Populations and Sustainability

Question 1

Phases of a population-growth curve

Answer 1

Phases of a population-growth curve:
1 - Slow growth -> small number of individuals present reproducing
2- Rapid growth = higher breeding individuals, br higher than dr
3 - Stable state = breeding rate and death rate the same as growth prevented by external constraints

Question 2

Limiting factors in ecosystems

Answer 2

Limiting factors:
-Abiotic = non-living > temp, pH, light
-Biotic = living -> predators, prey, disease, competition

Question 3

What is carrying capacity?

Answer 3

Carrying capacity = maximum population size an environment can hold
-Population size affected by migration

Question 4

What are density independant factors?

Answer 4

Density independant factors = factors that have an aeffect n the whole population regardless of its size

Question 5

Types of competition in ecosystems

Answer 5

-Interspecific = competition between different species
-intraspecific = compeition between individuals of the same species

Question 6

Interspecific compeition

Answer 6

Interspecific competition:
-2 or more different species compete for same resources
-Results in total resource reduction
-Less adapted species will be outcompeted
-Eg red and grey squirrels compete for food but grey is better adapted due to wider range of food

Question 7

What is the competitive exclusion principle

Answer 7

Competitive exclusion principle = if conditions remain the same - less adapted species decrease

Question 8

Intraspecific competition stages

Answer 8

Intraspecific competition:
-Resource plentiful
-Resources limits as population increases
-Less population -> less competition -> more survive

Question 9

Stages of a predator-prey relationship (graph)

Answer 9

Stages of a predator-prey relationship (graph);
-Increased prey, food for predators and they increase
-Decline in prey
-Decline no longer supports predator population - intraspecific competition - predators decrease
-Prey increases as a result
-Cycle repeats

Question 10

What is conservation?

Answer 10

-Conservation = maintenance of biodiversity through human action or management
-Leads to sustainable management
-Reclamation = restores damaged exosystems ie controlled fires

Question 11

What is preservation?

Answer 11

Preservation = protection of an area by restricting or banning human interference
-For sensitive and vulnerable areas with resources

Question 12

What is the importance of conservation?

Answer 12

Importance of conservation:
-Economic (to provide resources for surivval and for an income
-Social (enjoyment and exercise)
-Ethical (right to existent and role important within ecosystem)

Question 13

What are the aims of sustainability?

Answer 13

Aims of sustainability:
-Preserve the environment
-Ensure resources are available for future generationsly
-Allow humans in all societies to live comfortably

Question 14

What is coppicing?

Answer 14

-Coppicing = Produces sustainable timber on a small scale where tree trunk cut close to the ground
-new shoots from the cut surface and mature
-Rotational coppicing - woodland divided in sections and trees cut into until all has been coppiced then original coppiced trees cut as theyve grown back by then etc
-Maintains biodiversity as trees never grow enough to block light, and so sucession cannot occur and more sepcies survive

Question 15

How can timber companies sustainably produce timber?

Answer 15

Sustainable timber production:
-Practise selective cutting, removing only larger trees
-Replace trees through replanting rather than waiting for natural regeneration
-Plant trees optimal distance apart to reduce compeition
-Manage pathogens to maximise yield

Question 16

Sustainable fishing methods

Answer 16

Sustainable fishing methods:
-Fishing quotas
-Nets with different mesh sizes
-Allowing commercial and recrational fishing only at certain times a year

Question 17

Key principles of ecotourism

Answer 17

Key principles of ecotourism:
-Ensures tourism does not exploit natural environment
-Consults and engage with local communities on planned developments
-Ensures infrastructure improvements benefit local people

Question 18

How to promote sustainable agriculture?

Answer 18

Promoting sustainable agrictulture:
-Multiple cropping where multiple crops are grown on piece of land
-Growth of nitrogen-fixing crops to enhance soil fertility
-Improve fertilisation techniques to enhance yield
-Genetic engineering to grow crops viable for multiple conditions

Question 19

Outline sucession.

Answer 19

→ Primary sucession → Progressive colonisation of bare rock or other barren terrain by living organisms:
1 = Pioneer species colonate the area, changing the abiotic factors to be less hostile for other species to surivve
2 = Different species present at each stage, changing the environment so it becomes suitable for other species with different adaptations
3 = Climax community = stable state = high biodiversity
→ Secondary sucession → recolonisation of an area after an earlier community has been removed or destroyed

Question 20

What are the advantages and disadvantages of in-situ conservation?

Answer 20

→ Advantages → Conserves species without removal, ecosystem integrity maintains as species play role in ecosystem functioning, cheaper than ex situ
→ Disadvantages → habit may be too fragmented for sustainability, genetic diversity may be too low already, reserves may be damaged by ecotourism

Question 21

What are the advantages and disdvantages of ex-situ conservation?

Answer 21

→ Advantages → Protects organisms from predation and poaching, helps attract funding and awareness
→ Disadvantages → limited genetic diversity, difficult to provide suitable environment, organisms struggle when re-introduced into the wild

Question 22

How to conserve lowland bogs?

Answer 22

-Ensure that the peat and vegetation is undisturbed and wet, such as blocking surrounding ditches for a period of time to raise water table to bog surface
-Removal of surrounding seedling trees due to its high water requirement
-Controlled grazing to maintain its biodiversity