Biogeographic Regions of India
Biogeographic classification of India is the division of India according to biogeographic characteristics. Biogeography is the study of the distribution of species (biology), organisms, and ecosystems in geographic space and through geological time. There are ten biogeographic zones in India.
- Trans Himalayan zone.
- Himalayan zone
- Desert zone.
- Semiarid zone.
- Western ghat zone.
- Deccan plateau zone.
- Gangetic plain zone.
- North east zone.
- Coastal zone.
- Islands present near the shore line.
Trans- Himalayan Region
The Trans Himalayan regions of the states of Jammu and Kashmir and Himachal Pradesh are a moonscape land – an arid high altitude desert unlike any other part of the Indian subcontinent. The stark landscape is a panorama of high snow capped peaks and bare multi hued hills sculpted by the forces of nature. The high dusty valleys strewn with rock have altitudes ranging from 2,500m to 4,500m.
The Himalayas consist of the youngest and loftiest mountain chains in the world. The Himalayas have attained a unique personality owing to their high altitude, steep gradient and rich temperate flora. The forests are very dense with extensive growth of grass and evergreen tall trees. Oak, chestnut, conifer, ash, pine, deodar are abundant in Himalayas. There is no vegetation above the snowline. Several interesting animals live in the Himalayan ranges. Chief species include wild sheep, mountain goats, ibex, shrew, and tapir. Panda and snow leopard are also found here.
Adjoining the desert are the semi-arid areas, a transitional zone between the desert and the denser forests of the Western Ghats. The natural vegetation is thorn forest. This region is characterized by discontinuous vegetation cover with open areas of bare soil and soil-water deficit throughout the year. Thorny shrubs, grasses and some bamboos are present in some regions. A few species of xerophytic herbs and some ephemeral herbs are found in this semi-arid tract. Birds, jackals, leopards, eagles, snakes, fox, buffaloes are found in this region.
The mountains along the west coast of peninsular India are the Western Ghats, which constitute one of the unique biological regions of the world. The Western Ghats extend from the southern tip of the peninsula (8°N) northwards about 1600 km to the mouth of the river Tapti (21°N). The mountains rise to average altitudes between 900 and 1500 m above sea level, intercepting monsoon winds from the southwest and creating a rain shadow in the region to their East.
The varied climate and diverse topography create a wide array of habitats that support unique sets of plant and animal species. Apart from biological diversity, the region boasts of high levels of cultural diversity, as many indigenous people inhabit its forests. The Western Ghats are amongst the 25 biodiversity hot-spots recognized globally. These hills are known for their high levels of endemism expressed at both higher and lower taxonomic levels. Most of the Western Ghat endemic plants are associated with evergreen forests.
The region also shares several plant species with Sri Lanka. The higher altitude forests were, if at all, sparsely populated with tribal people. Rice cultivation in the fertile valley proceeded gardens of early commercial crops like areca nut and pepper. The original vegetation of the ill-drained valley bottoms with sluggish streams in elevations below 100m would be often a special formation, the Myristica swamp. Expansion of traditional agriculture and the spread of particularly rubber, tea, coffee and forest tree plantations would have wiped out large pockets of primary forests in valleys. The Western Ghats are well known for harboring 14 endemic species of caecilians (i.e., legless amphibians) out of 15 recorded from the region so far.
North-West Desert Regions
This region consists of parts of Rajasthan, Kutch, Delhi and parts of Gujarat. The climate is characterised by very hot and dry summer and cold winter. Rainfall is less than 70 cm. The plants are mostly xerophytic. Babul, Kikar, wild palm grows in areas of moderate rainfall. Indian Bustard, a highly endangered bird is found here. Camels, wild asses, foxes, and snakes are found in hot and arid sex positions.
Beyond the Ghats is Deccan Plateau, a semi-arid region lying in the rain shadow of the Western Ghats. This is the largest unit of the Peninsular Plateau of India. The highlands of the plateau are covered with different types of forests, which provide a large variety of forest products. The Deccan plateau includes the region lying south of the Satpura range. It extends up to the southern tip of peninsular India. Anaimudi is the highest peak of this region. The Deccan plateau is surrounded by the western and the eastern ghats.These ghats meet each other at the Nilgiri Hills. The Western Ghats includes the Sahyadri, Nilgiris, Anamalai, and cardamom Hills. many rivers such as Mahanadi, Godavari, Krishna, and Kaveri originates from the Western Ghats and flow toward the east. The Eastern Ghats are broken into small hill ranges by rivers coming from the Western Ghats. Most of these rivers fall into the Bay of Bengal. The Godavari is the longest river in the Deccan plateau. The Narmada and the Tapi flow westwards and fall into the Arabian sea.
In the North is the Gangetic plain extending up to the Himalayan foothills. This is the largest unit of the Great Plain of India. Ganga is the main river after whose name this plain is named. The aggradational Great Plains cover about 72.4mha area with the Ganga and the Brahmaputra forming the main drainage axes in the major portion.
The thickness in the alluvial sediments varies considerably with its maximum in the Ganga plains. The physiogeographic scenery varies greatly from arid and semi-arid landscapes of the Rajasthan Plains to the humid and per-humid landscapes of the Delta and Assam valley in the east. Topographic uniformity, except in the arid Western Rajasthan is a common feature throughout these plains. The plain supports some of the highest population densities depending upon purely agro-based economy in some of these areas. The trees belonging to these forests are teak, sal, shisham, mahua, khair etc.
