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the sum of all the organisms living within its boundaries and the abiotic factors with which they interact

conservation of energy

energy cannot be created nor destroyed but transferred or transformed

primary producers

the trophic level that ultimately supports all others, consists of autotrophs

primary consumers

herbivores. eat plants and other primary producers

secondary consumers

carnivores that eat herbivores

tertiary consumers

carnivores that eat other carnivores


decomposers that get their energy from detritus


nonliving organic material, such as the remains of dead organisms, feces, fallen leaves

primary production

amount of light energy converted to chemical energy by autotrophs during a given time period

gross primary production


net primary production


standing crop

total biomass of photosynthetic autotrophs present at a given time, whereas NPP is the amount of new biomass added in a given period of time

light limitation

depth of light penetration affects primary production through the photic zone of an ocean or lake

nutrient limitation

element that must be added for production to increase. adding other elements will do little to nothing to increase production


when cyanobacteria and algae surge because of excess nutrients added to water. reduce oxygen and clarity of water

actual evapotranspiration

annual amount of water transpired by plants and evaporated from a landscape

secondary production

the amount of chemical energy in a consumer's food converted to their own new biomass during a given time period

production efficiency

the percentage of energy stored in assimilated food that is not used for respiration

trophic efficiency


pyramid net production

representation of energy transfer in a food chain

biomass pyramid

the total of the physical mass of all the organisms at each trophic level

turnover time

the time it takes for the standing crop to develop or to be used up

green world hypothesis

states that terrestrial herbivores are held in check by various factors, like plant defenses that prevent herbivores from eating up all the plants`

biochemical cycles

nutrient cycles involving both biotic and abiotic elements

critical load

the amount of added nutrient, usually nitrogen or phosphorus that can be absorbed by plants without damaging ecosystem integrity

acid precipitation

lowers the pH of streams and lakes and affects soil chemistry and nutrient availability

biological magnification

the accumulation of toxins up the trophic levels

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