populations and sustainability Flashcards
what is interspecific competition
when organisms of different species compete with each other for the same recources
what is intraspecific competition
when organisms of the same species compete for the same recourse
what kind of feeback is at work in predator-prey cycles
negative feedback - a system reacts to change in a way that pushes levels back to a stable state
outline a brief predator prey cycle
- prey population increases, more food for predators, therefore predators more likely to survive and reproduce
- predator population increases, more prey are eaten, therefore prey are less likely to survive and reproduce.
- decreased prey populations means less food for predators, less likely to survive and reproduce
- predator population decreases, less prey being eaten therefore population increases, cycle begins again.
what is conservation
active managment of ecosystems with controlled human activity so natural recources can be used without running out + are available for future generations
what is sustainibility
using resources in such a way that the requirements of the current generation are met without depleting these resources for future generations.
what are some economic reasons for conserving ecosystems
ecosystems contain valuable recourses eg. drugs. these are traded on a global and local scale.
Wild insects pollinate crops for farmers
Conservation provides jobs
what are some social reasons for conserving ecosystems
ecosystems are attractive and aesthetic to look at, they improve the well-being of people
what are some ethical reasons for conserving ecosystems
organisms have a right to exist and so shouldn;t become extinct as a result of human activity.
We have a moral responsibility to conserve ecosystems for future generations
what are some ecological reasons for conserving ecosystems
can help prevent climate change as trees absorb CO2
prevents disruption to food chains
what is preservation
protection of an area by restricting human interference. Maintains ecosystems in their present condition, for example squaring of land and not allowing humans to enter
what are the aims of sustainibility
increase the efficiency of recource use
conserve ecosystems for future generations so they can use recources
enable less economically developed countries can as they can harvest their own unique recourses to replenish recourses we are using up - provides an economic opportunity
create a global balence of recourse use
what are 6 different ways a temperate woodland can be sustainably conserved
- selective felling -removing the largest trees (as well as diseased ones) to help more immature trees to grow. The felled trees are replaced with seeds.
- Coppicing – trees are cut close to the ground to encourage new growth. Since the stumps have good root systems, they can grow back more quickly than replanting young trees.
- Pollarding – a type of coppicing where the trees are cut higher up. This is to prevent deer from eating the new shoots. Growing saplings in plastic tubes also prevents grazing by deer and other large mammals
- Clearing trees in strips or patches – woodlands recover faster if they are surrounded by areas of established woodland, compared to larger, open areas
- Planting native trees – native trees are better for biodiversity than non-native trees because they have established interactions with other organisms in the ecosystem.
- Planting trees with plenty of space – to prevent competition and allow maximal growth.
what are the different threats to woodland
- woodland is cleared and converted to agricultural land
- woodland is cleared for development such as housing
- logging - cutting trees for sale of timber
- pollution - acid rain removes nutrients and minerals from the soil that trees need to grow
- global warming - changes rainfall patterns eg. long periods of drought
what are some of the things we use wood for
construction
fuel
paper
furniture
fencing
how can fishing be managed sustainably
- Fishing quotas – to limit the amount of fish that fishermen are allowed to catch.
- Controlling mesh size – nets with a small mesh increases the amount of by-catch (the unwanted fish that are accidentally caught). Using nets with bigger holes will allow small by-catch and young fish (so can survive and reproduce) that are too small to sell to slip out of the net.
- restrict fishing time of the year - can only fish at certain seasons this protects breeding season
- fish farming - fish are intensively reared in ponds/tanks or nets. Older fish are sold and younger fish are left to grow. maintains a constant supply of protein
how are fishing quotas set
scientists study different species and decide on how big their populations need to be for them to maintain their numbers. Then decide how many it’s safe to take without reducing the population too much.
international agreements are made which state the amount of fish each country can take and where from.
what is the issue with fishing quotas
the fish of wrong species or size are still caught, as they are not in the quota they end up being thrown back into the sea often dead or dying.
what is the issue with changing mesh sizes
can be difficult to determine exactly how big the mesh size should be in areas where multiple fish are fished for at the same time
what is the aim of preservation
protect environmentally sensitive ecosystems eg. antarctica and galapagos islands
what is rotational coppicing and what does rotational coppicing allow
rotational coppicing involves dividing an area up into different squares/regions. Coppicing one area and then moving and rotating round. This means when you reach the first point of coppicing eneough time has passed so that there is lots of new growth to recoppice.
no trees block sunlight
no succession occurs
maintains biodiversity
what is an unsustainable method of timber harvesting
large scale felling - trees do not regrow as destroying large areas of forest, no roots leading to soil erosion
