Ecosystems: Biotic and Abiotic Factors

• An ecosystem is a community where living organisms interact with their physical environment.

Components

• Ecosystems consist of biotic (living) and abiotic (non-living) factors.

Biotic Factors

• These are the living components of an ecosystem.
  • Producers create their own food via photosynthesis like plants and algae.
  • Consumers obtain energy by eating other organisms.
    • Primary consumers are herbivores that eat producers, for example rabbits and deer.
    • Secondary consumers are carnivores that eat primary consumers, for example foxes and snakes.
    • Tertiary consumers, often top predators, eat secondary consumers, such as eagles and lions.
    • Quaternary consumers are top predators that consume tertiary consumers, for example sharks and whales.
  • Decomposers break down dead organic matter, for example fungi and bacteria.

Abiotic Factors

• These are the non-living components of an ecosystem
  • Sunlight provides energy for photosynthesis.
  • Temperature affects metabolic rates and species distribution.
  • Water is essential for all living organisms and influences habitat types.
  • Nutrients such as minerals and organic matter, support plant growth.

Types of Ecosystems

• Terrestrial ecosystems are land-based, such as forests, grasslands, and deserts.
• Aquatic ecosystems are water-based, such as freshwater and marine environments.

Food Webs

• Food webs are complex networks illustrating feeding relationships and energy transfer in ecosystems.
• They are crucial for understanding ecosystem dynamics and species interdependence.

Definition

• A food web is a network of feeding connections among organisms in an ecosystem.
• It shows how energy and nutrients flow through trophic levels.
• It encompasses multiple pathways in contrast to a simple food chain.

Trophic Levels

• Food webs are organized into trophic levels, each with a different role in energy and nutrient flow.
  • Producers (autotrophs) create their own food via photosynthesis or chemosynthesis, forming the food web's base and include plants, algae, and some bacteria.
  • Primary Consumers are herbivores that eat producers, transferring energy to higher levels and include rabbits, grasshoppers and deer.
  • Secondary Consumers are carnivores that eat primary consumers, regulating herbivore populations
• Examples include foxes, small birds, and certain reptiles.
  • Tertiary Consumers are top predators that eat secondary consumers, help to maintain ecosystem health by controlling populations and examples include eagles, wolves, and large cats.
  • Quaternary Consumers: Apex predators at the highest level; feed on tertiary consumers and are few in number and examples include sharks and whales, grizzly bears and orcas.

Importance

• Demonstrates Interdependence of Species: This illustrates the interconnectedness within an ecosystem.
• Highlights Impact of Population Changes: Changes in one population can cascade through the food web.
• Ecosystem Stability: Food webs enhance ecosystem stability and resilience.
• Diverse food webs are better at withstanding disturbances.
• Nutrient Cycling: Food webs are crucial for recycling nutrients within ecosystems.

Global Biomes

• Biomes are large ecological areas characterized by specific climate, flora, and fauna.

Major Biomes

• Tropical Rainforest:
  • Climate: Warm temperatures (20-25°C), high humidity, and over 2000 mm annual rainfall
  • Biodiversity: Home to over half the world's plant and animal species.
  • Threats: Deforestation and climate change.
• Savanna:
  • Climate: Tropical climate with wet and dry seasons, average temperatures of 20-30°C, and 500-1500 mm rainfall.
  • Biodiversity: Supports large herbivores (e.g., elephants, giraffes) and predators (e.g., lions).
  • Threats: Agriculture and grazing.
• Desert:
  • Climate: Low precipitation (