1. Ecosystems Unit Activity 4.2 Changes in Ecosystems Over Time
Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Ecosystems Unit Activity 4.2 Changes in Ecosystems Over Time

2. Changes in Ecosystems over Time
We know ecosystems are comprised of carbon pools, and that carbon atoms move to and from these pools due to carbon-transforming processes like photosynthesis and cellular respiration. Now, we want to know how carbon pools are changing due to carbon-transforming processes over a specific time period. In other words, we want to investigate carbon FLUXES.
Credit: Craig Douglas, Michigan State University
Introduce two new groups of pools: organic and inorganic.
Explain that we will simplify the pools to look at just two: organic and inorganic. In this activity we will discuss fluxes that cause these two pools to change sizes.
Pass out Lesson 4.2 Carbon Fluxes Worksheet to each student.
Use Slides 2-5 of Lesson 4.2 Carbon Fluxes Presentation to show how we will simplify the ecosystem to two pools and two processes in order to think about how pools change size over time.
Tell students that in this Activity, they will keep track of carbon atoms as they move back and forth between the inorganic matter pool (atmosphere) and the organic matter pool (all other pools).

3. Inorganic vs organic Let’s simplify things…..
Carnivores
Let’s simplify things…..
instead of having 5 carbon pools (atmosphere, producers, herbivores, carnivores, soil), let’s look at just 2 carbon pools: organic and inorganic.
Organic Carbon
Inorganic Carbon
Atmosphere
Herbivores
Credit: Craig Douglas, Michigan State University
Introduce two new groups of pools: organic and inorganic.
Explain that we will simplify the pools to look at just two: organic and inorganic. In this activity we will discuss fluxes that cause these two pools to change sizes.
Pass out Lesson 4.2 Carbon Fluxes Worksheet to each student.
Use Slides 2-5 of Lesson 4.2 Carbon Fluxes Presentation to show how we will simplify the ecosystem to two pools and two processes in order to think about how pools change size over time.
Tell students that in this Activity, they will keep track of carbon atoms as they move back and forth between the inorganic matter pool (atmosphere) and the organic matter pool (all other pools).
Soil Carbon
Producers

4. Inorganic vs organic These two pools represent:
Organic carbon molecules that are stored in the producers, herbivores, carnivores, soil, and other living parts of the ecosystem
Inorganic carbon that is in the atmosphere in the form of CO2
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Introduce two new groups of pools: organic and inorganic.
Explain that we will simplify the pools to look at just two: organic and inorganic. In this activity we will discuss fluxes that cause these two pools to change sizes.
Pass out Lesson 4.2 Carbon Fluxes Worksheet to each student.
Use Slides 2-5 of Lesson 4.2 Carbon Fluxes Presentation to show how we will simplify the ecosystem to two pools and two processes in order to think about how pools change size over time.
Tell students that in this Activity, they will keep track of carbon atoms as they move back and forth between the inorganic matter pool (atmosphere) and the organic matter pool (all other pools).

5. Two process cause atoms to move from one pool to another.
Inorganic vs organic
Two process cause atoms to move from one pool to another.
Photosynthesis
Photosynthesis causes a flux of carbon atoms moving from the inorganic pool to the organic pool.
Cellular respiration causes a flux of carbon atoms moving from the organic pool to the inorganic pool.
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Introduce two new groups of pools: organic and inorganic.
Explain that we will simplify the pools to look at just two: organic and inorganic. In this activity we will discuss fluxes that cause these two pools to change sizes.
Pass out Lesson 4.2 Carbon Fluxes Worksheet to each student.
Use Slides 2-5 of Lesson 4.2 Carbon Fluxes Presentation to show how we will simplify the ecosystem to two pools and two processes in order to think about how pools change size over time.
Tell students that in this Activity, they will keep track of carbon atoms as they move back and forth between the inorganic matter pool (atmosphere) and the organic matter pool (all other pools).
inorganic carbon
Cellular Respiration

