THE REALM OF “INDOMALAYAN”

Indomalayan Realm from Space

Geographic regions around the world that have similar environmental conditions are capable of harbouring the same type of biota. This situation effectively separates the biosphere  into  biomes—ecological communities that have the same climatic conditions and geologic features and that support species with similar life strategies and adaptations

Biodiversity is not spread evenly across the Earth but follows complex patterns determined by climate, geology and the evolutionary history of the planet. These patterns are called “ecoregions”.

WWF defines an ecoregion as a “large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions”.

The boundaries of an ecoregion are not fixed and sharp, but rather encompass an area within which important ecological and evolutionary processes most strongly interact.

Terrestrial Biogeographical Realms

Accordingly, Our Planet is divided into 6 terrestrial realms namely Nearctic, Palearctic, Indomalayan, Australasian, Neotropical and Afrotropical realms other than the Oceanian and Antarctic realms.

Indomalayan Ream – Bioregions

Indomalayan is one of the most biodiversity rich ecological realms and poses a considerable magnitude of conservation issues that are at stake hence one of the primary goals of the Species Ecology is to provide science bound information pertaining to this ecologically unique mega diversity biome.

The Hindu Kush, Karakoram, Himalaya, and Patkai ranges bound the  bioregion on the northwest, north, and northeast; the ranges formed by the collision of the northward-drifting Indian subcontinent with Asia beginning 45 million years ago.

These ranges are a major biogeographic boundary between the subtropical and tropical flora and fauna of the Indian subcontinent and the temperate-climate Palearctic realm.

Formation of Himalayas

Over the past 65 million years, powerful global plate-tectonic forces have moved the Earth’s crust to form the band of Eurasian mountain ranges—including the Himalayas—that stretch from the Alps to the mountains of Southeast Asia

One of Gondwana’s fragments, the lithospheric plate that included the Indian subcontinent, pursued a northward collision course toward the Eurasian Plate. Between about 40 and 50 million years ago, the Indian subcontinent finally collided with Eurasia.

Himalayas appear as a gigantic crescent with the main axis rising above the snow line, where snowfields, alpine glaciers, and avalanches all feed lower-valley glaciers that in turn constitute the sources of most of the Himalayan rivers. 

This 4,000km crescent, stretching from Kyrgyzstan to Burma, is a geography of superlatives – the highest mountains, the deepest gorges, tracts of wild forest, the rolling high plateau of Tibet plus, in Bhutan and the Indian state of Assam in the eastern Himalayas, some of the greatest biodiversity on the planet.

The mountain ranges separating the plains of the Indian subcontinent from the Tibetan Plateau. The Himalayan region bound to the Indomalayan Realm is separated by the Trans-Himalayan region represented by Palearctic Realm.

For thousands of years the Himalayas have held a profound significance for the peoples of South Asia, as their literature, mythologies, and religions reflect. Since ancient times the vast glaciated heights have attracted the attention of the pilgrim mountaineers of India, who coined the Sanskrit name Himalaya.

THE HIMALAYAN RANGES

Also called the Oriental realm by biogeographers, the Indomalayan realm extends in the West from present day Afghanistan through the Indian subcontinent bioregion covering most of India, Bangladesh, Nepal, Bhutan, and Sri Lanka.

To the south-west lies the ancient mountain ranges of the Western Ghats. The Western Ghats, also called the Sahyadri – meaning Benevolent Mountains, are a north-south chain of mountains or hills that mark the western edge of the Deccan plateau region, parallel to the western coast of the Indian peninsula.

Since the Western Ghats are a result of a domal uplift, the underlying rocks are ancient – around 2000 million years old. The oldest of these rocks are found in the Nilgiris and the High Ranges of the southern Western Ghats.

Geologic evidence indicates that they were formed during the break-up of the supercontinent of Gondwana some 150 million years ago. 

The Western Ghats is an “Evolutionary Ecotone” illustrating “Out of Africa” and “Out of Asia” hypotheses on species dispersal and vicariance.

Their positioning makes the Western Ghats biologically rich and bio geographically unique – a veritable treasure house of biodiversity. The region has a spectacular assemblage of large mammals – around 30% of the world’s Asian elephant population and 17% of the world’s existing tigers call this region their home.

Indomalayan further extends to east, to the Indo-China bioregion including most of mainland Southeast Asia, including Myanmar, Thailand, Laos, Vietnam, and Cambodia, as well as the subtropical forests of southern China; also includes the Philippines, lowland Taiwan, and Japan’s Ryukyu Islands.

The Northern Indochina Subtropical Forests are globally outstanding for their biological diversity; this ecoregion has the highest species richness for birds among all ecoregions in the Indo-Pacific region and ranks third for mammal richness. The cool winter temperatures and high elevation here at the edge of the tropics promote a montane flora with a distinct Himalayan component.

Dry evergreen forests in this region is more appropriately called semi-evergreen forest because a significant proportion of canopy tree species are deciduous at the height of the dry season.

Extensive areas of this ecoregion in southern Laos and northeastern Cambodia occur with a largely deciduous forest canopy. The ecoregion is globally outstanding for species richness, especially for the large vertebrate assemblage and associated ecological processes.

Importantly, it also represents a rare instance of a nonmontane ecoregion with large expanses of intact habitat that can allow viable populations of these species to survive over the long term. 

To the South east the Indo-Malay achepelago extending through Indonesia as far as Java, Bali, and Borneo, east of which lies the Wallace line, the realm boundary separating Indomalayan from Australasia. 

Malay Archipelago, largest group of islands in the world, consisting of the more than 17,000 islands of Indonesia and the approximately 7,000 islands of the Philipines.

Over the years, we have systematically killed the natural balancers and caused irrevocable damage to the landscape. With just one big rain, mountains that withstood climatic variations with great stability for millions of years have become unstable and started to slide down.

There was a culture inclined more to food and clothing based on respect to land. There was a specific time for every activity influenced by natural factors – a time to sow, to harvest, to extract trees, to restrict diet etc. All of this seems to be a forgotten culture today.

Monitored and evaluated by experienced Conservationists, along with the new generation of Creators and Educators, a sensible future is in the making; aware of the precious natural assets of the region and its importance for the survival of ecologically sensitive landscapes of the Western Ghats.

It’s time to start respecting the land we depend on, protect our forests and secure our future.

Published by Indomalayan

A storyteller, filmmaker keen to observe, capture and create stories of life in harmony with nature. The creator of the Nature film series - Indomalayan Diaries, exploring the human stories and adventures of my travel diaries while exploring the ecoregions of the Indomalayan Realm. Raised from the Wayanad bioregion in the ancient mountain ranges of Western Ghats, a mountain kid by birth who loves the snow mountains of the Himalaya and pursuing his journey of exploring life in all biomes over every biogeographical realms and ecoregions across all continents of our planet.

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