18.2.1—Ecology terms

An ecosystem is the interacting system of a community of organisms and the environment they live in. It includes biotic components, abiotic conditions, energy flow and nutrient cycling. A habitat is where a species lives; its niche is the role it plays there.

Ecosystem — a system scale: populations interact with one another and with physical and chemical conditions.
Habitat — a place boundary: where the organism is found.
Niche — a role-and-resource boundary: how the organism obtains energy, uses conditions and interacts with other species and the physical environment.

Niche overlap means two species use some of the same resources or conditions. The more their roles and resource use overlap, the greater the potential for competition; distinct resource use can allow different species to fit into the same ecosystem. This is a relationship-level interpretation, not a biodiversity count or an automatic proof of competition.

Use the terms in this order:

1. Name the ecosystem as the interacting living-and-non-living system.
2. Identify the habitat as the place occupied by a species.
3. Describe the niche through energy use, physical conditions and interactions.
4. Compare niches when explaining overlap, possible competition or how multiple species can occupy an ecosystem; keep measurement of biodiversity for a separate assessment.

A habitat is not a niche: location alone does not describe a species’ role. Ecosystem, habitat and niche are concepts rather than sampling methods; this card does not introduce quadrats, correlation statistics or Simpson’s index.