Give various ecological services.

Healthy ecosystem are the base for a wide range of economic environmental and aesthetic goods and services.

The products of ecosystem processess are named as ecosystem services, for example, healthy forest ecosystems purify air and water, mitigate droughts and floods, cycle nutrients, generate fertile soils, provide wildlife habitat, maintain biodiversity, pollinate crops, provide storage site for carbon and also provide aesthetic, cultural and spiritual values.

Robert Constanza and his colleagues have very recently tried or put price tags on nature's life support services.

Researchers have put an average price tag of $US$ $\$ 33$ trillion a year on these fundamental ecosystems services which are largely taken for granted because they are free.

This is nearly twice the value of the global gross national product of $GNP$ which is ($US$ $\$ 18$ trillion).

Out of the total cost of various ecosystem services, the soil formation accounts for about $50$ per cent and contributions of other services like recreation and nutrient cycling are less than $10$ per cent each.

The cost of climate regulation and habitat for wildlife are about $6$ per cent each.