With the survival and well-being of humans beings so heavily dependent on biodiversity, its economic value assumes considerable importance. For instance the economic value of ecosystem services and components of biodiversity is estimated at around US $ 33 billio n, which is about 1.8 times more than the world's GNP. Another example is the pharmaceutical industry which still depends largely on wild bioresources; in India alone around 660 wild species are involved in all -India trade. Throughout the world, tourism based on appreciation of nature is growing, and it
constitutes a major income earner for many countries of South Asia.

Economic valuation should also show the economic costs associated with the loss or degradation of biodiversity and its components. This wi ll include on and off-site loss of subsistence, loss or decrease of employment, loss of income and foreign exchange earnings and the cost of replacing or mitigating the loss of bioresources and ecosystem functions.