The region consists of moist, dry, evergreen and montane (shola) tropical forests. The Western Ghats, and the Nilgiri region in particular, harbour a bewildering wealth of flora and fauna: mammals, birds, reptiles, amphibians, and fresh water fishes; much of which are endemic to the region. The NBR is 0.15% of India’s land area and has 20% of all angiosperms, 15% of all butterflies and 23% of all vertebrates. Of the 285 endemics in the Western Ghats, 156 (55%) are in the NBR (Daniel 1993).
The Western Ghats cover only 5% of total area of the country but host nearly 4000 species (27% of the total) of flowering plants.Four thousand species of flowering plants are known from the Western Ghats (Nair and Daniel, 1986). The gymnosperm flora is represented by Cycas circinalis (Cycadales), Decussocarpus wallichianus (Coniferales) and Gnetum ula and G. contractum (Gnetales). Amongst the lower plants around 150 species of pteridophytes, 200 species of bryophytes, 200-300 species of algae and 800 species of lichens are known. There are 600 species of fungi known from the Western Ghats (Nair and Daniel, 1986).
Because of its geographic isolation and subsequent evolution, the Western Ghats is one of the richest centers of endemism in India. Of the 4,000 species of flowering plants in Western Ghats, 1500 species are endemic (Nayar, 1996). The high level of diversity and endemism in Western Ghats has given it the status of one of the hot spot of the world (Myers, 1988). Two mega centers of endemism i.e. Southern Western Ghats and Northern Western Ghats fall in this region.According to Nair and Daniel, 2100 species of flowering plants are endemic to peninsular India, ‘most’ of which are ‘confined’ to the Western Ghats. More recent authors have suggested that there could be 1500 species of flowering plants endemic to the Western Ghats (Johnsingh, 2001). Although the exact number keeps varying with the author and time, what is of interest is that nearly 38% of all species of flowering plants in the Western Ghats are endemic. Further it is to be noted that 63% of India’s evergreen woody plants are endemic to the Western Ghats (Johnsingh, 2001).
The Nilgiri Biosphere Reserve is very rich in plant diversity. The Nilgiri mountains are considered as the most important centre of speciation of flowering plants in the Western Ghats (Blasco, 1970). About 3,200 species of flowering plants can be seen here of which 132 are endemic to the reserve. Of the 175 species of orchids found in the Nilgiri Biosphere Reserve, 8 are endemic.
The fauna of the Nilgiri Biosphere Reserve includes over 100 species of mammals, 350 species of birds, 80 species of reptiles and amphibians, 300 species of butterflies and innumerable invertebrates. 31 amphibians and 60 species of reptiles that are endemic to the Western Ghats also occur in the Nilgiri Biosphere Reserve (Daniel 1996).