Lesson 14: Threats to the Biological Cycle

Question 1

What % of tropical forests have been lost since the 1960s?

Answer 1

50%

Question 2

Where have tropical forests been lost in particular?

Answer 2

Africa and South America

Question 3

Which country has overtaken Brazil in rates of deforestation?

Answer 3

Indonesia

Question 4

How much rainforest has been cleared in Indonesia in how many years?

Answer 4

25% in 25 years

Question 5

How much temperate forest was deforested in the 19th century?

Answer 5

90%

Question 6

What forests have been threatened since mid-20th century?

Answer 6

Boreal forests

Question 7

How much CO2 does the terrestrial biosphere sequester?

Answer 7

1/4

Question 8

By 2015 what % of global forest cover had been cleared?

Answer 8

30%

Question 9

What % of forest was degraded or fragmented by 2015?

Answer 9

20%

Question 10

How many hectares of land is deforested annually?

Answer 10

13 million hectares

Question 11

What % of the Earth covered by forest? What % of this is natural?

Answer 11

30% covered
15 % natural

Question 12

What % of deforested land is for palm oil, soy, beef and paper production?

Answer 12

50%

Question 13

What are other reasons for deforestation?

Answer 13

Dams and reservoirs
Infrastructure
Open cast mining for rare minerals

Question 14

What are methods of deforestation?

Answer 14

Clear cutting - removes all primary forest
Slash and burn - used for agriculture- ash provides nutrients

Question 15

What impacts does deforestation have on the water cycle?

Answer 15

• reduced interception
• increased raindrop erosion and surface run-off increasing sediment in rivers
  -increased aridity downwind from loss of evapotrasnpiration

Question 16

What impacts does deforestation have on the carbon cycle?

Answer 16

• reduction in storage in soil and biomass
• reduction in CO2 intake through photosynthesis
• increased combustion flux to atmosphere

Question 17

How many hectares of tropical forests were there before 1950?

Answer 17

11.6 million hectares

Question 18

How many hectares of tropical forest were there by 1985?

Answer 18

3.8 million hectares

Question 19

How much forest has been deforested in Madagascar?

Answer 19

90%

Question 20

Why are the forests in Madagascar so vulnerable?

Answer 20

Expanding population with no other resources, no international aid, no help/money from the government, people have to fend for themselves, growing international demand for tropical hardwood

Question 21

How much does soil erosion now exceed in some areas of deforested land in Madagascar?

Answer 21

400 tonnes per hectare per year

Question 22

What causes coastal waterways to become clogged with sediment and become red?

Answer 22

Extensive logging of inland rainforests and coastal mangroves means that, after heavy rainfall, soil is washed from the hillsides into streams and rivers

Question 23

Define afforestation

Answer 23

Planting trees on land that has never had forest, or has been without forest for a long time

Question 24

Define reforestation

Answer 24

Planting trees in places with recent tree cover, replacing lost primary forests

Question 25

What is afforestation is made up of?

Answer 25

Monoculture e.g. palm oil

Question 26

Where in China was a green wall built to reduce desertification?

Answer 26

Three-North Shelterbelt Project

Question 27

How long was the green wall?

Answer 27

4500 km

Question 28

What are the impacts of afforestation on the carbon cycle?

Answer 28

-Monocultures of commercial trees such as in palm oil plantations often store less carbon
-Biodiversity may be impacted as a result of habitat changes
-Monocultures tend to be more disease prone

Question 29

What are the impacts of afforestation on the hydrological cycle?

Answer 29

-Monocultures tend to use more water leading to less infiltration and groundwater rates
-Decreased raindrop erosion.
-Evapotranspiration rates may alter downwind ecosystems

Question 30

What are the two types of grassland?

Answer 30

Temperate
Tropical/savannah

Question 31

When was there a biofuel rush across the American midwest?

Answer 31

2007 and 2015

Question 32

What crops were farmers encouraged to grow in the biofuel rush?

Answer 32

Corn, soya, canola, sugar cane

Question 33

What was the aim of grassland conversion in the USA?

Answer 33

-Increase the amount of ethanol being used in petrol
-Boost the economies of rural US states
-Reduce US dependence on overseas oil imports
-Reduce CO2 emissions from transport

Question 34

How much did corn rise by in 2013?

Answer 34

Trebled

Question 35

How many hectares of natural grassland were removed in the USA?

Answer 35

5.5 million hectares

Question 36

Which countries did the loss of grassland equal in terms of deforestation?

Answer 36

Brazil, Malaysia and Indonesia

Question 37

What are the benefits of natural grassland?

Answer 37

-Trap moisture and floodwater
Absorb toxins from the soil, maintaining their health
-Prevent soil erosion
-Acts as a carbon sink and a terrestrial carbon store

Question 38

What are the negatives of conversion?

Answer 38

-Soils release CO2 when grasslands are initially removed and through annual ploughing
-Biofuel crops need carbon-based nitrogen fertiliser and chemical pesticides
-Biofuels consume a lot of water
-Cultivated soils are liable to erosion