6.3.2 Populations and sustainability

Question 1

what is population size

Answer 1

the total number of organisms of one species in a habitat

Question 2

what affects population size - abiotic factors

Answer 2

amount of light, water or space

temperature

chemical composition of surroundings

when abiotic conditions ideal organisms can grow fast and reproduce successfully so population size will increase

when abiotic conditions are not ideal organisms cant grow as fast or reproduce as successfully so population size will decrease

Question 3

what affects population size - biotic factors

Answer 3

interspecific competition

intraspecific competition

predation

Question 4

biotic factors that affect pop. size - interspecific competition

Answer 4

competition between organisms of different species

1. organisms of different species compete with each other for the same resources
   - food, space ect.
2. means that resources available to both populations are reduced
   - so both populations will be limited eg. by a lower amount of food
   - have less energy for growth and reproduction so pop. sizes for both species lower
3. also affects the distribution of species
   - if one species is better adapted to the surroundings it will out-compete the less adapted species
   - this could cause the less adapted species to go elsewhere in order to increase their chance of survival

Question 5

biotic factors that affect pop. size - intraspecific competition

Answer 5

competition between organisms of the same species

1. population of a species increases when resources are plentiful
   - as the population increases there’ll be more organisms competing for the same amount of space and food
2. eventually, resources (eg. food and space) become limiting as there isn’t enough for all the organisms so the population begins to decline
3. a smaller population meases that there’s less competition for space and food, which is better for growth and reproduction - so the population starts to grow again
4. the maximum stable population size of the species that an ecosystem can support is the CARRYING CAPACITY

Question 6

biotic factors that affect pop. size - predation

Answer 6

predation is where an organism kills and eats another organism
- population n sizes of predators and prey are controlled by NEGATIVE FEEDBACK

1. as the prey population increase increases, there’s more food for predators, so the predator population grows
2. as the predator population increases, more prey is eaten - so the prey population begins to fall
   - negative feedback —> the prey population is restored to a more stable size
3. this means there’s less food for predators, so their population decreases (more negative feedback)
   - and so on….

however usually more complicated as other abiotic factors are also involved

Question 7

what are limiting factors

Answer 7

factors that stop the population size from increasing

can be biotic or abiotic

limiting factors determine the carrying capacity of an ecosystem

Question 8

conservation

Answer 8

the protection and management of ecosystems so that the natural resources in them can be used without running out

eg. the rainforest can be used for timber without any species becoming extinct so the natural resources can be used by future generations

Question 9

conservation - a dynamic process

Answer 9

conservation methods need to be adapted to the constant changes (caused naturally and by humans) that occur within an ecosystem

Question 10

what does conservation involve?

Answer 10

1. management - controlling how many resources are used and replaced
2. reclamation - restoring ecosystems that have been damaged it destroyed so they can be used again

Question 11

why is conservation important

Answer 11

economic

social

ethcial

Question 12

why is conservation important - economic

Answer 12

ecosystems provide resources for lots of things that humans need

• rainforests 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 arent conserved the resources we use know will be lost and there will be less trade in the future

Question 13

why is conservation important - social

Answer 13

many ecosystems bring joy to lots of people because they are attractive to look at and people use them for activities
- birdwatching and walking

the species and habitats in the ecosystems may be lost of they arent conserved so future generations wont be able to use and enjoy them

Question 14

why is conservation important - ethical

Answer 14

1. some people might think we should conserve ecosystems simply because its the right thing to do
   e. g. most people;e think organisms have a right to exist and they shouldn’t become extinct as a result of human activity
2. some people think we have a moral responsibility to conserve ecosystems for future generations, so they can enjoy and use them

Question 15

preservation

Answer 15

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

eg. Antarctica is a preserved ecosystem because it is protected from the exploitation by human
- only used for limited tourism and scientific research, not mining or other industrial use

Question 16

management of ecosystems to provide resources in a sustainable way - woodlands

Answer 16

temperate woodland can be managed in a sustainable way –> for every tree cut down a new one is planted

1. trees are cleared in strips or patches - woodland grown back more quickly in smaller areas between bits of existing woodland than it does in larger areas
2. cleared strips arent too large or exposed —> preventing soil erosion
3. coppicing - cutting down trees in a way that lets them grown back (new trees don’t need to be planted)
4. native tree species tend to be planted in preference to non-native species - better for biodiversity as native species have long-established interactions with the other native species , so there presence helps other species thrive
5. planted trees are attached to posts to provide support and are grown in plastic tubes to prevent grazing —> trees more likely to survive
6. trees arent planted close together —> so they arent competing with each other for space or resources, so are more likely to survive

Question 17

management of ecosystems to provide resources in a sustainable way - fishing

Answer 17

fish stocks are declining because of over fishing - less fish for us to eat, food chains affected and some species of fish may disappear

