In 1971, Odum defined ecosystem as any unit that included within it all the organisms (i.e. the community) of a given AREA interacting with the physical environment, so that a FLOW of energy results in a clearly defined TROPHIC structure, biotic diversity and material cycles.

In this context, the following terms NEED to be classified:

• The trophic structure is the LEVEL of nourishment. Plants form the first trophic level, herbivores form the second trophic level and carnivores form the subsequent trophic levels.
• Biotic diversity refers to the different kinds or types of organisms and their numbers.
• Material cycles refer to the exchange of materials between living and non-living parts of the system, the transfer of nutrients from one trophic level to another and their re-cyclization.

In 1971, Odum defined ecosystem as any unit that included within it all the organisms (i.e. the community) of a given area interacting with the physical environment, so that a flow of energy results in a clearly defined trophic structure, biotic diversity and material cycles.

In this context, the following terms need to be classified: