1. Ecosystems Unit Activity 4.3 How Fluxes Changes and Carrying Capacity
Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Ecosystems Unit Activity 4.3 How Fluxes Changes and Carrying Capacity
Image Credit: Craig Douglas, Michigan State University

2. Unit map
You are here
Use the instructional model to show students where they are in the course of the unit.
Show Slide 2 of the 4.3 How Fluxes Change and Carrying Capacity PPT.

3. Computer Model for Changing Fluxes
Read the handout to review the Constant Flux simulation and to learn about the Changing Fluxes Simulation.
How are the simulations different?
How do the fluxes change in the Changing Fluxes simulation?
Review the Constant Fluxes Model and introduce the Changing Fluxes Model.
Show Slide 3.
Pass out the 4.3 Computer Model for Changing Fluxes Handout to each student. In partners or as a whole class, have students read the handout. Discuss how the Constant Flux and Changing Fluxes Models are different. Review the idea of carrying capacity for Activity 2.4 and relate it to the photosynthesis flux.

4. The Simulation Show students how to use the simulation.
Show Slide 4 and open the simulation. Show students how to move the sliders and run an example. Point out the graphs and how they can slide the line of the graph to get data for a particular point in time.

5. Run 1 Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

6. Initial settings (0 years)
Run 1
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
500 kg
50 kg/yr
1 year kg
kg/yr
5 years
20 years
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

7. Initial settings (0 years)
Run 1
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
500 kg
50 kg/yr
1 year
523 kg
476 kg
73 kg/yr
95 kg/yr
5 years
590 kg
409 kg
69 kg/yr
81 kg/yr
20 years
672 kg
327 kg
63 kg/yr
65 kg/yr
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

8. Run 2 Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

9. Initial settings (0 years)
Run 2
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
800 kg
200 kg
50 kg/yr
1 year kg
kg/yr
5 years
20 years
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

10. Initial settings (0 years)
Run 2
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
800 kg
200 kg
50 kg/yr
1 year
791 kg
208 kg
41 kg/yr
5 years
761 kg
238 kg
54 kg/yr
47 kg/yr
20 years
706 kg
293 kg
60 kg/yr
58 kg/yr
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

11. Run 3 Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

12. Initial settings (0 years)
Run 3
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
500 kg
90 kg/yr
1 year kg
kg/yr
5 years
20 years
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

13. Initial settings (0 years)
Run 3
Initial settings (0 years)
Results of Run
CO2 pool
Organic pool
Carrying capacity
Time
Org. pool
Phs. flux
CR flux
500 kg
90 kg/yr
1 year
466 kg
533 kg
137 kg/yr
106 kg/yr
5 years
367 kg
632 kg
144 kg/yr
126 kg/yr
20 years
254 kg
745 kg
150 kg/yr
149 kg/yr
Students run the simulation (cont.)
Pass out the 4.3 Computer Model for Changing Fluxes Worksheet to each student. Have students follow the instructions to run the simulation. Students should record their data in the tables.
(Optional) Use slides 5-10 to discuss Run 1, 2, and 3 as a class. Students can complete the tables on slides 6, 9, and 12.

14. Discussion
What is the main setting that determines pool size after 20 years? Why?
What is the main setting that determines fluxes after 20 years? Why?
What is the limiting resource in a desert? Forest? Cornfield? Prairie?
Discuss the patterns.
Show Slide 14 of 4.3 How Fluxes Change and Carrying Capacity PPT. Have students share and discuss their answers to questions.