Lecture 29: Disturbance and Succession

Question 1

Define succession

Answer 1

Gradual change in community after a disturbance

Question 2

Define disturbance

Answer 2

Event that disrupts an ecosystem by changing resources, substrate availability and the environment dynamics

Question 3

Types of disturbances

Answer 3

Temporal: short-term and long-term
Spatial: local and regional

Question 4

Define disclimax community

Answer 4

Community whose species composition is maintained through frequent disturbances

Question 5

Explain the intermediate disturbance hypothesis (IDH)

Answer 5

Intermediate levels of disturbance allow for the greatest species diversity

Question 6

What happens at low levels of disturbance?

Answer 6

• competitive exclusion
• very little change
• dominated by climax species and k-selected species

Question 7

What happens at high levels of disturbance?

Answer 7

• not enough time for many species to colonize
• lots of change
• dominated by pioneer species and r-selected species

Question 8

What happens at intermediate levels of disturbance?

Answer 8

• enough time for species to colonize, but not enough time for competitive exclusion to occur
• moderate amount of change
• diversity is highest because it results in a community with good competitors and good colonizers

Question 9

Define stability

Answer 9

The persistence of a community in the face of disturbance

Question 10

Stability: resistance vs resilience

Answer 10

Resistance: the capacity of a community to maintain structure amidst potential disturbance

Resilience: The ability to recover after a disturbance

Question 11

Resistance: green vs red community

Answer 11

Green community: changes are very little, resulting in high resistance and rapid recovery

Red community: changes are greater, resulting in lower resistance and slow recovery