The Living World
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Interaction Between Abiotic and Biotic Components

Ecosystems consist of living (biotic) and non-living (abiotic) components that interact within them. The biotic components depend on other biotic components as well as abiotic components – this is known as interdependence.

This means that changing a biotic or abiotic component can significantly impact the rest of the ecosystem.

Interactions Between Abiotic and Biotic

The interdependence in an ecosystem is shown in a variety of ways. Abiotic factors help living organisms (biotic factors) survive through what they provide to the ecosystem. Abiotic factors include elements such as sunlight, heat, air, rock, soil and water which are vital to the growth and sustainability of the Biotic factors.

Take a flower for example:

1. The flower needs sunlight, the right amount of heat, water and nutrient-rich soil to grow. 

2. The sun provides heat and light, while consistent rainfall helps water the area. The soil is provided with nutrients from the weathering of minerals, so the soil is nutrient-rich.

3. Because of the abiotic factors, the biotic factor will grow and flourish within this ecosystem. 

Biotic factors can also rely on other biotic factors, with the main interaction being feeding. This is best shown as food chains and food webs

Food Chains and Food Webs

Food chains and food webs show the relationship between components in an ecosystem through feeding. In food chains and food webs, there are several roles to be played, which are: 

  • Producers: Plants which convert the energy from the sun into carbohydrates through photosynthesis.
  • Primary Consumers: Producers are eaten by primary consumers, which are herbivores or omnivores.
  • Secondary Consumers: Primary Consumers are eaten by secondary consumers, which are omnivores or carnivores.
  • Tertiary Consumers: Secondary Consumers are eaten by tertiary consumers, which are omnivores or carnivores.
  • Decomposers: Fungi and bacteria that help return energy to the soil, break down organic matter and recycle energy from organic matter. 

Food chains show the interactions and energy transfer from one biotic component to another. In a food chain, the source of energy is always the sun.

Food chain

Let’s consider the food chain below.

A black and white picture of a cow and a personDescription automatically generated

1. In this example food chain, the energy transfers from the sun to the grass, which in turn photosynthesises and grows. This makes the grass our producer.

2. The energy is transferred from the producer to our primary consumer, which is the cow when it eats the grass.

3. The energy is then transferred to the secondary consumer, which is the human, who eats the slaughtered cow in burger form.

4. Finally, energy transfers to the maggot, which is a decomposer, breaking down organic materials, including deceased organisms like the human in this case.

Food chains are simple, but useful ways of showing how energy transfers from a producer to consumers. 

Another way to show feeding relationships in an ecosystem is food webs, which are less simplistic. They usually show a more complex system of interdependence, with a variety of plants and animals that feed on each other in an ecosystem.

Food Web

Let’s consider the food web below.

A diagram of animals and birdsDescription automatically generated

The diagram above is a simplified version of a food web from the ecosystem of a woods or forest in the UK. Food webs help us see the complex relationship between the biotic elements of the ecosystem, but they also help us visualise the interdependence.

Using the diagram above, we can see that if we removed the grasshoppers, or their population size dramatically reduces:

  • The population of grasses and grains would increase would increase, as there are fewer species feeding off of them
  • The population of local birds would suffer, as they eat grasshoppers as their primary food source
  • The population of foxes would decrease, as part of their diet consists of birds

If we remove the owls or their population size dramatically reduces:

  • The population of mice and grasshoppers would increase as their primary predator was less prevalent or missing
  • The overabundance of mice and grasshoppers would lead to a greater amount of grass plants and grain being consumed
  • The bird population would increase as more grasshoppers are available to eat
  • The fox population would increase slightly as one of their food sources (mice) is in greater supply

Using the examples of food chains and food webs, it’s easy to understand how the interactions between components of an ecosystem keep the balance.

An overabundance of one component can have dramatic knock-on effects on other components. Human activity in sensitive ecosystems often causes severe consequences that are unplanned and can damage the function of the ecosystem.

Key Terms

InterdependenceTwo (or more) things that are dependent on each other
Food chainsA series of organisms each dependent on the next as a source of food
Food websA system of interlocking and interdependent food chains
Photosynthesis The process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen
HerbivoreAn animal that only eats plants
OmnivoreAn animal that eats a variety of food, both plants and animals
CarnivoreAn animal that feeds on other animals

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