North-east India is one of the richest flora regions in the country. It has several species of orchids, bamboos, ferns and other plants. Here the wild relatives of cultivated plants such as banana, mango, citrus and pepper can be grown
The two groups of islands, i.e., the Arabian Sea islands and Bay Islands differ significantly in origin and physical characteristics. The Arabian Sea Islands (Laccadive, Minicoy, etc.) are the foundered remnants of the old land mass and subsequent coral formations. On the other hand, the Bay Islands lay only about 220 km. Away from the nearest point on the main land mass and extend about 590 km. With a maximum width of 58 km the island forests of Lakshadweep in the Arabian Sea have some of the best-preserved evergreen forests of India. Some of the islands are fringed with coral reefs. Many of them are covered with thick forests and some are highly dissected.
India has a coastline extending over 5,500 km. The Indian coasts vary in their characteristics and structures. The west coast is narrow except around the Gulf of Cambay and the Gulf of Kutch. In the extreme south, however, it is somewhat wider along the South Sahyadri. The backwaters are the characteristic features of this coast. The east coast plains, in contrast are broader due to depositional activities of the east-flowing rivers owing to the change in their base levels.
Extensive deltas of the Godavari, Krishna and Kaveri are the characteristic features of this coast. Mangrove vegetation is characteristic of estuarine tracts along the coast for instance, at Ratnagiri in Maharashtra. Larger parts of the coastal plains are covered by fertile soils on which different crops are grown. Rice is the main crop of these areas. Coconut trees grow all along the coast.
Fauna and Flora of Biodiversity Hotspots in India
The Eastern Himalayas harbor an amazing diversity of life. There are 163 globally threatened species found in the Himalayas, including Asia’s three largest herbivores – Asian elephant, greater one-horned rhinoceros and wild water buffalo – and its largest carnivore, the tiger. The region is home to:
• 10,000 types of plants
- 300 mammals
- 977 birds
- 176 reptiles
- 105 amphibians
- 269 freshwater fish
The Himalayan grasslands have the densest population of Bengal tigers, which live alongside Asian elephants and one-horned rhinos. The mountains offer refuge for red pandas, golden langurs and takins. This is the only known location in the world where Bengal tigers and snow leopards share habitat.
The Eastern Himalayan Broadleaf and Conifer Forests blanket the lowlands to the foothills of the Himalayas in northern India, Nepal, and Bhutan. This Global ecoregion is made up of 4 terrestrial ecoregions: Eastern Himalayan subalpine conifer forests; Eastern Himalayan broadleaf forests; Northern Triangle temperate forests; and Northeastern Himalayan subalpine conifer forests. These middle-elevation forests range from 900 to 3,900 m (3,000 to 13,000 ft) and harbor a tremendous diversity of plant and animal species.
Temperatures vary widely throughout the year making it ideal for broadleaf evergreen trees at the lower elevations, and deciduous trees and conifers higher up. In the sub-alpine zone, above 3,000 meters, forests are slow to regenerate, a fact that makes them especially susceptible to degradation.
Eastern Himalayan forests are home to a number of extraordinary mammals such as the highly endangered golden langur (Presbytis bieti), lesser panda (Ailurus fulgens), clouded leopard (Neofelis nebulosa), Himalayan black bear (Selenarctos thibetanus), and the goat antelope called Takin (Budorcas taxicolor). Endangered endemic plants include many orchid species (Cymbidium whiteae, Paphiopedilum fairrieanum, P. wardii), and maple species such as the Accer oblongumand and Acer hookeri.
The Broadleaf Forests are home to 500 species of birds, of which 12 live almost nowhere else in the world. These forests constitute an important endemic bird area and support a high diversity of bird species such as the Kashmir flycatcher (Ficedula subrubra), Himalayan quail(Ophrysia superciliosa), Brooks’ leaf-warbler (Phylloscopus subviridis), and the Blyth’s tragopan (Tragopan blythi).
More than 200 other species of birds live in the Subalpine Forests, along with 88 species of mammals. Other birds characteristic of this ecoregion include the laughing thrushes (Garrulax spp.) of which there are several dozen species resident in the Eastern Himalayas.
It supports the life of 7,402 species of flowering plants,1814 species of non-flowering plants, 139 mammal species, 508 bird species, 179 amphibian species, 6000 insects species and 290 freshwater fish species. And many are still to be discovered. Western Ghats is a mountain range that runs through the states of Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu. Running parallel to the western coast and along the western edge of the Deccan Plateau, the hills cover over 1,60,000 square kilometre. And it is a UNESCO World Heritage Site.
The Western Ghats block southweat monsoon winds from reaching the Deccan Plateau and are consequently an area of high rainfall, particularly on their western side. Geological studies have found the west coast broke away from Madagascar 100 million years ago and appeared as cliff with an elevation ranging at 3,300 feet. Anamudi, the highest peak here, is located in Kerala. Outside of the Himalayas, the mountain at an elevation of 2,695 is also the highest peak in India.
The major river systems originating in the Western Ghats include Godavari, Kaveri, Krishna, Thamiraparani and Tungabhadra. They are lost faster than other species. The area covers five percent of India’s land with 27 per cent of all species of higher plants in India are found here and 1,800 of these are endemic to the region.