6. What is a “flux?” Photosynthesis Cellular Respiration
The amount of carbon that moves from one pool to another in a certain amount of time is called a “flux”.
Photosynthesis
Inorganic Carbon
In these slides we are counting individual carbon atoms, but real ecosystems have far too many carbon atoms to count.  For example, the organic matter in a small meadow contains more than 10,000,000,000,000,000,000,000,000,000 carbon atoms!
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides 6-8 to introduce the idea of a flux. Use the information on these slides to have students think about what causes a flux from one pool to another.
inorganic carbon
Cellular Respiration

7. Fluxes of carbon…
…change rates depending on what is happening in an ecosystem.
This means that if the ecosystem changes, the rate of the fluxes might be slower or faster.
…influence the number of carbon atoms in pools over time.
This means that pools of carbon can only get bigger or smaller if a flux occurs.
Use Slides 6-8 to introduce the idea of a flux. Use the information on these slides to have students think about what causes a flux from one pool to another.

8. Carbon Pools Change Size Over Time
If the organic pool has more carbon atoms than it did before, that means there is more living organic matter in the ecosystem than there was before. Remember the rule: Atoms last forever! If they moved into the organic pool they must have come from somewhere.
Photosynthesis
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides 6-8 to introduce the idea of a flux. Use the information on these slides to have students think about what causes a flux from one pool to another.
inorganic carbon
Cellular Respiration

9. Let’s Make a Graph
Fluxes occur over time. In this Activity, we will record how carbon atoms move from one pool to another over two years. We will do this under four environmental scenarios:
Scenario 1: fluxes are balanced
Scenario 2: winter and summer
Scenario 3: trees are planted
Scenario 4: drought
Introduce students to the 4 scenarios of the Activity.
A flux occurs over time. Here, we will consider carbon fluxes over the period of one year. Have students record the fluxes, or the number of carbon atoms that move between pools in one year.
Use Slide 9 to introduce the Activity’s main task: making graphs that show carbon fluxes between the atmosphere (inorganic carbon) and producer (organic carbon) pools.

10. Scenario 1: Fluxes are balanced
During this year, fluxes are balanced!
This means that photosynthesis happens at the same rate as cellular respiration.
Photosynthesis
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State UniversityHave students complete Scenario 1: Fluxes are balanced.
Use Slides for Scenario 1. Have students play through the first scenario, in which carbon fluxes are balanced. This round includes scaffolding for students and walks them through the graphing process. The following three scenarios provide less support, so use the first round to assess how well students are translating the data from the presentation onto the graphs on their worksheet.
Use Slides to introduce students to the fluxes in this scenario. Because the fluxes are balanced, photosynthesis and cellular respiration occur at the same rate.
inorganic carbon
Cellular Respiration

11. Scenario 1: Fluxes are balanced
Every year, 200 carbon atoms go through photosynthesis.
This means plants are growing!
Every year 200 carbon atoms go through cellular respiration by plants, animals or decomposers. This means plants, animals, or decomposers are moving!
Photosynthesis
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to introduce students to the fluxes in this scenario. Because the fluxes are balanced, photosynthesis and cellular respiration occur at the same rate.
inorganic carbon
Cellular Respiration

12. Scenario 1: Start Record data for the Start:
Make a Prediction: how will pools change size in 2 years?
200 per year
Record data for the Start:
800 carbon atoms start in the inorganic pool.
400 carbon atoms start in the organic pool.
Photosynthesis
800
400
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Show Slide 12 to have students make a prediction about how the pools will change in two years if the fluxes are balanced.
Cellular Respiration
200 per year

13. Scenario 1: Fluxes are Balanced
On your worksheet, use the triangle, circle, and square shapes to show how many carbon atoms are in each pool at the beginning of the scenario. Then, record data for Year 1 and Year 2.
1400
1200
1000
800
600
400
200
Number of Carbon Atoms
Start
Year 1
Year 2
Scenario 1: Fluxes are Balanced
400 atoms start in the organic pool
800 atoms start in the inorganic pool
There are a total of 1200 atoms in both pools
= Total Carbon Atoms
= Atoms in Organic Pool
= Atoms in Inorganic Pool
Credit: Michigan State University
Use Slide 13 to guide them through their initial recordings. Have them record their “start” data on their worksheet for scenario 1. They will use a square, circle, and triangle to represent the number of carbon atoms in each pool. Slide 13 shows what their chart should look like at the beginning of round 1.

