6.3.2 - Populations and Sustainability

Question 1

What are the two types of limiting factors in terms of population?

Answer 1

density dependent

density independent

Question 2

What are density dependent limiting factors?

Answer 2

limiting factors that only effect the population if its too large
eg. predators, disease, food availability, territory

Question 3

What are density independent limiting factors?

Answer 3

limiting factors that effect the population whatever size it is
eg. natural disasters, climate change, temperature, rainfall

Question 4

What is the carrying capacity of a population?

Answer 4

the maximum number of organisms that resources in an environment can support
-caused by limiting factors

Question 5

Describe and explain the shape of a population graph (number of organisms against time)

Answer 5

population starts very small without increasing and then begins to increase at a slow rate
-small no. individuals initially present reproduce (slow)
-birth rate > death rate
rapid population increase
-plentiful supply of resources
-birth rate > death rate
population plateaus
-birth rate slows down
-birth rate = death rate
-carry capacity is reached (due to limiting factors)

Question 6

Why does the population fluctuate at the carrying capacity?

Answer 6

increases - birth rate and survival rate increase (plentiful resources)
decreases - less resources available/more competition

Question 7

What is intraspecific competition?

Answer 7

competition within a species

Question 8

What is interspecific competition?

Answer 8

competition between different species

Question 9

Why is intraspecific competition more common than interspecific competition?

Answer 9

same species need the exact same resources eg. same food, mates, etc

Question 10

Describe and explain the shape of a predator-prey graph (number of organisms against time)

Answer 10

prey increase + prey decrease
-more prey survive and have chance to reproduce
-prey reproduction rate > death rate
predators increase
-more prey available as food for predators
prey population decreases
-more predators so more prey are eaten and the death rate of prey increases
-prey death rate > reproduction rate
predator population decreases
-less food (prey) available, leading to competition
-less predators survive and reproduce

Question 11

What is conservation?

Answer 11

the maintenance of biodiversity by managing the ecosystem

eg. SSSIs, national parks, botanical gardens

Question 12

What is preservation?

Answer 12

the protection of an area by restricting human involvement

-ecosystem is left alone

Question 13

What reasons are there for conservation and preservation?

Answer 13

• economic
• social
• ethical

Question 14

What is sustainability?

Answer 14

the use of resources so that they are available for future generations

Question 15

What are the aims of sustainability?

Answer 15

• preserve the environment
• ensure resources are available for future generations
• enable less economically developed countries to develop

Question 16

How can small scale timber production be made more sustainable?

Answer 16

coppicing

eg. willow, beech, ash
- tree trunk is cut close to the ground, where new shoots can form from the cut surface
- rotational
- harvested area increases in biodiversity

selective felling

eg. oak
- only cutting down some trees in an area, leaving the others to grow more

Question 17

How can large scale timber production be made more sustainable?

Answer 17

selective/rotational felling and replanting

Question 18

What are the advantages of selective/rotational felling and replanting?

Answer 18

• increases biodiversity

- replanted trees can be spaced apart to prevent disease

Question 19

What are the disadvantages of clear felling?

Answer 19

very environmentally damaging

• habitat loss
• soil composition (minerals/ions) lost

Question 20

What is clear felling?

Answer 20

large scale timber production where all the trees are cut down

Question 21

What is coppicing?

Answer 21

tree trunk is cut close to the ground, where new shoots can form from the cut surface and grow to create new plants

• done on a rotation
• usually on small scale timber production

Question 22

What is pollarding?

Answer 22

coppicing when tree trunks are cut higher up to prevent deer, etc eating the new shoots

Question 23

How can fishing be made more sustainable?

Answer 23

fishing quotas

controlling mesh size of nets

Question 24

How are human activities controlled in environmentally sensitive ecosystems?

Answer 24

park authorities (Snowdonia, Lake district)
-promotes understanding of park
-conserves + enhances wildlife, natural beauty and cultural heritage
Antarctic treaty (Antartica)
-tourism management
-conservation of plants and animals
-protected areas managed (eg. limited visits)
-scientific cooperation between nations
limiting human access (Antartica, Galapagos Islands)
controlled migration (Galapagos Islands)

Question 25

How are ecosystems managed to balance the conflict between preservation and human needs?

Answer 25

ecotourism
promoting sustainable agriculture
sustainable forest management with community forestry groups