It's About Time
The Nitrogen and Phosphorous Cycles
How do we affect the ecosystem, and what can we do to preserve it? Pupils explore chemicals that promote and inhibit plant growth, then discuss the importance of nitrogen and phosphorus to the survival of organisms and describe how...
Ohio State University
Ohio State University: Concepts of Plant Ecology
An advanced discussion of plant interactions and relationships. Energy flow, nutrient cycling and succession are discussed. Try the quiz to check your understanding.
Other
Marietta College: Ecosystems
Complete illustrated discussion of energy flow within ecosystems, including discussions of trophic levels, ecological pyramids, food chains and webs, biological magnification, and cycles.