14.7.2 Secondary Succession

Question 1

Secondary Succession

Answer 1

• Primary succession occurs when communities are eradicated, leaving barren rock.
• In secondary succession, a disturbance leaves behind intact soil.
• Examples of secondary succession include:
· Fields to small shrubs to weed trees to forests
· Lakes to marshes to wet fields to shrubs to trees to forests

Question 2

secondary succession

Answer 2

• Review: Community-level disturbances include fire, flood, glaciers, and human activity and can lead to
  primary succession.
• In secondary succession, an existing community is disrupted and leaves the soil intact. American settlers eliminated nearly all of the country’s virgin stands of deciduous forests.

Question 3

note

Answer 3

• Each stage on the left inhibits the preexisting vegetation. The secondary succession goes from field to small shrubs to weed trees to forest.
• Another example of secondary succession involves the
  gradual change from an oligotrophic to a eutrophic lake.
  An oligotrophic lake is a nutrient-poor, clear, deep lake with little phytoplankton. Over time, oligotrophic lakes fill in with sediments and nutrients, forming eutrophic lakes. When the lake becomes shallow enough, standing vegetation will grow; the region is now classified as a marsh or swamp. When the marshes fill in further, they give rise to wet fields and follow the sequence of fields to forest.

Question 4

What is a climax community?

Answer 4

• a community that will remain stable until the next disturbance

Question 5

Which of the following is likely to first move into an area undergoing secondary succession?

Answer 5

• weeds

Question 6

True or false?

Secondary succession always leads to a climax forest community.

Answer 6

• false

Question 7

True or false?

All major disruptive events such as fire and flood cause primary succession.

Answer 7

• false

Question 8

In terms of lakes, the successional sequence is __________ to __________ to __________ to __________.

Answer 8

• oligotrophic lakes; eutrophic lakes; marsh; wet fields

Question 9

Which of the following is a secondary disturbance?

Answer 9

• The American settlers eliminated nearly all the virgin stands, cutting the forest down to the soil.