Lecture 24 Exam Questions

Explain the idea of stabilization wedges, and list a few examples.

Describe lumped-parameter ecosystem models and individual-based ecosystem models and the strengths and weaknesses of each.

Exam Questions (Classes 12/7-12/9 Lectures 23/24)

1) What are the three classes of processes that cause carbon to cycle through aquatic and terrestrial systems?

1)Assimilatory and dissimilatory reactions of carbon (photosynthesis and respiration)
2) Co2 exchange between atmosphere and oceans
3) sedimentation of carbonates

2) Why/how has atmospheric CO2 concentrations decreased since the Paleozoic period and why will it be unlikely to reach this level again?

Answer: Initial Decrease due to sharp increase in rate of weathering of terrestrial environments (forests on land) and sedimentation (deposits) of organic coal beds.

Most geologic carbon is bound up in limestone sediments, returned to earth’s atmosphere very slowly as below continental plates etc

3) What are successful ways to improve soil productivity in tropic areas where land has been cleared for cash crops?

Answer: Limiting exploitation of resource pops to maximize sustainable yields
Increasing agricultural intensity on land that will bear it
Improving distribution between areas of production and areas of need

What is a stabilization wedge?

• Is a triangular structure that reduces/redirects Co2 output considerably over the next 50 years by 25 Gigatons. The triangle is made up of different wedges (7 to 8) that represent different solutions to this problem.
• Different categories such as nuclear fission. According to sources 15 strategies in 4 categories. The categories and number of solutions in each are:
1. Energy efficiency and conservation (4);
2. Fuel Switching (1), CO2 Capture and Storage (3);
3. Renewable Fuels and Electricity (4), Forest and Soil Storage (2);
4. Nuclear Fission (1)

You want to create a nature reserve to protect a variety of different species, some of whom are endangered. What kind of conditions would you want to guarantee the survival of various species:

• Minimize edge and fragmentation effects
• Internal Fragmentation: includes internal roads for logging, farming areas etc. within reserve
• Rounded edges minimize edge/elongated maximize
• Aggregate smaller areas into larger conservation blocs to create matrix of areas of high and low conservation status

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