EAS201 Lecture Notes - Lecture 25: Ecological Pyramid, Biogeochemical Cycle, Autotroph
22 Mar 2020
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When primary producers (autotrophs) produce organic matter via photosynthesis. Primary producers produce biomass and use it in three stages. 2. use some of the biomass to fuel their own metabolism and release energy as heat. 3. storing some of the biomass for future use. Gross production: the production of organic matter before use. Net production: the biomass that is left after it has been used to support metabolism. Heterotrophy uses organic matter as fuel for respiration (releases heat energy) Heterotrophs build body mass by eating other organisms. Energy is transferred along food chains in which one organism eats another. We can arrange species in a community into trophic levels. Trophic levels: indicate how many steps it is away from the autotroph level. Energy flows in one direction through the trophic levels. Energy is lost in each step while chemicals are recycled. Complex ecosystems have multiple food chains woven together. There can be up to 6 trophic levels.
