5.7 Lesson (Sem) - Ecological Succession

​Lesson - Ecological Succession

What is this?

What is happening here?

​Succession is the predictable, gradual series of changes in an ecosystem over time.

• It describes how life begins or returns to an area.

​Pioneer Species: The first organisms to live (colonize) in an area.

• They are tough—they can survive harsh conditions, grow fast, and reproduce easily.

• Lichens and Mosses

• Grasses and Weeds

• Phytoplankton and Algae

Climax Community: A mature, biodiverse, stable, and final community that has established itself after succession.

• It is generally a hardwood forest in Mississippi (e.g., oak, hickory trees).

• High biodiversity and stability

​ High Biodiversity means having a lot of variety of different organisms

​The main difference between the two types is SOIL.

• Primary Succession: Begins with NO SOIL. Just bare rock.

• Secondary Succession: Begins WITH SOIL still present.

​	​Primary Succession	​Secondary Succession
​Begins with:	​Bare rock	​Soil still present

​Primary Succession Starts with: Bare rock (no soil).

• Events: Lava flow, glacier retreat, new island formed, bare rock exposed.

• Pioneer Species: Lichens and Mosses.

• Timeframe: VERY SLOW (can take 1,000+ years).

New Island Forming
Glacier Retreating

Exposed Rock on Mountainside

Multiple Choice

After which events can primary succession occur?

• Volcanic eruption, glacier retreat
• Forest fire, clear-cutting
• Drought, flood

LICHENS (crusty or leafy patches on rocks) are a symbiotic relationship (mutualism) between an algae and a fungus

• release mild acids that chemically break down the rock.

• When the lichens die, they decompose, mixing with the tiny rock particles to form the first thin layer of soil.

• This new soil is the factor that allows the next stage (grasses) to move in.

​​Evaluating the Factors of Primary Succession

Lichens

​What is the primary role of lichens during primary succession?

​a. To release acids that break down bare rock to create the first layer of soil.
b. To grow quickly and cover the nutrient-rich soil that remains after a forest fire.
c. To form a dense canopy that provides shade for the seedlings of hardwood trees.
d. To filter pollutants out of the water so that aquatic plants can begin to grow.

Multiple Choice

In primary succession, what is the most important ecological role of the pioneer species, such as lichens?

• They provide food for the animals that will arrive in the climax community.

• They break down bare rock and contribute organic matter to form the first soil.

• They compete with shrubs and trees for sunlight and water.

• They are a sign that the ecosystem has reached a stable, climax state.

Stages of Primary Succession:

Bare Rock → Lichens & Mosses (Pioneer Species) →
Grasses & Weeds → Shrubs → Fast-Growing Trees (Pines) → Hardwood Forest (Climax Community)

Reorder

Place Primary Succession in Order:

• Bare Rock

• Lichens

• Grasses > Shrubs

• Fast-growing Trees

• Hardwood Forest

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Reorder

Place primary succession in order:

• rock > lichens

• grasses

• shrubs

• fast-growing trees

• hardwood trees

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

​Secondary Succession: Soil is already present, but the living organisms were removed.

• Events: Wildfire , flood, hurricane, abandoned farm land, logging.

• Pioneer Species: Grasses and Weeds

• Timeframe: Much faster than primary (50-200 years) - no need to breakdown rock to make soil

​Why does secondary succession occur much faster than primary succession?
a. Secondary succession only happens in aquatic environments like ponds.
b. Secondary succession starts with a climax community already in place.
c. Secondary succession begins on bare rock, which heats up faster.
d. Secondary succession begins where soil and seeds are already present.

Dropdown

Pioneer species for primary succession ​

Select answer

Pioneer species for secondary succession ​

Select answer

Multiple Choice

After which events can secondary succession occur?

• Forest fire, clear-cutting
• Volcanic eruption, glacier retreat

Dropdown

Soil has been removed ​

Select answer

Soil still there ​

Select answer

Dropdown

After wildfire​

Select answer

After lava flow ​

Select answer

Stages of Secondary Succession:

Soil → Grasses & Weeds (Pioneer Species)
→ Shrubs → Fast-Growing Trees (Pines) →
Hardwood Forest (Climax Community)

Reorder

Place Secondary Succession in Order:

• Soil

• Grasses

• Shrubs

• Fast-growing Trees

• Hardwood Forest

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Old Field Succession: A farmer stops planting a cotton field and abandons it. The soil is left behind.

• Years 1-2: Pioneer species (grasses, weeds) quickly cover the field.

