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OCR A level Geography - Earth's life support systems > 2.a. It is possible to identify the physical and human factors that affect the water and carbon cycles in a tropical rainforest. > Flashcards

2.a. It is possible to identify the physical and human factors that affect the water and carbon cycles in a tropical rainforest. Flashcards

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1
Q

The Amazon Rain Forest

What is the area of the amazon rainforest?

A

6 million km2

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2
Q

The Amazon Rain Forest

What percentage of the amazon rainforest is in Brazil?

A

70

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3
Q

The rain forest water cycle

what type of tress dominate the amazon rain forest?

A

Tall evergreen hardwood trees

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4
Q

what are the climatic features of the amazon rain forest?

A
  • high average annual temperatures
  • Little seasonal temperature variation
  • high annual rainfall (more than 2000mm)
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5
Q

what is responserble for the rainforests high temperatures?

A

intense insolation throughout the year

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6
Q

What helps the temperature stay below that exteme tropical desert landscapes?

A

cloud cover

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7
Q

What process recycles between 50 and 60 percent of precipitation in Amazonia?

A

evapotranspiration

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8
Q

what are the characteristics of precipitation in the ARF?

A

High annual rainfall (more than 2000mm per year) though a short diet Season occurs in places
High-intensity convectional rainfall
Interception by forest trees
intercepted rainfall accounts for 20-25 percent of all rainfall.

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9
Q

what are the characteristics of Evapotranspiration in the ARF?

A

High due to high temperatures, abundant moisture and dense vegetation
strong evapotranspiration-precipitation feedback loops sustain high rainfall.
Around half of incoming p is returned to the atmosphere by EVT.
Most evaporation is from leaf surfaces.

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10
Q

why is run-off high in the ARF and what are the characteristics of river discharge n the ARF?

A

rapid due to high rainfall and well drained soil. Depending on seasonal distribution of rainfall, river discharge may peak in one or two months of the year

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11
Q

Atmosphere TRF

A

hight temperatures allow the atmosphere to store large amounts of moisture

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12
Q

what are the characteristics of soil/groundwater etc in the ARF?

A

Abundant rainfall and deep soils lead to significant water storage in soils and aquifers.

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13
Q

Describe the role of trees in the ARF water cycle.

A

Rainforest trees play an important role in the water cycle, absorbing and storing water from the soil and releasing it through EVT

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14
Q

What do water losses result from?

A

River flow and export of atmospheric vapour to other regions. This loss of made good by the inward flux of moisture from the ocean.

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15
Q

what is the amazon rf conditions provide perfect conditions for?

A

Plant growth

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16
Q

What is the average net primary productivity in the ARF

A

averages 2500grams/m2/year

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17
Q

what is the biomass per hectare

A

between 400 and 700 tonnes/ha

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18
Q

How much carbon do large forest trees store per hectare above ground?

A

180 tonnes

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19
Q

How much carbon do large forest trees store per hectare below ground?

A

(in roots) 40 tonnes

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20
Q

How much does soil carbon store average per hectare?

A

between 90 and 200 tonnes

21
Q

How much carbon does the amazon rain forest absorb per year?

A

2.4 billion tonnes

22
Q

Describe the flux of CO2 in the TRF

A

Compared to other forest ecosystems, exchanges of carbon between the atmosphere, biosphere and soil are rapid. Warm, humid conditions ensure fast decomposition of dead organic matter and release of CO2.
Rates of carbon fixation and photosynthesis are high as well.

23
Q

What fact emphasises the speed at which dead organic matter is decomposed, mineralised and recycled?

A

The ARF has leached and acidic soils, with only limited carbon and nutrient stores. The fact that such poor soils can support such hight biomass is because of the speed that decomposition happens.

24
Q

How does Geology affect the water cycle in the TRF?

A

Impermeable catchments (e.g. large parts of the amazon basin are an ancient shield area, comprising of crystalline, impermeable rocks)have minimall water storage capacity, resulting in rapid run off.

25
Q

How does relief affect the water cycle in the TRF?

