Succession from Pioneer to Climax Community · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

How communities change

Science · Organisms & Life Processes · ages 17-18
Name ______________________   Date ____________

  1. Which statement describes biomass and diversity during succession?

    • Biomass often rises; diversity tracks vegetation cover
    • Biomass often rises; diversity can rise or fall
    • Biomass and diversity measure the same change

  2. Which example shows pioneers colonising a surface without soil?

    • Lichens growing on newly exposed rock
    • Oak trees in mature woodland
    • Crops rooted in cultivated soil

  3. Repeated mowing removes tree seedlings from a meadow. What does this do to succession?

    • Maintains an earlier community by limiting tree establishment
    • Restarts succession on newly exposed rock
    • Speeds woodland development by freeing space for new tree growth

  4. A forest fire removes many trees but leaves soil. Which classification fits the recovery?

    • Primary, since losing the tree canopy begins a new community
    • Deflected, because fire interrupts succession
    • Secondary, since recovery starts with soil still present

  5. How can pioneers on bare rock help later plants establish?

    • They reduce establishment by competing for available space
    • They help develop soil through weathering and organic matter
    • They preserve bare-rock conditions by removing litter

  6. What does the traditional term climax community describe?

    • A community at the stage of maximum species richness
    • A relatively stable later community under current conditions
    • A community defined by steady increases in biomass and species richness

  7. Pioneer lichens decline during succession because they eat all the rock.

    Circle one:   True   False

  8. Matched plots have equal soil, water and pioneer seed supply. One set is shaded. Which result supports shade limiting seedling survival?

    • More seedlings survive in the unshaded plots
    • More seedlings survive in shaded plots
    • Seedling survival is similar across shaded and unshaded plots
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How communities change W1-mt_3s3dVLP0Lf-s1

  1. Biomass often rises; diversity can rise or fall · Biomass often accumulates, but diversity can decline when a few species dominate.
  2. Lichens growing on newly exposed rock · Pioneers are early colonists. Lichens on newly exposed rock fit this description.
  3. Maintains an earlier community by limiting tree establishment · Mowing prevents tree establishment and can hold the meadow at an earlier stage.
  4. Secondary, since recovery starts with soil still present · Secondary succession begins after disturbance where soil remains.
  5. They help develop soil through weathering and organic matter · Weathering, trapped particles and dead organic matter can help soil develop.
  6. A relatively stable later community under current conditions · The term describes relative stability, not a permanent or universal endpoint.
  7. False · Lichens can weather rock. Later competition and shade can contribute to their decline; they do not consume rock as food.
  8. More seedlings survive in the unshaded plots · With other conditions matched, higher survival without shade supports an effect of shade.
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