12.1.3 Magnitude of biodiversity

. . Magnitude of biodiversity Biodiversity is often quantified as the number of species in a region at a given time. The current estimate of different species on earth is around - million. However, we really don’t know the exact magnitude of our natural wealth. This is called the ‘The Taxonomic impediment’. So far about . million species of microorganisms, animals and plants have been Fig. .1a Species biodiversity described. Each year about - thousand new species are identified and published worldwide, of which % are invertebrates. The number of undescribed species is undoubtedly much higher. India is very rich in terms of biological diversity due to its unique bio-geographical location, diversified climatic conditions and enormous eco-diversity and geo-diversity. According to world biogeographic classification, India represents two of the major realms (The Palearctic and Indo-Malayan) and three biomes (Tropical humid forests, Tropical Dry/ Deciduous forests and Warm Deserts/Semi deserts). With only about . % of the world’s total land surface, India is known to have over % of the species of animals that the world holds and this percentage accounts for about , known species. India is the seventh largest country in the world in terms of area. India has a variety of ecosystems, biomes with its varied habitats like, hills, valleys, plateaus, sea shores, mangroves, estuaries, glaciers, grasslands and river basins. It also reflects different kinds of climates, precipitation, temperature distribution, river flow and soil. India is one of the mega biodiversity countries of the world and has ten biogeographic zones with characteristic habitat and biota. "The world is currently undergoing a very rapid loss of biodiversity comparable with the great mass extinction events that have previously occurred only five or six times in the earth's history." - World Wildlife Fund