Topic 14
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Define Succession
It is when the mix of a species in a habitat changes over time
What term describes the unevenness of the distribution of concentrations of species over an area?
Spatial heterogeneity
What are the two opposing views of succession?
Clement: superorganism perspective Gleason: Individualistic viewpoint
What is the superorganism perspective?
There is a “true equilibrium state” that communities are working towards.
What is Gleason’s individualistic viewpoint?
communities were largely a coincidence of: 1. individual species characteristics 2. continuously varying environments 3. different probabilities of a species arriving somewhere
What is the intermediate disturbance hypothesis?
It predicts that species diversity will be highest at intermediate levels of disturbance.
How are attendance rates for the class?
Pretty Low
Why are attendance rates low?
People are tired
What happens to people who don’t show up to class?
They get creamed
Is the intermediate disturbance hypothesis effective in its predictions?
Not really, every ecosystem is different
In the intermediate disturbance hypothesis, what happens at low and high levels of disturbance?
At low levels of disturbance, competition is allowed to reduce diversity, and at high levels of disturbance, diversity is reduced as few species are adapted to all these events.
What is primary succession?
The process of change from an event that has effectively zeroed out the diversity. (newly established area)
What is secondary succession?
The process of change from an event that creates gaps in diversity, but does not clear all biological matter. (disturbance)
What are “the limits” of disturbance describing?
The point of too much or too little disturbance that affects species richness
What can we say about early successional species in forests?
They are strong dispersers and competitors for nutrients
What can we say about later successional species?
They are less good at dispersal, but are good competitors for light
What do early successional species do to nutrient concentrations in soil?
They actually increase nutritional value of soil
In glacial retreat primary succession, how can we describe the progression of succession?
It is stage like, with quickly establishing species opening pathways for different types of later growing populations
How does soil change in glacial habitats during primary succession?
Nutrient density rises and pH decreases