Indomalaya Ecozone

The Indomalaya ecozone is one of Earth’s eight ecosystems. It covers most of South and Southeast Asia and parts of East Asia. This area was originally known as the Oriental Region by most scientists (especially biogeographers). Indomalaya extends from Afghanistan to Pakistan through the Indian subcontinent and Southeast Asia to southern China, and through Indonesia toward Java, Bali, and Borneo. Indomalaya borders Australasia to the east and both are separated by the Wallace Line. Indomalaya also includes the Philippines, lowland Taiwan, and the Ryukyu Islands of Japan.

Most of Indomalaya was originally covered by tropical and subtropical moist broadleaf forests. Tropical and subtropical dry broadleaf forests were found mostly in India and parts of Southeast Asia. Now the tropical moist forests of Indomalaya are dominated by rainforest trees that come from the Dipterocarpaceae family.

The World Wildlife Fund divides the Indomalaya ecosystem into three bioregions: The Indian Subcontinent, Indochina, and Sunda shelf and the Philippines.

The Indian Subcontinent covers most of India, Pakistan, Bangladesh, Nepal, Bhutan, and Sri Lanka. The Himalayan Range, along with Hindu Kush, Karakoram, and Patkai Ranges, bind the region to the north, northwest, and northeast. These ranges were formed 45 million years ago when the Indian subcontinent collided with Asia. These ranges (excluding Patkai) border the temperate Palearctic ecozone.

Indochina includes Southeast Asia, Myanmar, Thailand, Laos, Vietnam, and Cambodia. It also includes the subtropical forests of southern China.

The Sunda Shelf & Philippines is also known as Malesia. It borders both Indomalaya and Australasia. This region includes the Malay Peninsula and the western Indonesian Islands (Sundaland). The Philippines, eastern Indonesian Islands, and New Guinea are also part of this region.

The flora of Indomalaya includes many families that existed on the ancient super continents of Laurasia and Gondwana. When India detached from Gondwanaland about 90 Mya (million years ago) it carried flora and fauna northward. When India collided with Asia about 40 Mya, species were thrown together and intermixed. As Australia and New Guinea drifted northward, the plates of Asia and Australia pushed up the islands of Wallacea, which were separated by narrow straits. More flora and fauna were intermixed between Indomalaya and Australasia. Many plant families from both ancient Laurasia and Gondwana are now found throughout the Indomalayan and Australasian regions.

Two orders of mammals are endemic to Indomalaya (Colugos and Tree shrews). The animal families of Craseonycteridae, Diatomyidae, Platacanthomyidae, Tarsiidae and Hylobatidae are also endemic to this ecozone. Leopards, tigers, water buffalos, elephants, rhinoceroses, tapirs, orangutans, and gibbons are all found within the Indomalayan ecosystem. The bird families of Irenidae, Megalaimidae, and Rhabdornithidae are endemic to this ecozone. Other birds found here include pheasants, pittas, babblers, and flowerpeckers.

Image Credit: Wikipedia CC By-SA 3.0 U

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