2.2.5 Relationships Between Ecosystems and Populations

Relationships Between Ecosystems and Populations

2.2.5

Draw

Find the 10 differences between the 2 images.

Objectives

Learners can:

• examine evidence of the relationships between changes in the ecosystem and changes in populations

• explore the significance of keystone species in ecosystems

• ecology

• food web

• invasive species

Prerequisite Vocab

• probability

New Vocab

Vocabulary

a chance an event will occur

Probability

The Domino Effect is when one event causes a series of other events to happen. Like when you line up dominoes and knock one over and all the other dominoes nearby collapse one after another.

Domino Effect

Open Ended

How does the Domino Effect relate to what happens in the environment?

Categorize

Options (6)

frog

weasel

mouse

rabbit

fox

owl

Using the food web diagram below, determine which populations would increase and which populations would decrease if a mild winter resulted in an increase of insects.

Increase

Decrease

• the ecosystem may eventually recover from natural damage

• ex. volcanic activity, forest fires

Natural Causes

• have a more permanent impact

• humans will maintain the changed environment for a long time making it more difficult to recover

• ex. changing forests to farmland

Human Activities

Open Ended

What is an example of a natural cause or human activity that could impact the environment?

In 1980, the eruption of Mount St. Helens in Washington State devastated the environment around the volcano. Decades later, the environment is recovering. However, species populations are different from what they once were.

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Population Changes

Multiple Choice

The volcanic ash and rock that covered the ground after the eruption in 1980 impacted what abiotic factor near Mount St. Helens?

• soil

• chipmunks

• lupine

• trees

Certain species are critical to the overall health of an ecosystem. These populations are called "keystone species." Wolves are predators that prey on elk, deer, and bison. They also prey on livestock and were seen as a threat.

In the late 1800s, there was a push to reduce the gray wolf populations in and around Yellowstone National Park. To protect farmers' livestock, the park attempted to control the wolf population through hunting, trapping, or poisoning up through the early 1900s.

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Keystone Species

Hunted to near extinction to protect livestock.

Gray Wolves Hunted

​Without a predator, elk populations increased. This larger population heavily reduced many plant populations.

Elk Populations Grew

​Diminishing plant populations affected other populations, such as beavers and songbirds.

Diminishing Populations

Without enough plants to stabilize the stream banks, soil washed away and impacted freshwater streams and lakes.

Abiotic Impacts

Multiple Select

How did a change in the gray wolf population impact the ecosystem directly and indirectly?

Select 2 correct answers.

• Stream bank erosion increased.

• Beaver populations lost habitat.

• Elk populations significantly decreased.

• Plant and tree populations increased.

Ecology is the study of ecosystems. Ecologists study aspects of environments, such as food webs, to determine possible outcomes of environmental changes.


Probability is the chance an event will occur. Using observations, scientists can predict the probability of environmental impact from different actions on the ecosystem.

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Ecology

Multiple Choice

Developers cut down trees to build a new shopping center. Which of the following concerns would an ecologist most likely study the probability of occurring?

Select 2 correct answers.

• the impact on local wildlife

• the impact on local waterwasys

• the impact on the local economy

• the impact on property values