Succession

Question 1

What is succession?

Answer 1

The process by which an ecosystem changes over time

Question 2

What happens in succession?

Answer 2

Biotic conditions change as the abiotic conditions change

Question 3

What are the two types of succession?

Answer 3

Primary and Secondary

Question 4

What is primary succession?

Answer 4

Happens on land that’s been newly formed or exposed (e.g volcanic eruption). There is no soil or organic material to start with

Question 5

What is secondary succession?

Answer 5

Happens on land that’s been cleared of all the plants but soil remains (e.g after forest fire)

Question 6

How does primary succession start?

Answer 6

When species colonise new land surface,seeds and spores are blown by the wind and begin to grow.

Question 7

What is the first species to colonise the area called?

Answer 7

Pioneer species

Question 8

What happens once primary succession has been started?

Answer 8

Abiotic conditions are hostile meaning only pioneer species can grow as they are specialised to cope with the conditions.

Question 9

What do pioneer species do to the abiotic conditions?

Answer 9

Change them so they die and microorganisms decompose the dead organic material forming bassic soil

Question 10

How does this decomposition affect the conditions?

Answer 10

Makes them less hostile meaning new organisms can move in and grow. These then die and are decomposed which add more organic material making the soil deeper and richer in minerals

Question 11

What does the deep and richer soil mean?

Answer 11

Larger plants e.g. shrubs can start to grow which retain even more water.

Question 12

What happens as more plants move in?

Answer 12

More habitats are created so more animals move in

Question 13

How does secondary succession occur?

Answer 13

It happens in the same way but there is already a soil layer so succession starts later-pioneer species are larger.

Question 14

At each stage in both primary and secondary succession, what happens to different plants and animals?

Answer 14

Ones that are better adapted for the improved conditions move in and out-compete plants/animals already there and become the dominant species.

Question 15

As succession goes on, what happens to the ecosystem?

Answer 15

Becomes more complex as new species move in with existing species meaning species diversity increases as well as amount of biomass

Question 16

What is the final stage of succession?

Answer 16

Climax community

Question 17

What is climax community?

Answer 17

Where the ecosystem is supporting the largest and most complex community of plants and animals it can so it won’t change much more ~(steady rate)

Question 18

Give an example of primary succession.

Answer 18

1)Pioneer species colonise the rocks e.g. lichens grow on and break down rocks, releasing materials
2)Lichens die,decompose forming thin soil which thickens as more organic material is formed so other species can grow
3)Larger plants that need more water can move in as the soil decomposes so soil will deepen as they die and decompose
4)Shrubs, ferns and small trees begin to grow which out-compete the grasses and smaller plants to become the dominant species
5)Soil is now deep and rich enough in nutrients to support larger trees so they become the dominant species and the climax community is formed.

Question 19

What do the species that make up a climax community depend on?

Answer 19

The climate of an ecosystem

Question 20

What is a climatic climax?

Answer 20

The climax community for a particular climate

Question 21

How can human activities affect a climax community?

Answer 21

Can prevent succession which stops the normal climax community from developing

Question 22

What is a plagioclimax?

Answer 22

When succession is stopped artificially (human activities) this is what a climax community is called.

Question 23

What is deflected succession?

Answer 23

When succession is prevented by human activity but the plagioclimax that develops is one that differs to any of the natural stages of the ecosystem

Question 24

Give an example of deflected succession.

Answer 24

Regularly mown field won’t develop woody plants even if the ecosystem could support them