Succession

Question 1

Define succession

Answer 1

The change in structure and composition of a community over time

Question 2

Define primary succession

Answer 2

The change of structure and composition of a community over time in an area that has never previously been colonised eg bare rock

Question 3

Describe succession of bare rock

Answer 3

1) the pioneer species, lichens, colonise the bare rock
2) weathering of rock from erosion by pioneer species and the accumulation of DOM leads to the formation of primitive soil, allowing the colonisation of animals such as ants
3) wind blows spores allowing mosses to grow and more soil to develop allowing colonisation of grasses
4) tall grasses allow shade tolerant species to grow
5) as plants and animals decay, soil becomes thicker with more nutrients
6) deeper rooted plants become established such as oak trees
7) these grow to form a climax community.

Question 4

Define climax communities

Answer 4

a stable, self perpetuating community that has reached equilibrium and no further changes occur

Question 5

As a xerosphere progresses what increases

Answer 5

Biomass
Biodiversity
resistance to invasion of new species
Stability to abiotic changes such as weather

Question 6

Define secondary succession

Answer 6

The changes in structure and composition following a disturbance or damage to an already existing habitat

Question 7

Why do changes occur faster in secondary succession in comparison to primary succession

Answer 7

Seeds, spores or reproductive organs of vegetables remain unharmed beneath the soil so assist with the recolonization of the climax community

Soil is still fertile and organisms are still present

Question 8

What are the stages in succession called

Answer 8

seres/ seral stages

Question 9

Define Disclimax/ plagoclimax

Answer 9

When human interference, eg grazing of cattle, prevents the devlopment of the climax community

Question 10

What is the difference between inter-specific competition and intra-specific competition

Answer 10

1) competition between individuals of different species

2) competition between individuals of the same species

Question 11

What factors affect succession

Answer 11

1) migration
2) competition
3) Facilitation= refers to the symbiosis (association) between organisms

Question 12

what is the difference between mutualism and commensalism

Answer 12

1) an interaction between organisms of two species from which both benefit
2) an interaction between organisms of two species from which one benefits but the other is not affected

Question 13

How does facilitation contribute to succession

Answer 13

provides increased resource availability and refuge from physical stress, predation and competition