Pyramid of Biomass – Definition, Types, Examples

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What is a Biomass Pyramid?

  • A pyramid known as the ecological pyramid or Eltonian pyramid depicts the link between the numbers, biomass, energy, and bioproductivity of different trophic levels in an ecosystem.
  • The ecological pyramids illustrate the system’s energy flow.
  • A biomass pyramid depicts the total living biomass or organic matter present at various trophic levels within an ecosystem.
  • Biomass is computed as the mass of living creatures present at each trophic level within a certain sample size. It can be expressed as grammes of dry weight or calories per unit area. Utilizing a bomb calorimeter to quantify biomass.
  • Trophic level describes the precise position of an organism in a food chain.
  • The producers (1st trophic level) are at the base of the biomass pyramid, followed by herbivores (primary consumers) and finally carnivores (secondary and tertiary consumers).
  • The biomass pyramid illustrates the energy flow from producers to consumers. We are aware that only 10% of energy is transmitted to the next trophic level, while the remainder is either utilised for metabolic processes or excreted.

What is Biomass?

  • In ecological terms, biomass refers to the total mass of all living or organic materials in an ecosystem at any one time.
  • Biomass can be separated into two classes: Community Biomass and Species Biomass
  • Biomass of all species in an ecosystem is known as species biomass.
  • Community biomass, on the other hand, refers to the total mass of all species that regard the designated community to be their habitat.
  • In terms of measuring biomass, species can range from people to microbes.

Features of Pyramid of Biomass

  • In this procedure, individuals at each trophic level are weighed rather than counted.
  • This yields a biomass pyramid, which depicts the total dry weight of all organisms at each trophic level at a given time.
  • To determine the biomass pyramid, the dry weight of all species in each trophic level is routinely collected and measured.
  • Since all trophic levels of creatures are weighed, the problem of size disparity is resolved. The unit for measuring biomass is grammes per square metre.

Types of Biomass Pyramid

Upward Pyramid

  • In the majority of terrestrial ecosystems, the biomass pyramid has a large base of primary producers and a lower trophic level on top.
  • Autotrophic producer biomass is at an all-time high.
  • The next trophic level, primary consumers, have a smaller biomass than producers.
  • The next higher trophic level, secondary consumers, have a lesser biomass than primary consumers.
  • There is a low amount of biomass at the highest trophic level.
Upward Pyramid of Biomass
Upward Pyramid of Biomass

Inverted Pyramid

  • In many aquatic ecosystems, the biomass pyramid may assume an inverted form.
  • This is due to the fact that the producers are tiny phytoplankton that multiply and reproduce rapidly. (In comparison, the number pyramid for aquatic ecology is vertical.)
  • Here, the base of the biomass pyramid is narrow, with consumer biomass always exceeding producer biomass, and the pyramid seems inverted.
Inverted Pyramid of biomass
Inverted Pyramid of biomass

Limitations of Pyramid of Biomass

  • Each trophic level looks to contain more energy than it actually does, which is one of the most severe downsides of a biomass pyramid.
  • Humans’ ingestion of other animals is a prime illustration of this.
  • The animal’s bone mass is determined. In contrast, the mass of the bones is not utilised at the next level of the biomass pyramid.
  • In a biomass pyramid, the mass that is not actually transmitted to the next trophic level is tallied.
  • Nevertheless, the biomass pyramid remains one of the most reliable methods for determining whether an ecosystem is out of balance.

Examples of Biomass Pyramid

A biomass pyramid illustrates the efficiency of energy transfer across all trophic levels. It might be upright or upside down. In marine ecosystems, biomass pyramids are inverted.

To comprehend the difference, let’s compare the biomass pyramids of terrestrial and marine ecosystems.

Biomass Pyramid of a Grassland Ecosystem

  • The biomass pyramid in a grassland ecosystem is vertical.
  • Grass has the highest biomass, followed by herbivores such as rabbits, rodents, and so forth. The major consumers are followed by secondary consumers (such as owls, lizards, and snakes) and tertiary consumers (eagle, etc.)
  • As the biomass is computed by multiplying the biomass of organisms by the number of species present at each trophic level, we can see that the biomass of the grass is significantly more than that of the primary consumers and drops further as we move up the trophic levels.

Biomass Pyramid of a Tree Ecosystem

  • The biomass pyramid represents energy flow more accurately than the number pyramid. In a tree ecosystem, for instance, the number pyramid is not perfect because one oak tree sustains hundreds of insects, which are then consumed by a smaller number of birds.
  • Oaktree (Producer) Caterpillars and other insects (Primary consumer) Woodpecker (Secondary consumer)
  • Here, the representation of the biomass pyramid is more accurate and upright.

