Estimates of the present global macroscopic species diversity vary from 2 million to 100 million, best of which is estimated somewhere near 13-14 million, the vast majority comprising arthropods.
The fact is, however, this that biodiversity is under threat across the globe. India also does not present any
different picture and its considerable biodiversity is under threat. Biodiversity here has been mainly measured by
the numbers of plants and vertebrates and their presence is greatest in the Western Ghats and northeast.
Both the areas are also included in the world’s list of hotspots of biodiversity i.e. small geographic areas with high
species diversity. Of the two areas, the Western Ghats have more endemic species which are found nowhere else,
Threats to species are mainly due to decline in the areas of their habitats, fragmentation of habitats and decline in
habitat quality. Hunting has also been found to be a cause of extinction, especially in the case of some mammals.
Fragmentation also raises the extinction risk, because isolated subpopulations can become extinct one by one due
to not being repopulated. Stochastic declines in small subpopulations make it more likely that they will become
extinct and this is further aggravated by the reduction of genetic variability in subpopulations. Species with
already restricted ranges are particularly vulnerable to these threats. For the terrestrial species, the declines in
habitat quality and quantity arise from the conversion of forests and grasslands into agricultural land, of natural
forests to monoculture plantations and from grazing and woodcutting pressures. In some areas, invasion by
exotic species of plants also results in habitat degradation. For example, Peruvian thorny tree Prosopis julijlora in
the dry parts of northern India have replaced the native species, Acacia milotica(Babool) and South American
flowering bush lantana Camara has spread in the sub-Himalayan belt. For aquatic and semiaquatic
species, the declines in habitat quality are due to diversion of ground and surface water, resulting in drying up of
streams and other water bodies, from siltation, and pollution from pesticides and other chemicals. Freshwater
fishes are also threatened by the introduction of exotic species which are either predator or competitors.
We should do our best to preserve the biodiversity in the country because it is valuable on account of many factors. It has great economic value. Economic value comprises pharmaceutical uses also. Ecosystem value is another important aspect of biodiversity. Loss of biodiversity may cause large unpredictable changes in an ecosystem, thereby adversely affecting agriculture and human health. Loss of biodiversity also indirectly affects tourism. Some areas in India, like Kerala or Tamil Nadu, attract people due to their richness with regard to biodiversity also. Last but not least, there is existence value of biodiversity. Conservation of biodiversity is a major area of concern. Joint Forest Management and Eco-development schemes were initiated in the 1980s and 1990s. Local communities exercise influence over the exploitation of the natural assets and they have the power to degrade them or prevent others from degrading them if they are motivated to do so. The best way of preserving the biodiversity is, undoubtedly, to assign the full rights to revenue flows from nonextractive uses such as tourism to the local communities, together with a democratic and transparent institution that allows them to resolve internal common pool problems. In addition, rights to extractive uses, at least with some restriction, would not degrade the resource. Local communities, if made to participate thus in preservation, feel some sense of confidence and this will act as an incentive both to maintain the resource and to exclude the outside appropriators. In several cases, the local communities may be motivated and taken into confidence, if they are simply allowed to use their respective areas for grazing, firewood collection, timber, and collection of other forest produce in and around existing “Protected Areas” (Wildlife Sanctuaries
and National Parks).