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Ecosystems

Succession, seres and the climatic climax

  • 3 things to know
  • Component 3 Section B

Overview

Four named seres, pioneer species and stages of a lithosere.

What you need to know

Answer each one before you reveal it.

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Key term

Define succession.

Key term

Distinguish primary and secondary succession.

Key term

What is a sere?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define succession.

    Model answer

    Succession is the sequence of changes in a plant community over time at one site. Each stage alters conditions and makes the site suitable for the next.

  2. 2

    Distinguish primary and secondary succession.

    Model answer

    Primary succession begins on a surface that has never carried vegetation, such as bare rock or new dunes. Secondary succession follows clearance of an existing community, where soil and seeds remain.

  3. 3

    What is a sere?

    Model answer

    A sere is the whole sequence of communities in one succession. Each community within the sequence is called a seral stage.

  4. 4

    Name the four named seres.

    Model answer

    A lithosere develops on bare rock and a psammosere on sand dunes. A hydrosere develops in fresh water and a halosere in salt water.

  5. 5

    What is a pioneer species?

    Model answer

    A pioneer species is the first to colonise a bare surface. Tolerance of harsh conditions matters more than the ability to compete.

  6. 6

    Name the pioneer species of a lithosere.

    Model answer

    Lichens and mosses are the pioneers of a lithosere. Chemical weathering by lichens begins to break the rock down into a thin soil.

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