LE 13: Succession and Disturbance Flashcards
What is succession?
Change in an ecological community over time
What is primary succession and its key point?
The development of communities in habitats that are initially devoid of plants and organic soils
- nutrients are not able to support life
- weathering and bacteria play a role in primary succession
Key point: making dirt that has usable nutrients that can support life
What is secondary succession and its key point?
Development of communities in habitats that have been disturbed and include no plants, but has organic soil
- plant community is developing
How do plant communities affect the development of other communities?
They develop niches for other species to fill in
- plant community changes = animal community changes
Why is intentional burning of prairies needed?
Some temperate regions do not turn into hardwood forests because of disturbances
prairies are intentionally burned because if they aren’t then they’ll turn into hardwood forests
What are the characteristics of chaparrals that undergo succession?
early phase = green/soft
- little to no canopy
- sage/mint scent
- winter rains, leaves replaced
- heavily dependent on marine layer for water
late phase = hard/ old growth if not disturbed
- scrub oaks and manzanita (fun fact: manzanita is good fire wood because it burns slow and fast)
What is a disturbance and its types?
interruption of a settled condition
- neither good or bad depending on the situation
types:
- natural = rain storm in desert, hurricanes, predators, fires
- unnatural = human noise, deforestation, controlled burns
What is the intermediate disturbance hypothesis?
A hypothesis that relates the amount of disturbance to its effect on diversity:
frequent disturbance: species good at recolonizing will live
- example: grasses
- affects community
intermediate disturbance: richer diversity
- example: prairie
no disturbance: outcompeting species with live but there is low diversity
- examples: trees like oaks and hickory
How does predation/herbivory relate to the intermediate disturbance hypothesis?
Predation/herbivory is a type of disturbance and is an example of the intermediate disturbance hypothesis:
- predators disturbing the environment = evenness in species
- certain species live better in disturbed vs undisturbed areas (red algae lives in undisturbed and green algae in disturbed)
How do Grazers maintain communities?
- clear space
- opens opportunities for more plants
- other animals can live there
- spread seeds
How does fire maintain a community?
controlled burns prevent uncontrolled burns
- stops natural burns from occurring
What is Chronosequence?
A sequence of communities that exists in a given location overtime.
- example: progression of ecological communities and the birds that appear after secondary succession
- example: decay is an ecological succession (types of bugs in dead bodies = give approx time of death)
Is there only one path to an outcome of a community?
no, multiple paths leads to similar outcomes
example: lakes -> fields
- plants expand laterally
- water levels declines and plants expand
- lake dries up and plants grow
- floor and unfolds or floods and then dries up
What does it mean when communities are transient?
They are ephemeral or short-lasting
- wet dry season and then it freeze thaws
- some organisms have adaptations to survive these changes or they lay dormant or they can leave and then come back
How does climate affect ecological succession?
can result in lasting changes
example: trees and glaciers
- as the glacier recedes, the tree population increases and the glacier can not come back
