, as well as the subtropical forests of southern China.

Sunda Shelf and the Philippines


Malesia is a botanical province which straddles the boundary between Indomalaya and Australasia. It includes the Malay Peninsula and the western Indonesian islands (known as Sundaland), the Philippines, the eastern Indonesian islands, and New Guinea. While the Malesia has much in common botanically, the portions east and west of the Wallace Line differ greatly in land animal species; Sundaland shares its fauna with mainland Asia, while terrestrial fauna on the islands east of the Wallace line are derived at least in part from species of Australian origin, such as marsupial mammals and ratite birds.



The flora of Indomalaya blends elements from the ancient supercontinents of Laurasia and Gondwana. Gondwanian elements were first introduced by India, which detached from Gondwana approximately 90 MYA, carrying its Gondwana-derived flora and fauna northward, which included cichlid fish and the plant families Crypteroniaceae and possibly Dipterocarpaceae. India collided with Asia 30-45 MYA, and exchanged species. Later, as Australia-New Guinea drifted north, the collision of the Australian and Asian plates pushed up the islands of Wallacea, which were separated from one another by narrow straits, allowing a botanic exchange between Indomalaya and Australasia. Asian rainforest flora, including the dipterocarps, island-hopped across Wallacea to New Guinea, and several Gondwanian plant families, including podocarps and araucarias, moved westward from Australia-New Guinea into western Malesia and Southeast Asia.



The subfamily Dipterocarpoideae comprises characteristic tree species in Indomalaya's moist and seasonally dry forests, with the greatest species diversity in the moist forests of Borneo.[2] Teak (Tectona) is characteristic of the seasonally dry forests of the Indomalaya, from India through Indochina, Malaysia, and the Philippines. Tropical pitcher plants (Nepenthes) are also characteristic of Indomalaya, and the greatest diversity of species is in Sumatra, Borneo, and the Philippines.

The tropical forests of Indomalaya and Australasia share many lineages of plants, which have managed over millions of years to disperse across the straits and islands between Sundaland and New Guinea. The two floras evolved in long isolation, and the fossil record suggests that Asian species dispersed to Australasia starting 33 million years ago as Australasia moved northwards, and dispersal increased 12 million years ago as the two continents approached their present positions. The exchange was asymmetric, with more Indomalayan species spreading to Australasia than Australasian species to Indomalaya.[3]



Two orders of mammals, the colugos (Dermoptera) and treeshrews (Scandentia), are endemic to the realm, as are families Craseonycteridae (Kitti's hog-nosed bat), Diatomyidae, Platacanthomyidae, Tarsiidae (tarsiers) and Hylobatidae (gibbons). Large mammals characteristic of Indomalaya include the leopard, tigers, water buffalos, Asian elephant, Indian rhinoceros, Javan rhinoceros, Malayan tapir, orangutans, and gibbons.

Indomalaya has three endemic bird families, the Irenidae (fairy bluebirds), Megalaimidae and Rhabdornithidae (Philippine creepers). Also characteristic are pheasants, pittas, Old World babblers, and flowerpeckers.

Indomalaya has 1000 species of amphibians in 81 genera, about 17 of global species. 800 Indomalayan species, or 80%, are endemic. Indomalaya has three endemic families of amphibians, Nasikabatrachidae, Ichthyophiidae, and Uraeotyphlidae. 329, or 33%, of Indomalayan amphibians are considered threatened or extinct, with habitat loss as the principal cause.[4]

More information is available under Indomalayan realm fauna.

