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Pyramids of energy are normally upright, but other pyramids can be inverted (pyramid of biomass for marine region) or take other shapes (spindle shaped pyramid). Ecological pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat ...
Out of a total of 28,400 terawatt-hours (96.8 × 10 ^ 15 BTU) of energy used in the US in 1999, 10.5% was used in food production, [3] with the percentage accounting for food from both producer and primary consumer trophic levels. In comparing the cultivation of animals versus plants, there is a clear difference in magnitude of energy efficiency.
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.
The efficiency with which energy or biomass is transferred from one trophic level to the next is called the ecological efficiency. Consumers at each level convert on average only about 10% of the chemical energy in their food to their own organic tissue (the ten-per cent law). For this reason, food chains rarely extend for more than 5 or 6 levels.
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.
Like many wetlands, some ecosystems do not organize as a strict pyramid because aquatic plants are less productive than long-lived terrestrial plants such as trees. Ecological trophic pyramids are typically one of three kinds: 1) pyramid of numbers, 2) pyramid of biomass, or 3) pyramid of energy. [6] Food webs have trophic levels and positions.
The publication appeared in the journal Ecology and establishes the ten percent law whereby only 10% of the energy consumed at one trophic level is transferred to higher trophic levels. [5] Having suffered from chronic gastro-intestinal and liver inflammation, Lindeman died in 1942 at the age of 26, probably from hepatitis. [6]
Carlson's index was proposed by Robert Carlson in his 1977 seminal paper, "A trophic state index for lakes". [3] It is one of the more commonly used trophic indices and is the trophic index used by the United States Environmental Protection Agency. [2]