M6 C24: populations and sustainability Flashcards
what are limiting factors of population growth?
availability of food
competition between predators#
build up of toxic by products from metabolism
disease
what is phase 1 of the population growth curve/
slow phase
what happens in the slow phase?
small no of individuals that are initially present will start to reproduce. birth rate higher than death rate so increase in population
what is phase 2 of the population growth curve?
rapid growth
what happens in rapid growth?
the number of breeding individuals increase so population multiplies exponetially
what is phase 3 of the population growth curve?
stable phase
what happens in the stable phase?
further population growth prevented by external constraints, small fluctuations
birth and death rates aprox equal
what can limiting factors be divided into?
abiotic and biotic factors
what are abiotic factors?
non living eg light, ph temperature
what are biotic factors?
living such as predators, disease, competition
what is carrying capacity?
maximum population size a environment can support
what is immigration?
movement of individual organisms into a area increasing population size
what is emigration?
movement of organisms away from an area decreasing population size
what are density indeopendent factors?
factors that have an effect on the whole population regardless of size eg earthquakes, fires, volcanoes, eruptions
what are the 2 types of competition?
interspecific and intraspecific
what is interspecific competition?
competition between different species
what is intraspecific competition?
competition between members of same species
what is the result of interspecific competition?
both compete for rescources so become limited for both species, this can limit food and there energy for growth and reproduction and smaller populations
what happens in inter specific competition when one species is better adapted than the other?
less adapted species will be out competed and will decline in number until it no longer exists
‘competitive exclusion principle’
why do fluctuations occur in intraspecific competition?
high availability increases population
population increase leads to limited availability for food so population decrease
less competition now so population increases again
is predataion a biotic or abiotic factor?
biotic
what is stage 1 in the predator/prey relationship?
increase in prey leads to increase in predator population as more food is available so they can survive and reproduce
what is stage 2 in the predator/prey relationship?
increase predator leads to decrease in prey, death rate greater than birth rate
what is stage 3 in the predator/prey relationship?
less prey means intraspecific competition as the predators have to compete with each other as there is less food available. decreases predator population
what is stage 4 in the predator/prey relationship?
reduced predator numbers result in less prey being killed, more prey therefore survive and reproduce. cycle starts again
what is conservation?
maintenance of biodiversity through human action or management.
what does conservation include?
includes maintaining diversity between species
maintaining genetic diversity within species
maintaining habitats
what is sustainable development?
management of ecosystems so natural resources can be used without running out
what is reclamation?
process of restoring ecosystems that have been damaged or deystroyed
what is preservation?
protection of an area by restricting or banning human interference so an ecosystem can remain in its original state
what is an argument against preservation?
no one can enjoy places where access is restricted, why have a resource if it isn’t being used?
what are some examples of preserved habitats?
nature reserves
marine conservation zones
why is conservation important economically?
provide resources that humans need to survive and provide an income. for example timber, medicinal uses, clothes, food ect
why is conservation important socially?
many people enjoy natural beauty of wild ecosystems and use them for beneficial activities such as walking, cycling, climbing
why is conservation important ethically?
all organisms have a right to exist and play an important role in their ecosystem, humans should not have the right to decide which ones survive and die.
responsibility for future generations to conserve the planet
what do humans need to survive at a basic level?
uncontaminated food
water supplies
clothes
shelter
access to medical care
what can an excessive demand for resources by humans result in?
destruction of ecosystems
reduction in biodiversity
depletion of resources
what is a sustainable resource?
renewable resource that is being economically exploited in a way that means it wont diminish/ run out
what are the aims of sustainability?
- preserve environment
-ensure resources are available for future generations
-all everyone in society to live comfortably
-enable less developed countries to grow by exploiting their resources - create an even consumption of resources between developed countries
what is coppicing?
technique where trunk is cut close to ground.
new shoots form from the cut surface and mature
eventually shoots cut and more are produced in their place
what can coppiced trees be used for?
a source of sustainable timber used for things such as fencing.
how does coppicing maintain biodiversity?
when used rotationaly, the trees never grow tall enough to block out light which can be a stressor for smaller trees. no succession
what is another technique used to produce small scale sustainable timber?
pollarding, trunk is cut higher up to avoid the new shoots being eaten by animals such as deer ect
what are ways that large scale timber production can be made sustainable?
selective cutting- only large removed
-replanting trees
-plant trees apart to reduce competition so there is a higher yield of wood
-manage pests
-ensure forests remain for indigenous people
what technique is used in large scale timber production?
felling which destroys trees and means they wont regrow
why has the fish population decreased?
overfishing due to the increasing population
what is a technique used to ensure that we have a sustainable population of fish/
- common fisheries policy in EU, areas have fish quotas
how do fish quotas maintain a sustainable population of fish?
have limits on numbers of fish that can be caught in certain areas to maintain natural population so they can reproduce and survive
what are other techniques that have been used to introduce sustainable fishing?
-nets with different mesh sizes, so small fishes can escape and breed
- allow commercial/ recreational fishing only at certain times to protect breeding season
-fish farming of certain species to protect other wilder species
how can ecotourism affect a ecosystem?
tourist movements such a repeated use of trails can contribute to soil erosion
how can conservation and farming be managed?
-semi-nomadic farming, moving where crops are grown each year allows soil to recover.
-as vegetation is removed, risk of soil erosion increases (loss of fertile land essential for agriculture and ecosystems)
-limited grazing/ farming to certain areas
how can conservation and research be managed?
making a widlife reserve where rangers can patrol to deter poachers to increase the populations of species so we can reserach them
