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Levels of Organization in an Ecosystem

  • Individual Organism: The basic unit of study in ecology, representing a single living thing.

  • Population: A group of individuals of the same species living in the same area.

  • Community: All the different populations that live together in a defined area.

  • Ecosystem: A community plus the abiotic factors that affect it.

  • Biome: A group of ecosystems that share similar climates and organisms.

  • Biosphere: The global sum of all ecosystems, where life exists.

Factors Affecting Organism Distribution

  • Abiotic Factors: Non-living components that influence life.

    • Light Intensity: Affects photosynthesis and plant growth.

    • Temperature: Influences metabolic rates in organisms.

    • Moisture Levels: Essential for survival; influences habitat types.

    • Soil pH and Mineral Content: Affects plant nutrition.

    • Wind Intensity and Direction: Influences temperature and moisture.

    • Carbon Dioxide Levels: Important for plant photosynthesis.

    • Oxygen Levels: Critical for aquatic organisms.

Abiotic Factors

  • Definition: Non-living parts of the environment crucial to the survival of living organisms.

  • Common Examples:

    • Light intensity

    • Temperature

    • Moisture levels (water)

    • Soil pH and mineral content

    • Wind intensity and direction

    • Carbon dioxide levels for plants

    • Oxygen levels for aquatic animals

Biotic Factors

  • Definition: Living components that influence the community.

  • Key Biotic Influences:

    • Availability of food

    • New predators arriving

    • New pathogens

    • Competition between species can limit reproduction.

Ecosystems

  • Interdependencies: Plants and animals within an ecosystem rely on one another for various resources.

Types of Succession

Primary Succession

  • Definition: Begins in environments lacking soil.

  • Examples:

    • Newly formed volcanic rock

    • Glacial retreats exposing bare rock

    • Sand dunes

Secondary Succession

  • Definition: Occurs when an existing ecosystem is disturbed but soil remains.

  • Examples:

    • Following forest fires

    • After floods

    • Following hurricanes

    • Human activities (farming, deforestation)

Key Differences Between Primary and Secondary Succession

  1. Starting Point: Primary lacks soil; secondary starts with existing soil.

  2. Speed: Primary is slower due to soil formation; secondary is faster due to existing nutrients.

  3. Pioneer Species: Primary succession begins with lichens/mosses; secondary with grasses and fast-growing plants.

Trophic Levels

  • Definition: Levels in a food chain that represent energy transfer between organisms.

Energy Flow in Trophic Levels

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

  • Primary Consumers: Herbivores that eat producers.

  • Secondary Consumers: Organisms that eat primary consumers (carnivores).

  • Tertiary Consumers: Organisms that eat secondary consumers.

Food Chains & Food Webs

  • Food Chain: Linear sequence of organisms where each is eaten by the next.

  • Food Web: Complex network of interconnected food chains.

Interspecific Interactions

Types of Interactions

  1. Competition: Involves different species competing for the same resources. Represented as (-/-).

    • Examples:

      • Plants competing for sunlight.

      • Fish competing for food in coral reefs.

  2. Predation: One species (predator) hunts another (prey). Represented as (+/-).

    • Examples:

      • Lions hunting zebras.

  3. Symbiosis: Close, long-term interactions.

    • Parasitism: One benefits at the other's cost (e.g., ticks on dogs). (+/-)

    • Mutualism: Both benefit (e.g., clownfish and sea anemones). (+/+)

    • Commensalism: One benefits, the other unaffected (e.g., remora with sharks). (+/0)

Ecological Pyramids

Types

  1. Pyramid of Numbers: Shows the number of organisms at each trophic level.

  2. Pyramid of Biomass: Represents the total mass of living matter at each level.

  3. Pyramid of Energy: Illustrates the energy flow through the food chain.

Biomass Transfer

  • Percentage: Approximately 10% of biomass transfers to the next trophic level; 90% used in life processes.

Calculating Efficiency of Trophic Levels

  • Formula: (energy transferred to the next level/ total energy in) x 100.

  • Example Calculation: Energy transferred (8,000 kJ) from producer (10,000 kJ) would yield 80% efficiency.

The Carbon Cycle

  • Overview: Describes how carbon moves through different Earth systems, including the atmosphere, organisms, and soil.

  • Importance of carbon in biological macromolecules and ecosystem functions.