Ecosystems. Why might a change in an ecosystem affect populations of species within that ecosystem?. Introduction.
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.
What is an ecosystem?
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.
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A Delicate Balance
The balance of an ecosystem is very delicate! Changes to the ecosystem, such as the introduction of a new speciesor drought, can be disastrous to all organisms within the ecosystem.
Let’s Look at an Example
Think About It
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.
Images courtesy of Jack and June Anthony of jjanthony.com
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Click here to play a quick game about other invasive species
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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
Part A) Simulating a stable ecosystem:
Click on All Off.
Click on Plant C (the third plant in the row) and select it from the menu.
Click on Herbivore A (the first herbivore in the row) and set it to eat Plant C.
Click on Omnivore A (the first omnivore in the row) and set it to eat Herbivore A.
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:
Click on Reset. (Plant C, Herbivore A, and Omnivore A should still be connected in a food chain.)
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.
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)
A community of living and nonliving things that function together.
A group of individual organisms that can interbreed and produce fertile offspring.
Non-native organisms that are harmful to the ecosystem they invade.
A period of dry weather caused by a lack of rain.
An Invasion of Kudzu!
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 invasivespeciesgrows over anything it touches, including trees, telephone poles, even houses!