Image to PDF 20250315 08.14.09

Ecology Overview

• Ecology is the branch of biology that investigates the interactions between organisms and their environment.

Key Terminology

• Biosphere (Ecosphere): The layer of Earth where life exists.

• Biome: A community of plants and animals adapted to a specific climate (e.g., forest biome, aquatic biomes).

• Ecosystem: A biological community of interactions among organisms and their physical environment (e.g., tropical forest ecosystem, desert ecosystem). All ecosystems combine to form the biosphere.

• Community: A group of populations of two or more different species in the same geographic area and time (e.g., Nile River community of bacteria, fish, frogs, and plants).

• Population: All individuals of the same species within an ecological community (e.g., sardines in the Black Sea).

Factors Influencing Ecosystems

• Ecosystems rely on the interactions between both living (biotic) and non-living (abiotic) components.

Biotic Factors

• Includes living elements such as bacteria, fungi, plants, animals, and archaea.

Abiotic Factors

• Definition: Non-living components that shape an ecosystem, influencing what types of organisms can survive.

• Examples:

  • Air: Essential for respiration.

  • Water: Vital for all life; freshwater is a limiting factor.

  • Soil and Minerals: Provide nutrients for plants, which anchor their roots in soil.

  • Temperature: Most organisms need stable temperatures; extreme changes can be harmful.

  • Light: The sun is the main energy source; the intensity affecting biodiversity.

  • pH and Salinity: Affect organism survival in different aquatic environments.

Producers, Consumers, and Decomposers

• Producers (Autotrophs): Organisms that produce their own food (e.g., plants, algae). They convert inorganic substances into organic food via photosynthesis. Types:

  • Photoautotrophs: Use light energy.

  • Chemoautotrophs: Use chemical energy.

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

  • Types of consumers based on diet:

    • Herbivores: Plant-eaters (e.g., rabbits, sheep).

    • Carnivores: Meat-eaters (e.g., lions, owls).

    • Omnivores: Eat both plants and meat (e.g., humans, bears).

• Decomposers: Break down dead organic material and waste, recycling nutrients back into the ecosystem (e.g., bacteria, fungi).

Energy Flow in Ecosystems

• Nutrient and Energy Balance: Managed by producers, consumers, and decomposers. Energy originates from the sun.

• Energy Transfer: Occurs through feeding relationships:

  • Primary producers undergo photosynthesis.

  • Herbivores are primary consumers feeding on plants.

  • Carnivores can be secondary or tertiary consumers, feeding on other consumers.

• Food Chain Example:

  • Maize (Producer) → Locust (Primary Consumer) → Lizard (Secondary Consumer) → Snake (Tertiary Consumer).

Ecological Pyramid

• Definition: Graphical representation showcasing relationships and energy flow between organisms at different trophic levels.

• Characteristics:

  • Biomass and energy decrease at higher trophic levels.

  • Energy transfer efficiency about 10%; highlighted as the 10% rule.

Biogeochemical Cycles

• Definition: Pathways that allow substances to move between biotic and abiotic components of the Earth.

  • Major cycles: Nitrogen, Carbon, Water.

Nitrogen Cycle

• Nitrogen is essential for protein and DNA synthesis but must be converted to usable forms (e.g., nitrates) by nitrogen-fixing bacteria.

Carbon Cycle

• Carbon is cycled through photosynthesis and respiration, influencing the energy dynamics and ecosystems.

Water Cycle

• Describes the movement of water through evaporation, condensation, and precipitation driven by solar energy.

Environmental Problems and Human Impact

Climate Change

• Caused by the enhanced greenhouse effect; results from the accumulation of greenhouse gases due to human actions (e.g., fossil fuel burning, deforestation).

  • Effects: Rising sea levels, habitat destruction, biodiversity loss, air quality issues, and increased migration and health problems.

Pollution

• Defined as the introduction of harmful contaminants into the environment:

  • Types:

    • Air Pollution: Chemical altercations in the atmosphere, leading to respiratory illnesses.

    • Water Pollution: Contaminants affecting aquatic ecosystems.

    • Noise Pollution: Excessive sounds disrupting wildlife and human life.

• Prevention Strategies: Utilization of public transport, tree planting, renewable energy, industrial regulations, and reducing emissions.