How Bare Rock Becomes Woodland

Science · Organisms & Life Processes · ages 17-18

Name ______________________ Date ____________

What happens to diversity and biomass across succession?
- Both fall toward the climax
- Both rise toward the climax
- Diversity rises while biomass falls
Which of these is a pioneer species?
- Lichens crusting bare rock
- Oak trees in mature woodland
- Sheep grazing a meadow
What is deflected succession?
- Succession frozen off course by grazing or burning
- Succession starting on bare lava
- Succession ending in stable woodland
Fire burns a forest but leaves the soil intact. What type of succession follows?
- Primary, because the trees are gone
- Deflected, because fire always means management
- Secondary, because the soil survives
How does a pioneer make the habitat less suitable for itself?
- It eats all the stone until none remains
- Its shade and litter suit later species better
- It poisons the soil against all plants
What is a climax community?
- The first weeds on bare ash
- The stable final community that replaces itself
- A field freshly ploughed for crops
A student says pioneers vanish because they consume all the rock. This claim is true.
Circle one: True False
Why are the first species on bare rock usually the first to disappear?
- They engineer soil and shade that favour their replacements
- They run out of rock to eat
- They are eaten by the shrubs they planted

Answer key

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

Both rise toward the climax · Each stage adds species and bulk, so both climb toward the climax community.
Lichens crusting bare rock · Pioneers are the first hardy colonists of bare ground, such as lichens on rock.
Succession frozen off course by grazing or burning · People deflect the march on purpose, holding moorland or meadow instead of letting woodland return.
Secondary, because the soil survives · Soil surviving means a restart, which is secondary succession.
Its shade and litter suit later species better · Pioneers build soil and shade that favour successors while dooming their own light hungry seedlings.
The stable final community that replaces itself · The climax, such as mature oak woodland, holds steady by replacing itself unless disturbed.
False · They vanish because the soil and shade they create favour later species over their own seedlings.
They engineer soil and shade that favour their replacements · Each stage changes the ground to suit its successor, so pioneers lose the bare bright conditions they need.