6.24 - Population and sustainability

Question 1

carrying capacity

Answer 1

the maximum population size that a environment can support

Question 2

limiting factors

Answer 2

prevent further growth of a population and in some cases cause it to decline

Question 3

limiting abiotic factors

Answer 3

• temperature
• light intensity
• pH
• water availability
• oxygen availability

Question 4

limiting biotic factors

Answer 4

• introduction of new predators
• introduction of new diseases
• intraspecific or interspecific competition
• food availability

Question 5

density independent factors

Answer 5

• factors that have an effect on the whole population regardless of its size
• can dramatically change population size
• e.g. earthquakes, fires, volcanic eruptions, storms

Question 6

interspecific competition

Answer 6

• competition between two or more different species for the same resources
• results in the reduction of the resource available to both populations
• if one species is more adapted, the less adapted species is likely to be outcompeted

Question 7

intraspecific competition

Answer 7

• competition within a species for a certain resource
  -availability of the resource determines population size
• results in fluctuations in the number of organisms in a population over time

Question 8

resources plants compete for

Answer 8

• pollinators
• water
• light
• space
• minerals in soil

Question 9

resources animals compete for

Answer 9

• social status
• food
• shelter
• territory
• mates
• oxygen (aquatic)

Question 10

competitive exclusion principle

Answer 10

where two species are competing for limited resources, the one that uses the resources more effectively will ultimately eliminate the other if conditions stay the same

Question 11

red and grey squirrels in the UK

Answer 11

• interspecific competition for food and territory
• grey squirrels are non native
• its population increased rapidly resulting in the disappearance of the native red squirrel in many places
• grey squirrels can eat a wider range of food and can store more fat as they are larger
• this increases their chance of survival and therefore their ability to reproduce, increasing population
• this further reduces food availability for red squirrels, reducing their ability to survive and reproduce, decreasing the population

Question 12

adaptations of predators

Answer 12

• forward facing eyes
• binocular vision
• depth perception
• adapted for short bursts of speed
• good senses
• sharp teeth/claws

Question 13

adaptations of prey

Answer 13

• defensive adaptations
• stamina
• good sense of hearing
• eyes on side of head and rectangular pupils
• wider field of vision
• camouflague

Question 14

predator prey relationship

Answer 14

• population of prey increases due to abundance of space and resources or favourable conditions
• increase in prey means an abundance of food for predators, meaning increased survival and reproduction, leading to an increase in the population of predators
• population of prey falls due to intraspecific competition for space and resources and interspecific competition from an increased amount of predation
• population of predators fall due to lack of food availability from a fall in prey and intraspecific competition
• less selection pressure from prey and intraspecific competition means the population of prey increases

Question 15

conservation

Answer 15

• the maintenance of biodiversity through human action or management
• the management of ecosystems so that the natural resources in them can be used without running out
• includes reclamation
• is dynamic and needs to adapt to constant change

Question 16

reclamation

Answer 16

• the process of restoring ecosystems that have been damaged or destroyed
• includes the use of controlled burning to halt succession and increase biodiversity

Question 17

preservation

Answer 17

• the protection of an area by restricting or banning human interference so that the ecosystem is kept in its original state
• most commonly used when preserving ecologically, archaeologically or palaeontologically sensitive resources easily damaged or destroyed by disturbance
• visitation is not allowed, except by those who monitor and manage such areas

Question 18

pristine habitats

Answer 18

• may contain very sensitive geological formations or unique ecosystems
• e.g. newly discovered/ virgin caves
• preserved
• some argue that there is no point in having a resource that cannot be used

Question 19

in situ conservation

Answer 19

• on site conservation methods
• protected areas, wildlife reserves, repopulation using breeding programmes

Question 20

advantages and disadvantages of in situ conservation

Answer 20

Advantages:
- conserves species without removal from their habitat
- ecosystem integrity is maintained
- less expensive
- suitable for large populations
Disadvantages:
- difficult to control conditions
- habitat may be too fragmented to ensure a sustainable population
- large area required
- conditions that caused the area to have a loss of species may still be present

Question 21

ex situ conservation

Answer 21

• conservation methods carried out off-site
• zoos, seed banks, botanic gardens, laboratories

Question 22

advantages and disadvantages of ex situ conservation

Answer 22

Advantages:
- conditions can be controlled
- protects organisms from predation and poaching
- techniques such as artificial insemination and genetic engineering are used to maximise reproductive success and genetic diversity
- smaller area required
Disadvantages:
- limited genetic diversity
- many animals may be unable to be reintroduced into the wild
- more expensive
- only suitable for small populations

Question 23

importance of conservation

Answer 23

• economic, provides resources needed to survive or provide an income
• social, means of relaxation and exercise
• ethical, moral responsibility for wildlife and future generations

Question 24

aims of sustainability

Answer 24

• preserve the environment
• ensure resources are available for future generations
• allow humans in all societies to live comfortably
• allow LEDCs to develop through exploiting their natural resources
• create a more even balance in the consumption of resources between MEDCs and LEDCs

Question 25

sustainable small-scale timber production

Answer 25

Coppicing:
- tree trunk is cut close to the ground
- new shoots form from the cut surface and mature
- eventually shoots are cut and more are produced in their place
- rotational coppicing takes place in managed woodlands
- woodland is divided up into sections and coppicing begins in each area over time
- maintains biodiversity as the trees never grow enough to block out the light
- pollarding is an alternative technique to coppicing, the tree is cut higher so animals cannot eat the new shoots

Question 26

sustainable large-scale timber production

Answer 26

• selective cutting/ only removing the largest trees
• replace trees through replanting
• plant trees optimal distance apart to reduce competition, resulting in higher yields
• manage pests and pathogens to maximise yields
• ensure forest remains for indigenous communities

Question 27

sustainable fishing

Answer 27

• international agreements made about number of fish that can be caught
• fishing quotas ensure a natural population of fish species remain so they can reproduce efficiently to maintain the population
• use of nets with different mesh sizes so immature fish can escape, allowing breeding to continue
• allowing commercial and recreational fishing only at certain times of the year, protecting the breeding seasons of some species
• introducing fish farming, maintaining a supply of protein while preventing the loss of wild species