BIOLOGY LESSON NOTE ON ECOSYSTEM AND ECOLOGICAL SUCCESSION

Topic: Ecosystem and Ecological Succession

Specific Objectives

• Define an ecosystem and identify its components.

• Explain the different types of ecosystems and their characteristics.

• Describe ecological succession and differentiate between primary and secondary succession.

• Explain the importance of ecological succession in maintaining ecosystem balance.

• Identify human activities that affect ecosystems and succession processes.

Lesson ContentE

1. Definition of Ecosystem

An ecosystem is a community of living organisms (biotic components) interacting with their non-living environment (abiotic components) in a specific area. The interaction between these components ensures the flow of energy and cycling of nutrients, maintaining ecological balance.

2. Components of an Ecosystem

Ecosystems consist of two main components:

Biotic Components (Living Organisms):

• Producers (Autotrophs): Plants and algae that produce food through photosynthesis.

• Consumers (Heterotrophs): Animals and humans that depend on plants and other animals for food.

• Decomposers (Saprotrophs): Fungi and bacteria that break down dead organic matter into nutrients.

Abiotic Components (Non-living Elements):

• Sunlight

• Water

• Temperature

• Soil and minerals

• Air (Oxygen and Carbon dioxide)

3. Types of Ecosystems

Ecosystems can be classified into two main categories:

Terrestrial Ecosystems:

• Forest Ecosystem: Dense tree growth, diverse plant and animal species.

• Grassland Ecosystem: Dominated by grasses, supports grazing animals.

• Desert Ecosystem: Extreme temperatures, minimal rainfall, adapted organisms.

• Tundra Ecosystem: Cold climate, little vegetation, found in polar regions.

Aquatic Ecosystems:

• Freshwater Ecosystem: Rivers, lakes, and ponds with low salt content.

• Marine Ecosystem: Oceans and seas with high salt content.

• Estuarine Ecosystem: Mix of fresh and salt water, rich in biodiversity.

4. Ecological Succession

Ecological succession is the natural and gradual process of change in the structure and composition of an ecosystem over time. It occurs in response to environmental changes and disturbances.

Types of Ecological Succession:

1. Primary Succession:

   - Occurs in areas where no life previously existed, such as newly formed volcanic islands or regions left by retreating glaciers.

   - Pioneer species like lichens and mosses break down rocks to form soil.

   - Gradually, grasses, shrubs, and trees establish, leading to a stable ecosystem (climax community).

2. Secondary Succession:

   - Occurs in areas where life previously existed but was disturbed by events like wildfires, floods, or human activities.

   - Unlike primary succession, soil is already present, so the recovery process is faster.

   - Plants and animals recolonize the area, restoring ecological balance.

5. Importance of Ecological Succession

• Restores damaged ecosystems.

• Maintains biodiversity.

• Enhances soil formation and nutrient cycling.

• Supports climate regulation.

6. Human Activities and Their Effects on Ecosystems

Human actions can disrupt ecological succession and ecosystem balance:

• Deforestation: Leads to loss of habitat and decreased biodiversity.

• Pollution: Harms both biotic and abiotic components of ecosystems.

• Urbanization: Alters natural landscapes and affects succession.

• Climate Change: Affects species distribution and ecosystem health.

Evaluation

• Define an ecosystem and list its major components.

• Differentiate between terrestrial and aquatic ecosystems with examples.

• Explain the concept of ecological succession.

• Compare and contrast primary and secondary succession.

• Why is ecological succession important for maintaining ecosystem balance?

• List three human activities that affect ecosystems and their impact.