20. Communities and Ecosystems

Which of the following should lead to an increase in a community's diversity?

Listed below are 4 stages of ecological succession in Glacier Bay, Alaska. However, they are in the wrong order. Select the answer option that puts these events in the correct chronological order.

I. The area is invaded by alder trees, which grow up to 9 meters tall.

II. Small flowers (dryas) begin to dominate the plant community.

III. Over hundreds of years, large trees such as spruce & hemlock become the dominant vegetation.

IV. Glacier ice melts, exposing bare rock with no living organisms. Mosses & liverworts colonize this area.

What is the reason that moderate levels of disturbance foster the highest diversity in a community?

Match the following terms to each of the scenarios below:

◆ Facilitation ◆ Tolerance ◆ Inhibition

1. Large trees create large, shaded areas, making it difficult for photosynthetic organisms to thrive.

2. Presence of alder plants increases nitrogen content in soil, allowing willow & poplar seedlings to thrive.

3. The early growth of algae in a community has no significant impact on the future presence of birds.

Which of the following statements most accurately describes ecological succession?