AP Environmental Science Unit 2 Review

Introduction

• Instructor: Mr. Smedes
• Focus on practicing writing style for the AP Environmental Science exam (APES).
• Importance of understanding Unit 2 concepts thoroughly.

Key Topics Covered

Biodiversity

• Definition: Diversity of life forms in an ecosystem.
• Three Levels:
  • Genetic Biodiversity: Variance of genes within a population; important for adaptability.
  • Species Biodiversity: Diversity of organisms in an ecosystem.
    • Species Richness: Count of different species.
    • Species Evenness: Balance of species population sizes.
  • Ecosystem Biodiversity: Variance of ecosystems within an area.

Benefits of Biodiversity

• Genetic diversity helps populations adapt to environmental changes.
• Species diversity fosters ecosystem resilience to disturbances.
• Ecosystem diversity supports broader biome resilience.

Ecosystem Services

• Provisioning Services: Resources provided by ecosystems (e.g., wood).
• Supporting Services: Processes aiding human activities (e.g., pollination).
• Regulating Services: Ecosystem roles in stabilizing environmental factors (e.g., carbon sequestration by trees).
• Cultural Services: Recreational and intellectual benefits (e.g., tourism).

Human Impact

• Disruption of ecosystem services, exemplified by events like oil spills.

Island Biogeography

• Influence of distance from mainland and island size on species richness.
• Specialist Species: More prevalent on islands, vulnerable to invasives.
  • Case study: Dodo bird extinction.

Ecological Tolerance

• Range of conditions an organism can endure.
• Zones:
  • Optimal Range: Ideal conditions for growth and survival.
  • Zone of Physiological Stress: Limited survival.
  • Zone of Intolerance: Conditions leading to death.

Natural Ecosystem Disturbances

• Periodic: Regular e.g., rainy season.
• Episodic: Occur under specific conditions e.g., hurricanes.
• Random: Unpredictable e.g., asteroid impacts.

Earth's Natural Climate Change

• Milankovitch Cycles: Natural orbital changes causing climate cycles over tens of thousands of years.
• Impact on sea levels and ecosystems.

Adaptation and Evolution

• Genetic mutations leading to survival advantages.
• Example: Development of opposable thumbs in early hominids.

Ecological Succession

• Primary Succession: Colonization of bare rock by pioneer species.
• Secondary Succession: Recovery of soil-based ecosystems post-disturbance.

Keystone Species

• Vital for ecosystem function; their removal can cause ecosystem collapse.
  • Examples: Wolves, beavers, mangroves.

Conclusion

• Emphasis on understanding vocabulary and concepts.
• Encouragement to "think like a mountain and write like a scholar" for exam preparation.