Ecosystem Dynamics Chapter 2

Ecosystem Overview

• An ecosystem integrates all living (biotic) and non-living (abiotic) factors of the environment.
• Defined by Sir Arthur G. Tansley in 1935 and further elaborated by Odum in 1974, focusing on energy flow, trophic structure, biodiversity, and material cycles.

Ecosystem Components

• Biotic Components (Living)

  • Producers (Autotrophs): Organisms that produce their own food, forming the base of the food web.
  • Consumers (Heterotrophs): Organisms that rely on others for food, categorized into:
    • Primary consumers: feed on producers.
    • Secondary consumers: feed on primary consumers.
    • Tertiary consumers: feed on secondary consumers.
  • Decomposers (Detritivores): Break down dead organic matter and recycle nutrients back into the ecosystem.

• Abiotic Components (Non-living)

  • Include physical and chemical factors influencing the environment, such as:
    • Climate
    • Soil
    • Water
    • Light
    • Wind
    • Nutrients
    • Topography

Ecosystem Structure and Function

• Refers to the spatial relationships of elements within an ecosystem.
• Vertical gradients in structure are influenced by abiotic factors like wind, light, humidity, and temperature.
• Stratification has been correlated with biodiversity:
  • Birds are affected by foliage density.
  • Bats are influenced by canopy openness.
  • Small mammals relate to canopy cover and microhabitat distribution.

Energy Flow and Thermodynamics

• Energy flows through ecosystems, usually starting with sunlight captured by producers.
• Thermodynamics laws govern energy exchanges:
  • Energy cannot be created or destroyed, only transformed.
  • Energy transformations are not 100% efficient, leading to energy loss at each trophic level.

Food Chains and Food Webs

• Illustrate energy transfer within an ecosystem.
• Trophic levels denote the position of organisms in a food chain:
  • Level 1: Producers
  • Level 2: Primary consumers
  • Level 3: Secondary consumers
  • Level 4: Tertiary consumers

Ecosystem Types and Biomes

• Major types of ecosystems include forests, deserts, grasslands, aquatic systems, etc.
• Biomes are large ecological areas classified by distinct climates, flora, and fauna.