Lecture 17 - Succession Flashcards Preview

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Define succession

The process of directional change in communities.


What are 2 major kinds of succession? Give an example for each

1. Primary succession
Occurs on a new sterile area, such as that uncovered by a retreating glacier or created by an erupting volcano.
ex: Sand dunes on Lake Michigan

2. Secondary succession
The recovery of distrubed sites, where a biological legacy (propagules, living organisms) exists.
ex: Bog


Name 3 factors that affect succession

1. Availability of colonizers. Ex: seeds, larvae
2. Abiotic and biotic environment. Ex: nutrient availability, soil formation, presence of herbivores
3. Processes among the successional species: Early species can help, hinder or not affect the establishment of later species (facilitation, inhibition).


Name 4 models of succession (Why does the community change through time in a directional matter)

1. Facilitation: early species facilitate later ones.
2. Inhibition: early species inhibit later ones, but eventually die.
3. Tolerance: Later species are more tolerant of limiting resources, so remain at later stages.
4. Random


Which factor of succession do each of this affect in the sand dune experiment?
1. Soil development
2. Seed arrival
3. Water shortage
4. Seed predation

1. Soil development: Facilitation
2. Seed arrival: Inhibition/random
3. Water shortage: Tolerance/facilitation
4. Seed predation: Inhibition


Why did the Late successional species in the sand dune experiment have a high mortality rate?

High mortality due to: seed predation by rodents and water shortage


How can succession change light regime of plants?

Plant species show physiological and morphological adaptation to specific position in a succession gradient (and access to light/ shade tolerance).


What is forensic entomology? How is it related to succession?

Studying bugs in dead corpses to roughly calculate when a victim died based on the developmental stage of the bugs when the body is discovered.

We can calculate the time based on known successions of bugs.


Explain the Seasonal succession of Plankton in Lakes.

Initially, the spring bloom forms a lot of small algae. Then, there's a clear water phase was due to grazers that came in, they couldn’t get there at the beginning , they had to wait for that first big bloom of algae and then they could come in and graze the algae. After when nothing is left, they start declining. When large algae come in during summer, they are too big for the grazers. Then winter wipes everything away.


Define climax in succession (old view then new view)
What's the final view?

Climax: The end point of succession

Old view: final or stable community in a successional series. It is self-perpetuating and in equilibrium with the physical and biotic environment.

New view: Ecosystem is open and in non-equilibrium.

Climax is rarely a deterministic, fixed endpoint of succession, but rather a continuum of endpoints, depending on soil conditions, among others.
Climax is an abstract ideal that is seldom reached


Why is the Climax is an abstract ideal that is seldom reached in many instances?

Climax is rarely a deterministic, fixed endpoint of succession, but rather a continuum of endpoints, depending on soil conditions, among others.

Reason: Impact of the abiotic (e.g. climate fluctuations) and biotic environment (e.g. grazing)


Define patch dynamics.
Give 2 examples.

perspective that dynamics of an ecosystem can be understood as a mosaic of patches.

1. Wind-blown forest gaps:
Tree falls > secondary succession > tree falls somewhere else nearby

2. Mussel bed build up and destabilization
Mussels grow > patch destabilizes > removed by currents > new succession


Relate the adaptive strategies of species in early and late stages of succession to the ideas of r and K selection.

R-selected species are early succession species, k-selected species are late succession species.


How do early-successional species continue to exist?

Constant shifting and opening up of the niches


Describe the difference between primary and secondary succession - which one occurs in forensic entomology?