• Written By Sagarika Swamy
  • Last Modified 21-06-2023

Energy Flow in Ecosystem: Definition, Process, Food Chain


Energy Flow in Ecosystem: One of the significant variables that support the survival of such a large number of creatures is the energy flow in the ecosystem. A network of links between living and non-living components makes up an ecosystem. Ecological energetics is the study of the movement of energy through an ecosystem.

The sun provides all the energy that living beings require. Green plants absorb around 1% of total radiant energy for distribution across the ecosystem. Despite its small size, this quantity is adequate to maintain all life on Earth. Continue reading the article to describe the energy flow in an ecosystem.

Describe the Energy Flow in Ecosystem

The flow of power that occurs along a food chain is called energy flow. Fuel enters the food chain at the level of the producers in the form of solar energy. The plants convert solar energy into chemical energy through the process of photosynthesis.

This chemical energy is passed from one trophic level to the next trophic level along a food chain or from one trophic level to another.

Nutrient Cycling in Ecosystem -Two Laws of Thermodynamics

There is a direct relationship between energy flow and thermodynamics or it can be said that energy flow follows the laws of thermodynamics. Energy flow is based on two different laws of thermodynamics:

(i) First Law of Thermodynamics

The first law of thermodynamics states that energy can neither be created nor destroyed. Here also, the source of energy, i.e., solar energy, can neither be created nor destroyed. It can only be transferred from one system to another as from one form to another form.

(ii) Second Law of Thermodynamics

In the second law, it is stated that during the transformation, a portion of the energy is dissipated into the surroundings as heat energy.

What Do You Understand by the Energy Flow?

Animals can use energy in two forms: Radiant and fixed energy. Radiant energy is the framework of electromagnetic waves, such as light. Fixed energy is potential chemical energy tied up in different organic substances that can be injured to discharge their energy content.

Organisms that can fix radiant energy can use inorganic substances to produce organic molecules and are called autotrophs. Organisms that cannot obtain energy from an abiotic source but depend on energy-rich organic molecules synthesized by autotrophs are called heterotrophs.

Those who obtain energy from living organisms are called consumers, and those who receive energy from dead animals are called decomposers. Look below for Energy Flow in Ecosystem Diagram:

Flow of Energy at Different Levels of Ecosystem

Fig: Energy Flow in Ecosystem Diagram

When the light energy spill on the green surfaces of plants, a part of it is converted into chemical energy, which is kept in various organic products in the green plants. When the herbivores eat plants as food and transform energy into chemical energy accumulated in plant products into kinetic energy, degradation of energy will occur through its conversion into hotness.

When herbivores are eaten up by carnivores of the foremost order (secondary consumers), further degradation will occur. Similarly, when top carnivores feed primary carnivores, again energy will be degraded.

Trophic Level

The producers and consumers in an environment can be organized into several feeding groups, each known as trophic level (feeding level). 

  1. Producers represent the first trophic level.
  2. Herbivores represent the second trophic level.
  3. Primary carnivores represent the third trophic level.
  4. Top carnivores represent the last level.
Tropical Level
Tropical Level

Explain Energy Flow in Ecosystem

A food chain may be explained as the transmission of energy and nutrients through a sequence of organisms through repeated processes of eating and being eaten. In the food chain, the initial link is a green plant or producer which produces chemical energy available to consumers.

For example, marsh grass is consumed by a grasshopper, the grasshopper is consumed by a bird, and that bird is consumed by a hawk. Thus, a food chain is developed, which can be written as follows: Marsh grass → grasshopper → bird → hawk.

Food Chain
Food Chain

The food chain in any ecosystem runs directly in which autotrophs are eaten by herbivores. Herbivores are eaten by carnivores and carnivores are eaten by top carnivores. Man forms the terrestrial links of many food chains.

Food chains are of three types:

  1. Grazing food chain
  2. Parasitic food chain
  3. Saprophytic or detritus food chain

Energy Flow in Ecosystem is Unidirectional or Bidirectional

Energy flow in an ecosystem is consistently unidirectional or one way, i.e., solar radiations – producers – herbivores – carnivores. It cannot pass in the reverse direction. There is a decrease in the content and flow of energy with the rise in trophic levels.

