Examples

Photosynthesizers

(primary producers) Herbivores

Primary carnivores Secondary carnivores Omnivores

Detritivores (decomposers)

Solar energy

Tissues of primary producers

Herbivores Primary carnivores Several trophic levels Dead bodies and waste products of other organisms

Green plants, photosynthetic bacteria and protists

Termites, grasshoppers, gypsy moth larvae, anchovies, deer, geese, white-footed mice Spiders, warblers, wolves, copepods Tuna, falcons, killer whales Humans, opossums, crabs, robins Fungi, many bacteria, vultures, earthworms

Trophic level

Secondary consumers

Red fox

Primary consumers

Primary producers

Secondary consumers

Red fox

Primary consumers

Primary producers

Food Web Red Fox

Pine

Maple

Balsam fir

Aspen, white birch Aquatic plants

55.7 Food Web of Isle Royale National Park This food web includes only large vertebrates and the plants on which they depend. Even with these restrictions, the web is complex.The arrows show who eats whom.

Pine

Maple

Balsam fir

Aspen, white birch Aquatic plants

55.7 Food Web of Isle Royale National Park This food web includes only large vertebrates and the plants on which they depend. Even with these restrictions, the web is complex.The arrows show who eats whom.

Energy flow

Energy flow

(calories/m2/day)

Trophic level

Energy flow

Energy flow

(calories/m2/day)

Trophic level

Plants Flow Energy

Most of the biomass in a grassland is found in the green plants, and most of the energy flows through them.

In forests, the majority of biomass is tied up in wood and is not available to most herbivores.

Trophic levels

Carnivores

A marine community produces an inverted pyramid of biomass. The producers are unicellular algae, which divide so rapidly that a small biomass can support a much larger biomass of herbivores.

Most of the biomass in a grassland is found in the green plants, and most of the energy flows through them.

Trophic levels

Carnivores

Herbivores

A marine community produces an inverted pyramid of biomass. The producers are unicellular algae, which divide so rapidly that a small biomass can support a much larger biomass of herbivores.

Producers (photosynthesizers)

In most aquatic ecosystems, the dominant photosynthesizers are bacteria and protists. Those unicellular organisms have such high rates of cell division that a small biomass of photosynthesizers can feed a much larger biomass of herbivores, which grow and reproduce much more slowly. This pattern can produce an inverted biomass pyramid, even though the energy pyramid for the same ecosystem has the typical shape (Figure 55.8c).

Much of the energy ingested by organisms is converted to biomass that is eventually consumed by detritivores, such as bacteria, fungi, worms, mites, and insects. These organisms transform the dead remains and waste products of organisms into free mineral nutrients that can again be taken up by plants. If there were no detritivores, most nutrients would eventually be tied up in dead bodies, where they would be unavailable to plants. Continued ecosystem productivity depends on the rapid decomposition of detritus.

Species richness and productivity influence ecosystem stability

We have seen that, up to a point, high primary productivity favors increased species richness, but is the reverse true? That is, does species richness also influence ecosystem productiv-

55.8 Pyramids of Biomass and Energy Energy pyramids (left column) allow ecologists to compare patterns of energy flow through trophic levels in different ecosystems. Biomass pyramids (right column) allow them to compare the amount of material present in living organisms at different trophic levels.

In forests, the majority of biomass is tied up in wood and is not available to most herbivores.

ity? Ecologists hypothesized that species richness might enhance ecosystem productivity because no two species in a community have the same relationship with the environment. Therefore, a richer mixture of species should result in a more complete use of the available resources. In addition, if the environment changes, a species-rich ecosystem is more likely to contain species that are already adapted to the new conditions than is a species-poor ecosystem. Therefore, ecol-ogists hypothesized that a species-rich ecosystem should also be more stable—that is, over time it should change less in both productivity and species composition than a species-poor ecosystem.

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Responses

  • Filiberta
    What is the food chain of a red fox?
    7 years ago
  • rosa burrowes
    What is a red foxes food chain?
    7 years ago
  • Jessika
    What are the trophic levels of a fox?
    7 years ago
  • andrew kyles
    Are earthworms primary consumers?
    7 years ago
  • Enrico
    What is a producer in a food web?
    7 years ago
  • MARY
    What are red fox food source?
    7 years ago
  • jasmine
    Is an red fox a secondary consumer?
    7 years ago
  • spartaco
    What is the food chain of a red wolf?
    7 years ago
  • claudia
    What primary consumers eat aspen?
    7 years ago
  • Paul
    What are primary producers?
    7 years ago
  • Juan
    What is a red pandas food chain?
    6 years ago
  • Samira
    What eats a fox in a food chain?
    6 years ago
  • elisabeth
    What is the food web for humans?
    6 years ago
  • KENNETH
    What trophic level are opossum?
    5 years ago

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