Indomalayan ecoregions

Ecoregions of the Indomalayan realm, color-coded by biome. Beige: deserts and xeric shrublands. Light brown: tropical and subtropical dry broadleaf forests. Green: tropical and subtropical moist broadleaf forests. Bright green: tropical and subtropical coniferous forests. light green: temperate broadleaf and mixed forests. Dark green: temperate coniferous forests. Light blue: flooded grasslands and savannas. Light purple: montane grasslands and shrublands. Magenta: mangroves.
Andaman Islands rain forests India
Borneo lowland rain forests Brunei, Indonesia, Malaysia
Borneo montane rain forests Brunei, Indonesia, Malaysia
Borneo peat swamp forests Brunei, Indonesia, Malaysia
Brahmaputra Valley semi-evergreen forests India
Cardamom Mountains rain forests Cambodia, Thailand, Vietnam
Chao Phraya freshwater swamp forests Thailand
Chao Phraya lowland moist deciduous forests Thailand
Chin Hills–Arakan Yoma montane forests Myanmar, India
Christmas and Cocos Islands tropical forests Australia
Eastern Highlands moist deciduous forests India
Eastern Java–Bali montane rain forests Indonesia
Eastern Java–Bali rain forests Indonesia
Greater Negros–Panay rain forests Philippines
Hainan Island monsoon rain forests China
Himalayan subtropical broadleaf forests Bhutan, India, Nepal
Irrawaddy freshwater swamp forests Myanmar
Irrawaddy moist deciduous forests Myanmar
Jiang Nan subtropical evergreen forests China
Kayah–Karen montane rain forests Myanmar, Thailand
Lower Gangetic Plains moist deciduous forests Bangladesh, India
Luang Prabang montane rain forests Laos
Luzon montane rain forests Philippines
Luzon rain forests Philippines
Malabar Coast moist forests India
Maldives–Lakshadweep–Chagos Archipelago tropical moist forests British Indian Ocean Territory, India, Maldives
Meghalaya subtropical forests India
Mentawai Islands rain forests Indonesia
Mindanao montane rain forests Philippines
Mindanao–Eastern Visayas rain forests Philippines
Mindoro rain forests Philippines
Mizoram–Manipur–Kachin rain forests Bangladesh, India, Myanmar
Myanmar coastal rain forests Myanmar
Nansei Islands subtropical evergreen forests Japan
Nicobar Islands rain forests India
North Western Ghats moist deciduous forests India
North Western Ghats montane rain forests India
Northern Annamites rain forests Laos, Vietnam
Northern Indochina subtropical forests China, Laos, Myanmar, Thailand, Vietnam
Northern Khorat Plateau moist deciduous forests Laos, Thailand
Northern Thailand-Laos moist deciduous forests Laos, Thailand
Northern Triangle subtropical forests Myanmar
Northern Vietnam lowland rain forests Vietnam
Orissa semi-evergreen forests India
Palawan rain forests Philippines
Peninsular Malaysian montane rain forests Malaysia, Thailand
Peninsular Malaysian peat swamp forests Malaysia, Thailand
Peninsular Malaysian rain forests Indonesia, Malaysia, Singapore, Thailand
Red River freshwater swamp forests Vietnam
South China Sea Islands disputed between China, Malaysia, Philippines, Taiwan, Vietnam
South China–Vietnam subtropical evergreen forests China, Vietnam
South Taiwan monsoon rain forests Taiwan
South Western Ghats moist deciduous forests India
South Western Ghats montane rain forests India
Southern Annamites montane rain forests Cambodia, Laos, Vietnam
Southwest Borneo freshwater swamp forests Indonesia
Sri Lanka lowland rain forests Sri Lanka
Sri Lanka montane rain forests Sri Lanka
Sulu Archipelago rain forests Philippines
Sumatran freshwater swamp forests Indonesia
Sumatran lowland rain forests Indonesia
Sumatran montane rain forests Indonesia
Sumatran peat swamp forests Indonesia
Sundaland heath forests Indonesia
Sundarbans freshwater swamp forests Bangladesh, India
Taiwan subtropical evergreen forests Taiwan
Tenasserim–South Thailand semi-evergreen rain forests Malaysia, Myanmar, Thailand
Tonle Sap freshwater swamp forests Cambodia, Vietnam
Tonle Sap–Mekong peat swamp forests Cambodia, Vietnam
Upper Gangetic Plains moist deciduous forests India
Western Java montane rain forests Indonesia
Western Java rain forests Indonesia
Central Deccan Plateau dry deciduous forests India
Central Indochina dry forests Cambodia, Laos, Thailand, Vietnam
Chota-Nagpur dry deciduous forests India
East Deccan dry evergreen forests India
Irrawaddy dry forests Myanmar
Khathiar–Gir dry deciduous forests India
Narmada Valley dry deciduous forests India
Northern dry deciduous forests India
South Deccan Plateau dry deciduous forests India
Southeastern Indochina dry evergreen forests Cambodia, Laos, Thailand
Southern Vietnam lowland dry forests Vietnam
Sri Lanka dry-zone dry evergreen forests Sri Lanka
Himalayan subtropical pine forests Bhutan, India, Nepal, Pakistan
Luzon tropical pine forests Philippines
Northeast India–Myanmar pine forests Myanmar, India
Sumatran tropical pine forests Indonesia
Eastern Himalayan broadleaf forests Bhutan, India, Nepal
Northern Triangle temperate forests Myanmar
Western Himalayan broadleaf forests India, Nepal, Pakistan
Eastern Himalayan subalpine conifer forests Bhutan, India, Nepal
Western Himalayan subalpine conifer forests India, Nepal, Pakistan
Terai–Duar savanna and grasslands Bhutan, India, Nepal
Rann of Kutch seasonal salt marsh India, Pakistan
Kinabalu montane alpine meadows Malaysia
Deccan thorn scrub forests India, Sri Lanka
Indus Valley desert India, Pakistan
Northwestern thorn scrub forests India, Pakistan
Thar desert India, Pakistan
Godavari–Krishna mangroves India
Indochina mangroves Cambodia, Malaysia, Thailand, Vietnam
Indus River Delta–Arabian Sea mangroves Pakistan
Myanmar coast mangroves Myanmar, India, Malaysia, Thailand
Sunda Shelf mangroves Brunei, Indonesia, Malaysia
Sundarbans mangroves Bangladesh, India

See also



  • Wikramanayake, E., E. Dinerstein, C. J. Loucks, D. M. Olson, J. Morrison, J. L. Lamoreux, M. McKnight, and P. Hedao. 2002. Terrestrial ecoregions of the Indo-Pacific: a conservation assessment. Island Press, Washington, DC, USA, [2].


  1. ^ Indomalayan realm Archived 2022-10-06 at the Wayback Machine biologyonline.com. Retrieved 29 August 2021
  2. ^ Appanah, Simmathiri and Jennifer M. Turnbull, eds. (1998). A Review of Dipterocarps: Taxonomy, ecology and silviculture. Center for International Forestry Research, 1998.
  3. ^ Ebach, Malte C. (2017). Handbook of Australasian Biogeography. CRC Press, Jan 6, 2017.
  4. ^ Bain, R.H., Biju, S.D., Brown, R.M., Das, I., Diesmos, A.C., Dutta, S.K., Gower, D.J., Inger, R.F., Iskandar, D.T., Kaneko, Y., Neng, M.W., Lau, Meegaskumbura, M., Ohler, A., Papenfuss, T., Pethiyagoda, R., Stuart, B.L., & Wilkinson, M. (2008). Amphibians of the Indomalayan Realm. [1]

7°00′N 97°00′E / 7.000°N 97.000°E / 7.000; 97.000