An ecological pyramid is a graphical representation which 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.

The pyramid then proceeds through the various trophic levels to the apex predators at the top.

Organisms which feed on autotrophs, the producers of the trophic pyramid, are known as herbivores or primary consumers ; those that feed on heterotrophs such as animals are known as secondary consumers.

The elimination of wolves from Yellowstone National Park had profound impacts on the trophic pyramid.

The trophic pyramid roughly represents the biomass ( usually measured as total dry-weight ) at each level.

Names of trophic categories are shown to the right of the pyramid.

Ecological trophic pyramids are typically one of three kinds: 1 ) pyramid of numbers, 2 ) pyramid of biomass, or 3 ) pyramid of energy.

< div style =" border: none ; width: 350px ;">< div class =" thumbcaption "> Top Left: A four level trophic pyramid sitting on a layer of soil and its community of decomposers.

Top right: A three layer trophic pyramid linked to the biomass and energy flow concepts.

The terrestrial forest ( summer ) and the English Channel ecosystems exhibit inverted pyramids. Note: trophic levels are not drawn to scale and the pyramid of numbers excludes microorganisms and soil animals.

Thus, organisms higher in the trophic pyramid have accumulated higher levels of < sup > 15 </ sup > N ( and higher δ < sup > 15 </ sup > N values ) relative to their prey and others before them in the food web.

* biomass pyramid-also called a ecological pyramid, it is a graph that illustrates the productivity in a trophic level

* Ecological pyramid or trophic pyramid, a representation of a food chain.

The simplified linear feeding pathways that move from a basal trophic species to a top consumer is called the food chain.

A simplified food web illustrating a three trophic food chain ( producers-herbivores-carnivores ) linked to decomposers.

Ecologists use simplified three trophic position food chain models ( producer, carnivore, decomposer ).

Original food-webs ( left ) are simplified ( right ) by aggregating groups feeding on common prey into coarser grained trophic species.

Eugene Odum, a founder of ecology, stated: " Any unit that includes all of the organisms ( ie: the " community ") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles ( i. e.: exchange of materials between living and nonliving parts ) within the system is an ecosystem.

Competition between species at the same trophic level of an ecosystem, who have common predators, increases drastically if the frequency of the common predator in the community is decreased by a large margin.

This management technique exploits the close interconnections of the food web, trophic cascade, to send a ripple down through the living community.

Plants are the fundamental base of nearly all food chains because they use the energy from the sun and nutrients from the soil and atmosphere, converting them into a form that can be consumed and utilized by animals ; this is what ecologists call the first trophic level.

** Ecosystems: biodiversity — biome — habitat — plankton — thermocline — carbon cycle — water cycle — nitrogen cycle — food web — trophic level — saprobe — decomposition

The transformity of energy becomes degraded, dispersed, and diminished from higher quality to lesser quantity as the energy within a food chain flows from one trophic species into another.

Real systems are much more complex than this — organisms will generally feed on more than one form of food, and may feed at more than one trophic level.

Baleen whales can consume zooplankton and krill directly, leading to a food chain with only three or four trophic levels.

Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs, as a resource for consumers on higher trophic levels ( including fish ), and as a conduit for packaging the organic material in the biological pump.

Food webs are limited representations of real ecosystems as they necessarily aggregate many species into trophic species, which are functional groups of species that have the same predators and prey in a food web.

The number of trophic links per consumer is a measure of food web connectance.

Food chains are nested within the trophic links of food webs.

Linkages connnect to nodes in a food web, which are aggregates of biological taxa called trophic species.

Common examples of an aggregated node in a food web might include parasites, microbes, decomposers, saprotrophs, consumers, or predators, each containing many species in a web that can otherwise be connected to other trophic species.

The intermediate levels are filled with omnivores that feed on more than one trophic level and cause energy to flow through a number of food pathways starting from a basal species.

Nonetheless, recent research has found that discrete trophic levels do exist, but " above the herbivore trophic level, food webs are better characterized as a tangled web of omnivores.

These complex multitrophic interactions involve more than two trophic levels in a food web.

The transformity of energy becomes degraded, dispersed, and diminished from higher quality to lesser quantity as the energy within a food chain flows from one trophic species into another.

A common metric used to quantify food web trophic structure is food chain length.

It is explicitly understood that natural systems are ' sloppy ' and that food web trophic positions simplify the complexity of real systems that sometimes overemphasize many rare interactions.

Feeding connections in the web are called trophic links.

In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web.

This can be applied to a food web to make it possible to draw direct inferences regarding diet, trophic level, and subsistence.

* web of life-also known as the food chain, food network, or trophic social network.

The flow of energy in an ecosystem is an open system ; the sun constantly gives the planet energy in the form of light while it is eventually used and lost in the form of heat throughout the trophic levels of a food web.

Stable isotope studies on Antarctic food webs by New Zealand scientists from the National Institute of Water and Atmospheric Research ( NIWA ) indicate Antarctic toothfish appear to occupy a similar trophic level in the Antarctic food web as orca and Weddell seals in McMurdo Sound, bluefin tuna in the Atlantic, and sperm whales from the Gulf of Mexico.

* Trophic cascade, when predators in a food web suppress their prey, releasing the next lower trophic level from predation

This is similar to the idea of trophic management, except that it manipulates the other end of the food web.

Neutrality means that at a given trophic level in a food web, species are equivalent in birth rates, death rates, dispersal rates and speciation rates, when measured on a per-capita basis.

Squat lobsters are large enough to be caught by top predators, and can thus form a " direct trophic shortcut " between the primary producers at the bottom of the food web, and the carnivores at the top.