5.4

Question 1

Give the definition of primary and secondary succession

Answer 1

Primary - Newly formed land or bare rock is colonised and forms a habitat
Secondary - previously occupied area is recolonised after a disturbance wipes out the precious community

Question 2

Give the definition of a pioneer species

Answer 2

First organisms to colonise an ecosystem e.g. moss/lichen/marram grass

Question 3

Explain how pioneer species are adapted to exploit their niche

Answer 3

Very adapted to hostile/dry conditions with little to no soil

Question 4

Explain how pioneer species change the abiotic conditions in an ecosystem

Answer 4

When the organisms die, they form a layer of humus or fertile soil. Over time this builds up, providing abiotic nutrient rich soil for other species to then colonise

Question 5

Give the definition of a climax community

Answer 5

When abiotic and biotic factors are in equilibrium and little to no new species are colonising

Question 6

Explain the stages of succession from colonisation to climax community (4/5 marks)

Answer 6

1. Pioneer species moves into inhospitable environment (E.g. bare rock) as they can survive in harsh environments
2. When they die, leftover humus forms soil
3. Soil improves abiotic conditions and more advanced species move in
4. New species outcompetes pioneer species
5. More new species more adapted for the environment move in and niches are made
6. Succession ends at a climax community where animals + plants are in equilibrium