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

why do population sizes of species vary

Answer 2

• because of abiotic factors
• e.g. light, water, space available
• temperature and chemical composition of surrounding
• and biotic factors
• interspecific and intraspecific competition
• predation

Question 3

what happens with ideal abiotic conditions for a species

Answer 3

organisms can grow fast and reproduce successfully

Question 4

why is ideal temperature of surroundings good for mammals

Answer 4

• ideal for metabolic reactions to take place
• they don’t use up as much energy maintaining body temperature
• more energy can be used for growth and reproduction
• population size will increase

Question 5

what happens when abiotic conditions are not ideal for a species

Answer 5

organisms cannot grow fast or reproduce successfully

Question 6

what happens when a mammal is facing unideal temperature of surroundings

Answer 6

• temperature os higher or lower than optimum body temperature
• have to use less energy to maintain right body temperature
• less energy available for growth and reproduction
• so population size decreases

Question 7

what is interspecific competition

Answer 7

when organisms of different species compete with each other for the same resources
- e.g. grey and red squirrels competing for the same food sources and habitats in the UK
- affects resources available, and distribution of species

Question 8

how does interspecific competition between two species impact resources available

Answer 8

• the resources available for each species is reduced
• e.g. if they share the same food source, it will be less available for both of them
• (plants compete for minerals and light)
• means that both populations are limited by a lower amount of food
• so have less energy for growth and reproduction
• so population sizes are lower in both species
• e.g. in areas where both red and grey squirrels live, both populations are smaller than if only one species was there

Question 9

why does interspecific competition affect the distribution of a species

Answer 9

• if two species are competing
• but one is better adapted to its surroundings than the other
• the less well adapted species is out-competed
• so won’t be able to exist alongside better adapted species
• e.g. since grey squirrels have been introduced in the UK, the native red have disappeared from large areas (grey has better chance of survival as is larger so can store more fat over winter

Question 10

what is intraspecific competition

Answer 10

organisms of the same species compete with each other for the same resources

Question 11

explain how intraspecific competition occurs

Answer 11

1) when resources are plentiful, the population of a species increases
2) as the population increases, the number of organisms competing for the same amount of space and food increases
3) eventually, space and food will become limiting, as there isn’t enough for all the organisms
4) the population begins to decline
5) the smaller population means that there is less competition for space and food, so it is better for growth and reproduction
6) this means the population grows again
7) the maximum stable population size of a species that any ecosystem can support is called the carrying capacity

Question 12

what is carrying capacity

Answer 12

the maximum stable population size of a species that any ecosystem can support

Question 13

how would you show intraspecific competition graphically

Answer 13

• graph continuously oscillates
• line going through the middle horizontally shows the carrying capacity

Question 14

what is predation

Answer 14

an organism (the predator) kills and eats (predates on) another organism (the prey)

Question 15

what are predator prey populations controlled by

Answer 15

negative feedback

Question 16

explain the negative feedback cycle of predator prey populations

Answer 16

1) as prey population increases, more food for the predators, so the predator populations grows
2) as the predator population increases, more prey is eaten, so the prey population begins to fall
- NEGATIVE FEEDBACK: as the prey population is restored to a more stable size
3) this means that there is less food for the predators, so their population decreases (more negative feedback)

Question 17

what are the limits to using predator-prey relationships

Answer 17

• usually more complicated
• as other factors involved
• e.g. the population of the prey might begin to decrease initially because there were too many for the amount of food available, and predation just accelerated this decrease

Question 18

what are the limiting factors of populations

Answer 18

factors that stop the population size of a species from increasing:

1) ABIOTIC: the amount of shelter in an ecosystem limits the population size of the species because there is only enough shelter for a certain number of individuals
2) BIOTIC: interspecific competitions limits the population size because the amount of resources available for the species decreases

• DETERMINE THE CARRYING CAPACITY OF AN ECOSYSTEM

Question 19

what is conservation and what does it mean

Answer 19

the protection and management of ecosystems so that the natural resources in them can be used without them running out, meaning that natural resources will still be available for future generations

e.g. using rainforests for timber without any species becoming extinct and without any habitats being destroyed

Question 20

why is conservation a dynamic process

Answer 20

the conservation methods need to be adapted to the constant changes (natural changes and those by humans) that occur within ecosystems

Question 21

what are the two things involved in conservation

Answer 21

MANAGEMENT: of ecosystems, so controlling how resources are used and replaced
RECLAMATION: of ecosystems, so restoring those that have been damaged or destroyed to be used again, e.g. restoring forests that have been cut down so that they can be used again

Question 22

what are the 3 main reasons for conservation of ecosystems

Answer 22

economic, social and ethical

• similar to that of conserving biodiversity

Question 23

what are the economic reasons of conserving ecosystems

Answer 23

• ecosystems provide resources for loads of things that humans need
• e.g. ecosystems giving drugs, clothes and food
• all economically important, as traded on a local and global scale
• if not conserved, resources used now will be lost, so less trade for future

