Ecological Pyramids – Definition, Types, Examples, Importance, Limitations

What are Ecological Pyramids?

An ecological pyramid (also called a trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes a food pyramid) is a diagram that shows the biomass or bioproductivity at each trophic level in an ecosystem.

• An ecological pyramid is a picture that shows how the different living things at different trophic levels are related to each other.
• G.Evylen Hutchinson and Raymond Lindeman gave it.
• You can see that these pyramids look like real pyramids, with the widest part at the base, where the lowest level of the food chain, the producers, live.
• The next trophic level, which are the primary consumers, move up to the next level, and so on.
• When making these types of ecological pyramids, all of the calculations must take into account all of the organisms in a certain trophic level. This is because a sample space of just a few numbers or species will lead to a lot of mistakes.
• A pyramid of energy shows how much energy is kept in the form of new biomass at each trophic level. A pyramid of biomass shows how much biomass (the amount of living or organic matter in an organism) is in the organisms.
• There is also a number pyramid that shows how many different organisms are at each trophic level.
• Most pyramids of energy stand straight up, but some can be upside down or have other shapes.
• Ecological pyramids start at the bottom with producers, like plants, and go up through the different trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The top of the food chain is the most important level.
• A bomb calorimeter can be used to measure biomass.

Definition of Ecological Pyramids

Ecological pyramids are graphical representations that show the distribution of energy, biomass, or numbers of organisms across trophic levels in an ecosystem, typically illustrating a decrease from the base to the apex.

Types of Ecological pyramid

There are present different types of Ecological pyramid such as;

• Pyramid of Numbers
• Pyramid of Energy
• Pyramid of Biomass

1. Pyramid of Numbers

A number pyramid is one of the varieties of ecological pyramids. The pyramid of numbers represents graphically the population or abundance of a species at each level of a food chain. The pyramid of numbers illustrates the number of creatures in each trophic level without taking their sizes or biomass into account.

• A number pyramid represents the total number of persons (population) existing at each trophic level.
• In 1972, Elton John coined the phrase “pyramid of numbers.”
• This pyramid is quite effective when it comes to counting the number of creatures.
• Simple counting can be performed throughout time to determine how an environment has changed. However, counting certain species, particularly early forms, might be challenging.
• According on the number of organisms, the number pyramid might be either upright or inverted.

Types of Pyramid of Numbers

a. Pyramid of Numbers – Upright

• From the lowest trophic level to the highest, the number of individuals declines in this pyramid.
• In the ecosystems of grassland and pond, this type of pyramid can be found. Due to their profusion, grasses occupy the lowest trophic level (base).
• Primary consumers, like grasshoppers, represent the next trophic level up.
• There are fewer grasshoppers per square metre than there are blades of grass.
• The next energy level is a simple carnivore, such as a rat. Rats have a smaller number than grasshoppers due to the fact that rats consume grasshoppers.
• The next higher trophic level includes secondary carnivores, such as snakes. They consume rat.
• The next trophic level above the apex predator, such as the Hawk, is the next higher level. As trophic levels increase, fewer individuals are present.

b. Pyramid of Numbers – Inverted

• The exact opposite of upright pyramids are inverted pyramids.
• This is evident in the tree ecology, where trees are the producers and insects are the consumers.
• Food wastage while eating, food wastage during digesting, and food use during respiration and physical activity all contribute to the population reduction of higher tropic species.

2. Pyramid of Energy

The energy pyramid is a straight pyramid that shows how energy moves from people who make it to people who use it. It also shows how different creatures play a part in energy transmission. As energy moves from one trophic level to the next, energy pyramids show how much energy is needed in the next level. The rule of thermodynamics says that energy can’t be created or destroyed; it can only change from one form to another. This can be used to describe how energy moves through this pyramid.

• The best way to figure out what each trophic level does in an ecosystem is to use an energy pyramid.
• An energy pyramid shows how much energy is at each trophic level as well as how much energy is lost when a species moves up or down a trophic level.
• So, the pyramid is always going up, and it has a big energy base at the bottom.

Characteristics of Pyramid of Energy

• The rate at which food (in the form of energy) moves through the food chain determines how energy pyramids are built.
• Even though some species have less mass, the total amount of energy they use and pass on is much higher than that of species with more mass.
• Most energy pyramids are tilted because each trophic level gives out less energy than it takes in.
• For example, in ecosystems with open water, producers have less bulk biomass than consumers.
• But the amount of energy saved and passed on should be more than it was on the last level.

