Biogeographic Regions

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Define Biogeographic Regions

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Biogeography is the scientific investigation of the distribution of species and ecosystems in geographic setting and across geological time. Biological communities and living Organisms often differ in a regular fashion through geographic gradients of elevation, isolation, latitude, and habitat area.

The biogeographic regions are basically “those predominant divisions of the earth’s surface of estimated continental extent, which are attributed by distinct assemblages of animal types”. That said, a Biogeographic region is basically an area of plant and animal distribution consisting of similar or shared properties throughout.

Introduction and Identification of Biogeographic Zones

  • Zone 1 – Trans-Himalayan

In the immediate north of the Great Himalayan range are the Trans-Himalayas which encapsulates three biogeographic provinces i.e. — Himalayan Sikkim, Ladakh mountains, and Tibetan plateau. It constitutes about 5.6% of the country's landmass. This area mostly lies between 14,800 to 19,700 feet and is very cold and dry. The extensive region of Trans-Himalayan comprises bare rock and glaciers. The only vegetation is the scanty alpine steppe. With its scanty vegetation, it has a superfluous wild sheep and goat community in the world. The snow leopard, black bears, marbled cat, marmots, wolf and kiang can be spotted here, as are the migratory Black-necked Cranes.

  • Zone 2 – Himalayas

This representation of the Himalayas has the youngest and loftiest mountain sequences in the world. The 2,400 kilometres long Himalayan mountain arc contains distinctive biodiversity in wake of its high altitude, rich flora, soothing temperature and steep gradient. Biogeographically, they create a part of the Palearctic realm. The Himalayas contain three biogeographical provinces i.e. — Central Himalayas, East Himalayas, West Himalayas, and Northwest Himalayas, which together comprise about 6.4% of the country's area.

  • Zone 3 – The Indian Desert

This area comprises two biogeographical provinces i.e. The Thar desert and The Rann of Kutch. The larger is the Thar or Great Indian Desert, consisting of Rajasthan and parts of Haryana and Punjab, moreover adjoining Pakistan. The Indian part of the Thar Desert occupies 170,000 km. The climate reflects very hot and dry summers while cold and arid winters. The area experiences rainfall less than 70 cm. A highly endangered bird—The Indian Bustard is found here, in addition to foxes, snakes, camels, gazelles, foxes, and spiny-tailed lizards.

The second biogeographical province— The Rann of Kutch that lies in Gujarat is a vast area of salt marsh spread across the border between India and Pakistan. This larger area has desert on one side and the sea on the other allowing several ecosystems and desert vegetation. Its deserts and grasslands are home to various wildlife that have adapted to its harsh conditions. These account for endangered and endemic animal and plant species, like the Indian wild ass. The Rann is home to many domestic and migratory birds such as the greater flamingo, lesser flamingo and the Houbara bustard. The Little Rann is an accommodation to the world's largest population of Indian wild ass with other mammals including the Indian wolf, desert fox, blackbuck, chinkara and others.

  • Zone 4 - Semi-Arid Areas

A transitional zone between the desert and the denser forests of the Western Ghats are the semi-arid areas. The area is characterized by discontinuous vegetation blanketed with bare soil and soil water that remains in deficit throughout the year.

  • Zone 5 - Western Ghats

The mountains running through the west coast of peninsular India comprising one of the unique biological regions of the world are the Western Ghats.

The diverse topography and different climate develop a wide range of habitats that support distinctive sets of plant and animal species. The Western Ghats hills are amongst the 25 biodiversity hot-spots identified globally, known for their high levels of endemism and association with evergreen forests.

  • Zone 6 - Deccan Plateau

On the farther side of Ghats is the Deccan Plateau, the largest unit of the Peninsular Plateau of India. The highlands of Deccan are blanketed with unique types of forests that offer a wide variety of forest products.

  • Zone 7 - Gangetic Plain

The biggest unit of the Great Plain of India is the Gangetic Plain. River Ganga is the main water stream after whose name this plain is named. The thickness of the plain is characterized by the alluvial sediments that vary significantly with their maximum in the Ganga plains.

Some of the highest population densities and Topographic uniformity from the trees belonging to these forests are teak, shisham, sal, khair etc.

  • Zone 8 - North-East India

One of the poorest regions in the country consists of several species of bamboos, orchids, ferns and other plants. Here the wild relatives of plants such as mango, banana, citrus and pepper can be grown and found.

  • Zone 9 - Islands

Comprising two groups of islands, i.e., the Arabian Sea and Bay Islands vary considerably in origin and physical features.

  • Zone 10 - Coasts

The Indian coasts differ in their structures and features with the Indian coastline extending over 7,516. 4 km. Extensive deltas of Krishna, Kaveri and Godavari, are the prominent features of this coast. Mangrove vegetation along the tracts of the coast at Ratnagiri in Maharashtra is a reflection of coastal plains. Different crops are grown with Rice being the main crop of cultivation. Coconut trees grow on the coastal plains. 

FAQ (Frequently Asked Questions)

Q1. How to Recognise Biogeographic Regions?

Answer: Some ways to identify the biogeographic regions are:

  • They must be affluent in the majority of living taxa

  • They must be found upon great geographic divisions

  • The presence or the absence of strange species, genera or families must make them distinctive. 

An example of a biogeographic region includes an endemic butterfly species residing in the continental area of the Western Mediterranean reflects the biogeographic region. Endemic species with limited distributions renders a significant contribution in describing biogeographic regions. An adult of Coenonympha corinna elbana living in a confined continental and insular region of the Western Mediterranean.

Q2. What are Biogeographic Zones?

Answer: In 1986, the Wildlife Institute of India (WII) delineated a program to divide India zoogeographical in an attempt to plan a protected area network for India. The program divided India into 10 biogeographic zones, and each zone is further subdivided into biogeographic provinces, which results in 27 in total number.

Q3. What is the Total Number of Biogeographic Zones?

Answer: There are a total of 10 biogeographic zones which are as follows:-

1. Trans Himalayan zone

2. Himalayan zone

3. Desert zone.

4. Semi-Arid zone.

5. Western ghat zone

6. Deccan plateau zone

7. Gangetic plain zone

8. Northeast zone

9. Coastal zone

10. Island