1. Biodiversity provides plant pollinators, predators, decomposers and contributed to soil fertility.

2. It helps in the purification of air and water, management of flood, drought and other environmental disasters.

3. Ecosystems with more diversity can withstand the environmental challenges better because genetically diverse species present in the ecosystem will have different tolerance ranges for a given environmental stress, hence they cannot be easily eliminated by any single stress at a time. However, if the ecosystem contains only few species, it will become a fragile or unstable ecosystem.

4. The species with high genetic diversity and the ecosystems with high biodiversity have greater capacity for adaptation against environmental perturbations.

Alexander Von Humboldt has observed that within a region, species richness increased with increased explored area, but only upto a limit.

The relationship between species richness and area for a number of taxa like angiospermic plants, freshwater fishes and birds is found to be a rectangular hyperbola.

On a log scale, the relationship becomes linear (straight line) and is described by the equation.

log S = log C + Z log A, where,

S = Species Richness Z = Slope of the line (regression coefficient)

A = area and C = y-intercept Ecoloeists have found out that the value of Z-hne ranges between 0.1 and 0.2 irrespective of the taxonomic group or the region.

But this analysis in very large areas like a continent, the Z value ranges between 0.6 and 1.2.

The Z value for frugivorous birds and mammals in the tropical forests is found to be 1.15.

â–² Fig. 7.1. Species area relationship

1. India contains 10 biogeographic regions which include the Himalayan, Trans-Himalayan, the Indian desert, the Semi-arid zone, the Western-Ghats, the Dec can Peninsula, the Gangetic Plain, North-East India and the Islands and Coasts which possess different biodiversity levels.
2. India is one of the world’s 12 leading biodiversity centres of the origin of cultivated plants.
3. Though India has only 2.4% of the land area of the world, it has 8.1% of the global species biodiversity.
4. There are about 45000 species of plants and 90,000-1,00,000 species of animals; many more species are yet to be discovered and named.
5. India probably has more than 1,00,000 species of plants and 3,00,000 species of animals to be discovered and described.
6. India has 5 natural world heritage sites,14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries and 2 hot spots.
7. About 33 per cent of the country’s recorded flora are endemic to India and concentrated in the North-East, Western-Ghats, North-West Himalayas and Andaman and Nicobar islands.