Unit 8: Energy Flow and Ecosystem Dynamics

Energy transfer follows the 10% rule—only about 10% of energy is passed to the next trophic level, while the rest is lost as heat.
Trophic levels:
- Producers (Autotrophs) – Convert sunlight into chemical energy via photosynthesis (e.g., plants, algae).
- Primary Consumers (Herbivores) – Eat producers (e.g., rabbits, deer).
- Secondary Consumers (Carnivores/Omnivores) – Eat herbivores (e.g., snakes, foxes).
- Tertiary Consumers (Apex Predators) – Eat secondary consumers (e.g., hawks, wolves).

Show the relative amount of energy at each trophic level.
Types:
- Energy pyramid – Displays energy flow (measured in kcal or joules).
- Biomass pyramid – Shows the mass of organisms at each level.
- Numbers pyramid – Shows the number of individuals at each level.

Definition: Non-native species that disrupt ecosystems by outcompeting native species.
Examples:
- Kudzu vine (USA) – Overgrows and smothers native plants.
- Zebra mussels – Outcompete native aquatic species.
Impact: Can cause biodiversity loss, habitat destruction, and economic damage.

The gradual change in ecosystems over time.
Two types:
- Primary Succession – Starts from barren land with no soil (e.g., volcanic islands, glaciers retreating).
- Secondary Succession – Occurs after a disturbance (e.g., fire, flood) but soil remains intact.
Pioneer species: First organisms to colonize (e.g., lichens, mosses).

Factors that restrict population growth.
Types:
- Density-dependent factors – Affected by population size (e.g., competition, disease, predation).
- Density-independent factors – Affect populations regardless of size (e.g., natural disasters, climate change).

Trophic levels relate to photosynthesis (Unit 7) since producers rely on sunlight to create energy.
Invasive species can disrupt biodiversity (Unit 9) by altering population dynamics.
Ecological succession is influenced by environmental cycles (Unit 6) such as carbon and nitrogen cycles.