Ecological Cycles.

1. Biogeochemical Cycles: The Role of Soil Microorganisms. Read about Carbon, Nitrogen, Sulfur, and Phosphorus cycles.
2. Introduction to the Global Carbon Cycle.
3. Carbon Storage and Accumulation in Forest Ecosystems.
4. The Ocean Carbon Cycle.
5. Nitrogen Fixation. Read about it here.
6. Carbon and Carbonite Metabolism in Coastal Aquatic Ecosystems. More on carbon cycling.
7. See a quick energy flow diagram here.
8. See a quick discussion of productivity.