14. Scenario 1: Year 1
Record data for Year 1: 200 carbon atoms move into the organic pool. 200 carbon atoms move out of the organic pool.
Photosynthesis
800
800
790
790
810
800
800
410
400
400
400
390
410
400
170
180
190
160
200
100
150
120
110
140
130 30 20 40 10 50 90 80 70 60
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Show the animation on Slide 14 to help students begin to complete the data in the graphs on their worksheet. Use Slides to present new data for the students to record on their graph.
inorganic carbon
200
190
110
130
120
100
140
150
170
160
180 50 30 20 10 90 40 80 70 60
Cellular Respiration

15. Scenario 1: Year 2
Record data for Year 2: 200 carbon atoms move into the organic pool. 200 carbon atoms move out of the organic pool.
Photosynthesis
800
800
790
790
810
800
800
410
400
400
400
390
410
400
170
180
190
160
200
100
150
120
110
140
130 30 20 40 10 50 90 80 70 60
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to present new data for the students to record on their graph.
inorganic carbon
200
190
110
130
120
100
140
150
170
160
180 50 30 20 10 90 40 80 70 60
Cellular Respiration

16. Scenario 1: Compare your results!
Draw lines connecting the triangles on your graph. Do the same for the squares, and then the circles.
Summarize what is happening to the size of the pools in your own words to a partner.
Compare your graph with your partner’s graph. Are they the same? Why or why not?
Finally, display Slides to have students compare their results to their partner’s graph.

17. Scenario 1: Compare your results!
1400
1200
1000
800
600
400
200
Number of Carbon Atoms
Start
Year 1
Year 2
Scenario 1: Fluxes are Balanced
400 atoms start in the organic pool
800 atoms start in the inorganic pool
There are a total of 1200 atoms in both pools
= Total Carbon Atoms
= Atoms in Organic Pool
= Atoms in Inorganic Pool
Finally, display Slides to have students compare their results to their partner’s graph.

18. Scenario 2: Summer to Winter
How do you think carbon fluxes change during summer and winter?
Have students complete scenario 2: Winter and Summer
Have students record data for the final scenarios, and also make predictions about the future.
Use Slide 18 to introduce Scenario 2: summer and winter.
Credit: Hannah Miller, Michigan State University

19. Scenario 2: Start (End of Winter)
Record your data for the start, which is the end of winter: 800 carbon atoms start in the inorganic pool. 400 carbon atoms start in the organic pool.
Photosynthesis
700
773
707
733
800
767
760
493
500
467
427
440
433
400
213
250
200
238
225
113
100
188
138
125
175
163
150 25 13 50 38 88 75 63
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Display Slide 19 to have students complete the “start” data on their Scenario 2 graph on their worksheet.
143
150
135
113
105
120
128 38 45 30 23 15 98 53 90 60 83 75 68 8
Cellular Respiration

20. Scenario 2: Summer 1
In the summer, plants are growing and doing lots of photosynthesis! They also do some cellular respiration.
Photosynthesis
Record your data for the summer 1: 250 carbon atoms move into the organic pool. 150 carbon atoms move out of the organic pool.
700
767
707
733
773
800
760
493
500
467
427
400
440
433
238
213
250
225
125
113
100
200
138
150
175
188
163 38 13 25 50 63 88 75
Inorganic Carbon
Organic Carbon
Use Slides to provide students with data for the first two years of the scenario.
Have students use what they observed in the first two years of the graph to predict what will happen in the final three years. Have students record their predictions.
Image credit: Hannah Miller, Michigan State University
Graphics Credit: Craig Douglas, Michigan State University
150
143
120
105
113
128
135 38 45 30 23 15 98 53 90 60 83 75 68 8
Cellular Respiration

