BIOSPHERE

*Food,form crops and domestic animals ,providing human metabolic requirements .

*Food for all forms of life,which live as interdependent species in a community,and formfood ch- -ins in nature on which man is dependent.

*Energy needs:Biomass fuelwood collected from forests and plantations,along with other forms of organic matter,used as a source of energy.

This relatively thin layer on the Earth in which life can exist.within the air ,water,rocks and considered as one gaint global living system ,that of Earth itself.With in this framework,those characterized by broadly similar geograph and climate as well as communities of plant and animal life can be divided for convinence in to different biogeographical realms.These occur on different differences and fnctional aspects in to distinctive recognizable ecosystems ,which give a distrinctive character to a landscape or waterscape .Their Easily visible and identfiable characteristics anc be valley ,hill range ,river or lake,.

The simplest of ecosystems to understand is a pond.It can be used as a model to understand the nature of any other ecosystms and to appreciate the changes over time that are sen in any ecosystem.The structural features of a pond include its size,depth and the quality of its water.The periphery,the shallow part and the deep part of the pond ,each provide specific conditiions for diiferent plant and animal communities .Functionally,a variety of cycles like the amount of water within in the pond at different times of the year,the quantity of nutrients flowing in to the pond form the surrounding terrestrial ecosystem ,all affect the 'Nature'of the pond