populations and sustainability Flashcards
what are stages of population growth curve
1) slow growth ( lag phase)
2) rapid growth ( log phase)
3) stable ( stationary phase)
what does lag phase and log phase show
birth rate > death rate
what does stationary phase show
birth rate equal to death rate
what are biotic factors which cause stability
predation
competition
diseases
what are abiotic factors which cause stationary
humidity
ph
light
temperature
o2 and h2o availability
what is carrying capacity
maximum population size that environment can support
what other factors affect population size
migration - immigration and emigration
density-independent factors ( natural disasters)
what are density independent factors
factors that affect population size despite initial size
what is interspecific competition
competition between different species
what is intraspecific competition
competition within same species
why does a graph with number of organisms over time fluctuate
1) resources in excess so enough for all so population size increases
2) population increases so resources begin to decrease so not enough resources for all therefore population decreases
3) as population decreases there will be more resources available again enough for all so population size increases again
what is the relationship between predator and prey
1)as prey population increases more food for predator
2) predator population therefore increases so more prey get eaten
3) prey population decreases so less food for predators
4)predator population decreases so less prey gets eaten
5) prey population increases
what is the importance of conservation
economic - provide resources
social - relaxation
ethical - right to exist
what is the aim of conservation
sustainable development
maintain biodiversity
what is preservation
protection of an area by reducing human interference
what is aim of preservation
protect environmentally sensitive ecosystems such as antartica and galapagos islands
maintain biodiversity
what are the aims of sustainability
ensure enough resources for future generations
enable LEDCs to develop
balance consumption of resources between MEDCs and LEDCs
preserve environment
what are small scale timber production
rotational coppicing - easy and quick. Trunk cut from near base of tree so more branches coming from cut so more wood.
pollarding - cutting trunk so it regrows with more shoots
what are advantages of coppicing
grows more branches
less sunlight blocked so no succession so maintains biodiversity
what is advantages of pollarding
cut higher up to avoid herbivores
what are large scale timber production
felling of large areas of forests
what are disadvantage of large scale timber production
tree will not regrow so not sustainable and may cause soil erosion
how is large scale timber production controlled
ensure protected area for locals
selecting cutting
replant trees at optimal distances to avoid competition
manage pests and pathogens
what are methods for sustainable fishing
fishing quotas to avoid overfishing
use bigger net mesh so immature fish can escape can grow and reproduce
restrict fishing time of year to protect breading season
fish farming to maintain protein supply and prevent loss of wild species
