Disturbance and Succession NOTES

• An event that causes loss of life in a community

• Measured by scale, intensity, and frequency

• Moderate disturbance can increase diversity in communities

I. Disturbance

II. Population Growth (post-disturbance and otherwise)

Carrying Capacity: maximum population size an ecosystem can sustain Limiting Factor/ Resource: factors that influence carrying capacity

K-strategists

r-strategists

carrying capacitylimiting factors

# of organisms

time

Many species of organisms in an area is a community.1. An existing______________of isreplaced by a different community over periods of time ranging from a few decades to thousands of years.

community organisms

III. Ecological Succession

Secondary succession

Primary succession

III. Ecological Succession

Early seral stages

Later seral stages

Mid seral stages

Climax stage

r-strategists

K-strategists

Pioneer species

2. Disturbance/ uninhabited area lichens, (produce acids to break down rocks), produce a thin soil, mosses, (change soil) , weeds, grasses, (pioneer species), perennial herbs, shrubs, trees, insects, birds, animals

III. Ecological Succession

In primary succession only

3. Climax community – stable collection of organisms – which reach a stage

stable than those that preceded.

Nature of the climax community depends on climate: varies from rainforest to shrubland to grassland, etc.

more

III. Ecological Succession

4. Trends in many successionsChange in community structure: Replacement of opportunistic, early-stage (r-strategists) with late-stage (K-strategists)Increased nutrients available.Increased biomass (living material)

Increase in diversity (especially with small, regular disturbances)Increased complexity (i.e. in food web)Increased stability between photosynthesis (producers) and respiration (consumers)

III. Ecological Succession