Biomass Pyramid of a Marine Ecosystem

  • The aquatic ecosystem’s pyramid of biomass is inverted. Here, the biomass of primary producers is significantly lower than that of zooplanktons, which in turn is lower than that of small fish and large fish, which have the highest biomass.
  • You may question how this is feasible, how fewer phytoplanktons can sustain the ecosystem’s energy flow.
  • Due to the higher repeatability and shorter longevity of phytoplanktons, despite the fact that their biomass is fewer at any given time, they often replenish to meet the needs of zooplankton and larger fish.

What is the difference between upright and inverted pyramid of biomass?

FeatureUpright Pyramid of BiomassInverted Pyramid of Biomass
ShapeNarrow at the top and broad at the bottomBroad at the top and narrow at the bottom
Proportion of BiomassMore biomass at the bottom than at the topMore biomass at the top than at the bottom
Trophic LevelsHigher trophic levels are at the topHigher trophic levels are at the bottom
Food ChainLong food chain with few organisms at higher levelsShort food chain with many organisms at higher levels
EcosystemStable and balanced ecosystemDisturbed or degraded ecosystem

An upright pyramid of biomass represents a stable and balanced ecosystem, where there is a large amount of primary producers (plants), a smaller amount of primary consumers (herbivores), and an even smaller number of secondary and tertiary consumers (carnivores). In contrast, an inverted pyramid of biomass occurs in disturbed or degraded ecosystems where there are fewer primary producers and a higher number of primary consumers, leading to an imbalance in the food chain.

What is the importance of biomass pyramid?

The biomass pyramid is an important tool for visualizing and understanding the distribution of energy and matter in an ecosystem. It provides insight into the relationship between different trophic levels and helps to understand the flow of energy and nutrients through the food chain.

Some of the key benefits of using a biomass pyramid include:

  1. Ecological balance: The biomass pyramid provides a graphical representation of the balance of an ecosystem, making it easier to identify imbalances or disruptions.
  2. Biodiversity: The biomass pyramid helps to understand the diversity of species in an ecosystem and the impact that changes in one species can have on the entire ecosystem.
  3. Food web dynamics: By illustrating the flow of energy through an ecosystem, the biomass pyramid helps to understand the dynamics of the food web, including the relationships between predators and prey and the roles of decomposers.
  4. Ecosystem health: The biomass pyramid provides a snapshot of the health of an ecosystem, as changes in the distribution of biomass can indicate changes in the overall health of the ecosystem.

Overall, the biomass pyramid is an important tool for ecologists and environmental scientists, as it provides valuable insights into the functioning of ecosystems and helps to inform conservation and management strategies.


What does a pyramid of biomass represent?

A pyramid of biomass represents the distribution of biomass or the amount of living matter within an ecosystem at different trophic levels. It is typically depicted as a triangular diagram, with producers (e.g. plants) at the bottom and higher trophic levels (e.g. herbivores, carnivores) successively at the upper levels. The size of each level represents the amount of biomass present in that trophic level. This diagram helps to visualize the flow of energy and nutrients in an ecosystem.

What does a biomass pyramid show?

A biomass pyramid shows the amount of living biological material (biomass) present at each trophic level of an ecosystem. It is usually represented as a triangular diagram, with the base of the pyramid representing the primary producers (e.g. plants) that form the foundation of the food chain. The higher the trophic level, the smaller the biomass, as energy is lost at each step of the food chain. The pyramid shape illustrates the idea that there is a decrease in the amount of energy available at each successive trophic level, starting from the primary producers at the base and moving up to the top predators at the apex.

Which units are used in a pyramid of biomass?

In a pyramid of biomass, the units used are typically units of mass or weight, such as grams (g), kilograms (kg), or metric tons (t). The unit of measurement is chosen based on the scale of the ecosystem being studied, as well as the amount of biomass present at each trophic level. The choice of unit may also depend on the purpose of the study and the level of detail desired. Regardless of the units used, the important aspect of a biomass pyramid is the relative comparison of the biomass present at each trophic level, not the absolute values.

Why is pyramid of biomass upright?

The pyramid of biomass is usually depicted as an upright triangle because it represents the decrease in biomass as you move up the trophic levels in an ecosystem. The base of the pyramid represents the primary producers, such as plants, which have the largest biomass because they are able to convert the sun’s energy into chemical energy through photosynthesis. As you move up the pyramid to higher trophic levels, such as herbivores and carnivores, there is a decrease in biomass because energy is lost at each step in the food chain due to processes such as respiration and waste production. The upright orientation of the pyramid emphasizes the concept of a decrease in the amount of available energy as you move up the food chain.

Which ecosystem will the pyramid of biomass be inverted?

The pyramid of biomass will be inverted in ecosystems where there is an abundance of primary consumers, leading to a shortage of primary producers. This usually occurs in disturbed or degraded ecosystems where the balance of the food chain has been disrupted. In such cases, decomposers and detritivores also increase in numbers, further contributing to the inversion of the pyramid.

What are the 2 types of biomass pyramid?

Upright Pyramid
Inverted Pyramid


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