Module 6 Section 7 - Populations and Sustainability

Question 1

What is a population definition

Answer 1

A population is all the organism of one species in a habitat

Question 2

What is population size?

Answer 2

Population size is the total number of organisms of one species in a habitat

Question 3

What are some abiotic factors that can affect population size?

Answer 3

The amount of light
Water
Space available
Temperature of surroundings

Question 4

What are some biotic factors that can affect population sizes?

Answer 4

1) interspecific competition
2) intraspecific competition
3) predation

Question 5

What is interspecifc competition + how it affects population size?

Answer 5

This is when organisms of different species compete with each other for the same resources. This means that resources available for both populations are reduced eg less food available so the populations are limited by food. This means they’ll have less energy for growth and reproduction so both population sizes will be lower.

Question 6

How can interspecifc competition affect distribution of species?

Answer 6

If two species are competing, but one is better adapted to its surroundings than the other, the less well adapted one is likely to get out-competed and won’t be able to exist alongside the better adapted species.

Question 7

Example of interspecifc competition

Answer 7

Grey squirrels were introduced to the UK. They now compete with the native red squirrels for the same food sources and habitat.

As they share the same source of food, there is less available to both of them so in areas where both red and grey squirrels live, both populations are smaller.

Since the introduction is the grey squirrel to the uk, the native red squirrel has disappeared from large areas. The grey squirrel is better adapted as it is larger and can store more fat than red squirrels. They can also eat a wider range of food than red squirrels.

Question 8

What is intraspecific competition?

Answer 8

Intraspecific competition is when organisms of the same species compete with each other for the same resources. It can cause a cyclical change in population size where population grows, shrinks, grows again so on.

Question 9

How does intraspecific competition affect population size?

Answer 9

1) when resources are plentiful, a population increases
2) as a population increases, there are more organisms competing for the same amount of space and food.
3) eventually resources such as food become limiting and there isn’t enough for all organisms
4) the population then begins to decline.
5) a smaller population means there’s less competition for space and food which is better for growth and reproduction so population starts to grow again.

Question 10

What is carrying capacity?

Answer 10

The maximum stable population size of a species than an ecosystem can support.

Question 11

What is predation?

Answer 11

Predation is when an organism (the predator) kills and eats another organism (the prey). The population sizes of predators and prey are interlinked and the populations are controlled via negative feedback.

Question 12

How does predation affect population size?

Answer 12

1) in a predator prey system, as the prey population increases, there is more food for predators so predator population grows
2) this means more prey is eaten so prey population begins to fall - this is negative feedback as it restores prey population to more stable size
3) this means there is less food for predators so population of predators decreases - also negative feedback.

Question 13

Example of predation

Answer 13

1) the lynx population grew after the snowshoe hare population grew as more food available for the lynx
2) more lynx meant more snowshoe hares eaten so population of hares fell (negative feedback)
3) reduced number of snowshoe hares meant there was less food for the lynx so the population of the lynx also fell.

However predator prey relationships are more complicated than this as other factors like availability of food for the prey can affect populations.

Question 14

What is a limiting factor?

Answer 14

Limiting factors are factors that stop the population size of a species increasing and determine the carry capacity of an ecosystem. They can be biotic or abiotic.

Question 15

Example of abiotic limiting factor

Answer 15

The amount of shelter in an ecosystem limits the population size of a species as there’s only enough shelter for a certain number of individuals.

Question 16

Example of a biotic limiting factor

Answer 16

Interspecifc completion limits the population size of a species because the amount of resources available to a species is reduced.

Question 17

What is conservation?

Answer 17

Conservation is the protection and management of ecosystems so that the natural resources in them can be used without running out. This means natural resources will still be available for future generations. It involves the controlling how resources are used and replaced.

Question 18

Why is conservation described as a dynamic process?

Answer 18

Conservation methods need to be adapted to the constant changes (caused naturally and by humans) that occur within ecosystems.

Question 19

How can conservation involve reclamation?

Answer 19

This means restoring ecosystems that have been damaged or destroyed so they can be used again, eg restoring forests that have been cut down so they can be used again.

Question 20

What are some economic reasons for conservation?

Answer 20

Ecosystems provide resources that humans need eg forests contain species that provide things like drugs, clothes and food. These resources are economically important because they are traded on a local and global scale. If ecosystems aren’t conserved, resources will be lost and there will be less trade in the future.

Question 21

What are social reasons for conservation?

Answer 21

Many ecosystems bring joy to lots of people because they’re attractive to look at ans people use them for activities eg birdwatching. The species and habitats in the ecosystems may be lost if they aren’t conserved,Mel future generations won’t be able to use and enjoy them.

Question 22

What are some ethical reasons for conservation?

Answer 22

Some people think we should conserve ecosystems simply because it’s the “right thing to do”. Organisms have the right to exists so they shouldn’t become extinct due to human activity. We have a moral responsibility to conserve ecosystems for future generations so they can enjoy and use them.

