Chapter 21 Outline
Case Study: A Fragile Crust
Nutrient Requirements and Sources
CONCEPT 21.1 Nutrients enter ecosystems through the chemical breakdown of minerals in rocks or through fixation of gases in the atmosphere.
- Organisms have specific nutrient requirements
- Minerals and atmospheric gases are the ultimate sources of nutrients
Nutrient Transformations
CONCEPT 21.2 Chemical and biological transformations in ecosystems alter the chemical form and supply of nutrients.
- Decomposition is a key nutrient recycling process
- Microorganisms modify the chemical form of nutrients
- Plants can recycle nutrients internally
Nutrient Cycles and Losses
CONCEPT 21.3 Nutrients cycle repeatedly through the components of ecosystems.
- Nutrients cycle at different rates according to identity and ecosystem type
- Catchment studies measure losses of nutrients from ecosystems
- Long-term ecosystem development affects nutrient cycling and limitations on primary production
Nutrients in Aquatic Ecosystems
CONCEPT 21.4 Freshwater and marine ecosystems receive nutrient inputs from terrestrial ecosystems.
- Nutrients in streams and rivers cycle in spirals
- Nutrients cycle tightly in lake ecosystems
- Imports and upwelling are important to nutrient supply in marine ecosystems
Case Study Revisited: A Fragile Crust
Connections in Nature: Nutrients, Disturbance, and Invasive Species
