India is one of the 17 identified mega diverse countries of the world. From about 70 per cent of the total geographical area surveyed so far, 45,500 plant species (including fungi and lower plants) and 91,000 animal species, representing about seven percent of the world’s flora and 6.5 per cent of the world’s fauna, respectively, have been described. Nearly 6,500 native plants are still used prominently in the indigenous healthcare systems.
From the biodiversity standpoint, India has some 59,353 insect species, 2,546 fish species, 240 amphibian species, 460 reptile species, 1,232 bird species and 397 mammal species, of which 18.4 per cent are endemic and 10.8 per cent are threatened. The country is home to at least 18,664 species of vascular plants, of which 26.8 per cent are endemic. With only 2.4 per cent of the total land area of the world, the known biological diversity of India contributes 8 per cent to the known global biological diversity. It has been estimated that at least 10 per cent of the country’s recorded wild flora, and possibly the same percentage of its wild fauna, are on the threatened list, many of them on the verge of extinction.
India, with varied terrain, topography, land use, geographic and climatic factors, can be divided into ten recognizable biogeographic zones. These zones encompass a variety of ecosystems – mountains, plateaus, rivers, forests, deserts, wetlands, lakes, mangroves, coral reefs, coasts and islands.
Trans-Himalayan Region: Trans-Himalayan Region, constituting 5.6 per cent of the total geographical area, includes the high altitude, cold and arid mountain areas of Ladakh, Jammu & Kashmir, North Sikkim, Lahaul and Spiti areas of Himachal Pradesh. This zone has sparse alpine steppe vegetation that harbours several endemic species and is a favourable habitat for the biggest populations of wild sheep and goat in the world and other rare fauna that includes Snow Leopard (Uncia uncia) and the migratory Blacknecked Crane (Grus nigricollis).
Himalayan Zone: Himalayan Zone, in the far North, constituting 6.4 per cent of the total geographical area includes some of the highest peaks in the world and makes India one of the richest areas in terms of habitats and species. The steep slopes, unconsolidated soils and intense rainfall render the zone extremely fragile.
The alpine and sub-alpine forests, grassy meadows and moist mixed deciduous forests provide diverse habitat for endangered species of bovids such as Bharal (Pseudois nayaur), Ibex (Capra ibex), Markhor (Capra falconeri), Tahr (Hemitragus jemlabicus), and Takin (Budoreas taxicolor). Other rare and endangered species restricted to this zone include Hangul (Cervus eldi eldi) and Musk Deer (Moschus moschiferus)
Indian Desert Zone: Indian Desert Zone, constituting 6.6 per cent of the total geographical area, includes the Thar and the Kutch deserts and has large expanses of grassland that supports several endangered species of mammals such as Wolf (Canis lupus), Caracal (Felis caracal), Desert Cat (Felis libyca) and birds of conservation interest viz., Houbara Bustard (Chamydotis undulate) and the Great Indian Bustard (Ardeotis nigriceps).
Semi-arid Region: Semi-arid Region, constituting 16.6 per cent of the total geographical area, is a transition zone between the desert and the dense forests of Western Ghats. Peninsular India has two large regions, which are climatically semi-arid. This semi-arid region also has several artificial and natural lakes and marshy lands.
The dominant grass and palatable shrub layer in this zone supports the highest wildlife biomass. The cervid species of Sambar (Cervus unicolor) and Chital (Axis axis) are restricted to the better wooded hills and moister valley areas respectively.
The Lion (Leo persica), an endangered carnivore species (restricted to a small area in Gujarat), Caracal (Felis caracal), Jackal (Canis aureus) and Wolf (Canis lupus) are some of the endangered species that are characteristic of this region.
Western Ghats: Western Ghats, constituting 4.0 per cent of the total geographical area, is one of the major tropical evergreen forest regions in India. The zone stretches from the hills to the South of the Tapti River in the North to Kanyakumari in the South and in the West, this zone is bound by the coast. This zone represents one of the biodiversity ‘hot spots’ with some 15,000 species of higher plants, of which 4,000 (27 per cent) are endemic to the region.
