Unit 4
India as a Mega Diversity Nation
Learning Outcomes
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Prerequisites
| Unity in diversity- that is India. Let us have a general understanding of our nation’s biodiversity and values.
India is a mega diverse country having only 2.4% of the world’s land area but it accommodates 7-8% species of flora and fauna. It includes more than 45,000 species of plants and 91,000 species of animals. The diverse physical features and climatic conditions of India are responsible for a variety of ecosystems such as forests, grasslands, wetlands, deserts, coastal and marine ecosystems. Have you heard about “hotspots”?. Biodiversity hotspot is a biogeographic region that contains significant reservoir of biodiversity and is under threat and destruction. India has four hotspots out of 34 identified globally. They are Himalaya, Indo-Burma, Western Ghats and Sundarlands. |
Key words
Mega diversity, Hot spots, Western Ghats, Sundalands
Discussion
2.4.1 India as a Biodiversity Nation
Why is India known as a mega diversity nation? Do you know why India’s diversity differs from other nations.?
India is a mega diverse country having only 2.4% of the world’s land area but it accommodates 7-8% of the world’s species of flora and fauna. It includes more than 45,000 species of plants and 91,000 species of animals. It is situated at the tri-junction of the Afro-tropical, Indo-Malayan and Palearctic realms, and all of this support rich biodiversity. India is also a recognized centre of crop diversity and produces hundreds of varieties of crop plants such as rice, maize, millets, etc. The diverse physical features and climatic conditions of India are responsible for a variety of ecosystems such as forests, grasslands, wetlands, deserts, coastal and marine ecosystems.
Geological events in the landmass of India have provided conditions for high levels of biological diversity. A split in the single giant continent around 70 million years ago, led to the formation of northern and southern continents. India’s special geographical position and radiation of species is responsible for its rich and varied biodiversity. Among the biologically rich nations, India stands among the top 10 or 15 countries for its great variety of plants and animals, many of which are not found elsewhere. India has 350 different mammals (rated eighth highest in the world), 1,200 species of birds (eighth in the world), 453 species of reptiles (fifth in the world) and 45,000 plant species, of which most are angio-sperms, (fifteenth in the world). These include especially high species diversity of ferns (1022 species) and orchids (1082 species). India has 50,000 known species of insects, including 13,000 butterflies and moths. It is estimated that the number of unknown species could be several times higher.
It is estimated that 18% of Indian plants are endemic to the country and found nowhere else in the world. Among the plant species the flowering plants have a much higher degree of endemism, a third of these are not found else where in the world. Among amphibians found in India, 62% are unique to this country. Among lizards, of the 153 species recorded, 50% are endemic. High endemism has also been recorded for various groups of insects, marine worms, centipedes, mayflies and fresh water sponges. Endemism is the phenomenon which is the presence of endemic species in an area. Endemic species are those which can live only in an unique ecosystem.
Apart from the high biodiversity of Indian wild plants and animals, there is also a great diversity of cultivated crops and breeds of domestic livestock. This is a result of several thousand years during which civilizations have grown and flourished in the Indian subcontinent. The traditional cultivars included 30,000 to 50,000 varieties of rice and a number of cereals, vegetables and fruit. The highest diversity of cultivars is concentrated in the high rainfall areas of the Western Ghats, Eastern Ghats, Northern Himalayas and the North Eastern hills. Gene-banks have collected over 34,000 cereals and 22,000 pulses grown in India. India has 27 indigenous breeds of cattle, 40 breeds of sheep, 22 breeds of goats and 8 breeds of buffaloes.
2.4.2 Hot spots of Biodiversity
The idea of hotspots was first given by ecologist Norman Myers in 1988. Biodiversity hotspot is a biogeographic region that contains significant reservoir of biodiversity and is under threat and destruction. The main criteria for determining a hotspot are endemism (the presence of species found nowhere else on earth) and the degree of threat. Biodiversity hotspots are regions with high species richness and a high degree of endemism.
According to CI, to qualify as a hotspot a region must meet two strict criteria:
- It must contain at least 1,500 species of vascular plants (> 0.5% of the world’s total) as endemics – which is to say, it must have a high percentage of plant life found nowhere else on the planet. A hotspot, in other words, is irreplaceable.
