Unit 14 — Ecosystems, Biodiversity, and Environmental Stewardship

Welcome back!

Life on Earth exists in an amazing variety of forms.

Tiny bacteria, towering trees, colorful birds, insects, fish, and people all share our planet.

Scientists study how living things interact with one another and with their environment.

Today you will learn how ecosystems function, why biodiversity is important, and how people can help protect Earth's natural resources.

Ecosystems Revisited

An ecosystem is a community of living organisms interacting with one another and with their physical environment.

Every ecosystem includes:

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

Each part contributes to the health of the whole system.

Biodiversity

Biodiversity means the variety of living things in an area or on Earth as a whole.

Biodiversity includes:

• different species
• genetic diversity within species
• different ecosystems

Greater biodiversity often helps ecosystems remain healthy and resilient.

Food Chains and Food Webs

Energy flows through ecosystems.

A simple food chain might be:

Sun

↓

Grass

↓

Grasshopper

↓

Frog

↓

Snake

↓

Hawk

Most organisms belong to many food chains.

Together these connected relationships form a food web.

Food webs show how changes to one species can affect many others.

Adaptations

Living things have adaptations that improve their chances of survival.

Examples include:

• camouflage
• migration
• thick fur
• sharp teeth
• long roots
• waxy leaves

Adaptations develop over many generations and help species survive in changing environments.

Habitats and Niches

A habitat is the place where an organism lives.

A niche is the role an organism plays within its ecosystem.

For example, a bee lives in gardens, forests, and fields, but its niche includes pollinating flowering plants.

Different organisms may share the same habitat while filling different niches.

Human Impact on Ecosystems

People can affect ecosystems in both positive and negative ways.

Positive actions include:

• protecting wildlife
• planting trees
• restoring habitats
• reducing pollution
• conserving water
• recycling resources

Negative impacts may include:

• habitat destruction
• pollution
• overharvesting
• introducing invasive species

Thoughtful decisions help preserve ecosystems for future generations.

Conservation

Conservation means protecting and wisely using natural resources.

Examples include:

• national parks
• wildlife refuges
• sustainable forestry
• responsible fishing
• habitat restoration

Conservation benefits both people and wildlife.

Activity

Choose one ecosystem.

Examples include:

• rainforest
• coral reef
• prairie
• wetland
• tundra
• temperate forest

Prepare a report describing:

• important species
• producers, consumers, and decomposers
• food webs
• major adaptations
• threats to the ecosystem
• conservation efforts

Include maps or illustrations if possible.

Practice

Answer these questions.

What is biodiversity?

How is a food web different from a food chain?

What is an adaptation?

What is the difference between a habitat and a niche?

How can people protect ecosystems?

Why is conservation important?

Review

Today you learned:

• ecosystems contain living and nonliving components
• biodiversity strengthens ecosystems
• food webs connect many organisms
• adaptations help species survive
• habitats and niches describe different aspects of an organism's life
• people can both harm and protect ecosystems
• conservation helps preserve Earth's natural resources

Healthy ecosystems support life on our planet and require responsible stewardship.

Looking Ahead

Next we will begin the Grade 5 Social Studies sequence by exploring the geography of North America, the growth of the United States, constitutional government, and the responsibilities of informed citizenship.