There is usually one or two species at each trophic level, which exert a more dominant influence over the function and structure of the community than others. This lack of specialization results in various interconnected links within a food chain and so the nutritional relationships take the form of a food web instead. It is usually the case however, that a number of primary producers are eaten by several different primary consumers, which are subsequently eaten by various secondary consumers. The dead body of the eagle may be consumed by fungus ( decomposer).Įach interaction, from the sun’s energy to the decomposers, makes up a link in the food chain. For example, in a grassland community, the grass (primary producer) is consumed by a mouse ( primary consumer), which is consumed by a snake ( secondary consumer), and subsequently an eagle ( tertiary consumer). iii) Decomposers (which are also heterotrophs) consume dead plant and animal material, recycling the nutrients back in to the earth.Ĭommunities can be described by the way that the energy is transferred through these trophic levels. Primary consumers, or herbivores eat the plant material while secondary and tertiary consumers, carnivores or omnivores, eat the primary consumers. ii) Consumers, or heterotrophs must obtain their nutrition from other organisms. Primary producers are usually green plants and algae. These trophic levels can be divided into three main groups: i) primary producers (also known as autotrophs) manufacture their own food using energy from the sun to perform photosynthesis. Trophic OrganizationĮach organism within a community can be categorized within a specific trophic level, which relates to the way which it obtains nutrition.

The features within communities are highly variable, and there are a number of characteristics that can be used as descriptors to distinguish them.

Definition of ecotone