Module 6.6 Flashcards
Populations and sustainability
what is the lag phase
individuals acclimatising to the habitat
only a few individuals in a population
rate of reproduction is slow
growth in population size is slow
what is the log phase
resources are plentiful and conditions are good
reproduction happens quickly and exceed mortality
population size increases rapidly
what is the stationary phase
the population size levels out at the carrying capacity
the habitat cannot support a larger population
reproduction and mortality are equal
what are limiting factors
a factor that limits the growth in population size to the carrying capacity
what is a density independent limiting factor
act just as strongly no matter the population size e.g. low temp
what is a density dependent limiting factor
factor influences a population more strongly as population size increases e.g. resource like food, water, light and oxygen or parasites and predation
what is a k-strategist
population size is determined by the carrying capacity
limiting factors exert a more significant effect as population size gets closer to carrying capacity
characteristics of k-strategists
low reproductive rate
slow development
late reproductive age
long lifespan
large body mass
what is an r-strategist
population size increases so quickly it can exceed carrying capacity before limiting factors have an effect
when carrying capacity is exceeded resources will be sparce or excessive waste build up may poison the species and they begin to die
characteristics of r-strategists
high reproductive rate
quick development
young reproductive age
short life span
small body mass
predator prey relationship
pred pop gets bigger, more prey eaten
prey pop gets smaller, less food for pred, pred pop gets smaller
less pred, prey pop gets bigger
what is competition
when resources are not present in adequate amounts to satisfy the needs of all individuals in the ecosystem
what happens when a resource is in short supply in an ecosystem
competition
as competition intensity increase reproduction rate lowers and death rate increase
what is intraspecific competition
competition between individuals of the same species
individuals best adapted to obtaining resources survive and reproduce those less adapted die
population enters stationary phase
what is interspecific competition
competition between individuals of a different species
can effect both population size and distribution within the ecosystem
what increases interspecific competition intensity
the more overlap between two species niches
if tow species have the exact same niche one is out competed by the other and the other dies out
what is conservation
maintenance and improvement of biodiversity including diversity between species, genetic diversity within species and maintenance of a variety of habitats and ecosystems
involves human intervention
what is preservation
maintenance of habitats and ecosystems in their present condition, minimising human impact
reasons for conservation
economic
social
ethical
ethical reasons for conservation
every species has value and humans have an ethical responsibility to look after them
economic reasons for conservation
many plants and animals are food sources, genetic diversity in wild strains may be needed in the future to breed disease resistance and improve yield
insects pollinating crops
social reasons for conservation
valuable source of potentially beneficial organisms e.g. medicine
natural predators can act as pest control which is preferable to chemicals
maintaining water quality, protecting soil, breaking down waste products
maintaining climactic stability
what is coppicing
stem of a deciduous tree is cut close to the ground
once cut new shoots grow from the cut surface
they new stems can be used for fencing firewood or furniture
what is pollarding
the stem of the tree is cut higher up to prevent deer eating the emerging shoots
