Ecology Ecological Succession 1 — Questions and Answers
Question 1: Which type of succession begins on a substrate that has never previously supported life, such as bare rock after a volcanic eruption?
- Secondary succession
- Primary succession (Correct answer)
- Allogenic succession
- Cyclic succession
Correct answer: Primary succession
Primary succession occurs on substrates with no prior soil or biological community, such as newly exposed rock after a lava flow.
Question 2: Which organisms are typically the first to colonize bare rock during primary succession?
- Grasses and shrubs
- Pioneer species such as lichens (Correct answer)
- Shade-tolerant trees
- Climax community species
Correct answer: Pioneer species such as lichens
Pioneer species like lichens are the first colonizers of bare rock because they can tolerate harsh, nutrient-poor conditions and help break down rock into soil.
Question 3: Secondary succession differs from primary succession primarily because secondary succession:
- Takes longer to reach a climax community
- Begins on a substrate that already has soil (Correct answer)
- Starts with no biological legacy
- Only occurs in aquatic ecosystems
Correct answer: Begins on a substrate that already has soil
Secondary succession occurs in areas where a community has been disturbed but soil and a seed bank remain, allowing recovery to proceed faster than primary succession.
Question 4: What is a climax community in the context of ecological succession?
- The first community to establish after a disturbance
- A stable, self-perpetuating community that represents the endpoint of succession (Correct answer)
- Any community dominated by a single species
- A community that forms only in tropical rainforests
Correct answer: A stable, self-perpetuating community that represents the endpoint of succession
A climax community is a relatively stable community that replaces itself over time and represents the endpoint of successional change under a given set of environmental conditions.
Question 5: The process by which each successional community modifies the environment and makes it more suitable for the next community is called:
- Competitive exclusion
- Facilitation (Correct answer)
- Inhibition
- Allelopathy
Correct answer: Facilitation
Facilitation occurs when early successional species alter environmental conditions in ways that make the habitat more suitable for later species to establish.
Question 6: During old-field succession in the eastern United States, which sequence correctly represents the typical order of community change?
- Annual weeds → shrubs → perennial grasses → forest
- Annual weeds → perennial grasses → shrubs → forest (Correct answer)
- Lichens → mosses → grasses → shrubs → forest
- Forest → shrubs → grasses → annual weeds
Correct answer: Annual weeds → perennial grasses → shrubs → forest
Old-field succession typically proceeds from annual weeds to perennial grasses to shrubs to forest, reflecting increasing competitive ability for resources over time.
Question 7: Which of the following is an example of secondary succession?
- Life colonizing a newly formed volcanic island
- Plant regrowth in a forest after a wildfire (Correct answer)
- Lichen establishing on a fresh lava flow
- Organisms settling on a new glacier retreat
Correct answer: Plant regrowth in a forest after a wildfire
Regrowth after a wildfire is secondary succession because soil and seeds remain, allowing the community to recover more quickly than if starting from bare rock.
Ecology Ecological Succession 1
Which type of succession begins on a substrate that has never previously supported life, such as bare rock after a volcanic eruption?