Trophic Levels and Food Webs

Terms:
trophic levels, food chain, assimilation efficiency, production efficiency, exploitation or consumption efficiency, ten percent rule, food web, connectance, resilience, persistence, ecological stability and complexity, detritivores, macro, meso, and microfauna, guilds, keystone species

assimilation efficiency: How well an organism is able to absorb energy from the amount it receives through intake, calculated by dividing absorbed or assimilated energy by intake.

connectance: A measurement of complexity in a community by dividing the number of link in a food web by the number of potential links.

detritivores: Species that feed on dead organic tissue.

ecological complexity: The number of species and their interactions in a community.

ecological stability: The ability of a community to retain its structure following a disturbance, measured by persistence and resilience.

exploitation or consumption efficiency: How well organisms from one trophic level can intake net production from the level below, calculated by dividing energy intake in trophic level n by net production in level n-1.

food chain: The direction of energy flow in an ecosystem from the bottom up.

food web: A diagram that illustrates all interactions and connections between species in a community.

guild:   Unrelated species feeding on the same resource, but in a different manner.

keystone species: Any species in a community that, if removed, will change the entire structure of that community. 

macrofauna: Soil organisms larger than 2 mm including snails, isopods, worms, and insects.

mesofauna: Soil organisms from 0.001 to 2.0 mm in size, including mites, nematodes, small worms.

microfauna: Soil organisms less than 0.001 mm in size, including bacteria and protozoa.

production efficiency: How well an organism can used absorbed energy for net production, or growth of new tissue, calculated by dividing net production by energy absorbed or assimilated.

resilience: A measurement for how quickly a community returns to equilibrium following a disturbance, shown by return time.

persistence: How well a community retains its species richness following a disturbance.

ten percent rule: The general observation that only ten percent of energy available at one trophic level is actually passed up to the next.

trophic levels: A classification of organisms in an ecosystem based on common feeding relationships.