6.3.2- Populations and Sustainability Flashcards
what is the expected population size at the end of the century?
11.2 billion
what is carrying capacity?
the maximum population size that can be maintained over a period of time in a habitat
what is a limiting factor?
the factor that limits the rate of population growth because it is the factor that is in the shortest supply
what are the two limiting factors and give examples of them?
-abiotic factors= temp, light, pH, water/oxygen availability, humidity
-biotic factors= competition, predators, disease
what does the lag phase of the typical population growth curve show?
-slow growth
-individuals acclimatising to their habitat
-low reproductive rate
what does the log/expodential phase of the typical population growth curve show?
-rapid growth
-plenty of resources and good conditions
-fast reproductive rate
-low mortality rate
what does the stationary phase of the typical population growth curve show?
-zero population growth, stable state
-population size levels out at the carrying capacity
-further growth prevented by limiting factor
-reproductive rate=mortality rate
what other 3 factors effect the population size and what do these mean?
-immigration= movement of individuals into a particular organism
-emigration= movement of individual organisms away from a particular area
-density independent factors= factors that have an effect on the whole population size regardless of its size (eg- volcano eruptions, earthquakes)
what is the equation for population growth?
pop change during period/pop at start of period x 100
what are the two types of competition and what do these mean?
-interspecific= between individuals of different species
-intraspecific= between individuals of the same species
what is a niche?
the role of a species within it’s habitat, consisting of both it’s biotic interactions
what is an example of interspecific competition in the UK and why did this occur?
red vs grey squirrel
-grey squirrel introduced in UK
-can eat a more variety of food and so can store more fat
-increases survival and its ability to reproduce
is the relationship between predator and prey interlinked?
yes
what does the graph that shows predator-prey relationships look like?
peaks and troughs of the prey population are mirrored by peaks and trough of the predator population, after a time delay.
how many stages of the predator-prey relationship are there?
4
what happens in stage one of the predator-prey relationship graph?
increase in prey population provides more prey for predators, allowing more to survive and reproduce, and so predator population increases
what happens in stage two of the predator-prey relationship graph?
the increased predator population eats more prey organisms, causing a decline in the prey population, and so the predator population increases
what happens in stage three of the predator-prey relationship graph?
the reduced prey population can no longer support the large predator population, and so intraspecific competition for food increases, resulting in a decrease in the size of the predator population
what happens in stage four of the predator-prey relationship graph?
reduced predator numbers results in less of the prey population being killed, so more prey organisms survive and reproduce, increasing the prey population
what is conservation?
the maintenance of biodiversity through human action or management.
what is sustainable development?
the management of ecosystems so that the natural resources within them can be used without running out
what is reclamation?
the process of restoring ecosystems that have been damaged or destroyed
what is preservation?
the protection of an area by restricting or banning human interference, so that the ecosystem is left in its original state
what are the three important reasons for conservation?
-economic reasons
-social reasons
-ethical reasons
explain the economic reasons for conservation?
-to provide resources that humans need to survive and to provide an income
-eg- rainforests supply resources for medicinal drugs, clothes and food that can be traded
explain the social reasons for conservation?
-people enjoy natural beauty
-people use areas for activities which are beneficial to health by providing a means of relaxation and exercise
explain the ethical reasons for conservation?
-organisms have a right to exist and play an important role within ecosystem
-moral responsibility for future generations to conserve the wide variety of existing natural ecosystems
what is a sustainable resource?
a renewable resource that s being economically exploited in such a way that it will not diminish or run out
what are the 5 aims of sustainability?
-preserve the environment
-ensure resources are available for future generations
-allow humans in all societies to live comfortably
-enable LEDCs to develop through exploiting their natural resources
-create an more even balance in the consumption of these resources between MEDCs and LEDCs.
what is coppicing?
a small scale timber production, to produce sustainable timber?
what occurs during coppicing?
-tree trunk cut close to ground
-new shoots form from cut and mature
-shoots are eventually cut and more grow in their place
-these shoots have multiple uses
what does rotational coppicing involve?
-woodland divided into sections and tress only cut in particular section until all have been coppiced
-begins in another area, allowing for new to grow
-process continued until reached first coppiced, which would have now grown to mature sized trees
what does rotational coppicing do?
maintains biodiversity
what is pollarding?
technique similar to coppicing, but trunk is cut higher so animals cannot eat the new shoots as they start to appear
what is felling trees an example of?
large scale timber production
what are the 5 ways that timber companies ensure felling is sustainable?
-practise selective cutting
-replace trees through replanting
-plant trees at an optimal distance to decrease competition
-manage pests and pathogens to maximise yields
-ensure that areas of forest remain for indigenous people
what are ways in which fishing has been made sustainable?
-fisheries policy, limit on the fish being caught in a particular area
-large mesh fishing nets, so only adult fish can be caught
-allowing commercial and recreational fishing only at certain times
-fish farming
