1. Understanding Ecosystems
Chapter 4

2. Lesson 1 Vocabulary
Environment— all of the living and nonliving things that affect an organism.
Ecosystem— a community and its physical environment together.
Population— all the individuals of the same kind living in the same environment.
Community— all the populations of organisms living together in an environment.

3. The tarpon in this photograph are not yet full-grown
The tarpon in this photograph are not yet full-grown! These fish don’t become adults until they are between 7 and 13 years old, when they can weigh more than 200 pounds. Tarpon live in salt water, but they can survive in a variety of ecosystems.

4. Lesson 1 (page 132)
Where do you live? You might name your street and town. You also live in an environment. An environment is all the living and nonliving things that surround you.
The living things in your environment are people, other animals, and plants. The nonliving things around you include water, air, soil, and weather.
The parts of an environment affect one another in many ways. For example, animals eat plants. The soil affects which plants can live in a place. Clean air and clean water help keep both plants and animals healthy.
All the living and nonliving things in an area form an ecosystem. An ecosystem can be very small. It might be the space under a rock.
Prairie dogs also live on the prairies and grasslands.

6. Lesson 1 (page 133) Ecosystems
The small ecosystem found under a rock has nonliving parts, too. They include pockets of air and the soil under the rock. You might find a few drops of water or maybe just damp soil. All ecosystems must have at least a little water.
The ecosystem under this rock has a climate. The climate in an area is the average weather over many years. Climate includes temperature and rainfall. The climate of an ecosystem depends on where the ecosystem is.
An ecosystem can also be as large as a forest. A forest can provide many kinds of food and shelter. This ecosystem may include hundreds of kinds of plants and animals.
Like all ecosystems, a forest has nonliving parts. They include water, air, soil, and climate.

7. Lesson 1 (page 134) Individuals & Populations
One plant or animal is an individual. For example, one blueberry bush is an individual.
A group made up of the same kind of individuals living in the same ecosystem is a population. A group of blueberry bushes is a population.
The members of a population might not live in a group. For example, frogs don’t live in families.
Many animals live in groups. People live in families. Wolves live in packs.

8. Lesson 1 (page 135) Populations
Some populations can live in more than one kind of ecosystem. For instance, red-winged blackbirds often live in wetlands, but they are also found in other areas.
Some populations can live in only one kind of ecosystem. One such animal is the Hine’s emerald dragonfly. This insect can live only in certain wetlands.
Ecosystems are often named for the main population that lives there. For example, one kind of ecosystem forms where a river flows into the ocean. There, fresh water mixes with salt water. Many trees can’t live in salty water, but mangrove trees have roots that allow them to get rid of the salt in the water. When many mangrove trees live in a salty ecosystem, it is called a mangrove swamp.
Mangrove Swamp

10. Lesson 1 (page 136) Communities
You live in a community. Other animals and plants do, too. A community is all the populations that live in the same place.
Have you visited the Everglades National Park? Many different populations make up this community. The plants include mangrove trees, cypress trees, and saw grass.
Animals found in the Everglades community include alligators, bobcats, and raccoons. Bird-watchers like to visit the Everglades.
In some ways, the Everglades is like all communities. The plants and animals there depend on one another. Some animals eat the plants. Other animals eat the plant eaters. The animals help spread the plants’ seeds. The plants provide shelter for the animals.

11. Lesson 1 Review
Which word describes a group of cows standing together?
Community
Ecosystem
Individual
Population