6.6 POPULATIONS/SUSTAINABILITY Flashcards
Define carrying capacity
- The maximum population size for a species in a particular ecosystem
- Reached at the staitonary phase of a growth curve
Draw a growth curve for carrying capacity
Explain why growth rate slows before entering stationary phase
Because:
- Waste product build-up
- Some nutrients are limiting
- Abiotic factors may no longer be suitible
Define K-stratergists
- Organisms that are most sensitive to limiting factors
- Their population size is determined by the carrying capacity (K)
Define R-stratergists
- Organisms that are less sensitive to limiting factors
- Population size is determined by reproduction rate (R)
Compare feautures of k-stratergists against r-stratergists
Describe the predator-prey relationship
1) When predator population gets bigger, more prey are eaten
2) The prey population gets smaller, leaving less food for the predators
3) With less food, fewer predators can survive and their population size reduces
4) With fewer predators, fewer prey are eaten, and their population size increases
5) With more prey, the predator population increases, cycle repeats
Define intraspecific competition
- Competition between individuals of the same species
Define interspecific competition
- Competition between individuals of different species
Explain the effect of increased competition
- Fewer organisms have sufficient resources to reproduce (decreased reproduction rate)
- Fewer organisms have sufficient resources to survive (decreases death rate)
- Thus, population size decreases overall
Explain how intraspecific competition can stabilise flunctuations of population size in the stationary phase
- If population size drops, competition reduced, the population size increases back to carrying capacity
- If population size increases, competition increased, the population size decreases back to carrying capacity
State the two effects of interspecific competition on species
- Affects the population size of a species
- Affects the distribution of a species in an ecosystem
Explain what makes interspecific competition more intense
- Overlap between the two species niches
- Because two species cannot occupy the same niche in an ecosystem (competative exclusion principle)
Define conservation
- Active and dynamic interventions by humans to maintain or improve biodiversity
Define preservation
- Attempting to keep habitats as they currently are, with no change and eliminating human intervention
State three threats to biodiveristy that result in conservation
1) Resource stripping
2) Habitat disruption
3) Introduction of alien species
State and explain three reasons to conserve/preserve biodiversity
1) Economical - Food crops need wild varietys to increase biodiversity, plants/microbes may be used for medicines, pollinating animals can increase crop production
2) Social - Tourism benefits, aesthetic
3) Ethical - All things should be protected
State three ways in which pollarding helps sustain small scale timber
- Preserves wood
- Extends lifespan
- Prevents grazing
State how coppicing sustains small scale timber
- Increases shoot growth at the base
State the five guidlines for large scale timber by FSC
1) Reforestation (one in one out)
2) No clear felling (cutting everything)
3) Ecological functionality
4) Selective felling
5) Benefit the local community
State the guidline company for large scale timber
- FSC
State the guidline company for fishing
- MSC
State and describe the three guidlines for fishing by MSC
1) Sustainability - fish to maintain carrying capacity
2) Ecosystem impacts - Not damage habitats within the ecosystem
3) Good management - Obey legal restrictions, adapt and change if necessary
State some legal restrictions of fishing by MSC
- Mesh sizing (small fish can escape)
- Restrict certain species
- Boat sizes
- Annual quotas
- Sail duration
- Monitoring/inspection
State some critisisms of MSC laws
- Fishing zones are too large to monitor
- Monitoring is expensive
- False reporting of catch sizes
- Dead fish thrown overboard due to over quota limit
Define aquaculture
- Fish farming
- A solution to overfarming of fish
State disadvantages of aquaculture
- It pollutes airways
- higher risk of parasites
- Ugly
State an alternative to fishing
- Aquaculture
Describe an alternative to aquaculture
- Changing human eating habits (e.g to primary consumer over higher consumer)
- (However, this just passes problem to another trophic level)
- People are resistant and change is slow