Levels of Pyramid of Energy

Producers

• The producers and the energy they can give off make up the first level of the energy pyramid.
• Most of these producers are autotrophs, which are organisms that make their own food by getting energy from non-living sources.
• These are often plants that get their energy from the sun.
• Some autotrophs get the energy they need from the soil instead of the sun. Autotrophs are things like earthworms and fungi that grow on their own.
• On the other hand, producers like mushrooms and earthworms get less energy from the soil than green plants do from the sun.
• At the bottom of the energy pyramid, you can only find heterotrophs, which are organisms that get their food from organic carbon, usually from other organisms.

Primary Consumers

• The second level of the energy pyramid is comprised of primarily herbivorous primary consumers.
• Herbivores are organisms that obtain all of their nutrition and sustenance from plants.
• After absorbing the sun’s energy, plants transmit it to their principal consumers.
• This facilitates the transfer of solar energy from one trophic level to the next.
• Although humans are not entirely dependent on primary consumers, their presence in the ecosystem is crucial. Otherwise, the system will malfunction.

Secondary Consumers

• Secondary users comprise the third level of the energy pyramid.
• Carnivores is a popular term for these organisms. Secondary consumers are organisms whose survival and nourishment depend on primary consumers.
• The carnivores would not exist if there were no primary consumers.
• The energy that was formerly provided by producers to the primary consumers is now transmitted to this level.
• This permits a more efficient transfer of energy.

Tertiary Consumers

• Tertiary users are located at the bottom of the energy pyramid. It refers to the proportion of secondary carnivores that ingest both primary and secondary consumers.
• At this stage, the energy level of the ecosystem is complete.
• The unused plant energy is returned to the environment, including the soil, water, and atmosphere. Afterwards, it is often sent into space.
• To preserve the stability of the planet, it is essential that all levels of the energy pyramid receive adequate energy.

Advantages of the pyramid of energy

• It takes into account the output rate over a period of time.
• The life spans of two animals with comparable biomass may vary greatly. Thus, comparing their total biomasses directly is inaccurate, but their productivity can be compared directly.
• Using energy pyramids, the relative energy chain within an ecosystem may be compared, as can the energy chains of other ecosystems.
• No inverted pyramids exist.
• Addition of solar energy is possible.

Disadvantages of the pyramid of energy

• The pace of an organism’s biomass production must be determined, which requires tracking its growth and reproduction over time.
• The problem of attributing species to a certain trophic level persists. In addition to allocating decomposers and detritivores to a particular level, there is the issue of classifying organisms in food chains.

Examples of Pyramid of Energy

• Suppose a deer consumes a plant containing 100 calories of dietary energy.
• Only 10 calories are stored as dietary energy because a portion of it is used for the deer’s metabolism. A lion that consumes a deer receives far less energy.
• As a result, as energy goes from the sun to the producer to the herbivore to the carnivore, its usefulness decreases.
• As a result, the energy pyramid will always remain erect.

3. Pyramid of Biomass

A biomass pyramid is a graphical representation of the biomass contained in a unit area at several trophic levels. It illustrates the relationship between biomass and trophic level, as well as the biomass available at any given time in each trophic level of an energy community.

• At a particular trophic level, biomass is the amount of living material present in an individual or group of individuals per unit of surface area.
• This type of ecological pyramid accounts for the amount of biomass present at each trophic level at each level.
• The pyramidal representation of biomass is based on the second rule of thermodynamics.
• This law states that energy cannot be generated or destroyed, but can be transported from one state to another.
• In particular, energy is transported from producers to consumers, etc., and subsequently turned into biomass.
• A biomass pyramid can be used to determine the quantity of biomass produced by organisms at different trophic levels.

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

a. 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.

b. Inverted Pyramid

A biomass inverted pyramid is a graphical representation of the biomass contained in a unit area at several trophic levels, with fewer producers at the base of the pyramid relative to consumers at higher trophic levels. In numerous aquatic ecosystems, the biomass pyramid may have an inverted form.

• Inverted pyramids are pyramids with a small base and a wide apex.
• It indicates that compared to herbivores and carnivores, the number of biomass at the first trophic level, also known as the producer level, is low.
• Inverted pyramids are its proper name.
• In certain aquatic habitats, the shape of the biomass pyramid may be inverted.
• The base of the biomass pyramid is modest, with consumer biomass exceeding production biomass at any one time, and the pyramid is inverted.

Example of Inverted Pyramid

Biomass Pyramid of a Marine Ecosystem

• The pyramid of biomass in the aquatic ecosystem is inverted.
• The biomass of primary producers is significantly less than that of zooplanktons, which is less than that of small and large fish, which have the greatest biomass.
• You may ask how this is feasible and how the ecosystem is able to thrive with so few phytoplanktons.
• Because phytoplanktons have a quicker rate of reproduction and a shorter life span, despite the fact that their amount is lower at any given time, they refill frequently to fulfil the increased demand of zooplankton and larger fish.
• A consumer can easily subsist on a modest amount of food if its production exceeds its consumption.

