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7th grade How an ecosystem rebuilds after a change worksheet

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How an ecosystem rebuilds after a change

Grade 7 Science Worksheet - Challenge Me

NameDate

Circle the best answer.

  1. An oak and hickory forest has been growing back for about 150 years after a fire. What has it most likely become, Ari?

    • A pioneer stage
    • Bare rock
    • A climax community
    • A grassland of annual plants

  2. In a climax forest, the number of oak trees goes up and down a little each decade. What does that show, Bo?

    • Its balance is steady but still shifts
    • Succession has started over
    • The forest is turning into rock
    • The counts must be wrong

  3. A storm knocks down part of a climax forest, but the soil stays. What happens in that part next, Esme?

    • Lichens must cover it first
    • Secondary succession starts again
    • It stays a climax forest, unchanged
    • It stays bare for good

  5. From 40 to 80 years after the field was left alone, how did tree cover change, Jun?

    • Up 50 (20% to 70%)
    • Down 20 (40% to 20%)
    • Up 30 (20% to 50%)
    • Up 70 (0% to 70%)

  6. When does tree cover first become larger than grasses and shrubs added together, Luz?

    Use the picture in question 4.

    • Year 100
    • Year 80
    • Year 40
    • Year 60

  7. A new lava flow covers the edge of an old forest. What grows first on that new rock, Milo?

    • Oak and hickory trees
    • Lichens and mosses
    • Shrubs from the old forest
    • Grasses from the old soil

  8. A field left alone 10 years ago now has grasses and young shrubs. What will most likely spread over the next 50 years, Noah?

    • Fewer plants of each type
    • More shrubs, then trees
    • Just the same grasses
    • Lichens and mosses on bare rock

  9. Ren says a lava flow gives secondary succession because it clears away plants. Agree or disagree?

    • Agree: any clearing gives secondary
    • Disagree: new lava has no soil, so it is primary
    • Disagree: plants can't grow on lava
    • Agree: lava adds soil right away

  10. Tala says primary succession is faster than secondary because it starts fresh. Agree or disagree?

    • Agree: lava already holds soil
    • Agree: bare rock is easier for plants
    • Disagree: both take one year
    • Disagree: it must build soil first, so it is slower

  11. Zee says a climax forest is finished and can't change again. Agree or disagree?

    • Agree: once trees grow, succession is over
    • Disagree: it turns back into rock each year
    • Agree: its counts stay exactly the same
    • Disagree: a disturbance can start succession again
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7th grade How an ecosystem rebuilds after a change worksheet – printable
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About this worksheet

How an ecosystem rebuilds after a change. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can tell primary succession (bare rock, no soil) from secondary succession (soil left behind).
  • I can put the stages in order and say how pioneers such as lichens and mosses help later plants.
  • I can read a succession graph by plant type and explain why a line rises or falls.

Standard: supports MS-LS2-4

Words to know

succession: The order in which plant types arrive and replace each other after a change

primary succession: Succession on new bare rock, such as lava, with no soil yet

secondary succession: Succession where a change cleared plants but the soil stayed

pioneer species: The first hardy living things on bare rock, like lichens and mosses

climax community: The steady community at the end, lasting until the next big change

Common mistakes

Your child mixed up primary and secondary succession. Primary starts on bare rock with no soil; secondary starts where the soil is left.

Your child put bigger plants too early. Small, hardy plants come first, and shrubs and trees take over later as the soil builds up.

Your child read the wrong line or the wrong year on a graph. Point to the line's label, then the year, then read across to the value.

Questions parents ask

What is the most common mistake with how an ecosystem rebuilds after a change?

Your child mixed up primary and secondary succession. Primary starts on bare rock with no soil; secondary starts where the soil is left.

Are these 7th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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