What is an ecosystem?
An ecosystem includes living organisms and the non-living parts of their environment, along with the interactions between them. A pond, forest, grassland, garden, or coral reef can be studied as an ecosystem. Its boundaries depend on the question being asked: a small pond can be a useful study area while still being connected to the wider landscape.
Biotic and abiotic components
Biotic components are living organisms, such as plants, animals, fungi, and bacteria. Abiotic components are non-living environmental factors, such as sunlight, water, temperature, soil, minerals, and air. These components influence each other. For example, soil moisture affects plant growth, while roots can change soil structure and help reduce erosion.
Producers, consumers, and decomposers
Producers—such as plants and algae—use energy from sunlight to make organic material through photosynthesis. Consumers obtain energy by eating plants or other organisms. Decomposers, including many fungi and bacteria, break down dead material and waste, returning nutrients to the environment. These roles help explain how energy moves and materials are recycled.
Food chains show one pathway
A food chain represents a simplified route for energy through organisms. For example: grass → grasshopper → frog → snake. The arrows point from the organism being eaten to the organism that obtains energy from it. A chain is useful for learning the basic idea, but real ecosystems contain many overlapping relationships and not every feeding interaction is so straightforward.
Food webs show connected pathways
A food web combines many food chains. A bird may eat insects and seeds; the same insect may feed on several plants and be eaten by more than one predator. A food web helps show why changes in one population can affect others. The effects depend on the species involved, the strength of their relationships, and other environmental conditions.
Habitats and adaptations
A habitat is the place where an organism lives and finds the resources it needs. Adaptations are characteristics that can help an organism survive and reproduce in its environment. A cactus’s water-storing tissues, a duck’s webbed feet, and seasonal behaviours are examples of features related to particular conditions. An adaptation is not a conscious choice made by an individual when it needs one; populations change over generations through evolutionary processes.
What happens when conditions change?
Imagine a pond where insect numbers decline. Animals that rely on those insects may have less food, while organisms eaten by the insects may become more common. The outcome is not always simple: predators may switch food sources, species may move, and weather or habitat changes can influence the result. Scientists study observations over time to distinguish likely causes from coincidence.
People and ecosystem health
People depend on ecosystems for food, clean water, materials, recreation, and other benefits. Pollution, habitat loss, invasive species, and climate change can put pressure on ecosystems, while habitat restoration, careful resource use, and pollution prevention can help. Ecosystems are diverse, so solutions should be informed by local evidence and the needs of the species and communities involved.
Check your understanding
- Name one biotic and one abiotic component of a pond.
- How does a food web differ from a food chain?
- Give one example of how a change in one population might affect another.
Show suggested answers
- Examples: a fish is biotic; water temperature is abiotic.
- A food chain shows one pathway; a food web connects many feeding pathways.
- If insects decline, animals that eat them may have less food; effects depend on other conditions and food sources.
These are example answers. Other answers may also be correct if they explain the idea clearly.
Key takeaway: Understanding grows when you connect new information to examples and practise explaining it clearly.