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