Year 12 / Functioning ecosystems and succession

Communities change over time.

Succession is a directional change in community composition after a new habitat forms or a disturbance occurs. Pioneer organisms can colonise exposed surfaces and modify the conditions experienced by later species.

Secondary succession begins where soil or biological material remains. Changes in light, nutrients, competition and disturbance shape the path; succession need not end in one fixed “climax” community.

INTERACTIVE MODEL

Ecological succession

Bare surface · little soilStageBare surfacePioneerLater

Explore: Move through stages and compare the species and habitat conditions.

\text{disturbance}\to\text{colonisation}\to\text{changing community}

WORKED EXAMPLE

A fire removes most plants but leaves soil and seeds.

The surviving soil means recovery is secondary succession.
Early colonisers alter shade and resources, allowing later species to establish.

Assumed knowledge

Ecosystem vocabulary.

Learning checkpoints & source

YOUR LEARNING CHECKPOINT

Sequence stages of succession.
Relate disturbance to community change.

QCAA Biology · Unit 3 · Functioning ecosystems and succession ↗

READY TO TRY IT?

Communities change over time.

Ecological succession

A fire removes most plants but leaves soil and seeds.

Put the idea to work.