21. Scenario 2: Winter 1 Record your data for the winter 1:
In the winter photosynthesis slows down, because many trees lose their leaves. Plants continue doing cellular respiration in winter.
Photosynthesis
793
800
767
740
727
700
733
Record your data for the winter 1:
20 carbon atoms move into the organic pool.
120 carbon atoms move out of the organic pool.
433
400
407
500
460
473
467 19 18 20 17 11 10 13 12 14 15 16 4 3 2 1 5 6 9 8 7
Inorganic Carbon
Organic Carbon
Use Slides to provide students with data for the first two years of the scenario.
Have students use what they observed in the first two years of the graph to predict what will happen in the final three years. Have students record their predictions.
Image credit: Hannah Miller, Michigan State University
Graphics Credit: Craig Douglas, Michigan State University
114
108
102
120 30 42 48 36 24 12 18 96 54 84 90 60 78 72 66 6
Cellular Respiration

22. Scenario 2: Summer 2
It’s summer again!
Photosynthesis
Record your data for the summer 2: 250 carbon atoms move into the organic pool. 150 carbon atoms move out of the organic pool.
700
767
707
733
773
800
760
493
500
467
427
400
440
433
238
213
250
225
125
113
100
200
138
150
175
188
163 38 13 25 50 63 88 75
Inorganic Carbon
Organic Carbon
Use Slides to provide students with data for the first two years of the scenario.
Have students use what they observed in the first two years of the graph to predict what will happen in the final three years. Have students record their predictions.
Image credit: Hannah Miller, Michigan State University
Graphics Credit: Craig Douglas, Michigan State University
150
143
120
105
113
128
135 38 45 30 23 15 98 53 90 60 83 75 68 8
Cellular Respiration

23. Scenario 2: Winter 2 Record your data for the winter 2:
It’s winter again!
Photosynthesis
793
800
767
740
727
700
733
Record your data for the winter 2:
20 carbon atoms move into the organic pool.
120 carbon atoms move out of the organic pool.
433
400
407
500
460
473
467 19 18 20 17 11 10 13 12 14 15 16 4 3 2 1 5 6 9 8 7
Inorganic Carbon
Organic Carbon
Use Slides to provide students with data for the first two years of the scenario.
Have students use what they observed in the first two years of the graph to predict what will happen in the final three years. Have students record their predictions.
Image credit: Hannah Miller, Michigan State University
Graphics Credit: Craig Douglas, Michigan State University
114
108
102
120 30 42 48 36 24 12 18 96 54 84 90 60 78 72 66 6
Cellular Respiration

24. So carbon pools change size. Even throughout the seasons of one year!
End of Summer
End of Winter
Photosynthesis
Photosynthesis
700
800
500
400
Inorganic Carbon
Inorganic Carbon
Organic Carbon
Organic Carbon
Image credit: Hannah Miller, Michigan State University
Graphics and animations credit: Craig Douglas, Michigan State University
Use Slides to have students discuss the patterns they see.
Cellular Respiration
Cellular Respiration

25. Make a prediction! On the last page of your worksheet, complete data for 3 more years of Scenario 4.
End of Summer
End of Winter
Photosynthesis
Photosynthesis
700
800
500
400
Inorganic Carbon
Inorganic Carbon
Organic Carbon
Organic Carbon
Use Slides to have students discuss the patterns they see.
Image credit: Hannah Miller, Michigan State University
Graphics Credit: Craig Douglas, Michigan State University
Cellular Respiration
Cellular Respiration

26. Scenario 2: Compare your results!
You have data for years 1 and 2. Make a prediction about what will happen in years 3, 4, and 5 in your graph for Scenario 2.
Draw lines connecting the triangles on your graph. Do the same for the squares, and then the circles.
Summarize what is happening to the size of the pools in your own words to a partner.
Compare your graph with your partner’s graph. Are they the same? Why or why not?
Use Slides to have students discuss the patterns they see.