Significant species endemic to this region include Nilgiri Langur (Presbytis jobni), Lion Tailed Macaque (Macaca silenus), Grizzled Giant Squirrel (Ratufa macroura), Malabar Civet (Viverricula megaspila), Nilgiri Tahr (Hemitragus bylocrius) and Malabar Grey Hornbill (Ocycerous griseus). The Travancore Tortoise (Indotestudo forstem) and Cane turtle (Heosemys silvatica) are two endangered taxa restricted to a small area in central Western Ghats.
Deccan Plateau: Deccan Plateau, constituting 42 per cent of the total geographical area, is a semi-arid region that falls in the rain shadow area of the Western Ghats. This bio-geographic zone of peninsular India is by far the most extensive zone, covering India’s finest forests, particularly in the States of Madhya Pradesh, Maharashtra and Orissa.
The zone comprising of deciduous forests, thorn forests and degraded scrubland support diverse wildlife species. Species such as Chital (Axis axis), Sambar (Cervus unicolor), Nilgai (Boselapbus tragocamelus) and Chousingha (Tetracerus quadricornis) are abundant in this zone.
Some other species like Barking deer (Muntiacus muntjak) and Gaur (Antilope cervicapra) are more frequent in, or are restricted to moister areas, but are still found in fairly large numbers.
Species with small populations include the Elephant (Elephas maximus) in Bihar-Orissa and Karnataka-Tamil Nadu belts, Wild Buffalo (Bubalus bubalis) in a small area at the junction of Orissa, Madhya Pradesh and Maharashtra and the hard ground Swamp Deer (Cervus duvauceli), now restricted to a single locality in Madhya Pradesh.
Gangetic Plain: Gangetic Plain, constituting 10.8 per cent of the total geographical area, is a flat alluvial region lying to the North and South of the Ganga River and its major tributaries and in the foothills of the Himalayas. The Gangetic plain is topographically homogenous for hundreds of kilometers. The characterstic fauna of this region include Rhino (Rhinoceros unicornis), Elephant (Elephas maximus), Buffalo (Bubalus bubalis), Swamp Deer (Cervus duvauceli), Hog-Deer (Axis porcinus) and Hispid Hare (Carprolagus bispidus). This zone gains considerable ecological significance in the context of increasing industrialization and pollution and the consequent environmental degradation and deforestation.
North-East Region: North-East Region, constituting 5.2 per cent of the total geographical area, represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese bio-geographical regions as well as being a meeting point of the Himalayan mountains and peninsular India. The North-East is thus the biogeographical ‘gateway’ for much of India’s fauna and flora and also a biodiversity hotspot. Adiverse set of habitats coupled with long term geological stability has allowed the development of significant levels of endemism in all animal and plant groups.
Coasts: The country’s extensive Coasts, constituting 2.5 per cent of the total geographical area with sandy beaches, mangroves, mud flats, coral reefs and marine angiosperm pastures make them the wealth and health zones of India. The coastline from Gujarat to Sunderbans is estimated to be 5,423 km long. Atotal of 25 islets constitute the Lakshadweep, which are of coral origin, and have a typical reef lagoon system, rich in biodiversity. However, the densely populated Lakshadweep islands virtually have no natural vegetation.
Andaman and Nicobar Islands: Andaman and Nicobar Islands, constituting 0.3 per cent of the total geographical area are one of the three tropical moist evergreen forests zones in India. The islands house an array of flora and fauna not found elsewhere. The elongated North-South oriented groups of 348 Andaman Islands have a biogeographical affinity with Myanmar. The Nicobar Islands, lying only 90 kms away from Sumatra have much stronger Indonesian and South-East Asian elements. These islands are centres of high endemism and contain some of India’s finest evergreen forests and support a wide diversity of corals.
