“Thinking in Systems” PART 2 - manipulating a system
The idea of this activity is to continue development of a systems model created in Thinking in Systems Part 1) with inputs, outputs, stocks (or “pools”), and flows (or “fluxes”). In this part, you will begin to manipulate your system in ways comparable to how traditional farmers discovered techniques to augment the cycle of phosphorus.
Recall the simple system you developed in Part 1.
The example system used in Part 1 was a city bike share system, where stations for specific types of bikes are installed throughout a city, bikes are shuffled around the city by users making one-way trips from place to place, and bicycles leave the system either by getting stolen or decommissioned. In this exercise, you will be asked to consider ways to augment your system to allow for higher productivity or operability within that system while operating within limits to growth that you identify.
1. Think about all the dimensions of your system from start to finish. Write down all the pressures for growth on the system as well as all the limits to growth within that system.
Example response from bike share system:
Pressures for growth:
Increasing number of users (people) using the bike share system
Many riders take similar routes, making scarce availability of bikes and/or docking stations
Increasing theft or disrepair of bicycles within system
Limits to growth:
Cost of introducing new bicycles and docking stations within system
- Availability of sources to manufacture new bikes and docking stations
Available real estate for docking station expansion
2. Identify strategies that respond to each of the pressures for growth you listed and that are sensitive to the limits to growth you listed. Think about the strategies used in traditional agriculture that Tim Crews described as analogies to strategies that you may choose to implement in your system.
3. Augment your system map to describe how strategies affect the performance of the system. Use additional visuals as needed.
4. When you have finished, graph a potential change within your system based on one of the pressures or limits you described. In the bike system example, you might project growth of bike numbers if the population grows by 10% over the next 15 years. What other factors might play a role and keep your line from being a simple increase or decrease? For our bike share program, an increase in population might also lead to an increase in bike theft.
If you were graphing the current phosphorus cycle, do you think that the pool of phosphorus in the soil would be growing, shrinking, or neither? What are the factors influencing this system?
5. How is your system similar to a natural system like the phosphorus cycle? How is it different? Share your ideas with a friend or record them in your science journal.