Succession

Question 1

What is succession

Answer 1

The process by which an ecosystem changes over time

The biotic conditions change as the abiotic conditions change

Question 2

What are the stages of succession called

Answer 2

Seres

Question 3

What are the two types of succession

Answer 3

Primary succession

Secondary succession

Question 4

Where does primary succession occur

Answer 4

Happens On land that’s been newly formed or exposed e.g.where a volcano erupts and forms a new rock surface

Question 5

Describe the characteristics of primary succession

Answer 5

• abiotic conditions are harsh e.g. No soil to retain water

- seeds and spores are blown in by wind

Question 6

What is the name of the first species to colonise the area

Answer 6

Pioneer species

This is the first sere

Question 7

How do pioneer species grow first?

Answer 7

They’re specialised to cope with the harsh conditions

e.g. Marram grass can grow on dunes by sea as they have deep roots to get water and can tolerate salty waters

Question 8

How do pioneer species change the abiotic conditions in a primary succession

Answer 8

They die and decompose which forms basic soil

Question 9

What happens once basic soils are made

Answer 9

Conditions become less hostile - basic soil helps retain water which means new organisms can grow. Then die and decompose adding more organic material making the soul deeper and richer in minerals, means larger plants like shrubs can start to grow in deeper soil (retains even more soil)

Question 10

Where does secondary succession occur

Answer 10

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

Question 11

Describe secondary succession

Answer 11

Happens in the same way as primary succession, but soil is already there so succession starts at a later Sere.

Pioneer species in secondary succession are larger plants e.g. Shrubs

Question 12

How do dominant species occur in the ecosystem

Answer 12

At each stage the different plants and animals that are better adapted for improved conditions move in and out compete the plants and animals already there

Question 13

What happens as succession occurs

Answer 13

An ecosystem becomes more complex, new species move in alongside existing species which means the species diversity increases

Question 14

What is the final sere of a succession

Answer 14

Climatic climax

Question 15

What is the climatic climax

Answer 15

When the ecosystem us supporting the largest and most complex community it can and the biotic and abiotic figures are in balance

Question 16

What determines the route of succession

Answer 16

The Abiotic conditions at the start of the process

E.g.
Lithosere - occurs of exposed rock
Psammosere - on sand
Hydrosere - on water

Question 17

What is a succession on a Lithosere

Answer 17

Bare rock to woodland

Question 18

What is the first step of succession for a Lithosere

Answer 18

• Pioneer species (e.g. lichens) colonise the rocks as they can live with very little water and nutrients.
• lichens break down rock releasing minerals
• surface becomes uneven when rock is broken, helps retain water

Question 19

What happens after the rock has been broken down in a Lithosere

Answer 19

Rocks get damp so mosses begin to grow and weather the rock surface.

Lichens and misses die and decompose forming thin soil

Question 20

What happens after the soil is beginning to appear in a Lithosere

Answer 20

Soil deepens, larger plants that need more water move in (e.g. grasses, fern, herbs and flowering plants)

Soil gets deeper as larger plants die and are decomposed by bacteria to form humus

Question 21

What happens after the larger plants begin to decompose?

Answer 21

Shrubs, ferns and small trees (birch) begin to grow.

They out-compete smaller plants to become dominant species

Question 22

What happens in the last stage of succession on a Lithosere

Answer 22

Soil is deep and rich in nutrients to support slow growing large trees (ash, oak)

Become dominant species and the climax community is formed