• need to maintain fish stock at a level where the fish continues to breed

–> SUSTAINABLE FOOD PRODUCTION

Question 18

sustainable fishing - quotas

Answer 18

limits to the number of certain fish species that fishermen are allowed to catch

• scientist study different species and decide how big their population needs to be to maintain their numbers and decide how many it is safe for fishermen to catch without reducing the population too much
• international agreements made that state the amount of fish each country can take and where they are allowed to take from

help conserve fish species by reducing the no. that are caught

problem:
fish of the wrong species are caught and thrown back into the idea, dead because of the restrictions

Question 19

sustainable fishing - mesh size of nets

Answer 19

1. there are limits to the mesh size of the fishnet, depending on what’s being fished
2. this is to reduce the number of ‘unwanted’ and discarded fish that are accidentally caught
   - using a bigger net size will let the unwanted species to escape
3. also means that younger fish will slip through the net, allowing them to reach breeding age

problem:
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 that are regulation size could be used with one inside of the other

Question 20

management of environmental resources - The Terai Arc

Answer 20

1. an area of forest and grasslands on the border between Nepal and India
   - a variety of plants and animals found here, including endangered species (Bengal Tiger and Asian elephant)
2. nearly 7 million people also live in this area and many depend on the forests resources to survive
3. areas of the forest are also being destroyed to make way for housing and other development
   - the destruction of habitat brings humans and animals in closer contact and increases conflict between the two –> which increases the likelihood of animals being shot and killed
4. WWF has worked with local people to help balance their needs with conserving the forest and its wildlife
   - provided people with solar cookers and biogas generators so don’t need to use wood from the forest as fuel
   - farmers are encouraged to plant mint hedges around their crops to keep animals who don’t like the taste of mint away

Question 21

management of environmental resources - The Maasai Mara

Answer 21

1. national reserve in Kenya - its a large area of grassland (savannah) - home to a population of wildebeest and zebra, lions and cheetahs, and the people who live there
2. the Massai people traditionally earn a living by raising livestock, such as cattle
   - this can bring them into conflict with conservationists –> overgrazing can destroy grassland for wildlife
3. conservation trusts are working with the Massai 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 economic needs of the Massai people are met while still allowing the area to be conserved

Question 22

management of environmental resources - UK peat bogs

Answer 22

1. upland UK lots of peat bogs - areas of wet peat. these peat bogs store water and carbon dioxide and are home to different plants and animals (Sphagnum moss)
2. farmers use peat bogs to graze sheep and deer - this can lead to conflict with conservationists because overgrazing causes loss of moss species, soil compaction (which increases water runoff) and general peat bog erosion
3. recent government-funded programs ( environmental stewardship scheme have given farmers money to use the peat bogs in a sustainable way
   - to carry out measures that reduce water runoff, ower the no. of livestock that use the beat bogs and to remove livestock over winter

Question 23

The galapagos islands

Answer 23

a small group of islands in the specific ocean

many rare species of animals and plants have evolved (can’t be found elsewhere)

recently no. of inhabitants and tourists has increased

Question 24

The galapagos islands - effects of human activities

Answer 24

1. non-native animals introduced
   - eat native species
   - decrease in pop of native species
2. non-native plants
   - compete with native plant species causing a decrease in the native population

Question 25

The galapagos islands - methods of control

Answer 25

1. eradication programs
   - removed wild goats (smaller islands) and wild dogs (larger islands)
   - quinine trees are kept in check using chemical herbicides and by uprooting young trees
2. when people visit the islands they are expected to follow a list t of rules
   - not bringing any live plants or animals to the island, or moving them between the islands
   - only allowed to visit the national park in company of a licensed guide

Question 26

Antarctica

Answer 26

southernmost continent

unique icy landscape

plants and animals adapted to its harsh conditions

Question 27

Antarctica - effects of human activities

Answer 27

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

Question 28

Antarctica - methods of control

Answer 28

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 now banned from Antarctica waters
   - heavy oil spills are likely to cause more damage and be harder to clean up than lighter fuels
3. tourist restrictions - only allowed on land at certain locations for a few hours
4. hunting and whaling have been banned for some time - fishing still continues

Question 29

The Lake District and Snowdonia National Parks

Answer 29

areas of hills and lakes

lake district in NW England

Snowdonia in Wales

both attract millions of visitors per year

Question 30

The Lake District and Snowdonia National Parks - effects of human activities

Answer 30

Lake district
walking on regions footpaths - erosion of footpaths and loss of soil from hillsides
- soil that ends up in waterways and lakes can disturb the pH of the water, causing knock-on effects for wildlife
- as paths become harder to walk on people start to trample and destroy the sensitive vegetation either side of the paths

Snowdonia
similar story - a lot of rain falls - leads to erosion of the paths, walkers often trample on the surrounding vegetation as they try to walk around the floods

Question 31

The Lake District and Snowdonia National Parks - methods of control

Answer 31

Lake district
conservation charities and the lake district national park authority attempt to carry out regular repair and maintenance work on the paths and encourage the regrowth of damaged vegetation
- walkers are also educated about the importance of sticking to the paths and not taking short cuts (as these increase erosion)

Snowdonia
volunteers have dug drains next to te paths to prevent the from flooding