27. Scenario 3: Trees are planted
Some trees were planted in an abandoned cornfield! This means that trees are taking carbon atoms out of the air and adding the atoms to their bodies. Photosynthesis happens at a faster rate than respiration.
Photosynthesis
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
inorganic carbon
Cellular Respiration

28. Scenario 3: Trees are planted
Make a prediction: how will pools change size in 2 years?
300 per year
Photosynthesis
800
400
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
Cellular Respiration
200 per year

29. Scenario 3: Start
300 per year
Record data for the Start: 800 carbon atoms start in the inorganic pool. 400 carbon atoms start in the organic pool.
Photosynthesis
800
400
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
Cellular Respiration
200 per year

30. Scenario 3: Year 1
Record your data for Year 1: 300 carbon atoms move into the organic pool 200 carbon atoms move out of the organic pool
Photosynthesis
700
707
800
773
733
760
767
493
500
467
427
440
400
433
255
270
285
240
300
120
105
225
135
150
210
180
195
165 15 30 45 75 90 60
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
190
200
180
110
120
100
130
140
160
150
170 50 30 20 10 90 40 80 70 60
Cellular Respiration

31. Round 3: Trees are planted: Year 2
Record your data for Year 2: 300 more carbon atoms move into the organic pool 200 more carbon atoms move out of the organic pool
Photosynthesis
600
607
700
673
633
660
667
593
600
567
527
540
500
533
255
270
285
240
300
120
105
225
135
150
210
180
195
165 15 30 45 75 90 60
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
190
200
180
110
120
100
130
140
160
150
170 50 30 20 10 90 40 80 70 60
Cellular Respiration

32. Scenario 3: Compare your results!
Draw lines connecting the triangles on your graph. Do the same for the squares, and then the circles.
Summarize what is happening to the size of the pools in your own words to a partner.
Compare your graph with your partner’s graph. Are they the same? Why or why not?
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.

33. Scenario 4: Drought
Drought! It hasn’t rained for months and trees are dry and dying.
This means that photosynthesis happens less, but plants, animals and decomposers still do cellular respiration.
Photosynthesis
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
inorganic carbon
Cellular Respiration

34. Scenario 4: Drought
Predict how pool sizes will change after a few years
100 per year
Photosynthesis
800
400
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
Cellular Respiration
200 per year

35. Scenario 4: Start
Record data for the Start: 800 carbon atoms start in the inorganic pool. 400 carbon atoms start in the organic pool.
Photosynthesis
800
400
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
Cellular Respiration

36. Scenario 4: Year 1
Record data for Year 1: 100 carbon atoms move into the organic pool 200 carbon atoms move out of the organic pool
Photosynthesis
800
893
827
900
867
840
833
300
333
307
367
400
373
360
100 35 40 45 30 25 10 65 20 50 15 75 70 55 80 85 60 95 90 5
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
190
180
200
140
110
100
120
130
160
150
170 50 30 20 10 90 40 80 70 60
Cellular Respiration

37. Scenario 4: Year 2
Record data for Year 2: 300 more carbon atoms move into the organic pool. 200 more carbon atoms move out of the organic pool.
Photosynthesis
1000
940
967
900
993
933
927
200
207
233
273
300
267
260
100 35 40 45 30 25 10 65 20 50 15 75 70 55 80 85 60 95 90 5
Inorganic Carbon
Organic Carbon
Credit: Craig Douglas, Michigan State University
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.
190
180
200
140
110
100
120
130
160
150
170 50 30 20 10 90 40 80 70 60
Cellular Respiration

38. Scenario 4: Compare your results!
Draw lines connecting the triangles on your graph. Do the same for the squares, and then the circles.
Summarize what is happening to the size of the pools in your own words to a partner.
Compare your graph with your partner’s graph. Are they the same? Why or why not?
Use Slides to complete the Scenarios 3 and 4. Each scenario has an accompanying graph on the worksheet.