succession pack 6

Question 1

succession

Answer 1

the sequence of changes in a community over a period of time

Question 2

climax community

Answer 2

the final stage of succession. it is normally stable, self sustaining and sometimes has one or more dominant species

Question 3

where does primary succession start

Answer 3

bare rock -> no soil

Question 4

what type of habitat does primary succession take place in?

Answer 4

in newly formed habitats where there has never been a community before

Question 5

pioneer phase - colonisation

Answer 5

• the process starts on newly formed habitats where there have been a community before
• pioneer species like lichens / algae start to grow
• these species can live in the harsh conditions : no soil, little water and minerals, wind exposure, extreme temperatures
• they add organic matter (humus) and with the substrate (ash/rock) start to produce thin soil, change in abiotic conditions

Question 6

development stage

Answer 6

• mosses can now group: change in biotic conditions. they add more organic matter to the soil, the soil can now hold more water and mineral ions
• small, shallow rooted plants can grow, more organic material added to soil
• as abiotic conditions in the habitat improves, larger, taller plants can grow these out. competes the shorter plants, they replace the previous community

Question 7

climax community

Answer 7

• a community dominated by trees is established
• remains unchanged unless abiotic or biotic conditions in the habitat change
• it’s self sustaining
• many different types of species and niches (high biodiversity), depends on the climatic conditions and species available

Question 8

when / where does secondary succession take place

Answer 8

on bare soil where an existing community has been cleared, this can be after events such as ploughing, fires, volcanoes, hurricanes, flooding or grazing has been stopped

Question 9

what is deflected succession

Answer 9

a community that remains stable only because human activity prevents succession from running its course

Question 10

describe the characteristics of a dominant species

Answer 10

the one that exerts an overriding influence over the rest of the plant, microbe and animal species. usually the larges and / or most abundant plant species in the community

Question 11

describe what happens to the number of niches and species as succession continues

Answer 11

increases and so does the number of species present

Question 12

why can the biodiversity be lower in a climax community

Answer 12

as dominant species outcompete others

Question 13

how can a climax community without trees occur?

Answer 13

properties of the soil and underlying rock -> sandy and freely draining so suffers drought conditions after only a few days without rain