Ecosystems
Understanding how living organisms interact with their environment
What is an Ecosystem?
A natural system made up of living organisms (biotic) and non-living components (abiotic) interacting together in a specific environment.
Components of an Ecosystem
Producers
Make food via photosynthesis (plants, algae)
Primary Consumers
Herbivores eating producers (rabbits, caterpillars)
Secondary Consumers
Carnivores eating primary consumers (foxes, birds)
Tertiary Consumers
Top predators (eagles, lions, sharks)
Decomposers
Break down dead material (bacteria, fungi)
Climate
Temperature, precipitation, sunlight, wind
Soil
Nutrients, pH, texture, drainage
Water
Availability and quality
Topography
Altitude, slope, aspect (direction facing)
Rocks
Geology influences soil type
Energy Flow in Ecosystems
Key Concepts
Food Chain
Simple linear sequence showing energy transfer from one organism to the next
Food Web
Complex network of interconnected food chains in an ecosystem
Energy Loss at Each Level
Only 10% of energy passes to the next level. 90% is lost as heat, movement, and waste. This creates a pyramid shape - fewer organisms at higher levels.
Available organisms:
Your food chain:
Click organisms above to build the chain
Nutrient Cycling
The nutrient cycle is the continuous movement of nutrients between living organisms and the environment. Nutrients are stored in three places and transferred between them.
BIOMASS
Living organisms
LITTER
Dead organic matter
SOIL
Available nutrients
Additional Processes
- Leaching: Rainfall washes nutrients deeper into soil (loss from system)
- Weathering: Rock breaks down, releasing minerals into soil (input to system)
Small-Scale UK Ecosystem: Freshwater Pond
Location & Characteristics
- Size: Small-scale (10-100m² typical)
- Temperature: Varies seasonally (0-20°C)
- Sunlight: Limited to top 2m (photic zone)
- pH: Usually neutral (6-8)
- Oxygen: High near surface, low at bottom
Decomposers
- Bacteria: Break down dead plants/animals
- Fungi: Decompose organic matter in mud
Nutrients are stored in mud at bottom and cycled back to producers.
Energy Flow
Only 10% of energy passes to each level. 90% is lost as heat, movement, and waste. This is why there are fewer organisms at higher trophic levels.
Human Impact: Eutrophication
Fertilizer runoff → excess nutrients → algal bloom → blocks sunlight → plants die → bacteria decompose plants → oxygen depleted → fish die
Interdependence
Interdependence means all organisms in an ecosystem depend on each other. Removing one species affects the entire food web.
Use the simulator below to see what happens when organisms are removed from a pond ecosystem.
Ecosystem: Living + non-living components interacting
Biotic: Living components
Abiotic: Non-living components
Producer: Makes own food (photosynthesis)
Consumer: Eats other organisms
Decomposer: Breaks down dead material
Food chain: Linear energy transfer
Food web: Interconnected food chains
Nutrient cycle: Movement of nutrients between stores
Interdependence: Organisms relying on each other
Test Your Knowledge
What is the definition of an ecosystem?