Succession Flashcards
(77 cards)
What is succession
The process of change in the structure and composition of a biological community over time
What two types of factors govern a species’ distribution?
Biotic
Abiotic factors
What changes do communities undergo over time?
Changes in: Composition Structure Diversity Productivity
What 4 ways can communities change over time
- Dispersal of species to new habitat
- New species replacing existing species
- New growth becoming old growth
- Disturbance events such as fire/ natural disasters
Define primary succession
the colonisation of habitats devoid of life
Where/ when does primary succession begin?
When an area is completely lifeless and soil has not yet formed i.e: barren rock/ rubble
What organisms colonise an area first in primary succession (2)
Prokaryotes and heterotopic bacteria
Which organism succeeds bacteria in primary succession?
Lichens and mosses
Describe the brief process of primary succession
Bacteria - Lichens and moss - grasses and shrubs - trees (Followed by animals etc)
What does soil form from?
Crumbled rock and organic matter
What needs to form before shrubs can grow?
Soil
How long can it take for sufficient soil to form?
100-1000s of years
Define secondary succession
The process of succession that occurs after an existing community is cleared by a disturbance
What type of succession occurs after a disturbance event?
Secondary
What type of succession occurs in an area devoid of life?
Primary
Is primary or secondary succession faster?
Secondary is faster
In a normal, functioning ecosystem, when does secondary succession stop?
It doesn’t
What is a disturbance?
A change in the composition and density of individuals in a community that shifts equilibrium
Give 3 examples of disturbances
Fire
Drought
Flood
Tree fall
What process does secondary succession happen in
Clear forest - herbaceous plants - woody shrubs - forest growth
What are pioneer communities?
Early stage inhabitants of a community
Which organisms start a stable ecosystem?
Pioneer communities
What are climax communities?
Final stage inhabitants
What are climax communities defined by?
Climatic factors - i.e: vegetation zones