Ecosystems

Why might a change in an ecosystem affect populations of species within

that ecosystem?

Have you ever seen a caterpillar munching on a leaf, or a bird drinking water from a puddle? Have you noticed that the leaves of some trees only change color as the weather gets cooler?

All of these observations, and others like them, are examples of the many different types of interactions that occur within ecosystems.

Introduction

An ecosystem includes all the living organisms existing together in a particular area. These organisms, like plants and animals, depend on each other to survive. They also interact with the nonliving elements of the area, such as water, soil, rocks, and climate.

What is an ecosystem?

Click here for more information about ecosystems.

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Ecosystems

The balance of an ecosystem is very delicate! Changes to the ecosystem, such as the

introduction of a new species or drought, can be disastrous to all organisms within the

ecosystem.

A Delicate Balance

Let’s Look at an Example

Kudzu

These three pictures show the growth of kudzu in an area over time. Predict how the invasion of kudzu will affect other plants and animals in this area.

Think About It

Images courtesy of Jack and June Anthony of jjanthony.com

Click here for more information about kudzu.

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Click here to play a quick game about other invasive species

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Kudzu vine

Time to Experiment!Part 1: Print these instructions before clicking on the link below. Use the virtual ecology lab to simulate the disruption of an ecosystem by an invasive plant species. Part 2: After completing part 1, start the simulation over and try to create a sustainable ecosystem in which all of your species survive. If one species has a population of zero at the end of the simulation, start over and try a different scenario. Which scenario creates the most stable ecosystem?

Go to Virtual Ecology Lab

Virtual Ecology Lab Instructions Part A) Simulating a stable ecosystem: a) Click on All Off.b) Click on Plant C (the third plant in the row) and select it from the menu.c) Click on Herbivore A (the first herbivore in the row) and set it to eat Plant C.d) Click on Omnivore A (the first omnivore in the row) and set it to eat Herbivore A.e) Click RUN and observe that the plant, herbivore, and omnivore populations eventually

reach equilibrium (their population numbers stop changing).Part B) Simulating the disruption of an ecosystem by an invasive plant species:a) Click on Reset. (Plant C, Herbivore A, and Omnivore A should still be connected in a

food chain.)b) Click on Plant A (the first plant in the row) and select it from the menu. This plant

represents an invasive species, a strong competitor to Plant C.c) Click RUN. What happens to the populations of each species in the ecosystem? Give

an explanation for the results. (hint: think of a chain reaction or domino effect)

PART A PART B

Ecosystem

A community of living and nonliving things that function together.

Examples: – aquatic ecosystems– desert ecosystems– forest ecosystems

Species

A group of individual organisms that can interbreed and produce fertile offspring.

Examples:– humans– cats– wolves

Invasive species

Non-native organisms that are harmful to the ecosystem they invade.

Examples:– Kudzu vine to the southeastern U.S.– Caribbean tree frog to Hawaii

Drought

A period of dry weather caused by a lack of rain.

1. Define– Ecosystem– Species

2. Explain how the invasion of kudzu affects other plants and animals within the ecosystem.

3. Why might a change in an ecosystem affect populations of species within that ecosystem?

Review

Credits

• The Habitable Planet – Ecology Lab• How Stuff Works• Kudzu Covered Houses• neoK12• NOVA beta – Invasive Species Matching Game• Geography 4 Kids• USDA National Invasive Species Information Center• Unless otherwise noted, all photos are from the

internet and were labeled free to use, share, or modify, even commercially.

Kudzu, a vine native to Asia, was introduced to the United States in 1876. Eventually, it was used all over the South as a way to control soil erosion. Unfortunately, kudzu became a major problem. The climate of the southeastern United States is perfect for kudzu. With no natural predators in the area, it can grow up to a foot per day (~30 cm)! This invasive species grows over anything it touches, including trees, telephone poles, even houses!

An Invasion of Kudzu!