Succession

Question 1

What is secondary succession?

Answer 1

Occurs when organisms recolonise a devastated ecosystem

Question 2

Describe the steps involved in succession

Answer 2

• primary succession starts when species colonise a new land surface
- seeds and spores are blown in by the wind and begin to grow
- the first species to colonise the area are called pioneer species
- the abiotic conditions are hostile (no soil to retain water)
- only pioneer species grow because they’re specialised to cope with the harsh conditions
• the pioneer species change the abiotic conditions, they die and microorganisms decompose the dead organic material which forms a basic soil
- this makes conditions less hostile (basic soil helps to retain water) which means new organisms can move in and grow
- these then die and are decomposed, adding more organic material, making the soil deeper and richer in minerals
- this means larger plants like shrubs can start to grow in the deeper soil which retains even more water
• at each stage, different plants and animals that are better adapted for the improved conditions move in, out compete the plants and animals that are already there and become the dominant species in the ecosystem
• as succession goes on, the ecosystem becomes more complex, new species move in alongside existing species which means the species diversity increases
• the amount of biomass also increased because the plants at later stages are larger and more dense
• the final stage is called the climax community
- the ecosystem is supporting the largest and most complex community of plants and animals it can

Question 3

What is deflected succession?

Answer 3

When some form of management diverts the ecosystem away from turning into a climax community e.g. grazing or mowing

Question 4

What is primary succession?

Answer 4

Occurs when organisms colonise an area that has not been occupied previously