Carbon cycle in the Amazon

Question 1

What conditions in the Amazon allow for optimum plant growth?

Answer 1

Humid equatorial climate

Question 2

What is net primary productivity?

Answer 2

The rate at which plants accumulate energy in the form of organic matter, minus the energy used for respiration

Question 3

Equation for NPP

Answer 3

NPP = GPP - respiration

Question 4

What is gross primary productivity?

Answer 4

The rate at which plants accumulate energy in the form of organic matter

Question 5

What is the average NPP in Amazon per year?

Answer 5

400-700 tonnes/Ha/year

Question 6

Ho much carbon does forest trees store?

Answer 6

180 tonnes C/Ha above ground and further 40 C/Ha in roots

Question 7

how much carbon does the soil store?

Answer 7

90-200 tonnes/Ha

Question 8

How much carbon does the Amazon absorb a year?

Answer 8

2.4 billion tonnes

Question 9

Why are carbon transfer rates so high?

Answer 9

warm, humid conditions ensure speedy decomposition of dead organic matter + quick release of CO2 = carbon fixation is rapid

Question 10

What is carbon fixation?

Answer 10

Carbon fixation is the process where photosynthetic organisms (plants) turn inorganic carbon into organic compounds (carbohydrates).

Question 11

Describe the soil type in the Amazon?

Answer 11

Acidic soils of poor quality with limited carbon and nutrient stores

Question 12

Why is soil quality so poor?

Answer 12

Because of the speed at which organic matter is broken down and recycled

Question 13

What are the principal carbon stores?

Answer 13

Forest trees

Question 14

How much carbon is stored in rainforest?

Answer 14

Approx 100 billion tonnes of carbon are stored in rainforest

Question 15

How much carbon. is released through decomposition?

Answer 15

1.7 billion tonnes

Question 16

How does decomposition alter the carbon cycle?

Answer 16

Dead organic matter accumulates at soil surface + within rainforest soils. High temp + humid conditions speed up decomposition of organic litter by bacteria, fungi + other soil organisms. Decomposition releases nutrients to soil which is immediately taken up by tree root systems + emits CO2 which is returned to atmosphere.

Question 17

How does deforestation alter carbon cycle?

Answer 17

Exhausts the carbon biomass store

• Croplands + pasture contain only small amount of carbon compared to forest trees. Eg biomass of grasslands in areas of former rainforest is 16.2 tonnes/ha.
• Deforestation drastically reduces inputs of organic material to the soil = depleted of carbon + exposed to strong sunlight, support fewer decomposer organisms -> reducing flow of carbon from soil to atmosphere.
• Destroys main nutrient store + removes most nutrients from ecosystem. No longer taken up by root systems of trees, they are washed out by rainwater + soils, without protective cover of trees are quickly eroded by run off.

Question 18

What do scientists propose to reduce deforestation and carbon emissions?

Answer 18

human-engineered soils (dark soils) which are made from inputs of charcoal, waste and human manure. The charcoal attracts micro-organisms and fungi and allows fertility to be retained long-term. If they can be successfully recreated it would allow intensive and permanent cultivation which would drastically reduce deforestation and carbon emissions