The trophic structure (from Greek trophos = feeder) of an ecosystem is the arrangement of organisms based on their feeding relationships. All organisms interact with each other through the food web, based on what they eat and what eats them. Thus the trophic structure controls the passage of energy and nutrients from one organism to another in an ecosystem.

The trophic structure of an ecosystem can be broken up into various trophic, or feeding levels. At the base of the trophic structure are the producers, which are sometimes called primary producers. These autotrophic organisms produce their own food using the processes of photosynthesis or chemosynthesis. The most common types of producers are green plants on land and algae in water. All other organisms in the trophic structure ultimately depend upon these producers for their energy and organic material. In a field ecosystem, the grasses would be an...