What is an Ecosystem?

Learning Objectives

By the end of this unit, you will be able to define an ecosystem and identify its biotic and abiotic components, explain how living things and their environment are interconnected, and understand how changes in an ecosystem can affect the survival of its species.

What is an Ecosystem?

Think of a fierce hunter. Did you imagine a bird? Probably not. But many birds hunt! Bald eagles hunt. They swoop down to the water and catch fish with their claws. White-tailed hawks hunt. They dive through the air to catch grassland animals like mice. These birds live in different places. They eat different foods. But they both show the connections between living things and their ecosystems!

A bald eagle dives toward the water with its wings and talons outstretched.

Like all living things, bald eagles and white-tailed hawks live in ecosystems. An ecosystem includes all the living and non-living things within an area. An ecosystem can be small, like a family garden. It can also be large, like the Amazon Rainforest. It might be terrestrial, like the white-tailed hawk's grassland ecosystem. Or it might be aquatic, like the ponds and rivers where an eagle hunts for fish. Organisms living within an ecosystem rely on one another to survive. They also rely on the ecosystem's non-living components or parts.

Biotic and Abiotic Factors

Biotic and abiotic factors are two distinct components of an ecosystem that play critical roles in shaping its structure and function.

Biotic factors refer to all the living organisms within an ecosystem. These can include plants, animals, fungi, and microorganisms. Biotic factors interact with each other and the abiotic factors of the ecosystem to create a complex web of relationships and dependencies.

Abiotic factors refer to an ecosystem's non-living components. These can include sunlight, temperature, water, air, soil, and other physical and chemical factors. Abiotic factors shape the physical environment of the ecosystem and determine which organisms can survive and thrive within it.

Drag the terms to the correct category.

Biotic and abiotic factors are essential for maintaining the balance and stability of any ecosystem. Understanding the interactions between these two components is essential for understanding how ecosystems work and how they can be protected and managed.

environment: biotic and abiotic factors

Connections in Ecosystems

How do plants, animals, insects, and the environment interact in an ecosystem? Building a terrarium is one way to explore the connections between members of an ecosystem. In this DE Original, learn how to create your tiny ecosystem within a terrarium.

Terrariums can show us how plants, animals, and insects interact similarly to the natural ecosystem, making them a great tool for understanding how living things rely on their ecosystem to survive.

Bald eagles (<i>Haliaeetus leucocephalus</i>) in Homer, Alaska. White-tailed Hawk (Buteo albicaudatus)

Bald Eagles - Mike Criss / White-Tailed Hawk – blogspot.com

Bald eagles and white-tailed hawks rely on other animals in their ecosystems for food. But animals need more than just food to survive. They also depend on other parts of their ecosystems. They depend on a supply of water. They depend on materials for nests or shelters. The living and non-living parts of ecosystems are interconnected in many ways.

Think of a bald eagle hunting for fish in a river. It depends on the fish it catches for food. But it also depends on the water in the river. It depends on the organisms that the fish eat. It depends on the tree where it has a nest. It depends on the temperature of the surrounding air. The list goes on. The survival of an individual eagle depends on many factors in its ecosystem. These factors also affect the size of the eagle population.

Similarly, white-tailed hawks are connected to their grassland ecosystem's biotic and abiotic parts. For example, a hawk depends on the soil conditions in which the grasses in its ecosystem grow. Those grasses are part of a hawk's grassland food web. The hawk is also connected to the water in its ecosystem, which supplies it with drinking water and also supports plant growth. Climate, temperature, and other abiotic factors also affect the hawk's survival.

A diagram with arrows connects organisms to their food sources.

Food Webs will be discussed in more detail later in the course.

Living things rely on other living things in the ecosystem. They also rely on the non-living factors around them. Can you predict what happens when there is a change to one of the factors in an ecosystem?

How Ecosystems Change

Ecosystems are always changing, and there are many reasons why this happens. Sometimes, it happens slowly, like when trees grow and make more shade on the ground. Other times, it happens quickly, like when there's a big storm or a wildfire.

Sometimes, people can cause changes to ecosystems. For example, when people cut down lots of trees, it's called deforestation. This can be for things like making space for farms or getting wood. But when this happens, it changes the ecosystem and can make it hard for animals and plants to live there.

Half of the trees have been clear-cut from a hillside, leaving behind empty land.

Even when trees are removed for an important reason, the changes greatly impact the ecosystem.

Another way people can change ecosystems is by introducing new plants or animals. Sometimes these new things can cause big problems. For example, a plant called kudzu was brought to America long ago. It started growing too much and pushing out other plants. This made it hard for animals that rely on those plants to survive.

A school bus is overgrown with kudzu.

The plant, known as kudzu, is growing out of control.

When things change in an ecosystem, it can greatly affect the animals and plants. For example, in Florida, there are too many Burmese pythons. These snakes are not from Florida; people brought them there as pets. When Hurricane Andrew hit Florida in 1992, some of the snakes escaped. Now, there are too many pythons, and they're eating too many other animals. This makes it hard for some animals to find enough food to survive.

A close-up of a Burmese python being held near the grass.

Snake species native to Florida have a harder time surviving since Burmese pythons were introduced to their ecosystem.

Understanding how all the different things in an ecosystem are connected is important.

This can help us predict what might happen if things change, and it can also help us fix ecosystems that have been damaged.

In conclusion, an ecosystem is a group of living things and their environment that work together. This environment includes living things like plants and animals and non-living things like water, air, and soil. Everything in an ecosystem depends on each other to survive and keep the ecosystem healthy. Ecosystems can change over time because of nature or things that people do, affecting the survival of animals and plants. It's important to understand how ecosystems work and how everything in them is connected so we can help protect them.