6.3.2 - populations and sustainability Flashcards
phase one of a population growth curve
a period of slow growth - the number of individuals that are present reproduce increasing the total population - the birth rate is higher than the death rate
phase 2 of a population growth curve
a period of rapid growth - total population multiplies exponentially. no constraints act to limit the population explosion
phase 3 of a population growth curve
a stable state - further population growth is prevented by external constraints - birth and death rates are approximately equal
limiting factor
prevent the further growth of a population and in some cases cause it to decline.
carrying capacity
the maximum population size that an environment can support
immigration
movement of individuals into a particular area increasing population size
emigration
movement of individual organisms away from a particular area decreasing population size
density independent factors
factors that have an effect on the whole population regardless of its size, dramatically changing the population size (e.g. earthquakes)
interspecific competition
competition between different species
intraspecific competition
competition between members of the same species
what is interspecific competition the result of?
reduction of the resource available for the populations.
stages of intraspecific competition
1 - resource is plentiful, everyone can have enough to survive and reproduce so pop increases
2 - due to increased population, resources are limited meaning the population will decrease
3 - less competition means less organisms are competing for the same resources - more organisms survive and reproduce, resulting in population growth.
predation
where a predator kills and eats prey.
predator prey relationship steps
stage one - increase in prey population provides more food for the predators - increasing predators
stage two - more predators means a decline in prey population
stage three - less prey means less food for predators so predator population decreases
stage four - reduced predators means more prey
why is the predator prey population not simple?
other factors will influence population size, like availability food, or the presence of other predators
conservation
the maintenance of biodiversity through human action or management
reclamation
the process of restoring ecosystems that have been damaged or destroyed
preservation
protection of an area by restricting or banning human interference so that the ecosystem is kept in its original state.
when is preservation needed?
in order to keep ecologically, archeaologically or palaeontologically sensitive resources
economic importance of conservation
to provide resources that humans need to survive and provide an income - mecidinal drugs, clothes and food that can be traded
social importance of conservation
many people enjoy the natural beauty of wild ecosystems as well as using them for activities which are beneficial to health by providing a means of relaxation
ethical importance of conservation
all organisms have the right to exist and most play an important role within their ecosystem. many people believe that we should not have the rught to decide which organisms should survive. we also have a moral responsibility
sustainable resource
renewable recourse that is being economically exploited in such way that will not run out
aims of sustainability
- preserve the environment
- ensure resources are available for future gens
- allow humans in all societies to live comfortably
- enable less developed countries to develop
