6.6 population and sustainability Flashcards
define carrying capacity
the maximum population size that can be maintained over a period of time in a particular habitat
Define limiting factor
the factor whose magnitude slows down the rate of a natural process
What are the three phases of population growth
lag phase
log phase
stationary phase(carrying capacity)
describe the lag phase
may only be a few individuals and they are still acclimating to their habitat and at this point rate of reproduction is low and growth in population is slow
describe the log phase
resources are plentiful and conditions are good
reproduction happens quickly and the rate exceeds mortality
population size increases rapidly
describe the stationary phase
the population size has levelled out at the carrying capacity of the habitat and the habitat cannot support a larger population
the rate of reproduction and mortality equal and the population size remains fairly stable
What are the two different types of limiting factors
density independent
density dependant
describe how limiting factors can be density independent
they act strongly irresponsive of the size of the population for example low temperatures will kill the same proportion of the population irrespective of its size
Describe how limiting factors can be density dependant
where the factor increases the population more strongly as population size increases for example the availability of resources
what are the 2 different types of strategists
k-strategists and r-strategists
describe the characteristics of k-strategists
low reproductive rate
slow development
long lifespan
larger body mass
Define k-strategists
species whose population size is determined by the carrying capacity and limiting factors exert a more and more significant effect as population size gets closer to the carrying capacity
Describe the characteristics of r-strategists
high reproductive rate
quick development
short life span
small body mass
define r-strategists
its population can grow very quickly and surpass carrying capacity before the limiting effectors begin to have an effect and once carrying capacity has been surpassed there is a shortness of resources
‘boom and bust’
define interspecific competition
competition between individuals of different species
define intraspecific competition
competition between individuals of the same species
what can the relationship between predator and prey be described as
cyclic
Describe the predator and prey relationship
when prey populations get smaller predators have less food so their populations decrease
the decrease in predator populations leads to increased prey populations as theyre are less predators hunting them
and as prey populations begin to rise so do predator a they have more food
describe how intraspecific competition keeps population sizes relatively stable
If the population size drops there will be less competition and population size increases and vice versa
what experiment did Gause do
he grew two species of paramecium both separately and together as an investigation into interspecific competition
What did Gause conclude from his experiment
that the more overlap there was between two species niche’s results in more intense competition and one can be out-competed by the other and die out of become extinct in the habitat
Define conservation
maintenance of biodiversity including diversity within species and maintenance of a variety of habitats and ecosystems
define preservation
maintenance of habitats and ecosystems in their present conditions and minimising human impact
What are some threats to biodiversity
over-exploitation
habitat destruction
species introduced to an ecosystem by humans that outcompete native species
What are some conservation strategies
control predators and poachers
move individuals to enlarge populations
preserve habitats by preventing pollution
vaccinate individuals against disease
Why conserve biodiversity
ethics
economic and social reasons
define coppicing
the stem of a deciduous tree is cut close to the ground and once cut new shoots from the cut surface grow and mature into narrow stems
define pollarding
cutting the stem higher up to prevent deer eating the emerging shoots
what is rotational coppicing
dividing a forest into sections and cut one section each year so by the time they want to coppice again the new stems have matured and are ready to be cut
Why is rotational coppicing beneficial
it is good for biodiversity
it lets more light in
provides different types of habitat
Explain why in the past large-scale timber production was bad
Destroyed habitats, reduced mineral levels in soil and left soil susceptible to erosion.
Soil may run off into waterways polluting them
describe modern sustainable forestry techniques
any tree harvested is replaced with another tree either grown naturally or planted
the forest must maintain its ecological function
local people should benefit from the forest
selective cutting
control pests and pathogens
how do you manage fish stocks
fisheries and aquacultures
what are the three principles for sustainable management of fisheries
fishing must take place at a level which allows it to take place indefinitely
fishing must be managed to maintain the structure
a fishery must adapt to changes in circumstances and comply with regulations
What are the benefits and disadvantages of aquaculture rather than capture fisheries
aquaculture can provide sustainable fish stocks restricting impact on oceanic fish stocks
It is expected to feed more people than capture fisheries
Where is the Terai region
In the south of Nepal
What are some characteristics of the Terai region
It is made up of marshy grasslands, savannah and forests
it is densely populated and home to endangered species such as the bengal tiger
What has been the effect of human activity in the Terai region
it has been under pressure for the expansion of agriculture into forested areas
grazing from farm animals, over exploitation of forest resources and replacement of traditional agricultural crop varieties
Describe how the Terai region has been managed
the WWF were focused on conserving the forest landscape.
They introduced community forest initiatives local people had rights to exploit the forest as well as responsibilities to look after it.
Biogas schemes and wood-efficient stoves were introduced to reduce the demand for firewood
eradicating invasive species
creation of forest corridors between national parks
Has the management of the Terai region been successful
yes, the tiger population has been steadily growing due to their use of the corridors
Where is the Maasai Mara
It is a famous destination for wildlife watchers in Kenya
Describe the characteristics of the Maasai Mara
It has large populations of antelopes and other large mammals
It has high endemic poverty but a lot of tourism so there had been a scope to develop conservation compatible land use that rewards local people financially and conserves habitats and species that are the basis of tourism
Describe how the Maasai Mara is conserved
creation of National parks in 1945
Rest of the land was used agriculturally as many Maasai took tenure of small plots of the land
PWC - conservancies that set an area of land aside for conservation which have positive social and economic outcomes
What are the negative consequences of conservancies
land-owners must move their livestock out during tourist season and their are constraints on how they use their land
Describe how peat forms
where lack of oxygen prevents complete decomposition of organic matter usually in a waterlogged area
what are some threats to peat bogs
Pressure from expansion of agriculture and forestry as well as landfill and peat extraction means that lowland peat bogs now covers less than a 1/10th of its original cover
What has been the effect of human activity on the Galapagos islands
50% of vertebrae and 25% of plant species are endangered
2001 oil spill
death of 150 000 sharks/year
invasive species increasing competition for resources and can eat native species
How are the effects of human activity managed in the Galapagos islands
at least 36% of coastal areas have become ‘No-Take’ zones
removal and prevention of invasive species
treat the problems caused by the invasive species
What are some threats to biodiversity in the lake district
Spruce and pine in conifer plantations support limited biodiversity
invasive species such as rhododendron outcompete native species
cliff, rock and scree communities are damaged by climbers and walkers
What are some solutions to the threats to biodiversity in the Lake district
varied planting
invasive species are physically removed
seasonal restriction on walking
farmers are paid to maintain hay meadows
What are the impacts of humans on Snowdonia
farmers dig open drainage ditches which increase risk of flooding due to increased run off
conifers are planted as cash crop
heather is no longer burnt so that sheep can graze on it
What are the solutions to the impacts on Snowdonia
blocking drainage ditches
burning controlled fires before heather gets too old and dry to prevent larger fires
