Energy Flow in Ecosystems: Its Definition & Productivity

Energy Flow – Energy is the ability to be able to do a job and cause changes in several things. Living things, be it humans, plants or animals need energy to be able to maintain the functions of the body or anatomy and live life.

An example of energy is sunlight which is needed by every living thing. Without sunlight, plants will not photosynthesize and cannot channel their energy. This energy will undergo changes in the ecosystem, so it is referred to as energy flow. More about the flow of energy, the following explanation.

Definition of Energy Flow

Energy flow is a series of sequences of transferring energy forms from one form to another starting with sunlight, then moving to producers, moving again to primary consumers or herbivores, moving again to high-level consumers or carnivores until they reach the saprobes.

Energy flow can also be defined as the transfer of energy from one trophic level to the next. In the process of transferring energy, there is always a reduction in the amount of energy in each sequence of transfer through the trophic level which eats up.

Energy can change from one form to another. Examples include chemical energy, electrical energy, mechanical energy and heat energy. The change from one form of energy to another is known as an energy transformation.

Basically, the flow of energy starts from sunlight which is then converted by producers into chemical energy in the form of organic compounds. The energy changes into these organic compounds, consumed by consumers until there is another transfer and change of energy from plants to consumers.

Chemical energy that has been changed in the form of organic matter is then used by organisms for the growth and development of these organisms. In ecosystems, the flow of energy occurs in food chains, food webs, ecological pyramids and trophic levels.

To be clearer, here is the flow of energy that occurs in these events.



Energy Flow in Food Chains

The food chain is one of the events where the flow of energy can occur. The flow of energy that occurs in the food chain is considered very important for the sustainability of natural ecosystems.

In natural ecosystems, only plants are able to capture energy from sunlight and then convert it into chemical energy. So that the efficiency of these plants is considered very important in the survival of living things.

The flow of energy that occurs in food chain events, is somewhat inefficient. This means that not all the energy of living things occurs in a trophic that is completely obtained by living things from other trophics.

For example, producers produce energy with a magnitude of twenty kilo calories per square meter each year. However, only about ten percent of energy can be obtained by primary consumers in the food chain.

The energy flow that occurs in events is considered inefficient for several other reasons. Here’s an explanation.

  • At each trophic level, living things are able to convert most of their energy into heat when they carry out the process of cellular respiration and daily activities.
  • Living things can also change some parts of the energy into an organic molecule and can not be eaten by other living things, for example, is excrement.
  • Not all living things die, because they are eaten by other living things. Most of the living things die, without being eaten by other living things and directly experience the process of decomposition by decomposers. Therefore, the flow of energy will stop at creatures that die without being eaten by other living things.

Because of these three reasons, the flow of energy in the food chain is considered inefficient as well as the flow of energy that occurs in other events.

The flow of energy that occurs in food chain events, has levels in the ecosystem or also called trophic. Here is the trophic in the food chain when the flow of energy occurs.

  • Producers are the first trophic level, which are included in producers are organisms that are able to produce their own food substances. These organisms are referred to as producers.
    An example is living things that occupy the first trophic level in the food chain, namely plants.
  • Primary consumers are first-level consumers, namely organisms that occupy the order of the second trophic level. In general, primary consumers are herbivorous animals and mostly eat plants.
  • Secondary consumers are organisms that occupy the order of the third trophic level and are also known as second-level consumers. Secondary consumers, generally occupied by carnivorous animals, most of which are meat eaters.
  • Top consumers are organisms that occupy the highest trophic level or the last trophic level. In general, top consumers are groups of omnivores, plant and animal eaters who are at the top consumer position.
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To be clearer, here is an example of the flow of energy that occurs in a meal chain event.

1. Grass food chain

Plants in the energy flow of the food chain, occupy the first trophic as autotrophs. However, cows are herbivores that eat grass and carnivores are living things that will eat herbivores like cows.

2. Parasitic food chain

The food chain will occur if there is an interaction between organisms in an ecosystem that has a relationship with parasitism, for example, such as the food chain in mushrooms and tree roots.

3. Decomposing food chain

In the decomposer food chain, organisms that have died will still have energy that functions as an energy source for decomposers. Organisms included in decomposers are fungi, bacteria and algae.

Energy Flow in Food Webs

A food web is a combination of various interconnected food chains in an ecosystem. The more complex the food webs that are formed, the higher the level of stability of an ecosystem. Therefore, to be able to maintain the stability of an ecosystem, a food chain must not be interrupted due to the destruction of one or several organisms.

As with food chains, trophic levels in food webs also occur. Trophic levels are groupings of organisms according to their position in the food chain. Thus, the level or number of trophic levels is determined by the number of organisms that serve in the food chain.

Each level of the trophic has its own nickname. At the first level, it has a trophic nickname as an autotrophic organism. At the second level, the nickname is herbivore, at the third level the trophic nickname is primary carnivore, while at the fourth level the trophic nickname is secondary carnivore.

Because it has a relationship with the food chain, the flow of energy in food webs is not much different from the flow of energy that occurs in food chains.



Energy Flow in Ecosystems

The flow of energy that occurs in ecosystem events is actually almost the same, it’s just the organisms in it that differentiate it. Some examples of energy flow in ecosystems are as follows.

