Changing Ecosystems

What will happen if seeds are watered with salty water instead of fresh water? Are plants growing at cool temperatures capable of storing as much energy as similar plants growing at warm temperatures? What happens to an ecosystem when one group of organisms increases or decreases in number.

Try it!

Your goal is to sprout seeds comparing two different types of water in the process.

Materials:

• Seeds (any type that sprout quickly will do)
• Plain water
• Salty water (make up your own and compare the amount of salt used with friends)
• Paper towels
• Two zip closure bags
• Marking pen

Procedure:

1. Place 20 seeds in salty water and 20 seeds in fresh water overnight.
2. The next day prepare two different paper towels as follows:
   • Moisten one with the salty water.
   • Moisten one with the plain water.
3. Remove the seeds from the salty water and place them on top of the paper towel soaked in the salty water.
4. Fold the paper towel over the top of the seeds so they are covered. (If possible, fold it again so it is in quarters.)
5. Slide the paper towel into a zip closure bag.
6. Label the bag "salty water."
7. Remove the seeds from the plain water and place them on top of the paper towel soaked in the plain water.
8. Fold the paper towel over the top of the seeds so they are covered. (If possible, fold it again so it is in quarters.)
9. Slide the paper towel into a zip closure bag.
10. Label the bag "plain water."
11. Place both bags in a warm (not too hot or too sunny) location.
12. After three to five days, open the bags and count the number of seeds in each bag that have sprouted.

Analysis:

1. What differences in sprouting did you observe?
2. Was the factor being tested in this experiment biotic or abiotic?
3. What was the factor?
4. Do you think all kinds of seeds would react the same way to a change in salt concentration?

Click here to check your answers.

Data Interpretation:

Now you get to analyze how another abiotic factor can change what goes on in an ecosystem.

Use a sheet of graph paper to graph the following data. Place the temperatures on the x-axis across the bottom of your graph and place the mg glucose/hour on the y-axis at the left of your graph.

Compare your graph with a sample graph.

Analysis:

1. What is the abiotic factor shown in the graph?
2. What is the biotic factor that is changes when the abiotic factor changes?
3. What does an increase in temperature do to the rate of sugar (glucose) production?
4. Why do you think the graph drops sharply at higher temperatures?

Check for our answers.

Application:

The photo below shows slices of a mat of microorganisms found in a hot spring at Yellowsone National Park. If you look closely you will notice layers of green, red and tan. Each layer contains different microorganisms. The organisms in each layer work with those in other layers to provide each other with the things they need to stay alive. In this situation, what do you think might happen if one kind of organism was suddenly destroyed? Could similar things happen in larger ecosystems?

You were correct if you guessed that the other microorganisms would be greatly affected if one kind was destroyed. Changes in populations, no matter how large or small, will have an effect on other populations and communities in the ecosystem.

Try it!

Design an experiment to test the effect of changing an abiotic or biotic factor on an ecosystem of your own. Search the Internet for "Bottle Biology" for some ideas and to see what other people have done. Share your research with family or friends.