EVS- Unit 2

Ecosystem Overview

  • An ecosystem is a complex network of interactions among living organisms (plants, animals, microorganisms) and their physical environment.

  • Key Concepts:

    • Energy and Matter Exchange: Involves food webs, nutrient cycles, and ecological processes.

    • Size and Complexity: Ecosystems can range from microcosms (like puddles) to vast biomes (like the Amazon rainforest).

    • Ecological Balance: Organisms coexist and depend on each other for survival.

Components of an Ecosystem

Structure of an Ecosystem

  1. Abiotic Components: Non-living factors influencing ecosystems:

    • Examples: Temperature, water, sunlight, soil composition, topography.

  2. Biotic Components: All living organisms within the ecosystem:

    • Producers (Autotrophs): Organisms that produce their own food via photosynthesis or chemosynthesis (e.g., plants, some bacteria).

    • Consumers (Heterotrophs): Organisms that obtain energy by consuming other organisms:

      • Herbivores (eat plants).

      • Carnivores (eat other animals).

      • Omnivores (eat both plants and animals).

    • Decomposers: Break down organic matter, returning nutrients to the ecosystem (e.g., bacteria, fungi).

  3. Trophic Levels: Hierarchical levels based on feeding relationships:

    • Primary Producers: Plants and algae.

    • Primary Consumers: Herbivores.

    • Secondary Consumers: Carnivores that eat herbivores.

    • Tertiary Consumers: Apex predators that eat other carnivores.

  4. Food Chains and Webs:

    • Food chains: Show linear feeding relationships.

    • Food webs: Depict complex interconnections among species.

  5. Habitat and Niche:

    • Habitat: Physical environment where an organism lives.

    • Niche: Functional role, including habitat and interactions.

Functions of an Ecosystem

  1. Energy Flow: Energy from sunlight is absorbed by producers and flows through trophic levels.

  2. Nutrient Cycling: Nutrients are continuously recycled (e.g., carbon, nitrogen).

  3. Biogeochemical Cycles: Movement of nutrients through various Earth systems (e.g., carbon cycle, nitrogen cycle).

  4. Ecological Succession: Ecosystems change over time due to disturbances or new species.

    • Primary Succession: Occurs on bare land (e.g., post-volcano).

    • Secondary Succession: Follows a disturbance in an existing community (e.g., after a forest fire).

  5. Ecosystem Services: Benefits to humans from ecosystems (e.g., pollination, water purification, climate regulation).

Importance of Ecosystems

  • Biodiversity: Supports a variety of species and promotes ecosystem stability.

  • Provisioning Services: Essential resources for humans (food, water, timber).

  • Regulating Services: Climate and water regulation, air quality improvement.

  • Supporting Services: Nutrient cycling, soil formation.

  • Cultural Services: Recreational, aesthetic, and cultural benefits (e.g., tourism).

  • Economic Benefits: Direct, indirect, and non-use values from ecosystems.

  • Resilience and Adaptation: Healthy ecosystems withstand changes and provide natural buffers.

  • Global Stability: Contributes to processes like carbon and water cycles critical for climate and biosphere functioning.

Energy Flow in Ecosystems

  • 10% Rule: Only 10% of energy at one trophic level is passed to the next; the rest is lost as heat.

  • Importance of Energy Flow: Supports biodiversity, nutrient cycling, and ecosystem stability.

Ecological Pyramids

  • Graphical representations of relationships among trophic levels:

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

    2. Pyramid of Biomass: Total mass of living matter at each level.

    3. Pyramid of Energy: Energy flow through trophic levels over time.

Types of Ecosystems

Desert Ecosystem

  • Characterized by low rainfall, extreme temperatures.

  • Plants and animals have adaptations to survive arid conditions.

Aquatic Ecosystem

  • Water-based ecosystem, including oceans, lakes, rivers.

  • Plays a critical role in ecological balance.

Pond Ecosystem

  • Community of organisms in a freshwater environment.

  • Classified into producers, consumers, and decomposers.

Conclusion

  • Ecosystems are crucial for clean air, water, and food, supporting life on Earth.

  • Understanding and protecting ecosystems is essential for biodiversity and human well-being.

  • Sustainable practices help preserve natural balance for future generations.