3.1 - Great Wall Of Africa (Afforestation + Biosphere)

Question 1

What impact do forest fires have on the carbon cycle?

Answer 1

• release trapped carbon within plants
  
  • also remove litter which could have decomposed

Question 2

How does soil moisture have an impact on the carbon cycle?

Answer 2

• Dry soils emit CO₂
• west soils store 3x the amount of carbon that vegetation does

Question 3

What impact does soil health have on the carbon cycle?

Answer 3

• decomposition of vegetation and roots allows for:
  
  • release of methane into atmosphere
  • add nutrients into soil (more photosynthesis + plant growth)
• provides humus for soil formation
• protects against soil erosion
• nitrogen fixing draws down nitrogen from atmosphere
  
  • removes nitrates from atmosphere
  • thus gets rid of nitrogen oxides released by use of fossil fuels

Question 4

Why is it important that nitrogen levels are controlled?

Answer 4

• nitrogen is 300x more potent GHG than CO₂

Question 5

How much of the world’s energy does North America use?

Answer 5

• most per capita
  
  • 10x that of Sub-Saharan Africa

Question 6

How much of the global forest cover has been cleared?

Answer 6

• 30%
  
  • 20% has been degraded
• rest is fragmented

Question 7

What was the aim of the Great Green Wall initiative?

Answer 7

• Currently Sahara desert is expanding due to desertification
  
  • aims to reverse or reduce this
• aiming for sustainable management and use of forests and rangelands

Question 8

How many countries have taken part in the Great Green Wall intiative?

Answer 8

• 11
  
  • Senegal has made most progress
  • planted 11 million trees

Question 9

How large is the Great Green Wall?

Answer 9

• 15km wide
• 8000km long
• 11 million trees

Question 10

How is the Great Green Wall supposed to achieve its goal?

Answer 10

• increases water retention of soil
  
  • shade reduces rate of evaporation
  • tree roots hold water in soil
• reduces intensity of dust storms
• ensures soil remains consolidated and isn’t blown away

Question 11

What human impact has the Great Green Wall had?

Answer 11

• Provides employment in more rural areas of Africa
  
  • reduces the need for RUM, potentially better quality of life
  • 200 women are employed and paid well
  • allows farmers to grow food for income instead of subsistence
  • produce is cheaper as can be grown in areas previously infertile
• incentives given to farmers to plant trees

Question 12

What is the problem with young trees?

Answer 12

• release more CO₂ than is absorbed during initial growth
  
  • could becoming a problem on a global scale in short term

Question 13

What problems are there with the Great Green Wall initiative?

Answer 13

• Trees need to be irrigated
• rainfall may not fall in certain places due to position of atmospheric pressure bands
• may require complex infrastructure
• hard to maintain unless people are trained and funding is there
• non native trees have been used
  
  • have a high mortality rate

Question 14

How much is the Great Green Wall projected to cost?

Answer 14

• $8bn
• completion projected in 2050

Question 15

How successful has the Great Green Wall been so far?

Answer 15

• reduced dust storm intensity by 12%
• 66bn trees grown so far