Science: Ecological Succession Worksheet

Question 1

Define ecological succession in your own words.

Accepted Answer

Ecological succession is the gradual change in the types of species living in an ecosystem over time, often after a new habitat forms or a disturbance changes an existing community.

Question 2

Explain the difference between primary succession and secondary succession.

Accepted Answer

Primary succession begins in an area where no soil exists, such as bare rock after lava cools. Secondary succession begins where soil is already present after a disturbance, such as after a fire or abandoned farmland.

Question 3

A volcanic eruption covers land with new rock. Which type of succession will most likely occur first, and why?

Accepted Answer

Primary succession will occur first because the eruption leaves behind bare rock with little or no soil, so the ecosystem must begin with pioneer species that can help create soil.

Question 4

Name one common pioneer species and explain why it is successful early in succession.

Accepted Answer

Lichens are a common pioneer species because they can grow on bare rock, tolerate harsh conditions, and help break down rock into smaller particles that contribute to soil formation.

Question 5

Describe how soil forms during primary succession.

Accepted Answer

Soil forms as pioneer species such as lichens and mosses weather rock and add organic matter when they die and decompose. Over time, this mixture of rock particles, dead material, water, and air becomes soil.

Question 6

After a forest fire, grasses begin to grow in the burned area within a year. What does this suggest about the type of succession taking place?

Accepted Answer

This suggests that secondary succession is taking place because the fire disturbed the community but usually left the soil in place, allowing grasses and other plants to return relatively quickly.

Question 7

Put these stages in order from earliest to latest in a typical land succession: shrubs, grasses, mature forest, pioneer species.

Accepted Answer

The correct order is pioneer species, grasses, shrubs, and mature forest.

Question 8

Explain why biodiversity often increases as succession continues.

Accepted Answer

Biodiversity often increases during succession because as soil deepens, shelter increases, and resources become more available, more kinds of plants, animals, and microorganisms can survive in the area.

Question 9

A farmer stops using a field, and over many years the field becomes a forest. Describe one likely sequence of changes in plant life.

Accepted Answer

A likely sequence is that grasses and weeds grow first, then shrubs appear, followed by young trees, and eventually the area develops into a more established forest with larger trees.

Question 10

Why are disturbances such as fires, floods, or storms important in many ecosystems?

Accepted Answer

Disturbances are important because they can remove dominant species, open space and resources for new organisms, recycle nutrients, and restart succession in ways that support ecosystem renewal and diversity.

Question 11

Some scientists prefer the term stable community instead of climax community. Explain why this change in wording can be helpful.

Accepted Answer

The term stable community can be helpful because ecosystems are rarely permanent or unchanging. Communities may stay relatively stable for a time, but they can still change when conditions shift or disturbances occur.

Question 12

Compare the speed of recovery in primary and secondary succession and explain the reason for the difference.

Accepted Answer

Secondary succession usually happens faster than primary succession because soil, seeds, roots, and microorganisms may already be present after a disturbance. Primary succession is slower because soil must first develop before many plants can grow.

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Science: Ecological Succession

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