You may think of a forest as just a collection of trees, but a forest actually has many different animals and plants that interact with and depend on each other. It is a complex living system, or ecosystem.
Food is one important way that forest plants and animals are connected with each other. Forest plants use sunlight to make food. Through a process called photosynthesis that takes place in their leaves, they convert the sun’s energy to food energy. The plants use this food energy to live and grow.
Animals are not able to make their own food energy and must rely on plants for food. Some animals, called herbivores, eat plants directly. Some animals, called carnivores, eat other animals that eat plants. And some organisms, called decomposers, eat dead plants and animals.
A food chain describes the transfer of energy from one organism to another in an ecosystem. One simple food chain is grass being eaten by a rabbit and then the rabbit being eaten by an owl. We can show this food chain using an equation like this:
sun → grass → rabbit → owl
Notice that this food chain, like all food chains, starts with the sun. The arrows that follow show the food energy being passed from one organism to the next.
In reality, it is rare for an animal to eat only one type of food. A food web shows the many different foods the animals in an ecosystem eat. It gives a clearer picture of the ways food energy is passed through an ecosystem and shows how the plants and animals in an ecosystem are connected.
Food is just one way that plants and animals depend on each other. In addition, animals need plants for shelter and shade. And plants need animals to pollinate flowers, spread seeds, and eat insects.
- What is a food chain?
- Do all forest food chains include the sun? Why or why not?
- How is a food web different from a food chain?