Biotic and Abiotic Factors: Examples and Differences

What is biotic and abiotic?

The words come from Greek: bios means life and a- means "not", so abiotic means "not living". Ecologists use the two terms to sort everything in a habitat into one of the two groups.

Biotic factors are anything that is alive or comes directly from living things. They include organisms that eat, compete with, shelter or infect each other.
Abiotic factors are the physical and chemical conditions of the environment. They do not need to be alive and cannot reproduce.

Biotic factors: examples

Producers, such as plants and algae, which make food by photosynthesis.
Consumers, such as rabbits, foxes and birds, which eat other organisms.
Decomposers, such as fungi and bacteria, which break down dead material and recycle nutrients.
Competitors, which are organisms that need the same food, water or space.
Parasites and pathogens, which live on or in another organism and harm it.

Abiotic factors: examples

Temperature, which controls the rate of chemical reactions in living things.
Light intensity and day length, which affect photosynthesis and the timing of flowering and breeding.
Water availability and humidity, which limit where plants and animals can survive.
Soil pH and mineral content, which affect which plants can grow.
Oxygen and carbon dioxide in water and air, which living things need for respiration and photosynthesis.
Wind, salinity and altitude, which shape the conditions a habitat provides.

Biotic vs abiotic factors

Feature	Biotic factors	Abiotic factors
Definition	Living parts of an environment	Non-living parts of an environment
Examples	Plants, animals, fungi, bacteria	Temperature, light, water, soil, air
Can they reproduce?	Yes	No
Effect on an ecosystem	Predation, competition, disease, decomposition	Sets the limits of what can survive

How do abiotic and biotic factors interact?

The two kinds of factor depend on each other. Abiotic factors set the limits, and biotic factors respond within those limits.

For example, a cactus in a desert survives because of its abiotic environment: little rainfall, high temperature and bright sun. Its stem stores water, and its spines reduce water loss. Biotic factors then act on the population: a shortage of water limits how many cacti grow, and a herbivore that eats them lowers their numbers further.

Coral reefs show the same link. Corals live in a narrow range of sea temperature. When the water becomes too warm, the corals expel the algae that live in their tissues and turn white, a process called bleaching. The abiotic change (heat) directly affects the biotic organisms (the corals and their algae).

Is dead material biotic or abiotic?

This is a judgement call. Fallen leaves and dead animals come from living things, so many courses class them as biotic. Others treat them as abiotic because they are no longer alive. Check how your syllabus or textbook defines the terms before you answer an exam question.

Common mistakes

Treating "biotic" as the same as "natural". Both biotic and abiotic factors can be natural. Abiotic only means non-living.
Listing a biotic factor as abiotic because it is not an animal. Plants, fungi and bacteria are all biotic.
Forgetting that the two interact. Changing an abiotic factor, such as temperature, often changes the biotic population that depends on it.
Using "abiotic" for things that are only dead. Check the convention before deciding.

Frequently asked questions

What are biotic and abiotic factors?

Biotic factors are the living parts of an environment, such as plants, animals, fungi and bacteria. Abiotic factors are the non-living parts, such as temperature, light, water, soil and air. Together they make up an ecosystem, and each affects the other.

What is the difference between biotic and abiotic?

Biotic means living or coming from living things, and abiotic means non-living. The term "biotic" covers organisms and their interactions, while "abiotic" covers the physical and chemical conditions, such as temperature, sunlight and water availability.

Give examples of abiotic factors.

Examples include temperature, sunlight, water, humidity, soil pH, mineral content, wind, salinity and the amount of oxygen or carbon dioxide in air or water. Each of these can limit which organisms can live in a habitat.

Is a tree biotic or abiotic?

A tree is biotic, because it is a living organism. Its leaves, roots and wood are all part of a living organism while it is alive. Water and sunlight that the tree uses are abiotic factors in its environment.

Try it yourself

Open the Food Web tool and watch the meadow and pond food web. Each organism is a biotic factor, and the arrows show which ones eat which. Remove a species to see the chain reaction, then spill a pesticide and watch the populations change. For the wider field that studies these interactions, read what is environmental science?