POPULATIONS AND SUSTAINABILITY Flashcards
Population
The total number of organisms of one species in a habitat
Interspecific competition
When organisms of different species compete with eachother for the same resources
Resources available to both populations are reduced which means that both populations will be limited by a lower amount of food, they will have less energy for growth and reproduction so population size will decrease
Can affect the distribution of a species- if 2 compete but one is better adapted the less well adapted will be likely to be outcompeted
Intraspecific competition
When organisms of the same species compete with eachother for the same resources
Population of a species increases when resources are plentiful but as the population increases there will be more organisms competing for the same amount of space and food
Eventually resources such as food and space become limiting so the population begins to decline
A smaller population means that there is less competition for space and food which is better for growth and reproduction so the population begins to grow again
The maximal stable population of a species that an ecosystem can support is called its carrying capacity
Predation
Where an organism kills and eats another organism, the population size of predators and prey are controlled by negative feedback
As the prey population increases, more food is available for predators so the predator population grows
As the predator population increases, more prey is eaten so the prey population is reduced back to its stable size
This means there is less food for the predators so their population size decreases
Limiting factors which stop the population size from increasing
Abiotic- amount of shelter, only enough for a certain number of individuals
Biotic- interspecific competition limits the population size of a species because the amount of available sources is reduced
Determine the carrying capacity of an ecosystem
Observing ecosystems
The protection and management of ecosystems so that the natural resources in it can be used without them running out
Dynamic process- needs to be adapted to the constant changes that occur within ecosystems
Involves management of ecosystems- how resources are used and replaced
Reclamation- restoring ecosystems that have been damaged or destroyed so they can be used again
Importance of observing ecosystems
Provides resources for lots of things that humans need
Many ecosystems bring joy because they are attractive to look at and people use them for activities
It’s the right thing to do, could be considered a moral responsibility to conserve ecosystems for future generations
Preservation
The protection of ecosystems so that they are kept exactly as they are and nothing is removed
Woodland ecosystems
Sustainable- enough resources are taken to meet the needs of people today but without reducing the ability of people in the future to meet their own needs
Temperate woodland- for every tree that is cut down, a new one is planted in its place
Trees are cleared in strips or patches- woodland grows back quicker in smaller areas between bits of woodland than in larger open areas
The clear strips/patches aren’t too large or exposed so lots of soil erosion can occur on large areas of bare ground, if the soil is eroded, newly planted trees won’t be able to grow
Timber is harvested by coppicing- cutting down trees in a way that lots of them grow back
Native tree species tend to be planted in preference to non native species this is better for biodiversity because native species have long established interactions with other native species so their presence should help species of non native tree species
Planted trees are attached to posts that provide support and are grown in plastic tubes to prevent them being eaten by grazing animals
Trees aren’t planted too close together
Fishing quotas
Fish stocks are declining because of overfishing
Fishing quotas limit to the amount of fish species that fishermen are allowed to catch
Scientists study different species and decide how big their populations need to be for them to maintain numbers
International agreements are made that state the amount of fish each country can take and where from
Help conserve fish by reducing the numbers. Sight and killer so the amount killed is reduced
Problems with fishing quotas and solutions
Fish the wrong species or size are caught and thrown back into the sea often dead or dying
New rules for the Common Fishermen Policy are banning the discarding of fish and the whole fish will be bought back to the shore to be counted against the quota
Controlling mesh size of fishing nets
Limits to the mesh size of the fish net
Reduces the number of unwanted and discarded fish that are accidentally caught
Younger fish slip through the net allowing them to reach breeding age
Controlling mesh size of fishing net problems and solution
Can be difficult to determine the mesh size in areas where several fish species are fished for at the same time
2 nets, each of which meet regulations could be placed one inside of the other
Conservation and preservation balanced with human needs (3 places)
The Terai Arc
Maasai Mara
UK peat bogs
The Terai Arc
An area of forest and grassland in the border between Nepal and India, a variety of plants and animals are found here including endangered species like the Bengal Tiger and Asian elephant
Nearly 7 million people also live in this area and depend on the forests resources
Areas of the forest are being destroyed to make way for housing and other development
WWF has worked to help balance their needs with conserving the forest and its wildlife, the charity has provided people with things like solar cookers and biogas generators so they don’t need to use wood from the forest as fuel, farmers are also encouraged to plant mint hedges around their crops to keep animals away
