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

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

Palearctic

realm.

Indochina

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.

History

The flora of Indomalaya blends elements from the ancient supercontinents of

podocarps and araucarias

, moved westward from Australia-New Guinea into western Malesia and Southeast Asia.

Flora

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]

Fauna

Two orders of mammals, the

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 (

pittas, Old World babblers, and flowerpeckers

.

Indomalaya has 1000 species of

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

mangroves

.

Indomalayan tropical and subtropical moist broadleaf forests ecoregions v t e
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

Indomalayan tropical and subtropical dry broadleaf forests ecoregions v t e
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

Indomalayan tropical and subtropical coniferous forests ecoregions v t e
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

Indomalayan temperate broadleaf and mixed forests ecoregions v t e
Eastern Himalayan broadleaf forests	Bhutan, India, Nepal
Northern Triangle temperate forests	Myanmar
Western Himalayan broadleaf forests	India, Nepal, Pakistan

Indomalayan temperate coniferous forests ecoregions v t e
Eastern Himalayan subalpine conifer forests	Bhutan, India, Nepal
Western Himalayan subalpine conifer forests	India, Nepal, Pakistan

Indomalayan tropical and subtropical grasslands, savannas, and shrublands ecoregions v t e
Terai–Duar savanna and grasslands	Bhutan, India, Nepal

Indomalayan flooded grasslands and savannas ecoregions v t e
Rann of Kutch seasonal salt marsh	India, Pakistan

Indomalayan montane grasslands and shrublands ecoregions v t e
Kinabalu montane alpine meadows	Malaysia

Indomalayan deserts and xeric shrublands ecoregions v t e
Deccan thorn scrub forests	India, Sri Lanka
Indus Valley desert	India, Pakistan
Northwestern thorn scrub forests	India, Pakistan
Thar desert	India, Pakistan

Indomalayan mangroves ecoregions v t e
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

Bibliography

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].

References

^ Indomalayan realm Archived 2022-10-06 at the Wayback Machine biologyonline.com. Retrieved 29 August 2021
^ Appanah, Simmathiri and Jennifer M. Turnbull, eds. (1998). A Review of Dipterocarps: Taxonomy, ecology and silviculture. Center for International Forestry Research, 1998.
^ Ebach, Malte C. (2017). Handbook of Australasian Biogeography. CRC Press, Jan 6, 2017.
^ 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

[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]

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