Question 23

What are some ecological reasons for conservations?

Answer 23

1) conserving species and habitats can help prevent climate change. Eh when trees are burnt, CO2 is released which contributes to global warming. If trees are conserved this doesn’t happen.

2) it also helps prevent the disruption of food chains. Disruption of food chains can have knock on effects on other organisms.

Question 24

What is preservation?

Answer 24

It’s the protection of ecosystems so they’re kept exactly as they are. Nothing is removed from a preserved ecosystem and they’re only used for activities that don’t damage them. Visitors are banned

Question 25

How can temperate woodland be managed ina a sustainable way?

Answer 25

1) trees are cleared in strips or patches - woodlands grows back quicker in smaller areas between woodland than larger open spaces.

2) the cleared patches are not too large or exposed- lots of soil erosion can occur on large areas of bare grounds. If soil is eroded, newly planted trees won’t grow.

3) timber is sometimes harvested by coppicing - trunk is cut close to ground level. Several new shoots grow from cut surface. Protects young shoots from grazers. Process repeated after certain time and can be repeated indefinitely on broadleaves species.

4) native trees tend to be planted in preference to non-native species. Better for biodiversity as native species have long-estabilished interactions with other native species so their presence should help species thrive in an area.

5) planted trees are attached to pots to provide support ans are grown in plastic tubes to stop them being eaten by grazing animals. Increasing likelihood of trees surviving and becoming mature adults.

6) trees aren’t planted too close together so trees are not competing with each other for space and resources so more likely to survive.

Question 26

What has led to a decline in fish stocks?

Answer 26

Overfishing

Question 27

What is sustainable food production?

Answer 27

Having enough food without using resources faster than they renew

Question 28

How can using fish quotas conserve fish stocks?

Answer 28

Fishing quotas are limits to the amount of certain fish species that fisherman are allowed to catch. Scientists study different species and decide how big their populations need to be to maintain their numbers. They then decide how many it’s safe for fisherman to take without reducing population too much.

International agreements are made (common fisheries policy in EU) that state the amount of fish each country can take and where they’re allowed to take from.

Fishing quotes conserve fish species by reducing the numbers that are caught and killed so populations are reduced less and aren’t at risk of going extinct.

Question 29

What is a problem with fishing quotas?

Answer 29

Fish of the wrong species or size are still caught and end up being thrown back into dea dead or dying because restrictions don’t allow fisherman to bring them ashore. However new rules for the common fisheries policy are banning the discarding of fish like this and the whole catch will have to be brought ashore and counted against the quota.

Question 30

How does controlling mesh size of nets conserve fish?

Answer 30

Governments can set limits for the mesh size of fishing nets which reduce the number of “unwanted” and discarded fish that are accidentally caught eg shrimp caught along with cod. Using a bigger mesh size allow smaller species to escape.
This also means younger fish will slip through the net, allowing them to reach breeding age.

Question 31

What is a problem with controlling the mesh size of nets?

Answer 31

It can be difficult to determine exactly how big the mesh size should be in areas where several different fish species are fished for at the same time. And two nets each of which meets regulations could be used inside one another effectively reducing the reported mesh size.

Question 32

Examples of areas that are managed to reduce conflict between conservation + human needs

Answer 32

1) Terai arc
2) The Maasai Mara
3) UK peat bogs

Question 33

What is the Terai arc + conflicts?

Answer 33

1) the Terai arc is an area of forest and grasslands on the border between Nepal and India. A variety of species are found there, including endangered species like the Bengal tiger and Asian elephant.

2) nearly 7 million people live in this area and many depend on the forest’s resources to survive.

3) Areas of the forest are being destroyed to make way for housing and other development. This destruction of habitat brings humans and animals into closer contact and increases conflict between the two. Eg elephants can trample crop fields and tigers can kill livestock. This increases likelihood of these animals being shot and killed.

Question 34

How is the Terai arc preserved?

Answer 34

Conservation charity the WWF has worked with local people to help balance their needs with conserving the forest and wildlife. Eg the charity has provided people with solar cookers ans biogas generators so they don’t need to use wood for fuel.

Farmers are encouraged to plant mint hedges around their crops to keep animals (which don’t like the taste of mint) away.

Question 35

What is the Maasai Mara + conflicts?

Answer 35

1) the maasai Mara is a national reserve in Kenya. It’s a large area of grassland (savannah) which is home to huge populations of wildebeest and zebra, as well as lions and cheetahs. The Maasai Mara is named after the Maasai people who live in the area.

2) The Maasai people traditionally earn a living by raising livestock such as cattle. This can bring them into conflict with conservationists eg overgrazing by livestock can destroy grassland for wildlife.

Question 36

How is the Maasai Mara conserved?

