Ecosystems

Ecosystems

Definition of Ecosystem

• An ecosystem encompasses all organisms and nonliving components within a specific area.

Components of Ecosystem

• An ecosystem includes both biotic and abiotic factors:

  • Biotic Factors: Living things

  • Examples:

    • Plants

    • Animals

    • Protists

    • Fungi

    • Bacteria

  • Abiotic Factors: Non-living things

  • Examples:

    • Soil

    • Water

    • Light

    • Air

    • Minerals

Food Chains and Food Webs

Types of Food Chains

• Photosynthetic Food Chain

  • Sunlight is the primary energy source.

  • Involves producers, primarily green plants with chloroplasts utilizing light energy to create carbon compounds.

• Chemosynthetic Food Chain

  • Involves bacteria that obtain energy from sulfur compounds (sulfide energy).

  • Typically associated with environments like hydrothermal vents.

Trophic Levels

• Organisms in an ecosystem are categorized into trophic levels based on their role in the food chain:

  • 1st Trophic Level (Producers):

  • Organisms that produce their own food (e.g., green plants).

  • 2nd Trophic Level (Primary Consumers):

  • Herbivores that consume producers.

  • 3rd Trophic Level (Secondary Consumers):

  • Carnivores that eat primary consumers.

  • 4th Trophic Level (Tertiary Consumers):

  • Apex predators that eat secondary consumers (e.g., vultures, eagles, lions, and tigers).

  • Decomposers:

  • Organisms such as bacteria and fungi that break down dead organic matter, returning nutrients to the soil.

Food Chains vs. Food Webs

• Food Chain:

  • A linear sequence showing the flow of energy from one trophic level to the next.

  • Involves one organism at each level.

• Food Web:

  • More complex networks involving multiple organisms at various trophic levels, illustrating interrelated food chains.

Ecological Pyramids

Ecological Efficiency

• Refers to the energy transfer efficiency from one trophic level to another.

• Example of Energy Distribution (in Joules):

  • Primary Producers (1st level): 1,000,000 J of sunlight

  • Primary Consumers (2nd level): 100,000 J

  • Secondary Consumers (3rd level): 10,000 J

  • Tertiary Consumers (4th level): 1,000 J

Energy Loss in Trophic Levels

• Approximately 90% of energy is lost as it moves through trophic levels due to respiration, growth, and waste:

  • Example:

  • Plant material consumed by a caterpillar (200 J):

    • Feces: 100 J

    • Growth: 33 J

    • Cellular Respiration: 67 J

Pyramid of Biomass

• Biomass is defined as the total amount of living tissue within a given trophic level.

• The pyramid of biomass visually represents the relative amounts of organic matter available at each trophic level, demonstrating how biomass decreases from producers to apex predators.