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A pyramid of biomass shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time. It is a graphical representation of biomass (total amount of living or organic matter in an ecosystem) present in unit area in different trophic levels.
The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way ...
Of all the net primary productivity at the producer trophic level, in general only 10% goes to the next level, the primary consumers, then only 10% of that 10% goes on to the next trophic level, and so on up the food pyramid. [1] Ecological efficiency may be anywhere from 5% to 20% depending on how efficient or inefficient that ecosystem is.
An ecological pyramid is a graphical representation that shows, for a given ecosystem, the relationship between biomass or biological productivity and trophic levels. A biomass pyramid shows the amount of biomass at each trophic level. A productivity pyramid shows the production or turn-over in biomass at each trophic level.
A four level trophic pyramid sitting on a layer of soil and its community of decomposers. A three layer trophic pyramid linked to the biomass and energy flow concepts. In a pyramid of numbers, the number of consumers at each level decreases significantly, so that a single top consumer , (e.g., a polar bear or a human ), will be supported by a ...
Thus, the net production at one trophic level is / / / = / or approximately ten percent that of the trophic level before it. For example, assume 500 units of energy are produced by trophic level 1. One half of that is lost to non-predatory death, while the other half (250 units) is ingested by trophic level 2.
Top-down effects occur when the population density of a consumer affects that of its resource; [10] for example, a predator affects the density of its prey. Top-down control, therefore, refers to situations where the abundance, diversity or biomass of lower trophic levels depends on effects from consumers at higher trophic levels. [10]
In practice, trophic levels are not usually simple integers because the same consumer species often feeds across more than one trophic level. [4] [5] For example, a large marine vertebrate may eat smaller predatory fish but may also eat filter feeders; the stingray eats crustaceans, but the hammerhead eats both