India is one of the recognized megadiverse countries of the world. In terms of species richness, India ranks seventh in mammals, ninth in birds and fifth in reptiles. In terms of endemism of vertebrate groups, India’s position is tenth in birds with 69 species, fifth in reptiles with 156 species and seventh in amphibians with 110 species.
India’s share of crops is 44% as compared to the world average of 11 %. India also has 23.39 % of its geographical area under forest and tree cover. Of the 34 globally identified biodiversity hotspots, India harbours two hotspots, i.e., Eastern Himalayas, Western Ghats
Biogeography deals with the geographical distribution of plants and animals. There are 10 biogeographic zones which are distinguished clearly in India. They are as follows –
1) Trans-Himalayas: An extension of the Tibetan plateau, harboring high-altitude cold desert in Laddakh (J&K) and Lahaul Spiti (H.P) comprising 5.7 % of the country’s landmass.
2) Himalayas: The entire mountain chain running from north-western to northeastern India, comprising a diverse range of biotic provinces and biomes.
3) Desert: The extremely arid area west of the Aravalli hill range, comprising both the salty desert of Gujarat and the sand desert of Rajasthan.
4) Semi-arid: The zone between the desert and the Deccan plateau, including the Aravalli hill range.
5) Western Ghats: The hill ranges and plains running along the western coastline, south of the Tapti river, covering an extremely diverse range of biotic provinces and biomes.
6) Deccan peninsula: The largest of the zones, covering much of the southern and south-central plateau with a predominantly deciduous vegetation.
7) Gangetic plain: Defined by the Ganges river system, these plains are relatively homogenous.
8) North-east India: The plains and non-Himalayan hill ranges of northeastern India, with a wide variation of vegetation.
9) Islands: The Andaman and Nicobar Islands in the Bay of Bengal, with a highly diverse set of biomes. 0.03% of the country’s landmass.
10) Coasts: A large coastline distributed both the the west and east, with distinct differences between the two; Lakshadeep islands are included in this with the percent area being negligible.
1. Algae: Algae are defined as a group of predominantly aquatic, photosynthetic, and nucleus-bearing organisms that lack the true roots, stems, leaves, and specialized multicellular reproductive structures of plants.
The fresh-water algae are generally green or blue-green in colour, whereas the marine ones are red or brown. These are autotrophic plants, as they can manufacture their own food.
2. Fungi: Non-green, non differentiated plants characterised by total absence of chlorophyll are called Fungi. They grow either on dead, rotten organic matters as saprophytes or live as parasites on other living bodies, which are referred to as hosts. Moulds and mushrooms are the familiar examples of saprophytic fungi. The maximum diversity of fungi is in the Western Ghats followed by the eastern Himalaya and the western Himalaya. About 3500 species are endemic to the country.
3. Bacteria: Non-chlorophyll, micro-organisms which lead saprophytic or parasitic existence. Many of them are pathogenic; Saprophytic bacteria are rather beneficial. They are soil borne and many of them are used in industries.
4. Lichens: A lichen is a peculiar combination of an alga and a fungus, the two live deriving mutual benefit. They are group of greyish green plants which grow on rocks, three-trunks, dead wood, etc. · The algae manufactures carbohydrate food which becomes available to the fungus, and the latter absorbs and retains water and thus keeps the algal cells moist. So it is a nice example of symbiosis. They are most common in wetlands, rare in rivers and streams and are not found in ground water.
5. Protozoa: Protozoa are simple, single-celled animals. They are the smallest of all animals. Most protozoa are microscopic. They do breathe, move and reproduce like multi-celled animals e.g. amoebas, Flagellates, etc.
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