Changing Ecosystems / Study Guide

Changing Ecosystems / Study Guide

Ecosystems in Balance

Imagine you are observing a forest environment. You see a mouse eating some grass near a tree. Suddenly an owl swoops down and grabs the mouse. The grass, the mouse, and the owl ar all interacting with each other. They are all part of an ecosystem.

An ecosystem is all of the living and nonliving things that interact in an area. In a balanced ecosystem, all organisms have the resources that they need. For example, in a forest ecosystem, a deer will be able to find grass and leaves to eat, water to drink, and a place to find shelter. In an unbalanced ecosysystem, plants and animals will not be able to find the resources, such as food and water, that they need to survive.

Changes are constantly happening in an ecosytem. Organisms, wind, water, and other parts of the environment cause these changes. The majority of changes to an ecosystem are minor and do not disrupt the balance. The life cycle, rain, and predators hunting prey are all examples of minor changes to ecosystems. These grizzly bears live in a balanced ecosystem.

Multiple Choice

Which statement is true?

• An ecosystem includes both living and nonliving things

• An ecosystem includes only living things

• An ecosystem includes only nonliving things

Multiple Select

Which of these are descriptions of balanced ecosystems?

• The organisms have all the resources they need.

• There is not enough water for all of the plants and animals.

• There are many different types of healthy animals and plants

• There is not enough food for all of the animals in the ecosystem.

Multiple Select

Which changes would keep an ecosystem in balance?

• In September, a wolf kills a deer. The following spring, a new deer is born.

• All of the ice in a polar ecosystem melts.

• There is heavy rain followed by several days of sunshine.

• A disease kills all of the trees in a forest.

Although ecosystems are usually balanced, sometimes drastic changes happen. These drastic changes can be caused by nature or by humans. When a drastic, or major, change occurs, the organisms that live in that ecosystem cannot find the resources that they need in order to survive. The either have to adapt to the new ecosystem or move to a new area where they can find the resources they need to live.

Drastic changes that happen in nature include floods, drought, and volcanic eruptions. Natural events that cause major changes in ecosystems are not caused by humans.

There are many natural events that can cause ecosystems to change.

Multiple Select

A huge swarm of hungry locusts lands on the Wallace family farm. Within minutes, the insects are devouring grasses and plants in the area. What changes do you think these locusts will cause in this ecosystem?

• They will eat all the plants, leaving no food for other herbivores.

• They will provide food for birds and other animals.

• They will destroy crops.

Multiple Select

Which of the following show ways in which nature can cause major changes to ecosystems?

Multiple Select

Scientists currently hypothesize that an asteroid impact led to the extinction of the dinosaurs. This impact would have caused ash to block the Sun. How would this ash affect the dinosaurs ecosystem and cause them to become extinct?

• Because the Sun was blocked out, plants were not able to make food, and they died.

• The dinosaurs that were herbivores died because there were no plants to eat.

• The dinosaurs that were carnivores died because there were fewer animals for them to eat.

• The nutrients from the ash in the air made the plants grow bigger.

Beavers create dams with mud, rocks, and trees. They also build lodges to live in, and they create artificial ponds to protect themselves from predators. Their work disrupts the surrounding habitats. The changes they make to their ecosystem may be helpful to some organisms and harmful to others.

Multiple Select

What are some ways a beaver could damage the ecosystems when it creates an artificial pond?

• It could flood the homes of animals that live on the side of the dam where the pond forms.

• It could keep animals that live further down the stream from getting the water they need to survive.

• It could provide a place for tadpoles and young fish to live until they are fully grown.

• It could restore wetland areas, giving certain species of fish a place to live.

Multiple Select

Which pictures show major changes caused by nature?

People can also cause major changes to ecosystems. These major changes can disrupt the ways that ecosystems work. Humans change ecosystems by building houses and clearing forests. These activities cause major changes to ecosystems by forcing animals from their homes, disrupting migration patterns, and changing food webs.