What is the Pyramid of Biomass?

• At a particular trophic level, biomass is the amount of living material present in an individual or group of individuals per unit of surface area.
• This type of ecological pyramid accounts for the amount of biomass present at each trophic level at each level.
• The pyramidal representation of biomass is based on the second rule of thermodynamics.
• This law states that energy cannot be generated or destroyed, but can be transported from one state to another.
• In particular, energy is transported from producers to consumers, etc., and subsequently turned into biomass.
• A biomass pyramid can be used to determine the quantity of biomass produced by organisms at different trophic levels.

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.

Example of Biomass Pyramid

• Mice will consume grass seeds. The owl consumes the mice, while the mice consume the owl.
• In this food web, grass has the most biomass.
• Consequently, its biomass is located at the base of the pyramid.
• In contrast, the owl has the lowest biomass in the food chain and hence occupies the top of the pyramid.
• Pond ecosystem is the best illustration of an inverted pyramid. The ecosystem’s primary producer, phytoplankton, has a lesser mass than the ecosystem’s consumers, which are primarily fish and other insects.

Energy Flow in an Ecological Pyramid

• Energy is transported between trophic levels when one organism consumes another and gets energy-rich compounds from its prey’s body.
• However, because these transfers are inefficient, the length of food chains is restricted.
• A portion of the energy that enters a trophic level is stored as biomass, a component of the bodies of animals.
• This is the energy available to the next trophic level, as only energy stored as biomass may be consumed.
• Only about 10% of the energy accumulated as biomass in one trophic level (per unit time) is eventually stored as biomass in the next trophic level (per unit time).
• This pattern of fractional transfer limits the length of food chains; after a given number of trophic levels, often between three and six, there is insufficient energy flow to support a population at a higher level.

Features of the Ecological pyramid

The Ecological Pyramid, a pivotal tool in ecosystem studies, possesses distinct features that elucidate the distribution and relationships of organisms within an ecosystem. These features are as follows:

1. Trophic Homogeneity: Organisms situated on the same tier of the pyramid share analogous food-consumer relationships, indicating their shared trophic level within the ecosystem.
2. Stratification: Embedded within the ecosystem, the ecological pyramid is demarcated into two to four distinct strata or layers, each representing a specific trophic level.
3. Base Occupancy by Producers: The foundational tier of the ecological pyramid is predominantly occupied by producers. Both in number and biomass, producers are markedly abundant at this level, serving as the primary energy source for the subsequent trophic levels.
4. Apex Occupancy by Top Predators: Residing at the zenith of the ecological pyramid are the apex predators. Their presence signifies the culmination of the food chain within the ecosystem.
5. Diminishing Numbers with Ascending Levels: As one progresses from the base to the apex of the pyramid, there is a conspicuous decline in the number of organisms. Conversely, the size and volume of these organisms tend to augment.
6. Constrained Energy Supply at the Apex: The pinnacle of the ecological pyramid witnesses a tapering supply of food energy. This progressive reduction in available energy is manifested in the pyramid’s narrowing and pointed apex.
7. Biomass and Size Augmentation: While the quantity of organisms dwindles at the pyramid’s higher tiers, there is a concomitant increase in their size and overall biomass.

These features collectively provide a comprehensive overview of the energy flow, biomass distribution, and population dynamics within an ecosystem, making the ecological pyramid an indispensable instrument in ecological research.

Importance of Ecological Pyramid 

The Ecological Pyramid serves as a pivotal instrument in understanding and analyzing the intricate dynamics of ecosystems. Its significance in ecological studies is multifaceted, as elucidated below:

1. Energy Transfer Efficiency: The pyramid provides a lucid depiction of energy flow across various trophic levels. It elucidates the efficiency, or often the inefficiency, of energy transfer from one level to the subsequent one, offering insights into energy conservation within the ecosystem.
2. Trophic Interrelationships: By delineating the dietary patterns of organisms, the pyramid offers a comprehensive view of the food-consumer relationships within ecosystems. This aids in understanding the interdependencies and potential vulnerabilities of various trophic levels.
3. Ecosystem Health Monitoring: The pyramid acts as a barometer for the overall health and vitality of an ecosystem. By comparing data collected over time, researchers can discern the impacts of environmental changes on organisms and the ecosystem at large.
4. Biodiversity Assessment: The pyramid furnishes data regarding the biodiversity of a region, highlighting the richness or paucity of species and their distribution across trophic levels.
5. Impact of Disturbances: The pyramid underscores the ramifications of disturbances in the food chain. Disruptions, whether due to pollution, overhunting, or other anthropogenic factors, can have cascading effects across trophic levels, potentially jeopardizing the entire ecosystem.
6. Ecosystem Equilibrium: The pyramid aids in maintaining and restoring the balance of ecosystems. By understanding the dynamics of energy flow and organism interrelationships, measures can be devised to prevent further degradation and to rejuvenate damaged ecosystems.
7. Predictive Analysis: The pyramid facilitates predictive analyses, allowing ecologists to forecast the potential impacts of changes at one trophic level on those above and below it. This predictive capability is crucial for proactive ecosystem management.

