Chapter 6 - Human impact on the environment.

Question 1

What is the main cause of species extinction?

Answer 1

Human activity.

Question 2

Why do species become endangered/extinct?

Answer 2

• Natural selection.
• Loss of habitat.
• Overhunting by humans.
• Competition from introduced animals.
• Pollution.

Question 3

What are the different ways habitat can be lost?

Answer 3

• Deforestation.
• Drainage of wetlands.
• Hedgerow loss (removes the biological corridor).

Question 4

Why may organisms be overhunted?

Answer 4

• For trophy hunting.
• For traditional medicinal practices.
• Bush meat industry.
• Overfishing.
• Agricultural exploitation.

Question 5

What is conservation?

Answer 5

It is the sensible protection, preservation, management and restoration of natural habitats and their ecological communities, to enhance biodiversity while allowing for suitable human activity.

Question 6

What are the different ways that conservation can be addressed?

Answer 6

• Protecting habitats.
• International co-operation restricting trade (e.g. CITES).
• Gene banks (E.g. breeding programmes, sperm banks, seed banks etc.).
• Education (E.g. WWF public-awareness campaigns).
• Legislation.
• Ecotourism.

Question 7

What are the reasons for conserving species?

Answer 7

• Ethical reasons.
• Agriculture and horticulture.
• Survival of the species is more likely if the environment changes.
• Potential medicinal uses.

Question 8

What is monoculture?

Answer 8

The growth of large numbers of genetically identical crop plants in a defined area.

Question 9

What problems arise from removing hedgerows in agriculture?

Answer 9

It removes the biological corridor which removes a habitat for insects, nesting sites for birds and reptiles, food for many species etc. They act as wildlife corridors allowing species to move from one area to another which helps to maintain biodiversity.

Question 10

What problems arise from monoculture?

Answer 10

It provides only one habitat and so it reduces species diversity. It also means that yield progressively declines because…

• Roots are always the same length so all the minerals from the same depth of soil are removed (increased use of inorganic fertilisers).
• Same species is susceptible to the same pests.

Question 11

What are the reasons for deforestation?

Answer 11

• Timber is used extensively (building materials, paper and fuel).
• Framing (for biofuels or grazing cattle).

Question 12

What are the consequences of deforestation/

Answer 12

• Soil erosion (tree roots bind soil together).
• Upland deforestation causes lowland flooding.
• No trees for infiltration (wet soils are a lot colder which reduces germination, and oxygen availability decreases).
• Less rainfall (evaporation is slower than transpiration).
• Habitat loss and reduction in biodiversity.
• More Carbon Dioxide in the atmosphere.

Question 13

How can forests be managed so its sustainable?

Answer 13

• Coppicing (Cutting trees close to the ground then leaving them to re-grow).
• Selective cutting.

Question 14

What is overfishing?

Answer 14

Where the rate at which fish are harvested exceeds the rate at which they reproduce.

Question 15

What are the problems with Drift netting and Trawling?

Answer 15

Drift - Non-target species are caught (e.g. dolphins).

Trawling - Equipment damages ocean beds.

Question 16

What effects does overfishing have on other wildlife?

Answer 16

Prey species may be caught (e.g. krill) and this will disrupt the whole food web.

Question 17

What are the methods to regulate fishing and allow stocks to recover?

Answer 17

• Specific mesh size (Large enough for small fish to swim through).
• Quotas set, only a certain amount can be brought to land.
• Exclusion zones allow the fish to replenish stocks.
• MSC fish.
• Fish farming.

Question 18

Why does farming fish have an advantage over beef/pork etc.?

Answer 18

• Fish convert their food into protein more efficiently.
• Greater proportion of the fish is edible.
• Fish farming has a lower carbon footprint.

Question 19

What problems does fish farming cause?

Answer 19

• Diseased fish, very densely stocked.
• Pollution, can cause eutrophication.
• Escaped fish, outcompete wild fish and spread disease.
• Poor resource use, salmon fish feed made from other fish.
• Environmental toxins, more concentrated in farmed fish.

Question 20

What is a planetary boundary?

Answer 20

Limits between which global systems must operate to prevent abrupt and irreversible environmental change.

Question 21

What is an Environmental Impact Assessment?

Answer 21

They…

• Describe the project/site and the environment.
• Consider alternatives.
• Describe the significant effects on the environment.
• Mitigation, ways to avoid negative impacts.

Question 22

What will happen at the ‘tipping point’ of a planetary boundary?

Answer 22

A small change will have a very large and unpredictable effect on the environment. The change to the factor and the response produced are not linear.

Question 23

How many of the planetary boundary’s have we already crossed, how many have we avoided and which ones aren’t quantifiable?

Answer 23

4 - Biodiversity integrity, Climate change, Biogeochemical flows and Land system change.
Avoided Ozone depletion.
Atmosphere aerosols and novel entities aren’t quantifiable.

Question 24

What does crossing he Climate change boundary mean?

Answer 24

That enough Greenhouse gases have been released that if emissions were to stop immediately, the average temperatures would still rise for decades.

Question 25

What is a biofuel?

Answer 25

A fuel that has been made by a biological process (e.g. anaerobic digestion) rather than by geological processes(e.g. long-term heat and compression) that formed fossil fuels.

Question 26

What are the issues related to growing biofuels?

Answer 26

• The food VS fuel debate.
• Deforestation for land leads to soil erosion and biodiversity loss.
• Reduction in water availability as they require a large amount of irrigation water.

Question 27

Why has human activity less to many species extinction?

Answer 27

Human activity has led to environmental changes to happen to fast for natural selection to produce organisms that are suitably adapted to their habitat. In many cases, they fail to reproduce enough to maintain the species.

Question 28

How could we reverse the crossing of the Land-System-Change boundary?

Answer 28

Farming should be concentrated to the most productive areas, a global reduction in meat would reduce land under cultivation and genetically modified plants would play an important role.