Ecosystems
An ecosystem is more than a collection of organisms. It is a system made of living organisms, the physical environment around them, and the interactions that connect them.
What Is an Ecosystem?
An ecosystem includes all of the living organisms in an area, the nonliving physical environment, and the interactions among these components.
A pond, forest, desert, coral reef, or even a small area of soil can be studied as an ecosystem. Ecosystems can be very large or very small.
Big idea: An ecosystem includes both biotic (living) and abiotic (nonliving) components.
Biotic and Abiotic Factors
Biotic Factors
The living components of an ecosystem, including plants, animals, fungi, bacteria, and other organisms.
Abiotic Factors
The nonliving components, including temperature, water, sunlight, soil, pH, salinity, and available nutrients.
Biotic and abiotic factors constantly interact. For example, temperature and rainfall influence which plants can survive, while plants can affect soil conditions and the availability of food and shelter for other organisms.
Levels of Ecological Organization
Energy and Matter in Ecosystems
Energy enters most ecosystems through sunlight and is captured by producers. It then moves through consumers and decomposers.
Energy flows through an ecosystem, while matter such as carbon, nitrogen, and water is continually recycled.
Think of it this way: energy flows; matter cycles.
Habitat and Niche
A habitat is the physical place where an organism lives.
A niche describes an organism's role and way of interacting with its environment, including how it obtains resources and interacts with other organisms.
Habitat
Think: Where does it live?
Niche
Think: What does it do in the ecosystem?
Ecosystem Stability and Change
Ecosystems are dynamic systems. Populations change, environmental conditions change, and disturbances can alter relationships among organisms.
Drought, fire, disease, invasive species, habitat destruction, and changes in temperature can all affect ecosystems.
Because organisms are interconnected, a change in one part of an ecosystem can influence other parts.
Common Misconceptions
If You See This on a Test, Think This
Quick Practice
1. What are the two major components of an ecosystem?
2. What is the difference between a population and a community?
3. Is sunlight biotic or abiotic?
4. What is a habitat?
5. What happens to energy as it moves through an ecosystem?
Key Takeaways
- An ecosystem includes living organisms, abiotic factors, and their interactions.
- Biotic factors are living; abiotic factors are nonliving.
- Ecological organization ranges from organisms to the biosphere.
- Energy flows through ecosystems.
- Matter cycles through ecosystems.
- Habitat describes where an organism lives; niche describes its role.
- Ecosystems are dynamic and can change when conditions or populations change.
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