 Energy enters an ecosystem through the autotrophs  Autotrophs then pass the energy on to the different levels of heterotrophs (consumers) through ingestion or decomposition  Types of consumers › primary consumers (herbivores) › secondary consumers (carnivores) › ditritivores (decomposers)

 Primary productivity - a term used to describe the amount of energy produced by photosynthetic organisms in a community  Gross primary productivity is the total organic matter produced  Net primary productivity (NPP) is a measure of the amount of organic matter produced in a community in a given time that is available for heterotrophs  Biomass – total mass of all the organisms living in an ecosystem

 the amount of organic material per square meter per year that an ecosystem produces

 Secondary productivity - the rate of a biomass production by heterotrophs  Where does all the energy in plants go? › Not consumed by herbivores, but by decomposers › Passed through the herbivores body to it’s feces and consumed by the decomposers › Consumed by herbivores and lost as heat produced by work

 Community Energy Budgets › Communities with higher productivity can in theory support longer food chains  Factors Limiting Community Productivity › The amount of sunlight it receives, determines how much photosynthesis can occur

 There are usually far more individuals at the lower trophic levels of any ecosystem than at the higher levels  The biomass of the primary producers in an ecosystem is greater than the biomass of the primary consumers

 Some aquatic ecosystems have inverted biomass pyramids  But the pyramid of energy is cannot be inverted

 The energy loss in each successive trophic level limits the amount of carnivores that an ecosystem can support