- It has to have lost at least 70% of its original habitat. (It must have 30% or less of its original natural vegetation). In other words, it must be threatened.
In 1999, CI identified 25 biodiversity hotspots in the book “Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions”. The 35 biodiversity hotspots cover 2.3% of the Earth’s land surface, yet more than 50% of the world’s plant species and 42% of all terrestrial vertebrate species are endemic to these areas. In 2011, the Forests of East Australia region was identified as the 35th biodiversity hotspot. Therefore, according to Conservation International, at present, there are 36 biodiversity rich areas in the world that have been qualified as hotspots, which represent just 2.5% of earth’s land surface, but support over 50% of the world’s endemic plant species, and nearly 43% of bird, mammal, reptile and amphibian species as endemics.
2.4.3 Biodiversity hotspots in India
India, the seventh largest country in the world by geographical area (constitutes 2.4% of the total geographical area of the world) with varied physiographic divisions, climatic regimes, and ecological habitats exhibits a rich floral diversity, and harbours nearly 8% of the globally known flora, of which 28% of floral elements are endemic to the country. India is one of the 17 mega diversity countries in the world. India has four hotspots out of 34 identified globally (Conservation International 2013), which are as following:
- Himalaya:
It includes the entire Indian Himalayan region. [Jammu and Kashmir, Himachal Pradesh, Uttarakhand, northern part of West Bengal (Darjeeling), Sikkim, northern part of Assam and Arunachal Pradesh] and that falling in Pakistan, Tibet, Nepal, Bhutan, China and Myanmar. The Himalayan mountains with elevation ranging from less than 500 m to more than 8,000 m supports a variety of ecosystems, from alluvial grasslands (the tallest in the world) and subtropical broadleaf forests along the foothills to temperate broadleaf forests in the mid hills, mixed conifer and conifer forests in the higher hills, and alpine meadows above the tree line. - Indo-Burma:
It includes the entire North-eastern India, except Assam and Andaman group of Islands (and Myanmar, Thailand, Vietnam, Laos, Cambodia and southern China) The Indo-Burma hotspot is the largest among the 36 recognized hotspots of the world with a total geographical area of 2,308,815 km2. Forests are the most species-rich ecosystems in the hotspot. The hotspot supports a variety of forest types, from evergreen forests with a high diversity of canopy tree species, through semi-evergreen and mixed deciduous forests, to relatively (tree) species-poor deciduous forests. The limestone karst formations found throughout the hotspot support highly unique ecosystems, with high levels of endemism, particularly among plants, reptiles and molluscs, and these unique species are found nowhere else.
- Western Ghats and Sri Lanka:
They include entire Western Ghats (and Sri Lanka). The Western Ghats of southwestern India and the highlands of southwestern Sri Lanka, separated by 400 km, but strikingly similar in their geology, climate and evolutionary history, covering an area of 1,89,611 km2 have been designated as the biodiversity hotspot. The Western Ghats, a biogeographically important formation of the Gondwana-land, is formed of the Malabar plains and the chain of mountains running parallel to India’s west coast, about 30 to 50 km inland. The Western Ghats indigenously known as ‘Sahyadri’ covers an area of about 1,64,280 km², constituting 5% of the total area of India. It stretches for about 1,600 km, starting down-wards from the Tapti River in Gujarat to the country’s southernmost tip Kanyakumari in Tamil Nadu. The mountain range is interrupted by a number of natural gaps and passes, and the widest being the 24–30 km one, called the Palakkad (Palghat) Gap. - Sundalands:
It includes Nicobar group of Islands (and Indonesia, Malaysia, Singapore, Brunei, Philip-pines). The Sundaland hotspot covers a group of some 17,000 islands in the western half of the Indonesian archipelago, and stretching around 5,000 km along the equator between Asia and Australia. The hotspot covers about 1.6 million km2 area; majorly occupied by the islands of Borneo (725,000 km²) and Sumatra (427,300 km²). The Sundaland hotspot is adjacent to three other hotspots, namely Wallacea to the east, Indo-Burma to the west, and the Philippines to the north. The landscape comprises of high mountain ranges (Mount Kinabalu with 4,101 m elevation, is the highest peak), volcanoes (23 are active), alluvial plains, lakes, swamps, and shallow coastal waters.
Recap
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Answer to Objective type questions
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Assignment
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Reference
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