Succession 23.4 Flashcards
What is succession?
The process by which ecosystems change over time that results from changes in the environment
Give an example of succession
The types of plants that are present as you move inland from a beach
Name the types of succession
Primary and secondary succession
What is primary succession?
This is when the area of land is newly formed or bare rock and so has no soil or organisms are present
What is secondary succession?
This is when an area of land has soil but no living organisms are present like land after a fire
When does primary succession occur?
- When volcanoes erupt and the lava solidifies to solid rock
- When sand is blown to form dunes
- When silt is deposited in rivers
- When glaciers retreat to reveal rock
What is a seral stage?
The stages in which succession occurs
Name the seral stages in succession?
Pioneer community, Intermediate community and Climax community
How are pioneer communities formed and what species are in them?
This begins when an inhospitable environment is colonised by pioneer species such as lichen. The species are carried in by seeds or spores from passing animals or the wind
How are pioneer species adapted to cope with the environment?
- Produce large numbers or spores or seeds
- Can germinate quickly
- Can photosynthesize very well to produce their own energy even when there aren’t many abiotic factors
- Can fix nitrogen from the air so don’t need soil
- Can tolerate extreme environments
How are intermediate communities formed?
The rock will weather and break down into smaller particles however this doesn’t support other species. When the pioneer species die, they will decompose and introduce nitrogenous nutrients into the soil known as hummus. This means secondary colonisers will be brought in by spores and this can also bring in animals to eat the secondary colonisers
How are tertiary colonizers introduced into the intermediate community?
The secondary colonisers will also die and decompose to make even more nutrient rich soil so eventually tertiary coloniser seeds will blow in like grass shrubs. They can survive in harsh conditions and usually have waxy cuticles to prevent water loss. The environment will become more favourable, the more organisms are introduced in.
How are dominant species introduced to these environments?
The dominant species is the species that is the most abundant in that environment and has the most success
How is the climax community formed?
This community has been formed by the gradual increase of organisms in the intermediate succession until the environment became stable. Here many organisms are present and biodiversity generally increases
Why might biodiversity not be the highest in the climax community?
Because in the climax community, dominant species might outcompete the pioneer species and eliminate them so therefore decreasing biodiversity