1. Ecosystems that occur on land

  • Sun > vegetables such as mustard greens, spinach, cabbage > caterpillars as the second trophic level > sparrows, the third trophic level and > the eagle as the fourth trophic level.
  • The sun as a source of energy > fruits > humans.
  • Sun > grass or other wild plants > caterpillar > chicken as third trophic > weasel as fourth trophic.
  • Sun > plants, rice > grasshoppers or insects > chickens > snakes or other predators as the fourth trophic.

2. Ecosystems that occur in the waters

Some of the ecosystems included in aquatic ecosystems are river ecosystems, swamp ecosystems, marine ecosystems, lake ecosystems and ecosystems that occur in the environment or water areas.

In aquatic ecosystems, the ecosystems that occur are slightly different from the ecosystems that occur on land. Autotrophic organisms are present in ecosystems in waters, autotrophic organisms are phytoplankton and algae that live in waters. Phytoplankton is one type of plankton that is able to photosynthesize.

Here’s an example.

  • Sun > phytoplankton > snails > fish > bigger fish, like sharks.
  • The sun > phytoplankton > fish > larger predators such as seals > other larger predators, such as killer whales.
  • Sun > phytoplankton > crustaceans > shrimp-eating birds.
  • Sun > phytoplankton > zooplankton > whales.

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Ecological Pyramid

Ecological pyramid, is an illustration of the inter-trophic arrangement based on density, dry weight, population and the ability to store energy in each trophic. The function of this ecological pyramid is to show a picture of the comparison between trophics in an ecosystem. There are three kinds of ecological pyramids, the following explanation.

  1. Number pyramid, which is a pyramid that describes the number of each individual at each trophic level in a particular ecosystem. In general, the number pyramid is narrower upward and the organisms in the number pyramid start from the trophic level from the lowest to the highest.
  2. Biomass pyramid, this pyramid describes the reduced transfer of each energy at each trophic level in a particular ecosystem. The shape of the biomass pyramid usually tapers towards the apex but can also be inverted.
  3. The energy pyramid, the last ecological pyramid is the energy pyramid which describes the loss of energy when the transfer of food energy occurs at each trophic level. This energy pyramid is able to provide the most accurate picture of the flow of energy in an ecosystem.
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Ecosystem Productivity

The main source of energy for life is sunlight. Energy from sunlight can enter biotic components through producers, namely photoautotrophic organisms, and then converted into chemical energy stored in organic compounds.

The chemical energy will then flow from producers to consumers as well as various trophic levels through food chain pathways or events. Chemical energy is then used by organisms for the growth and development of these living things.

The ability of organisms in an ecosystem to be able to receive and store energy is called ecosystem productivity. The productivity of the ecosystem consists of primary productivity as well as secondary productivity and final consumers.

Regarding primary and secondary productivity, the following is a further explanation.

a. Primary productivity

Primary productivity is the speed of autotrophic organisms as producers to convert energy from sunlight into chemical energy in the form of organic materials. Only a small portion of the energy from sunlight can be absorbed by producers.

Primary productivity, differs in each ecosystem, the largest ecosystem of primary productivity is in tropical rain forest ecosystems and mangrove forest ecosystems. Furthermore, primary productivity is divided into two, namely gross primary productivity or PPk and net primary productivity or PPb.

Gross primary productivity or PPk, is all of the organic matter that can be produced through photosynthesis and in photoautotrophic organisms, approximately 20 percent of PPk is used by photoautotrophic organisms to carry out respiration, grow and develop.

Meanwhile, net primary productivity or PPb is the remainder of the gross primary productivity energy that has just been stored. Biomass in autotrophic or producer organisms is estimated to reach 50 percent to 90 percent of all organic matter from photosynthesis. This shows that chemical energy stores that can be transferred to the next trophic are through the relationship of eating and being eaten in an ecosystem.

b. Secondary productivity and ecological efficiency

Secondary productivity is the speed of heterotrophic organisms in converting chemical energy which was originally organic matter eaten is converted into new chemical energy stores in the organism’s body.

Chemical energy in organic matter, which moves from producers to heterotrophic organisms or primary consumers is then used for living activities and only a part of this energy can be converted into chemical energy stored in the body of organisms as net productivity.

Likewise with the energy transfer that occurs in secondary and tertiary consumers, it will always decrease whenever this energy transfer occurs. The comparison of net productivity between one trophic and another trophic above it is called ecological efficiency. According to estimates, only about 10 percent of the energy can be transferred as biomass from the previous trophic to the next trophic.


Sunlight is a source of energy for every living thing, if there is no sunlight, the flow of energy cannot be established. Energy flow occurs in an ecosystem, where living organisms are in it, both terrestrial and aquatic ecosystems.

In the flow of energy that occurs in every ecosystem, one organism and another occupies certain trophics. Trophic is the level in the ecosystem. In general, the first trophic is occupied by producers which consist of organisms capable of producing their own energy, such as plants. Then the second trophic is the organism that occupies the first consumer level, usually herbivores. The third trophic is the secondary consumer and is usually filled by herbivorous animals. While the fourth trophic level is the top consumer, which is generally filled by omnivorous animals, namely plant and meat eaters.

That is an explanation of the flow of energy, as well as the productivity and trophic levels that exist in an ecosystem. If Sinaumed’s doesn’t understand the material on energy flow, or wants to know more about the material in biology for grade 10 high schools, Sinaumed’s can dig deeper by reading books.

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