Ecosystems and Food Chains

What Is an Ecosystem?#

Look around you — whether you are in a forest, a pond, a desert, or even your backyard, you are looking at part of an ecosystem. An ecosystem is a community made up of all the living things in an area AND all the non-living things they interact with.

Living Things (Biotic Factors)#

Living things in an ecosystem are called biotic factors. They include:

• Plants — trees, grasses, mosses, ferns
• Animals — insects, birds, fish, mammals
• Fungi — mushrooms and mold
• Bacteria — tiny organisms you cannot see

All of these living things depend on each other in some way. Some eat others; some provide shelter; some clean up dead materials.

Non-Living Things (Abiotic Factors)#

Non-living things are called abiotic factors. They include:

• Sunlight — the energy source for most life on Earth
• Water — needed by every living thing
• Soil — provides nutrients and a place to grow
• Temperature — affects which organisms can survive
• Air — supplies oxygen and carbon dioxide

How They Work Together#

Imagine a forest ecosystem. The sunlight shines through the leaves. Trees use sunlight, water, and carbon dioxide to make food. Squirrels eat the tree's nuts. Hawks eat squirrels. When organisms die, fungi and bacteria break down their remains and return nutrients to the soil. Then the cycle begins again!

Ecosystems can be large — like the Amazon Rainforest — or small — like a single pond or even a rotting log. No matter the size, the living and non-living parts work together to keep the ecosystem healthy.

Why Ecosystems Matter#

Ecosystems give us clean air, fresh water, food, and medicine. Protecting ecosystems means protecting our own survival. Every living thing plays a role, even the tiniest bacterium.