In essence, the Ecological Pyramid stands as an indispensable tool in the realm of ecological research, offering profound insights into the functioning, health, and sustainability of ecosystems. Its comprehensive representation of energy flow, trophic relationships, and ecosystem dynamics underscores its paramount importance in the preservation and management of our planet’s diverse biomes.

Limitations of Ecological Pyramid 

The Ecological Pyramid, while instrumental in understanding ecosystem dynamics, is not without its limitations. These constraints, which can potentially hinder a comprehensive understanding of ecological interactions, are outlined as follows:

1. Exclusion of Vital Organisms: The pyramid often overlooks certain organisms like fungi and microorganisms, despite their pivotal roles in ecosystem functioning. Similarly, saprophytes, which are integral in nutrient recycling, are not represented, leading to an incomplete portrayal of ecosystem dynamics.
2. Applicability to Simple Food Chains: The pyramid’s design is primarily suited for simple food chains, which are seldom representative of natural ecosystems. Natural ecosystems often consist of intricate food webs with multiple interconnected trophic pathways, which the pyramid fails to capture.
3. Absence of Temporal Variations: The pyramid does not account for diurnal or seasonal variations, nor does it consider the impacts of changing climates on trophic interactions. Such temporal factors can significantly influence energy flow and organismal distributions.
4. Species at Multiple Levels: The pyramid does not accommodate the possibility of a single species occupying multiple trophic levels, a scenario that can arise in complex food webs.
5. Energy Transfer Rate: While the pyramid depicts energy distribution across trophic levels, it does not provide insights into the rate or efficiency of energy transfer between these levels.
6. Omission of Important Energy Sources: Vital energy sources, such as litter and humus, which play crucial roles in nutrient cycling and soil health, are conspicuously absent from the pyramid’s representation.
7. Inadequate Representation of Food Webs: The pyramid’s structure is not conducive to representing the multifaceted interactions of a food web, where organisms can occupy and interact across multiple trophic levels.
8. Overlooking Trophic Overlaps: The pyramid does not consider scenarios where the same species exists at different trophic levels, a common occurrence in intricate ecosystems.

In summary, while the Ecological Pyramid offers valuable insights into energy distribution and trophic interactions within ecosystems, it is imperative to recognize its limitations. A holistic understanding of ecosystems necessitates the integration of the pyramid’s insights with other ecological tools and methodologies.

Quiz

Which of the following best describes an Ecological Pyramid?
a) A physical structure found in ancient Egypt.
b) A graphical representation of the distribution of organisms in an ecosystem.
c) A method to calculate the age of fossils.
d) A tool to measure the height of trees.

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The Pyramid of Energy is always:
a) Inverted
b) Upright
c) Horizontal
d) Zigzag

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Which of the following pyramids can be inverted in certain ecosystems?
a) Pyramid of Energy
b) Pyramid of Biomass
c) Pyramid of Numbers
d) None of the above

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What percentage of energy is typically transferred from one trophic level to the next?
a) 50%
b) 20%
c) 10%
d) 90%

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Which organisms play a crucial role in decomposing organic matter but are often overlooked in traditional Ecological Pyramids?
a) Carnivores
b) Herbivores
c) Saprophytes
d) Producers

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The base of the Ecological Pyramid typically represents:
a) Primary consumers
b) Secondary consumers
c) Tertiary consumers
d) Producers

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Which pyramid represents the total mass of living matter at each trophic level?
a) Pyramid of Numbers
b) Pyramid of Biomass
c) Pyramid of Energy
d) None of the above

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In which pyramid is energy loss at each level most evident?
a) Pyramid of Numbers
b) Pyramid of Biomass
c) Pyramid of Energy
d) All of the above

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Which of the following is NOT a limitation of Ecological Pyramids?
a) Overlooks saprophytes
b) Suited mainly for simple food chains
c) Represents the rate of energy transfer
d) Doesn’t account for species occupying multiple trophic levels

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The apex of the Ecological Pyramid represents:
a) Producers
b) Primary consumers
c) Apex predators
d) Herbivores

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FAQ

References

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