Humans also produce pollution that can change ecosystems. Land pollution, such as landfills, leaves garbage on the land that can kill animals if they eat it. Land pollution can also poison the soil, making it difficult for plants to grow. Air pollution, which can be caused by cars and factories, causes acid raid that can damage trees. Water pollution, such as oil spills, can kill the organisms that live in or drink the water.

Humans can also damage ecosystems by introducing species that do not normally live in the ecosystem. Because these species usually do not have any natural predators in their new ecosystem, they can disrupt the balance of the ecosystem. These species are known as invasive species. Often, they will kill off another species by using up the resources that the other species needs.

Multiple Select

Landfills have an impact on the environment and local ecosystems. Which of the following statements about landfills are true.

• A landfill takes up space that once contained habitats for animals and plants.

• The garbage and chemicals from the landfill could pollute the land, nearby water sources, and the air.

• Landfills create new safe habitats for lots of plants and animals.

• Some people throw out of dangerous chemicals that end up in landfills and can pollute the environment.

Multiple Select

A forest is cleared away to make space for a new neighborhood. Which of the following could happen as a result?

• The routes that animals take to migrate from one location to another could be blocked.

• Animals that are not killed may need to move to find new habitats.

• All of the animals will be able to find habitats in the new construction.

Multiple Choice

What is an ecosystem?

• something that is harmful to the environment

• all of the living and nonliving things that interact in an area

• a species that is at risk of extinction

• the resources (like food and water) an organism needs to survive

Multiple Choice

Decide if this event would be a major or minor change to an ecosystem.

A forest fire burns down all of the trees in a large area of the forest.

• major change to an ecosystem

• minor change to an ecosystem

Multiple Choice

Decide if this event would be a major or minor change to an ecosystem.

A swarm of locusts eats all of the plants in an area.

• major change to an ecosystem

• minor change to an ecosystem

Multiple Choice

Decide if this event would be a major or minor change to an ecosystem.

A rainstorm waters the plants and replenishes a lake.

• major change to an ecosystem

• minor change to an ecosystem

Multiple Choice

Is this ecosystem changing event nature or human caused.

Chemicals from a factory are released in the water, causing animals to die.

• nature causing change to an ecosystem

• humans causing change to an ecosystem

Multiple Choice

Is this ecosystem changing event nature or human caused.

A hurricane causes major flooding.

• nature causing change to an ecosystem

• humans causing change to an ecosystem

Multiple Choice

Is this ecosystem changing event nature or human caused.

An invasive species is introduced from an aquarium.

• nature causing change to an ecosystem

• humans causing change to an ecosystem

Multiple Choice

Is this ecosystem changing event nature or human caused.

Lightning hits a tree and starts a forest fire.

• nature causing change to an ecosystem

• humans causing change to an ecosystem

Multiple Select

How can you tell if an ecosystem is balanced?

Select all choices that are true.

• Only minor changes occur in the ecosystem.

• Plants and animals have everything they need.

• A major change has just occurred in the ecosystem.

• One species has eaten all of another type of animal in the ecosystem.

Multiple Select

Select the pictures that show minor changes to an ecosystem.

Check all that are true.

Multiple Select

Select the pictures that show major changes that are caused by humans.

Check all that are true.

Multiple Select

The emerald ash borer beetle is an invasive species in the eastern United States. It came to the U.S. on wood that was shipped from Asia. The beetle kills ash trees. The woodpecker is a bird that has a beak that can burrow into the bark of trees. This bird is one of the beetle's only natural predators. As the population of these beetles increase, what are some of the major changes they could cause to ecosystems in the eastern United States.

• They could provide a food source for woodpeckers, leading to an increase in the woodpecker population.

• They could cause the population of ash trees to increase.

• They could kill many of the ash trees.

• They could force the animals that lived in ash trees to find new homes.

Multiple Choice

Based on the picture, why is this a balanced ecosystem?

• The giraffes have water to drink and leaves to eat.

• Humans have built houses on the giraffes' entire habitat.

• There has recently been a drought, and the plants are dying.

• none of the above