• Years 3-10: Shrubs and fast-growing Pine trees begin to grow, competing for light.

• Years 10-50: The pines grow tall, shading out the original grasses.

• Years 50-100+: Slower-growing, shade-tolerant Oak and Hickory trees grow up under the pines, eventually replacing them to form the climax forest.

Factors Affecting Secondary Succession:​

• Factor 1: Presence of Soil. This is why it's so much faster. The soil, seeds, and roots are already there!

• Factor 2: Competition for Light. The stages are a battle for sunlight.

  • Grasses are replaced by taller shrubs.

  • Shrubs are replaced by even taller, fast-growing pine trees.

  • Pines are replaced by shade-tolerant oaks that can grow underneath them.

Multiple Choice

In secondary succession, which factor is most crucial for the development of a new community?

• The presence of existing soil

• The presence of pioneer species

• The introduction of invasive species

• The availability of sunlight

​Pond Succession

• Ponds are not climax communities. They are temporary and will eventually fill in.

• This is a type of primary succession.

• Factors: Sediment (dirt) washes into the pond, and dead aquatic plants build up on the bottom.

• Stages: Pond → Marsh (shallow, with reeds) → Meadow (pond is filled in) → Shrubs → Forest.

​A diagram shows a pond ecosystem gradually filling with sediment and dead leaves, with the final stage being a hardwood forest. This is a form of [1] succession. The original pond is eventually replaced by a marsh, and then a meadow, because sediment and organic matter builds up on the bottom. The final, stable ecosystem of an oak-hickory forest is known as the [2].
1 - primary, secondary
2 - pioneer community, climax community

Reorder

Place pond succession in order:

1

2

3

4

• 1
• 2
• 3
• 4

Multiple Choice

A diagram shows a pond slowly drying up and filling in over time, eventually becoming a forest . Which statement best evaluates the factors involved in this process?

• The primary factor is an increase in water, which allows larger trees to grow in the pond.

• The main factors are a decrease in available water and the buildup of sediment, which allows land plants to move in.

• The process is secondary succession, driven by the pioneer species of lichens and mosses.

• The process is primary succession, driven by a wildfire that burned all the aquatic plants.

Drag and Drop

A diagram shows a pond ecosystem gradually filling with sediment and dead leaves, with the final stage being a hardwood forest. This is a form of ​

Placeholder

succession. The original pond is eventually replaced by a marsh, and then a meadow, because ​

Placeholder

builds up on the bottom. The final, stable ecosystem of an oak-hickory forest is known as the ​

Placeholder

Drag these tiles and drop them in the correct blank above

primary

sediment

secondary

climax community.

pioneer species

Multiple Choice

What is the climax community of a pond ecosystem?

• the pond is the climax community

• a meadow

• a hardwood forest

​Type of Succession	​Starting Condition	​Pioneer Species	​Climax Community
​Primary	​Bare Rock	​Lichens and Mosses	​Hardwood Forest
​Secondary	​Soil present	​Grasses and Weeds	​Hardwood Forest
​Pond	​Depression in earth fills with Water (no plants yet)	​Phytoplankton and Algae	​Hardwood Forest

​Ecological Succession Comparison

Match

Match the type of succession

• begins on bare rock

• begins with soil still present

• depression in earth fills with water

Primary Succession

Secondary Succession

Pond Succession

• Primary Succession

• Secondary Succession

• Pond Succession

Match

Match the pioneer species

• lichens and mosses

• grasses and weeds

• phytoplankton and algae

Primary Succession

Secondary Succession

Pond Succession

• Primary Succession

• Secondary Succession

• Pond Succession

PRACTICE
Questions

Multiple Choice

In a Mississippi ecosystem, which of the following best describes the climax community that will eventually form after a long period of stability?

• A grassland filled with wildflowers and weeds

• A dense forest dominated by hardwood trees like oak and maple

• A fast-growing pine forest with a thick underbrush of shrubs

• A wetland area populated by cattails and sedges

Multiple Choice

What is the correct order of primary succession in a forest ecosystem?

• Bare rock -> lichens -> grasses-> shrubs -> small trees -> mature forest
• Mature forest -> shrubs -> grasses -> lichens -> bare rock
• Grasses -> lichens -> bare rock -> shrubs -> small trees -> mature forest

Multiple Choice

What is the pioneer species of primary succession?

• Grasses
• Lichens

• Shrubs
• Weeds

Multiple Choice

A severe wildfire burns a large section of Mississippi's De Soto National Forest. The fire burns the trees and plants, but the soil remains intact. Which statement best describes the ecological succession that will follow?

