1. Cycles of Matter
Unlike the one-way flow of energy, matter is recycled within and between ecosystems
Biogeochemical cycles: Elements, chemical compounds, and other forms of matter pass from one organism to another and from one part of the biosphere to another

2. The Water Cycle
Evaporation: The process by which water changes from liquid to an atmospheric gas. 
Transpiration: Water evaporating from the leaves of plants.
What might interrupt/change
this cycle?

3. Nutrient Cycles
Nutrients: Chemical substances an organism needs to sustain life. 
Passed between organisms and the environment through biogeochemical cycles.
The carbon cycle, nitrogen cycle, and phosphorus cycle are especially important.
Oxygen involved in all.

4. The Carbon Cycle Carbon plays many roles.
calcium carbonate (CaCO3) in animal skeletons and some rock types
CO2 gas in atmosphere, used by plants (Carbohydrates)
Greenhouse gas that keeps us warm and cozy.

5. The Nitrogen Cycle All organisms require nitrogen:
DNA & RNA, Amino Acids (Proteins)
Nitrogen gas (N2) makes up 78 percent of Earth's atmosphere. (Breath it in)
In-soil nitrogen fixation is necessary for plants to obtain usable form
nitrogen fixation: Bacteria in soil and on roots of plants called legumes, convert nitrogen gas into ammonia
Other soil bacteria convert nitrates into nitrogen gas in a process called denitrification. This process releases nitrogen into the atmosphere once again.

6. The Phosphorus Cycle Phosphorus essential in DNA & RNA
Less common on the biosphere
Some parts of phosphorus cycle are very slow

7. Nutrient Limitation
primary productivity: rate at which organic matter is created by producers in an ecosystem
When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly, this substance is called a limiting nutrient.

8. Nutrient Limitation
When a limiting nutrient for an ecosystem suddenly comes in in large quantities, this can boost primary production so much that the system is disrupted:
Algal Bloom: an immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient
Often a result of agricultural run-off