Amazon rainforest

Question 1

Facts about the Amazon rainforest

Answer 1

• worlds largest tropical rainforest
• covers 40% south america
• hot and very wet climate
• very dense vegetation

Question 2

What are precipitation levels like and why?

Answer 2

• precipitation is very high - mostly exceeds 2000mm per year
• due to high humidity and unstable weather conditions associated with the tropics
• there is high evaporation over the Atlantic Ocean and the moisture-laden air is blown towards the Amazon
• often in the form of torrential downpours

Question 3

What are evaporation levels like and why?

Answer 3

• warm temperatures means evaporation is high - this increases precipitation
• around 25% of rainfall evaporates
• of the other 75%, half is used by plants and returned to the atmosphere by evapotranspiration, the other half infiltrates into the soil

Question 4

What is interception like?

Answer 4

the dense canopy can intercept up to 75% of total rainfall - less infiltration into the soil

Question 5

What is river discharge like?

Answer 5

• average discharge is approximately 175,000m^3/s
• 1/5 of total discharge into oceans of all the worlds rivers

Question 6

What is the impact of human activity on the water cycle?

Answer 6

• half of the worlds rainforests have already been wiped out to make way for commercial farming, mining, logging and settlements
• atmosphere becomes less humid because evapotranspiration reduced
• fewer trees = decreased interception, compacting the ground and encouraging overland flow
• soil more exposed to sunlight, becomes baked, dry and more vulnerable to erosion
• increased runoff = increased flood risk

Question 7

How has evapotranspiration changed in Mato Grosso in Brazil?

Answer 7

• in 2000, contributed around 50km^3 per year of evapotranspiration
• however deforestation has reduced forest flux rate by approx 1km^3 per year
• as a result, by 2009 forests were contributing around 40km^3 per year of evapotranspiration

Question 8

How can deforestation reduce cloud formation?

Answer 8

• forests emit salts and organic fibres when they transpire
• this acts as condensation nuclei and can assist in rain and cloud formation
• their loss inhibits cloud formation and reduces rainfall

Question 9

How will temperatures change due to deforestation and what will the effect be?

Answer 9

• temperatures will increase by 2-3 degrees by 2050
• a 4 degree increase could kill at least 85% of the rainforest

Question 10

How much forest was lost between 2000-2010?

Answer 10

3.6m ha per year

Question 11

How has river discharge changed as a result of deforestation?

Answer 11

20% increased river discharge

Question 12

What is the amazon carbon cycle like?

Answer 12

• warm and wet climate is ideal for plant growth, promoting photosynthesis which absorbs huge quantities of carbon dioxide from the atmosphere
• plants and trees are a huge carbon store, wood is 50% carbon
• respiration from plants, trees and animals returns carbon dioxide to the atmosphere
• decomposers thrive in the warm and wet conditions which released carbon dioxide into the atmosphere
• carbon stored in the soil

Question 13

What effect has deforestation had on the rainforest carbon cycle?

Answer 13

• turning carbon sinks into sources
• between 2000-2007, an area of rainforest larger than Greece has been destroyed

Question 14

How has burning affected the rainforest carbon cycle?

Answer 14

• releases carbon stored in trees back into the atmosphere
• around 30% anthropogenic carbon emissions come from burning
• forests that have experienced disturbances such as logging and burning store 40% less carbon than undisturbed forests

Question 15

What is the effect of deforestation on stores and flows within the carbon cycle?

Answer 15

• photosynthesis ceases so no carbon dioxide absorbed from atmosphere
• plant and animal respiration drops
• rain washes ash away into the ground increasing carbon content of the soil - this may increase carbon in runoff
• decomposers largely absent from environment

Question 16

How would replacing trees with crops/grassland affect stores/flows?

Answer 16

• would reintroduce stores and flows, but operating at much less efficient levels
• grassland absorbs less than 25% CO2 absorbed by tropical rainforests

Question 17

Facts about wildfires and their effect on the carbon cycle

Answer 17

• number of wildfires has increased by 78% in the last few years
• in 2018, there were over 23,000
• by 2050, wildfires will have released over 17 billion tonnes CO2

Question 18

Facts about deforestation and its effect on the carbon cycle

Answer 18

• forests absorb 1.5b tonnes CO2/year, in 2010 8b tonnes were released
• the Amazon has released 20% more CO2 than it has absorbed in the past decade
• in 2004, 6.7m acres forest was cleared, equivalent to 18,300 acres per day - at that rate 50% of the rainforest would be cleared by 2050

Question 19

How is deforestation being mitigated against?

Answer 19

• creation of national parks eg. the Para rainforest reserve (15 million hectares), there are currently 68 official national parks within the Amazon basin
• reforestation and renewable energy plan with the US - pledges to restore 12m hectares of deforested land and increase renewable energy use by 2030
• US and Brazil agree to obtain up to 20% of their electricity from renewable power by 2030

Question 20

What is the Amazon cooperation treaty organisation and what are its aims?

Answer 20

• in 1978, the eight countries of the Amazon basin signed the treaty
• created a set of regional criteria and indicators for the sustainability of the Amazon - allows countries to collect and analyse data more efficiently and facilitates monitoring, evaluation and periodic reporting on progress achieved