1 – 6% of solar radiation is trapped by producers in their photosynthetic activity. The rest is dissipated as heat. From an energy point of view, it is essential to understand the following:

  1. The capability of the producers in the absorption and then conversion of solar energy into a chemical form of energy.
  2. The use of this is built into the form of energy by the consumers.
  3. The sum of assimilated energy in the form of food or edibles.
  4. The loss of energy through respiration, heat, and excretion. 
  5. Gross net production.

Flow of Energy in A Food Chain Models

For a better understanding of the energy flow concept in an ecosystem, there are two types of energy flow models:

Single-channel Energy Flow Model 

a. This model illustrates the unidirectional flow of energy.
b. Whatever the energy captured by the green plants does not revert back to solar input. As it moves progressively through the various trophic levels, it is no longer applicable to the previous level.
c. The system would crash if the primary source, the sun, were cut off.
d. There is a progressive decline in energy level at each trophic level. So, the shorter the food chain, the greater would be the available food energy.

Food web
Food Web

Y-shaped or 2-channel Energy Flow Model

a. It is applicable to both terrestrial and aquatic ecosystems. In this energy model, one arm represents the herbivore food chain and the other arm represents the decomposer (detritus) food chain. 
b. The primary producers (green plants) are entirely different for each arm.

This model also indicates that two food chains are in fact, under natural conditions, not completely isolated from one another. 
(i) It conforms to the basic stratified structure of an ecosystem.
(ii) It separates the eating and detritus food chains in both time and space.
(iii) Micro consumers and macro consumers differ greatly in size and metabolic relations.

Food Web

A complex of interrelated food chains makes up a food web. The Food web maintains the stability of the ecosystem or environment. The greater the number of alternative pathways, the more stable is the community of living things.

Why is the Energy Flow in Ecosystem Important?

The energy flow in an ecosystem is essential. All organisms in an ecosystem function due to the energy they get from the energy flow. The ecosystem’s very functioning depends on the flow of energy (starting with solar radiation) and the cycling of materials.

The ecosystem maintains itself and has stability through the process of energy flow. The more the levels in the food chains, the less energy available at the top.

This explains why the top carnivores such as big cats, tigers and large whales are the first to become endangered species when their ecosystems are under pressure from human beings. Thus, the importance of energy flow for the sustenance of an ecosystem is obvious. Without energy flow, an ecosystem will not be operational.


Sun is the ultimate source of energy. An ecosystem is a functional unit with energy flowing among abiotic components very effectively. Energy flow in an ecosystem is always unidirectional. Energy in an ecosystem is never destroyed but is converted from one form to another.

What is the 10 per cent law of energy flow? Only 10% of energy is passed to the successive trophic level. The sun’s energy is available to the organisms at higher trophic levels since the sun is the only natural source of energy provided at higher trophic levels. If any links in a food chain or food web (interconnected food chains) are removed, efficient energy flow will not occur.

FAQs on Energy Flow in Ecosystem

Q.1. What are the stages of energy flow in an ecosystem?
Energy flow can be described through food chains as the transfer of energy from one organism to the next, beginning with the autotrophs and moving up the chain as animals are consumed by one another. Another way to display this type of chain or simply to display the trophic levels is through food/energy pyramids.

Q.2. What is the flow of energy in an ecosystem called?
The feeding level from producers to consumers is called a trophic level. The energy flows only one way through various trophic levels.

Q.3. How can the energy flow in an ecosystem be described?
Energy flow in an ecosystem is always unidirectional or one way, i.e., solar radiations – producers – herbivores – carnivores. It cannot pass in the reverse direction. There is a decrease in the content and flow of energy with the rise in trophic levels.

Q.4. What is an energy flow diagram?
The energy flow diagram is a simple flow chart used to show energy and energy transformation visually and quantitatively.

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