India has two biodiversity hot spots, namely:
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Himalaya (Eastern Himalayas)
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The Western Ghat
Eastern Himalaya
Phyto-geographically, the Eastern Himalaya forms a distinct floral region and comprises of Nepal, Bhutan, states of East and North-East India, and a contiguous sector of Yunnan province in South-Western China.
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In the whole of Eastern Himalaya, there are an estimated 9,000 plant species, out of which 3,500 (i.e. 39 per cent) are endemic.
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In the Indian portion, there occurs some 5,800 plant species, roughly 2,000 (i.e. 36 per cent) of which are endemic.
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At least 55 flowering plants endemic to this area are recognized as rare, for example, the Pitcher Plant (Nepenthes khasiana).
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The area has long been recognized as a rich centre of primitive flowering plants and is popularly known as the ‘Çradle of Speciation’.
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Species of several families of monocotyledons, Orchidaceae, Zingiberaceae and Arecaceae are found in the area. Gymnorperms and Pteridophytes (ferns) are also well represented here.
The area is also rich in wild relatives of plants of economic significance e.g. rice, banana, citrus, ginger, chilli, jute and sugarcane.
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It is also regarded as the centre of origin and diversification of five palms of commercial importance, namely coconut, arecanut, palmyra palm, sugar palm and wild date palm.
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Tea (Thea sinensis) has been cultivated in this region for the last 4,000 years. Many wild and allied species of tea, the leaves of which are used as a substitute for tea, are found in the North East, in their natural habitats.
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The Taxol plant (Taxus wallichiana) is sparsely distributed in the region and is listed under the red data category due to its overexploitation for extraction of a drug effectively used against cancer.
As regards faunal diversity, 63 per cent of the genera of land mammals in India are found in this region. During the last four decades, two new mammals have been discovered from the region – Golden Langur from Assam-Bhutan region, and Namdapha Flying Squirrel from Arunachal Pradesh, indicating the species richness of the region. The region is also a rich centre of avian diversity – more than 60 per cent of the bird species found in India have been recorded in the North East. The region also hosts two endemic genera of lizards, and 35 endemic reptilian species, including two turtles. Of the 240 Indian amphibian species, at least 68 species are known to occur in the North East, 20 of which are endemic.
From Namdapha National Park itself, a new genus of mammal, a new subspecies of a bird, six new amphibians’ species, four new species of fish, at least 15 new species of beetles and six new species of flies have been discovered.
Western Ghats
The Western Ghats region, which is spread into 6 states of India, is considered to be one of the most important bio-geographic zones of India, as it is one of the richest centres of endemism.
Due to varied topography and microclimatic regimes, some areas within the region are considered to be active zones of speciation.
The region has 490 arborescent taxa, of which as many as 308 are endemic. About 1,500 endemic species of dicotyledonous plants are reported from the Western Ghats. 245 species of orchids belonging to 75 genera are found here, of which 112 species in ten genera are endemic to the region. As regards the fauna, as many as 315 species of vertebrates belonging to 22 genera are endemic, including 12 species of mammals, 13 species of birds, 89 species of reptiles, 87 species of amphibians and 104 species of fish.
The extent of endemism is high amongst amphibian and reptile species. There occur 117 species of amphibians in the region, of which 89 species (76 per cent) are endemic. Of the 165 species of reptiles found in Western Ghats, 88 species are endemic. Many of the endemic and other species are listed as threatened.
Nearly 235 species of endemic flowering plants are considered endangered. Rare fauna of the region include – Lion Tailed Macaque, Nilgiri Langur, Nilgiri Tahr, Flying Squirrel, and Malabar Gray Hornbill.