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Ecological Pyramids Definition : graphical models representing the quantitative differences that exist between Trophic levels. Pyramids of numbers Pyramids of biomass Pyramids of Productivity/Energy. Pyramids of Numbers.
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Ecological PyramidsDefinition: graphical models representing the quantitative differences that exist between Trophic levels Pyramids of numbers Pyramids of biomass Pyramids of Productivity/Energy
Pyramids of Numbers Basic pyramid – represents the number of organisms at each trophic level. • Can display different patterns depending on the type of ecosystem represented. • Large lower level organisms = smaller numbers at that level. • No equation given
Pyramids of Biomass • Represents the amount of dried tissue at each trophic level. • Quantities of biomass and energy decrease along the food chain(hence: pyramid shape) • Equation: • gms/meters² or • Joules/meters² (energy)
Pyramids of Productivity/Energy • Equation: • (B₂ - B₁ )/ Time (t) = NP • Normal pyramid shows the loss of energy in comparison with the movement up the Trophic levels. • Each step will be 10% the size of the previous step • The exception to the normal pyramid is when portions of a food web are supported by inputs of resources from outside of the local community. • Ex: global warming = increase in solar energy • Ex: addition/subtraction of non-native species to an environment.