Watch the following video that shows the stages of ecological succession, and then answer the following questions.

1. What is the main difference between primary and secondary succession?

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   During primary succession, the soil must be formed from rock. During secondary succession, the soil is already established.

2. In the earliest stage of succession, what organisms colonized the lava rock?

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   Lichens and sword ferns colonized the lava rock.

3. As the lichen grows, what happens to the rock on which it grows?

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   The lichen breaks up the surface of the rock and starts the soil formation processes.

4. What are three characteristics of early colonizers?

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   Early colonizers are fast growing, and the wind usually disperses the seeds, and it needs lots of light.

5. How old is the mature forest that is shown in the video?

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   The mature forest is over 300 years old.

6. What are the characteristics of the plants in a mature forest?

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   Plants in the mature forest have seeds that are not wind dispersed, are slow growing and have large roots, tolerate shade, and need a lot more nutrients to grow.