Answer 36

Conservation trusts are working with the Maasai people to help them make money from their land through conservation and ecotourism projects rather than farming, and to farm in a sustainable way. So the colonic needs of the Maasai people are met while the area is conserved.

Question 37

What are UK Peat Bogs + conflicts?

Answer 37

1) lots of upland parts of the UK are home to peat bogs - areas of wet peat. These peat bogs store water and carbon dioxide and home to make species such as Sphagnum moss - these mosses actually help the peat bog form by retaining water.

2) Farmers use the peat bogs to graze sheep and deer. However, this can lead to conflict with conservationists because overgrazing causes loss of moss species, soil compaction (which increases water runoff down sheep paths, taking sediment with it) and general peat bog erosion.

Question 38

How are UK peat bogs conserved?

Answer 38

Recent government-funded programmes like the environmental stewardship scheme, have given farmers money to use the peat bogs in a sustainable way eg to carry out measures to reduce water runoff, to lower the number of livestock that use the peat bogs and to remove livestock over winter.

Question 39

What are some environmentally-sensitive ecosystems?

Answer 39

1) the Galápagos Islands
2) Antarctica
3) the Lake District + snowdonia national parks

Question 40

What are the Galápagos Islands + effects of human activities

Answer 40

The Galápagos Islands are a small group of islands in the Pacific Ocean. Many rare species have evolved here and can’t be found elsewhere. Recently the number of inhabitants and tourists increased.

1) Non native animals introduced to the islands by humans eat some native species. This has caused a decrease in the populations of native species. Eg non native dogs, cats and black rats eat young giant tortoises and Galápagos land iguanas. Goats have eaten much of the plant life on some of the islands.

2) non native plants have also been introduced. These compete with native plant species, causing a decrease in their populations. For example, quinine trees are taller than some native plants so they block out light to the native plants which then struggle to survive.

Question 41

What are the methods of control in the Galápagos Islands?

Answer 41

1) eradication programmes have removed wild gifts from some of the smaller islands and wild dogs from the largest island. Quinine trees are kept in check using chemical herbicides and by uprooting young trees.

2) when people visit the Galápagos national park, they are expected to follow a list of rules, which includes not bringing any live plants or animals onto the islands, or moving them between islands. People are also only allowed to visit the national park in the company of a licensed guide.

Question 42

What is Antarctica + effects of human activities?

Answer 42

Antarctica is the world’s southernmost continent. It has a unique icy landscape with plants and animals adapted to harsh conditions. It has attracted many tourists and research scientists.

1) visitors to Antarctica have caused pollution in the past by dumping sewage into the sea and leaving rubbish. Shipping accidents have lead to oil spills, which severely affect wildlife.

2) hunting, whaling and fishing have all reduced wildlife populations in the area.

Question 43

What are the methods of control in Antarctica?

Answer 43

1) all waste apart from food waste and sewage must be taken away by ship for disposal in other countries. Many research stations now treat their sewage before releasing it, to reduce its effects on the environment.

2) Ships that use thick oil as fuel are banned from Antarctic waters- heavy oil spills are more likely to cause more da age and are harder to clean up.

3) there are tourist restrictions eg tourists are only allowed on land at certain locations for a few hours.

4) hunting and whaling have been banned, although fishing still continues.

Question 44

What is Lake District and snowdonia + effects of human activities?

Answer 44

The Lake District and snowdonia are both national parks. Both are areas of hills and lakes. Lake District is in north west England. Snowdonia is in Wales. Both attract millions of visitors per year.

1) many of the visitors to the Lake District go walking on the region’s footpath which causes erosion of the footpaths and loss of soil from hillsides. Soil that ends up in waterways and lakes can disturb the pH of the water and cause knock on effect for wildlife. As paths become harder to walk on, people may trapple and destroy sensitive vegetation either side of the path.

2) in snowdonia a lot of rain falls in the snowdonia hills, which leads to erosion of the paths. Walkers often trample the surrounding vegetation as they try to walk around floods.

Question 45

What are the methods of control in the Lake District and Snowdonia?

Answer 45

1) in Lake District, conservation charaities and the lake destruct national park authority attempt to carry out regular repair and maintenance work on the paths and encourage the regrwoth of damaged vegetation. Walkers are also educated about the importance of sticking to the paths and not taking short cuts as these increase erosion.

2) in snowdonia, volunteers have dug drains next to the paths to prevent them from flooding.

Question 46

What are the benefits of coppicing?

Answer 46

1) new stems grow more rapidly than saplings
2) lifespan of tree is extended
3) provides a variety of light levels.
4) fewer large trees means more light for smaller plants
5) provides a variety of habitats
6) roots prevent soil erosion/maintains soil quality
7) prevents succession
8) large machinery not needed

Question 47

What is coppicing?

Answer 47

Trunk cute close to ground level. Several new shoots grow from cut surface. Protect young shoots from grazers. Process repeated after certain time. It can be repeated indefinitely. Usually happens to broad leaved species