Question 24

what are the social reasons of maintaining ecosystems

Answer 24

• many ecosystems bring joy to people
• as attractive to look at and used for activities (birdwatching and walking)
• species and habitats may be lost if not conserved
• so future generations won’t be able to enjoy them

Question 25

why do we need to conserve ecosystems ethically

Answer 25

- many people believe it is the right thing to do - organisms have a right to exist, so shouldn't become extinct due to human activity - humans have a moral responsibility conserve ecosystems for future generations, so they can enjoy and use them

Question 26

what is preservation, and how is it different to conservation

Answer 26

the protection of ecosystems so that they are kept exactly as they are - nothing is removed from them and they are only used for activities that do not damage them

Question 27

what is an example of a preserved ecosystem

Answer 27

antarctica - as protected from exploitation by humans, and only used for limited tourism and scientific research - NO mining or other industrial activities

Question 28

how can ecosystems be managed to provide resources sustainably

Answer 28

enough resources are taken to meet the needs of people today, but without reducing the ability of people in the future of meeting their own needs

Question 29

where is the temperature woodland

Answer 29

between the tropics and the polar circles

Question 30

what is the basis of sustainably managing temperate woodlands

Answer 30

for every tree cut down for timber, a new one is planted - means that the woodland never becomes depleted - cutting and planting trees needs to be done carefully to be successful

Question 31

how is timber management carried out sustainably

Answer 31

1) trees are cleared in strips and patches: - as woodland grows back quicker in smaller areas between bits of existing woodland than in larger, open areas - the patches and strips aren't too large or exposed, so prevents lots of soil erosion occurring on large areas of bare ground, which would mean newly planted trees won't be able to grow 2) timber is harvested via COPPICING: the trees are cut down in a way that lets them grow back, so new trees don't need to be planted (tree trunk cut close to the ground, and then new shoots form here and mature, then these are cut and more emerge) 3) native tree species are planted rather than non-native species: - better for biodiversity, as native species have longer established interactions with other native species (fungi, plants, animals), so presence helps species thrive in these areas - some species may not be able to adapt to other non-native tree species emerging 4) trees attached to posts to provide support 5) trees grown in plastic tubes to stop them from being eaten by grazing animals, so more likely to survive to becoming mature adults 6) trees aren't planted too close together, so that they aren't competing with each other for space and resources, so more likely to survive

Question 32

why are fish stocks declining

Answer 32

we are overfishing

Question 33

what does overfishing cause

Answer 33

- less fish for us to eat - food chains in the ocean are affected - some species of fish may disappear altogether

Question 34

briefly overview how declining fish stocks can be combated

Answer 34

we must maintain fish stocks at a level where the fish continue to breed

Question 35

what is sustainable food production

Answer 35

having enough food without using resources faster than they renew

Question 36

what are two examples of conserving fish stocks

Answer 36

using fishing quotas and controlling size of mesh nets

Question 37

how do fishing quotas conserve fish stocks

Answer 37

- fishing quotas are limits to the amount of certain 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 their numbers - so can decide how many it is safe for fishermen to take without reducing the population too much - internations agreements are made [the Common Fisheries Policy in the EU] that state the amount of fish each country can take, and where they are allowed to take them - so they conserve fish species by reducing the numbers that are caught and killed, so population not reduced too much, and not at risk of being extinct

Question 38

what are the problems of using fishing quotas

Answer 38

- fish of the wrong species and size are still caught, and end up being thrown back in the sea, already dead or dying (restrictions are for bringing them back ashore) - new rules for the Common Fisheries Policy means the banning of discarding fish like this, so whole catch must be brought ashore and counted against quota

Question 39

how does controlling mesh sizes of nets conserve fish stocks

Answer 39

- different limits to mesh size of fishing nets depending on species being caught - reduces the number of "unwanted" and discarded fish accidently caught - bigger mesh sizes allows unwanted species to escape - also means younger fish will slip through net, so can reach breeding age

Question 40

what are the limits of controlling mesh sizes of fishing nets

Answer 40

- difficult to determine the size of the mesh size in areas with several different fish species being fished at the same time - two nets could be used one inside the other, which reduces the reported mesh size

Question 41

what does conservation and preservation need to be balanced with

Answer 41

human needs

Question 42

what are 3 areas where conservation, preservation and human needs are managed

Answer 42

1) The Terai Arc 2) The Masai Mara 3) UK Peat Bogs

Question 43

what is the Terai Arc

Answer 43

- area of grasslands on the border between Nepal and India - variety of plants and animals are found here, e.g. endangered species like Bengal Tiger and Asian elephant - nearly 7 million people live in this area, and many depend on the forest's resources to survive HUMAN NEED: areas of forest are being destroyed to make way for more housing and other development, destroying habitats and making humans and animals in closer contact, increasing conflict between the 2 ( elephants trample and eat crop fields and tigers kill lifestock)

Question 44

what are the human conflicts in the Terai Arc

Answer 44

HUMAN NEED: - areas of forest are being destroyed to make way for more housing and other development - destroying habitats and making humans and animals in closer contact, increasing conflict between the 2 ( elephants trample and eat crop fields and tigers kill livestock) - increases the likelihood of animals being shot and killed