• Primary succession will occur, starting with lichens colonizing the bare ground.

• Secondary succession will occur, starting with grasses and weeds that can grow in the existing soil.

• Primary succession will occur, as all the original organisms were removed by the fire.

• Secondary succession will occur, starting with the immediate regrowth of the climax community of oak trees.

Multiple Choice

A farmer in the Mississippi Delta abandons a large, plowed cotton field. The nutrient-rich soil is left exposed. What are the most likely pioneer species, and why will this type of succession be relatively fast?

• Lichens will colonize the soil, but the process will be slow.

• Grasses and weeds will colonize, and the process will be fast because the soil is already present.

• Oak and hickory trees will grow first, and the process will be fast because they are the climax community. d

• Mosses will colonize, and the process will be slow because they must first create new soil.

Multiple Choice

A hurricane's storm surge washes over a Mississippi barrier island, covering large areas with sand and saltwater and destroying the existing shrubs and grasses. However, the sandy soil underneath remains. What type of succession will occur, and what will be the likely pioneer species?

• Primary succession; lichens, because all life was destroyed.

• Primary succession; grasses, because the new sand is like bare rock.

• Secondary succession; grasses and salt-tolerant weeds, because the soil is still present.

• Secondary succession; oak trees, because they are the climax community and will grow back first.

Multiple Select

A volcano erupts, and the lava cools to form a new island of bare rock. Which two of the following are the most critical factors that initiate primary succession in this new environment?

• The presence of nutrient-rich soil from the volcano.

• The ability of pioneer species, like lichens, to grow on bare rock.

• The immediate arrival of fast-growing pine trees.

• The process of new soil being formed by pioneer species.

• The quick return of the original climax community.

Categorize

Options (4)

An abandoned cotton field in Mississippi.

A new island formed by volcanic lava flow.

A forest after logging operations clear-cut the trees.

An area exposed by a retreating glacier.

Classify the event as leading to either primary or secondary succession.

Priimary Succession

Secondary Succession

Reorder

Place ecological succession in order:

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Multiple Choice

6. Which sequence best represents the stages of succession that would most likely occur?

• bare rock → forest → moss → lichens

• grassland → forest → marsh → lake

• lake → marsh → grassland → shrubs → forest

• pine forest → grassland → shrubs → lichens

Multiple Choice

Which diagram best represents a climax community?

• Picture A

• Picture B

• Picture C

• Picture D

Multiple Choice

Stable, final stage of succession that can take a hundred or more years to achieve

• adaptation

• pioneer species

• niche

• climax community

Multiple Choice

Which of the following best describes secondary succession?

• A process that involves only aquatic ecosystems

• A process that occurs in an area with existing soil and previously existing life

• A process that is faster than primary succession

• A process that occurs in an area where no life previously existed

Multiple Choice

What is the primary difference between primary and secondary succession?

• Primary succession occurs in areas with existing soil, while secondary succession starts on bare rock.

• Primary succession begins on bare rock, while secondary succession occurs in areas with existing soil.

• Primary succession involves only plant species, while secondary succession involves only animal species.

• Primary succession is faster than secondary succession.

Multiple Choice

Which series of pictures BEST represents ecological succession?

• A

• B

• C

• D

Multiple Choice

Which of the following is a characteristic of a climax community?

• Low species diversity

• Frequent disturbances and changes

• Dominance of pioneer species

• High biodiversity and stability

Multiple Choice

In ecological succession, what role do decomposers play?

• They are the first organisms to colonize a barren environment.

• They break down dead organic matter, returning nutrients to the soil.

• They compete with pioneer species for resources.

• They prevent the establishment of new species.

Multiple Choice

What is the primary role of pioneer species in an ecosystem?

• To compete with existing species for resources

• To establish a climax community

• To modify the environment and make it suitable for other species

• To prevent the growth of invasive species

Multiple Choice

First species to arrive in an area are called ?

• invasive species

• abiotic components

• pioneer species

• parasites

Multiple Choice

Which of the following best describes the role of lichens in primary succession?

• They provide food for herbivores

• They break down rock to form soil

• They are the final species to establish in a climax community

• They compete with grasses for sunlight

Multiple Choice

The graph above shows the growth of a population of bacteria over time. Which statement best explains why the population growth levels off after day 25?

• The rate of immigration began to exceed the rate of emigration.

• The population reached the carrying capacity of its environment due to limited resources.

• The population shifted from logistic growth to exponential growth.

• A density-independent factor, such as a temperature drop, destroyed the population.