Topic 7: Succession

Question 1

Succession definition

Answer 1

The changes over time, in the species that occupy a particular area

Question 2

Ecosystems

Answer 2

All of the interaction, biotic and abiotic factors in a specific area

Question 3

Humus

Answer 3

Dead and decaying organic matter
It improves the water-holding capacity of the soil, soil depth and nutrients

Question 4

Abiotic factors

Answer 4

Physical conditions of the environment
E.g. temperature,PH,rainfall and humidity

Question 5

Biotic factors

Answer 5

The living parts of the environment
E.g. competition,food availability,predation

Question 6

Community

Answer 6

The populations of different species living in the same habitat at a particular time, all part of a food web

Question 7

Lichen

Answer 7

An organism that consists of a fungus and an algae

Question 8

Annual

Answer 8

A plant that completes its lifecycle within a single growing season

Question 9

Biennial

Answer 9

A plant that lives for/flowers every 2 years

Question 10

Perennial

Answer 10

A plant that lives for more than 2 seasons

Question 11

Herbaceous

Answer 11

A plant that is a perennial but has leaves that die back to the ground at the end of each season

Question 12

Shrub

Answer 12

A woody plant that branches near ground level

Question 13

tree

Answer 13

A woody plant with a single main stem-the trunk

Question 14

Primary succession

Answer 14

The change in species composition over time in a habitat that has not previously been inhabited
Happens on newly formed/exposed land
There is no soil or organic matter to start

Question 15

3 examples of primary succession

Answer 15

A glacier retreating and exposing rock
Sand being piled in dunes by wind and sea
Volcanoes erupting and depositing lava

Question 16

First stage of primary succession

Answer 16

The colonisation of an inhospitable environment by organisms called pioneer species

Question 17

What is the pioneer species in the colonisation of rock and why ?

Answer 17

Lichen, they can grow in these areas because they are adapted to cope with the harsh conditions

Question 18

Role of lichen in the colonisation of bare rock

Answer 18

When they die, they decompose and release sufficient nutrients to support a community of small plants,
They change the abiotic environment by forming soil and nutrients

Question 19

What happens after the role of lichen in the colonisation of bare rock?

Answer 19

Mosses are often in the next stage, followed by ferns. The plants decompose which adds more humus to the solution. This improves the water holding capacity of the soil.
Different species gradually replace these plants and increase soil nutrients, which allows tree seedlings to become established and grow
Trees will out-compete plants that aren’t shade tolerant

Question 20

What features may pioneer species have

Answer 20

Produce large numbers of seeds
Rapid seed germination
Ability to photosynthesise
Ability to fix atmospheric nitrogen
Tolerant to extreme conditions

Question 21

Why may pioneer species need to produce a large amount of wind dispersed seeds or spores

Answer 21

To reach isolated situation

Question 22

Why do pioneer species have a rapid germination of seeds

Answer 22

They dont need a period of dormancy to germinate

Question 23

Climax community

Answer 23

It is the final stage of succession
It is a stable state
It has a balanced equilibrium of many plant and animal species
E.g. generally deciduous oak woodland, Britain

Question 24

Animals and succession

Answer 24

Animal species change as succession progresses because there is a greater variety of habitats and breeding sites, and food and niches
So biodiversity increases

Question 25

Exam question, Describe and explain how succession occurs

Answer 25

1. Colonisation by pioneer species
2. Leads to a change in environment
3. E.g. more humus
   4.enables other species to colonise and survive
   5.larger herbaceous plants can grow in deeper and more nutrient rich soil
   6.this leads to an increse in biodiversity
   7.stability increases, less hostile environment
4. A climax community is established

Question 26

Severe abiotic factors

Answer 26

Harsher environment=fewer adapted species, so less survive and there is less species diversity
There is then a smaller number of food chains/more simple food webs
Lower stability, communities are more likely to fail
In this environment,generally the abiotic factors determine the species present
Humans can make them worse

Question 27

Less harsh abiotic factors

Answer 27

The less harsh environment, the more species, the greater the species diversity
In this environment, it is the biotic factors e.g competition, that determine whether particular species survive

Question 28

When does secondary succession occur ?

Answer 28

It occurs when land that already sustains life is suddenly altered,this could be due to land clearance for agriculture or a forest fire
Any natural disaster or human activity

Question 29

Secondary succession

Answer 29

The stages to return to a climax community are the same bit,occur more quickly
There is soil and seeds & spores may already be present
Some of the species in the new climax community may be different because land has been altered
There are no pioneer species in secondary

Question 30

Conservation

Answer 30

Is the management of earths natural resources so that the maximum use of them can be made in the future
Conservation of habitats frequently involves management of succession

Question 31

Main reasons for conservation

Answer 31

Ethical
Economical
Cultural
Aesthetic

Question 32

Ethical reasons for conservation

Answer 32

We share the planet and co-exist with other species

Question 33

Economic reasons for conservation

Answer 33

We need to maintain ecosystems because there are a lot of substances we find useful from living organisms

Question 34

cultural and aesthetic reasons for conservation

Answer 34

Habitats and organisms enrich our lives-variety=interest and creativity for humans