Question 45

how can human conflict be managed at the Terai Arc

Answer 45

- work of conservation charities like WWF with local people to balance needs with conservation of the forest and wildlife - provide local people with solar cookers and biogas generators - so don't need wood from the forest for fuel - encouraging farmers to plant mint hedges around their crops to keep animals away (don't like the taste of mint)

Question 46

what is the Maasai Mara

Answer 46

- a national reserve in Kenya - large area of grassland (savannah) - home to huge populations of wildebeest, zebra, lions and cheetahs - named after Maasai people that live here

Question 47

what are the human conflicts of the Maasai Mara

Answer 47

- Maasai people traditionally earn a living by raising livestock, such as cattle - brings conflict with conservationists - as overgrazing by livestock can destroy grassland for wildlife

Question 48

how can the human conflicts of the Maasai Mara be reserved

Answer 48

- conservation trusts work with Maasai people to help them make money from land via conservation and ecotourism projects rather than farming - farm in a sustainable way - meets economic needs to Maasai people, and conserves the area

Question 49

what are peat bogs

Answer 49

- in many upland parts of the UK - areas of wet peat - bogs store water and CO2 - home to lots of different plants and animals - e.g. Sphagnum moss, which help the peat form by retaining water

Question 50

what are the human conflicts of peat bogs

Answer 50

- farmers use peat bogs to graze sheep and deer - overgrazing causes loss of moss species, soil compaction (increasing water runoff down sheep paths, taking desiment with it) and general peat bog erosion

Question 51

how are the human conflicts of peat bogs being managed

Answer 51

- recent government funded programmes, e.g. the Environmental Stewardship Scheme - give farmers money to use peat bogs in sustainable ways - including measures to reduce water runoff, lower number of livestock using peat bog, and removing livestock over winter

Question 52

what are examples of environmentally-sensitive ecosystems being affected by human activities

Answer 52

The Galapagos Islands Antarctica Lake District and Snowdonia National Parks

Question 53

what are the Galapagos Islands

Answer 53

a small group of islands in the Pacific Ocean - home to rare species of plants and animals that have evolved here, and aren't found anywhere else - attracted sailors, explorers, scientists - now number of inhabitants and tourists have increased considerably

Question 54

what are the effects of human activities on the Galapagos Islands

Answer 54

1) non-native animals introduced by humans to eat native species, reducing their population - e.g. non-native dogs, cats and black rats eating young giant tortoises and Galapagos land iguanas, and goats eating much of plant life on some islands 2) non-native plants being introduced to the islands, decreasing native populations as competing with them - e.g. quinine trees being taller than some native plants, so block out light to native plants, which struggle to survive

Question 55

what are the methods of control taking place in the Galapagos Islands

Answer 55

1) eradication programmes to remove wild goat from some smaller islands and wild dogs from largest, and keeping quinine trees in check using chemical herbicides and uprooting young trees 2) when people visit the national park, must follow list of rules, e.g. not bringing in live plants or animals onto the islands, or moving them between islands, and only allowed to visit here with a licensed guide

Question 56

what is Antarctica

Answer 56

- the world's southernmost continent - icy landscape with plants and animals adapted to harsh conditions - attracts many visitors, e.g research scientists and tourists

Question 57

what are the effects of human activity on Antarctica

Answer 57

1) visitors have caused pollution in the past by dumping sewage into the sea and leaving rubbish, as well as shipping accidents leading to oil spills, severely affecting wildlife 2) hunting, whaling and fishing reducing wildlife population in the area

Question 58

what are the methods of control in Antarctica

Answer 58

1) all waste except for food and sewage must be taken away by ship for disposal in other countries, and many research stations will treat their sewage before releasing it, to reduce effects on the environment 2) ships using thick oil as fuel are banned from the waters, as heavy oil spills cause more damage and are harder to clean up than lighter fuel spills 3) tourist restrictions, so only allowed on land at certain locations for few hours 4) hunting and whaling have been banned for a while, but fishing still happens

Question 59

what is the Lake District and Snowdonia National Parks

Answer 59

- beautiful national parks - areas of hills and lakes - in North West England and Wales - attract millions of visitors a year

Question 60

what are the effects of human activity on Lake District and Snowdonia

Answer 60

1) visitors walk on region's footpaths, leading to erosion of footpaths and loss of soil from hillside, which could end up in waterways and lakes, distributing the waters pH, so knock on effects for wildlife. - means that the paths also become harder to walk on, so people begin to trample and destroy sensitive vegetation on either side of the paths 2) similar in Snowdonia, where lots of rain falls on the hills, so paths get eroded, and people trample on surrounding vegetation to walk around the floods

Question 61

what are the methods of control in Lake District and Snowdonia

Answer 61

- lake district: conservation charities and Lake District National Park Authority attempt to carry out regular repair and maintenance work on the paths and encourage regrowth of damaged vegetation - walkers are educated about importance of sticking to paths and not taking short cuts, which can increase erosion - snowdonia: volunteers have dug drains next to paths to stop them from flooding