4.7 - Ecological Succession

Question 1

What is ecological succession?

Answer 1

A series of predictable stages of growth that a forest goes through

Question 2

What are the two types of succession?

Answer 2

1. Primary succession
2. Secondary succession

Question 3

What is primary succession?

Answer 3

• starts from bare rock in an area with no previous soil formation
• Moss & lichen spores carried by the wind grow directly on rocks, breaking them down to form soil

Question 4

What is secondary succession?

Answer 4

• starts from already established soil, in an area where a disturbance (fire/tornado/human land clearing) cleared out the majority of plant life
• Grasses, sedges, wildflowers, and berry bushes have seeds dispersed by wind or animal droppings

Question 5

How are the stages of succession categorized?

Answer 5

Stages are characterized by which types of plant species dominate the ecosystem; different species are adapted to the conditions of the different stages

Question 6

What are the three stages of succession?

Answer 6

1. Pioneer or early succession species
2. Mid-successional species
3. Late successional or climax community species

Question 7

What are primary or early succession species?

Answer 7

species appear first, when the ground is simply bare rock, or bare soil after a disturbance

Question 8

Characteristics of early succession

Answer 8

• seeds spread by wind or animals, fast growing, tolerant of shallow soil and full sunlight
• moss, lichen (bare rock) | wildflowers, raspberries, grasses/sedges

Question 9

What are mid succession species?

Answer 9

species appear after pioneer species have helped develop deeper soil with more nutrients by their cycles of growth/death

Question 10

Characteristics of mid succession

Answer 10

• relatively fast growing, larger plants that need deeper soils with more nutrients than pioneers, sun tolerant
• shrubs, bushes, fast-growing trees like aspen, cherry, and pine

Question 11

What are Late successional or climax community species?

Answer 11

species appear last, after soil is deepened and enriched with nutrients by cycles of growth and death by early & mid successional species

Question 12

Characteristics of late successional or climax community species

Answer 12

• large, slow-growing trees that are tolerant of shade and require deep soils for large root networks
• maples, oaks, other large trees

Question 13

Explain primary succession

Answer 13

• Occurs in an area that hasn’t previously been colonized by plants (bare rock)
• Moss and lichen (spores dispersed by wind) are able to grow directly on rock by secreting acids that break down rock & release minerals containing nutrients they need (N/P/K)
• Chemical weathering of rocks by moss & lichen combined with organic matter from moss & lichen dying form initial shallow soil
• Examples: volcanic rock, rock exposed after glacial retreat

Question 14

Explain secondary succession

Answer 14

• Occurs in an area that already has established soil, but has had most plant life removed by a disturbance
• Pioneer species are still wind-dispersed seeds of plants that are fast-growing and sun tolerant, but grasses/wildflowers/weeds instead of moss/lichen
• Soil is already established & sometimes even enriched by nutrient-rich ash from fire; overall more rapid process than primary succession