A

Most of the amazon basin comprises extensive lowlands. In areas of gentle relief water moves across the surface (overland flow) or horizontally (groundwater flow) into streams and rivers

26
Q

How does temperature affect the water cycle in the TRF?

A

Hight temperatures through out the year mean high evapotranspiration. Convection is strong, leading to high atmospheric humidity. Water is cycled continually.

27
Q

What percentage of NPP across all terrestrial ecosystems does the TRF account for?

A

15-20

28
Q

Globally, how much forest do we deforest per year and what percentage of this happens in the tropics?

A
  • 10 million hectare (roughly the size of Portugal)
    -95 percent of this happens in the tropics
29
Q

Globally, how much forest do we deforest per year and what percentage of this happens in the tropics?

A
  • 10 million hectare (roughly the size of Portugal)
    -95 percent of this happens in the tropics
30
Q

how much primary forest has been destroyed now?

A

one third

31
Q

Describe the trend of deforestation in recent years

A

Generally very high until 2003/4. Has now dressed significantly.

32
Q

What happened in April 2014 in Madeira?

A

Devastating floods occurred, the Madeira river is the largest tributary of the amazon river. The river reached record levels at Porto Velho and vast expanses of floodplain were inundated. 60 people died, 68,000 evacuated, outbreaks of Cholera.

33
Q

How did human activity cause he flooding of the Madeira tributary.

A

In the upper Madeira river basin , human activity has modified stores and flows in the water cycle.
deforestation has decreased water storage in trees, soils(eroded) and permeable rocks (high run off)

34
Q

By what factor does converting forest to grassland increase run-off

A

27, Half of all rain on grasslands goes into rivers.

35
Q

Why are rainforest trees essential to the water cycle.

A
  • Extract water from the soil
    -Intercepting and transpiring rainfall
  • Stabilising forest albedo and ground temperatures
    -Sustains high atmospheric humidity, essential for cloud formation
36
Q

How much if the Bolivian rain forest was deforested for substinence farming?

A

30.000KM2

37
Q

How much carbon does the rainforest release through decomposition per year?

A

1.7 billion tonnes.

38
Q

what is the current biomass of the amazon rain forest?

A

180 tonnes/ hectares

39
Q

Explain how deforestation and creation of grass and croplands exhaust the carbon biomass store

A

Crops lands and grass lands store a minimal amount of carbon compared to primary forest. At the same, less nutrients enter the soil and the flow of carbon to the atmosphere is reduced.
deforestation also slows down the rapid nutrient flows needed to cyst. the forests hight biomass.

40
Q

Deforestation influences the water cycle in the TRF, how does this impact the soil?

A

more nutrients and minerals are washed out of the soil by surface run-off.

41
Q

How much rainforest has Brazil committed to restoring by 2030?

A

120,000km2

42
Q

what 3 categories do modern efforts to protect the rain forest broadly fall into?

A
  1. Legislation
  2. Reforestation
  3. Improving agricultural techniques
43
Q

what is the Parcia project?

A

A sustainable forestry scheme which aims to develop an 100km2 timber plantation on previously deforested land., The plan is for 20 million fast growing hard wood trees.

44
Q

why can’t the the Parcia project replicate the biodiversity of primary forest?

A

Because its a monoculture.
(But it is sustainable because it sequesters carbon).

45
Q

What is the REDD scheme?

A

REDD+ is a framework created by the UNFCCC Conference of the Parties (COP) to guide activities in the forest sector that reduces emissions from deforestation and forest degradation, as well as the sustainable management of forests and the conservation and enhancement of forest carbon stocks in developing countries. It aims at the implementation of activities by national governments to reduce human pressure on forests that result in greenhouse gas emissions at the national level, but as an interim measure also recognizes subnational implementation.

46
Q

Why is permanent cultivation not possible in Amazonia?

A

Low soil fertility, so cultivators have to move often, leaving deforested areas to turn into grass lands.

47
Q

How can soil fertility be improved in Amazonia?

A

Rotational cropping and integrating crops and livestock

48
Q

How do scientists want to help reduce deforestation for cropping?

A

Trying to recreate the man made dark soils that indigenous populations use for cropping.

OCR A level Geography - Earth's life support systems (9 decks)

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