Chapter 18 Flashcards
(30 cards)
What is succession?
The change in a community structure over time
What is primary succession?
Succession that occurs at a location that was not previously occupied by a community.
What is secondary succession?
Succession that occurs at a location that was previously occupied by a community, but had then underwent a disturbance that removed all/part of the existing community.
What sites can undergo primary succession (5)?
Rock outcrops
Cliffs
Lava fields
Sand dunes
Newly exposed glacial till
What are the 6 successional stages?
1) Bare Surface
2) Colonization by Pioneering Species
3) Soil Formation
4) Arrival of small plants
5) Intermediate species
6) Climax community
What stages does early succession occur at?
stages 1-3
Bare surface, colonization by pioneering species, and soil formation
What stage does mid-succession occur at?
Stages 4-5
Arrival of small plants and intermediate species
What stage does late succession occur at?
Step 6
Climax community
What are some pioneering species?
Beachgrass, crabgrass, any plants generally categorized as “weeds”.
What are some intermediate species?
Shrubs and fast-growing trees
What are some species found in a climax community?
Slow-growing trees such as oak.
What is the difference in stages between primary and secondary succession?
Secondary succession begins at stage 2
What would happen in the 1st summer after a crop field was abandoned?
Crabgrass would grow rapidly. Dormant seeds in the soil, that were trapped under the farm crops, would receive light & moisture and begin to germinate.
What would happen in the 2nd summer after a crop field was abandoned?
Other plants begin to invade such as white aster and ragweed
What would happen in the 3rd summer after a crop field was abandoned?
Broomsedge and perennial bunchgrass will colonize the field to give it organic material.
Pine seedlings will begin to grow in open areas
What would happen in 5-10 years after this crop field was abandoned?
Pine trees begin to shade the broomsedge, leaving room for new growth.
What are the 2 hypothesis formed about succession?
Monoclimax Hypothesis
Initial Floristic Composition
Which hypothesis has been found to be true?
Initial Floristic Composition
What is the monoclimax hypothesis?
The community is a highly integrated superorganism. Is seen as analogous to the development of an individual organism.
What is the initial floristic composition hypothesis?
Succession at any site depends on which species arrives first.
Species replacement is not orderly, and some species suppress/exclude others from colonizing.
Succession is individualistic, dependent on the species that colonize a site and the arrival order.
What are the 3 models of succession?
Facilitation
Inhibition
Tolerance
What is the facilitation model of succession?
Early successional species change the environment, making it more suitable for later species to invade and grow.
What is the inhibition model of succession?
Early colonizing species modify the environment in ways that inhibit the establishment/growth of later species.
What is the tolerance model of succession?
Species in earlier successional stages don’t aid or inhibit later successional species.
