3.1 Ecosystems

Understanding Ecosystems

• Definition: A biological community of interacting organisms (biotic) and their physical environment (abiotic).
• Interaction: Energy and nutrients are transferred through these interactions.

Biotic Components

• Living parts of an ecosystem, categorized by nutrition:
  • Producers (Autotrophs): Produce their own food (e.g., plants via photosynthesis).
  • Consumers (Heterotrophs): Obtain food by eating other organisms (primary, secondary, tertiary).
  • Decomposers (Saprotrophs): Break down dead organic matter (e.g., bacteria, fungi).

Food Chain, Food Web, and Pyramid of Numbers

• Food Chain: Linear series of organisms where each is food for the next.
• Food Web: Interconnected food chains, showing complex feeding relationships.
• Pyramid of Numbers: Graphical representation of organism numbers at each trophic level (decreases up the chain).

Interdependence between Organisms

• Symbiosis: Close, long-term interaction between two different species.
• Parasitism: One organism (parasite) benefits at the expense of another (host).
• Predation: One organism (predator) kills and eats another (prey).

Abiotic Components

• Non-living chemical and physical parts of an ecosystem.
• Examples:
  • Air
  • Soil
  • Water
  • Climatic Factors: Sunlight, Temperature, Humidity, Wind.

Types of Ecosystems

• Terrestrial Ecosystems (Land-based):
  • Forest Ecosystems
  • Grassland Ecosystems
  • Desert Ecosystems
  • Tundra Ecosystems
• Aquatic Ecosystems (Water-based):
  • Freshwater Ecosystems (rivers, lakes, wetlands)
  • Marine Ecosystems (oceans, coral reefs)

Forest Ecosystem

• Flora: The plants of a particular region.
• Fauna: The animals of a particular region.