Unit 13 — Ecosystems, Biodiversity, and Environmental Change

Welcome back!

Life on Earth exists in a network of connections.

Every organism depends on other living things and on the physical environment.

Changes to one part of an ecosystem can affect many other organisms.

Scientists study these relationships to better understand and protect the natural world.

Today you will investigate ecosystems, biodiversity, food webs, and environmental change.

Ecosystems

An ecosystem consists of living organisms interacting with one another and with their physical environment.

Every ecosystem includes:

• plants
• animals
• fungi
• microorganisms
• water
• air
• soil
• sunlight

Energy and matter move continuously through these systems.

Healthy ecosystems depend on balanced interactions among their components.

Producers, Consumers, and Decomposers

Organisms play different roles within ecosystems.

Producers

Usually plants and algae.

They make their own food using sunlight through photosynthesis.

Consumers

Animals that obtain energy by eating plants or other animals.

Consumers may be:

• herbivores
• carnivores
• omnivores

Decomposers

Organisms such as fungi and many bacteria that break down dead organisms and recycle nutrients back into the environment.

Each group is essential for maintaining healthy ecosystems.

Food Chains and Food Webs

Energy flows through ecosystems.

A simple food chain might be:

Sun

↓

Grass

↓

Rabbit

↓

Fox

Most organisms participate in many feeding relationships.

These interconnected pathways form a food web.

Food webs provide a more complete picture of ecosystem interactions.

Biodiversity

Biodiversity is the variety of living organisms within an ecosystem or across Earth.

Biodiversity includes:

• different species
• genetic variation within species
• different ecosystems

Greater biodiversity often improves an ecosystem's stability and ability to recover from change.

Adaptations

Organisms possess adaptations that improve survival.

Examples include:

• camouflage
• migration
• thick fur
• specialized beaks
• deep root systems
• seasonal behavior

Adaptations develop over many generations through natural processes.

They help organisms survive in changing environments.

Environmental Change

Ecosystems constantly change.

Natural causes include:

• storms
• floods
• droughts
• wildfires
• volcanic eruptions

Human activities may also influence ecosystems through:

• pollution
• habitat loss
• deforestation
• introduction of invasive species
• climate change

Scientists study these changes to better understand their effects and develop solutions.

Conservation

Conservation means protecting and wisely managing natural resources.

Examples include:

• restoring habitats
• protecting endangered species
• reducing pollution
• conserving water
• planting trees
• using resources responsibly

Conservation helps maintain healthy ecosystems for future generations.

Human Responsibility

People depend on healthy ecosystems for:

• food
• clean water
• clean air
• medicine
• recreation
• natural resources

Responsible environmental stewardship benefits both people and wildlife.

Small individual actions, combined with larger community efforts, can make a meaningful difference.

Activity

Choose one ecosystem.

Examples include:

• rainforest
• desert
• prairie
• coral reef
• tundra
• temperate forest
• freshwater lake

Prepare a report describing:

• major organisms
• producers, consumers, and decomposers
• food web
• important adaptations
• environmental challenges
• conservation efforts

Include labeled illustrations or diagrams.

Practice

Answer these questions.

What is an ecosystem?

How do producers differ from consumers?

What role do decomposers play?

What is biodiversity?

Why are adaptations important?

How can people help protect ecosystems?

Review

Today you learned:

• ecosystems contain living and nonliving components
• producers, consumers, and decomposers each perform essential roles
• food webs describe complex feeding relationships
• biodiversity strengthens ecosystems
• adaptations improve survival
• ecosystems change naturally and through human activity
• conservation protects Earth's natural resources

Understanding ecosystems helps us appreciate the connections that sustain life on our planet.

Looking Ahead

Next we will begin Grade 6 World History by exploring archaeology, early human societies, and the development of the world's first civilizations.