Succession: how ecosystems rebuild after a change

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   A new lava flow on an island (model data)

   question	answer
   what happened	a lava flow covered the land
   ground now	bare rock
   soil on it	none

2. 1.

   Ari reads the site card. Which kind of succession begins here, and why?

   • Secondary succession, because people will plant the first species
   • Secondary succession, because the lava cleared the old plants away
   • Primary succession, because the new rock has no soil on it
   • Secondary succession, because the rock still holds soil under the lava

3. A forest after a fire (model data)

   question	answer
   what happened	a fire cleared the forest
   ground now	ash on the soil
   soil on it	still there

4. 2.

   Bo reads the site card. Which kind of succession begins here, and why?

   • Secondary succession, because tall trees are the first to grow back
   • Secondary succession, because the soil is still there for new plants
   • Primary succession, because the fire left the ground with no soil
   • Secondary succession, because someone must plant the new forest first

5. A field that is no longer farmed (model data)

   question	answer
   what happened	the farmer stopped farming and left the field alone
   ground now	bare soil
   years since farming stopped	1

6. 3.

   Esme reads the site card. Which kind of succession begins here, and why?

   • Secondary succession, because crops must be planted first
   • A climax community, because the field is already grown over
   • Primary succession, because farming took the soil away
   • Secondary succession, because the field's soil is still there

7. Table

   Stage cards for new lava rock (model data), 4 rows. Columns: stage card. Row 1: trees. Row 2: bare rock. Row 3: lichens and mosses. Row 4: grasses.

8. 4.

   Jun puts the cards in order for primary succession, first to last. Which list is right?

   • bare rock, lichens and mosses, grasses, trees
   • bare rock, trees, lichens and mosses, grasses
   • bare rock, lichens and mosses, trees, grasses
   • bare rock, grasses, lichens and mosses, trees

9. Primary succession on lava rock (model data)

   stage	what grows
   1	bare rock
   2	lichens and mosses
   3	?
   4	shrubs
   5	trees

10. 5.

    Kira reads the stage table for primary succession. What belongs in the box for stage 3?

    • a climax community
    • bare rock
    • trees
    • grasses

11. An oak and hickory forest after a fire (model data)

    question	answer
    what happened	a fire cleared the forest
    soil on it	still there, with ash

12. 6.

    Luz reads the card. In this secondary succession, which plants usually grow back first?

    • annual plants, then fast-spreading grasses
    • tall oak and hickory trees, then shrubs
    • lichens and mosses, which first turn the ground into soil
    • shrubs, then small pine trees
13. 7.

    Milo reads the graph. At year 30, which plant type covers the most ground?

    • Trees, at 10 percent
    • Grasses, at 60 percent
    • Lichens and mosses, at 30 percent
    • Grasses, at 40 percent
14. 8.

    Pia reads the graph of an old forest. What does the line say about the tree cover?

    • It stays near 80 percent, with small ups and downs
    • It stays at 80 percent, with no change
    • It keeps falling, so grasses are taking over
    • It keeps rising, so the forest is still young

15. Lichens on new lava rock (model data)

    question	answer
    site	new lava rock
    year	3
    living things	lichens
    soil	none yet

16. 9.

    Ren reads the card. What are the lichens called in succession?

    • Intermediate species, the shrubs and small trees in the middle stages
    • Pioneer species, the hardy first living things in a new place
    • Permanent species, the first plants that stay the main cover for good
    • Climax species, the steady group of species at the end of the stages

17. A forest long after a fire (model data)

    question	answer
    years since the fire	150
    species mix	like the forest before the fire
    change now	steady, with small changes in counts

18. 10.

    Zee reads the card. What is this stage of succession called?

    • A pioneer stage, in which hardy first species stay the main cover
    • An intermediate stage, in which shrubs and small trees take over
    • A climax community, in which nothing changes in any way
    • A climax community, steady until the next disturbance