- Ecological pyramid
An interesting face(or Trophic pyramid) is a graphical representation designed to show the
biomassor productivity at each trophic levelin a given ecosystem. "Biomass pyramids" show the abundance or biomass of organisms at each trophic level, while "productivity pyramids" show the production or turn-over in biomass. "Ecological Pyramids" begin with producers on the bottom and proceed through the various trophic levels, the highest of which is on top.
=Pyramid of Biomass= An "Ecological Pyramid of Biomass" shows the relationship between biomass and trophic level by quantifying the amount of biomass present at each trophic level. Typical units for a biomass pyramid could be grams per meter2, or calories per meter2. Biomass pyramids provide a single snapshot in time of an ecological community.
One problem with biomass pyramids is that they can make a trophic level look like it contains more
energythan it actually does. For example, all birdshave beaks and skeletons, which despite taking up massare not eaten by the next trophic level. In a "Pyramid of Biomass" the skeletons and beaks would still be quantified even though they do not contribute to the overall flow of energy into the next trophic level.
Biomass pyramids can also be misleading, in that they do not include the turn-over in biomass at a given trophic level. This can lead to "inverted pyramids", in which a small biomass of
autotrophssupports a larger biomass of herbivores. This often occurs in aquatic ecosystems, where algaeand phytoplanktoncan maintain a high level of productivity despite being grazed by longer lived fishand zooplankton.
=Pyramid of Productivity= An "Ecological Pyramid of Productivity" is often more useful, showing the production or turnover of biomass at each trophic level. Instead of showing a single snapshot in time,
productivitypyramids show the flow of energythrough the food chain. Typical units would be grams per meter2 per year or calories per meter2 per year. As with the others, this graph begins with producers at the bottom and places higher trophic levels on top. When an ecosystem is healthy, this graph generally looks like the standard "Ecological Pyramid". This is because in order for the ecosystem to sustain itself, there must be more energy at lower trophic levels than there is at higher trophic levels. This allows for organisms on the lower levels to maintain a stable population, but to also feed the organisms on higher trophic levels, thus transferring energy up the pyramid. The exception to this generalization is when portions of a food webare supported by inputs of resources from outside of the local community. In small, forested streams, for example, many consumers feed on dead leaveswhich fall into the stream. The productivity at the second trophic level is therefore greater than could be supported by the local primary production.
When energy is transferred to the next trophic level, typically only 10% of it is used to build new biomass, becoming stored energy (the rest going to metabolic processes). As such, in a "Pyramid of Productivity" each step will be 10% the size of the previous step (100, 10, 1, 0.1, 0.01, 0.001 etc.).
The advantages of the "Pyramid of Productivity":
* It takes account of the rate of production over a period of time.
speciesof comparable biomass may have very different life spans. Therefore their relative biomasses is misleading, but their productivity is directly comparable.
* The relative energy flow within an ecosystem can be compared using pyramids of energy; also different
ecosystemscan be compared.
* There are no inverted pyramids.
* The input of solar energy can be added.
The disadvantages of the "Pyramid of Productivity":
* The rate of biomass production of an organism is required, which involves measuring growth and reproduction through time.
* There is still the difficulty of assigning the organisms to a specific trophic level. As well as the organism in the food chains there is the problem of assigning the
decomposersand detritivores to a particular trophic level.
productivitypyramids usually provide more insight into a ecological community when the necessary information is available.
* [http://www.eelsinc.org/id43.html Food Chains and Food Webs]
Wikimedia Foundation. 2010.
Look at other dictionaries:
ecological pyramid — noun A diagram that shows the relative amounts of energy or matter, or numbers of organisms within each trophic level in a food chain or food web … Wiktionary
Ecological footprint — The ecological footprint is a measure of human demand on the Earth s ecosystems. It is a standardized measure of demand for natural capital that may be contrasted with the planet s ecological capacity to regenerate. It represents the amount of … Wikipedia
Pyramid (disambiguation) — A pyramid is any three dimensional structure where the upper surfaces are triangular and converge at one point. Pyramid may also refer to:* Pyramid (geometry), a conic solid with polygonal base * Egyptian pyramids, the pyramids of Egypt **… … Wikipedia
Ecological niche — Black smokers create ecological niches with their unusual environment In ecology, a niche ( … Wikipedia
Ecological succession — Succession after disturbance: a boreal forest one (left) and two years (right) after a wildfire. Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a… … Wikipedia
Ecological Self — is central to the school of Experiential Deep Ecology , which, based on the work of Norwegian philosopher Arne Næss, argues that through the process of self actualisation, one transcends the nations of the individuated egoic self and arrives at a … Wikipedia
Pyramid Lake (Nevada) — Infobox lake lake name = Pyramid Lake image lake = Pyramid lake sat.jpg caption lake = View from space (September 1994) image bathymetry = caption bathymetry = coords = coord|40|0|N|119|30|W|type:waterbody region:US NV|display=inline,title type … Wikipedia
ecological food pyramid — ekologinė piramidė statusas T sritis ekologija ir aplinkotyra apibrėžtis Grafinė piramidės pavidalo individų mitybos struktūros ir funkcijų išraiška. Yra 3 piramidžių tipai: skaičių, biomasės ir energijos. atitikmenys: angl. ecological food… … Ekologijos terminų aiškinamasis žodynas
Food pyramid — may refer to:*Food guide pyramid, a core concept in nutritional guides around the world. **MyPyramid, the USDA s 2005 version of the food guide pyramid. *Ecological pyramid or trophic pyramid, a representation of a food chain … Wikipedia
Population pyramid — This distribution is named for the frequently pyramidal shape of its graph. A population pyramid, also called an age structure diagram, is a graphical illustration that shows the distribution of various age groups in a population (typically that… … Wikipedia