BIOB50H3 Lecture Notes - Lecture 20: Ecological Pyramid, Allochthon, Herbivore
Document Summary
The ecological roles or organisms are determined by their trophic interactions what they eat and what eats them: this determines the influence of an organism on the movement of energy and nutrients through an ecosystem. In terrestrial ecosystems, only a small portion of the biomass is consumed and most of the energy flow passes through the detritus. Much of the detritus in streams, lakes, and estuaries is derived from terrestrial organic matter. These external energy inputs are called allochthonous inputs. Energy produced by autotrophs within the system is autochthonous energy: allochthonous inputs typically more important in streams and rivers, autochthonous inputs typically more important in lakes and. Some organisms do not conveniently fit into trophic levels: for example, omnivores feed at multiple trophic levels. Other organisms are frequently ignored altogether in food webs marine systems: parasites, etc. The amount of energy transferred from one trophic level to the next depends on food quality and on consumer abundance and physiology.