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Statistics Of Case Studies > The Amazon - W&C > Flashcards

The Amazon - W&C Flashcards

1
Q

Where are tropical rainforests found

A

In a band between the tropics and cover parts of South Americs, Central Africa and south-east Asia. A smaller area exists in North-eastern Australia

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2
Q

Where does the Amazon rainforest lay

A

Mostly Within Brazil, with the remainder mainly in Peru and Columbia

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3
Q

How big is the Amazon rainforest

A

The largest rainforest and covers 2.1 million square miles

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4
Q

What percentage of the earths surface do tropical rainforests cover

A

6%

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5
Q

What percentage of global photosynthesis do tropical rainforests account for

A

30-50%

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6
Q

How much of the worlds oxygen do tropical rainforests emit

A

28%

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7
Q

What is the annual rainfall in rainforests

A

2000+mm

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8
Q

What is the average temperature in tropical rainforests

A

27*C

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9
Q

What do the characteristics of tropical rainforests make ideal conditions for

A

Plant growth

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10
Q

What do rainforests have

A

A very high biodiversity

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11
Q

What percentage of the worlds species of plants and animals are tropical rainforests home to

A

50%

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12
Q

Why are inputs to the water cycle of a rainforest high

A

Because precipitation is very high, occurring throughout the year and usually in daily torrential downpours. It is a consequence of low pressure and high humidity in the tropics.

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13
Q

How much precipitation does the dense canopy of the rainforest intersect

A

75%

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14
Q

What happens to the intercepted water

A

Some is evaporated and some reached the ground via stem flow or drips from leaves.

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15
Q

How much of the available rainwater is used by plants and returned to the atmosphere by evapotranspiration

A

50%

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16
Q

How much of the available rainwater is infiltrated into the soil

A

50%

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17
Q

What is critical to the regions water supply

A

Trees of the forest as, through the process of transpiration, trees ensure water enters the atmosphere and in turn produces rain.

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18
Q

What fraction of its own precipitation does the Amazon Basin produce in the recycling of evapotranspiration

A

1/3, the other 2/3 arrive as moisture-laden air from the Atlantic Ocean

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19
Q

How do raindrops from tropical storms cause soil erosion

A

They hit the ground with great force

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20
Q

What does a continuous canopy prevent

A

Soil erosion because the canopy acts as an umbrella so water is transferred through stem flow so have less force than just rain hitting the ground

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21
Q

How is rain water transferred to the forest floor

A

By a combination of drip flow and stem flow. Drip-tips help the tree to shed water from each leaf, and the rest trickles down branches and stems

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22
Q

What do most rainforests plants have

A

Very shallow roots that take rainwater and dissolved nutrients directly from the decomposing leaf litter

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23
Q

What is the estimated loss of the Amazon basin in the last 50 years

A

17%

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24
Q

What is the primary reason the Amazon basin has lost 17% of its primary rainforest

A

Cattle ranching (80%)

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25
Q

When is the impact of cattle ranching mostly seen

A

In the east and south-east parts of the basin (Brazil) and in the north-western arc (Columbia and Ecuador)

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26
Q

How does the removal of trees have a massive impact on the rainforest water cycle

A

It almost wipes out some of the components and significantly affecting others

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27
Q

What does reduced evapotranspiration from cleared areas mean

A

The air is less moist, resulting in a reduction in cloud cover and less pricks prion.

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28
Q

With fewer trees, what happens to the rainfall

A

Most rainfall reaches the frond immediately as there is little compacting it. The water leaves the area as overland flow so less is returned to the atmosphere locally. The increased rates of runoff increase the risk of flooding.

29
Q

In cleared areas, why does temperature increase

A

Becsuse more solar radiation is reflected by cleared land (than the darker forest canopy)

30
Q

What limits the chance of regrowth if the forest has been cleared

A

Exposed soil is at risk of erosion

31
Q

In a fully forested area, what usually happens to rainfall

A

It is recycled within the local region

32
Q

What are the effects some studies have shown about the replacement of forests by pasture or crops

A

It leads to a reduced atmospheric humidity and suppressing precipitation. This is because rainforests allow a considerable amount of water to be returned to the atmosphere through evapotranspiration. However, other studies have shown an increase in local rainfall downwind of a deforested area.

33
Q

What has a recent study suggested that rainfall levels in the wider region are likely to do where there is extensive deforestation

A

Reduce

34
Q

What have some studies found about the changing patterns of rainfall

A

air that has passed over extensive forest produces twice as much run compared to air that has passed over little forest. The study estimates that future deforestation of the Amazon rainforest could lead to a 20% decline in regional rainfall.

35
Q

At a local level, why have some cleared areas experienced an increase in rainfall

A

Due to ‘vegetation breezes’

36
Q

What are vegetation breezes

A

Air over cleared land warms faster, rises quicker and creates localised low pressure, drawing moist air from forested areas. The result is an increase in cloud coverage, thunderstorms and rainfall over the cleared , at the expense of forested areas.

37
Q

Why is there less rain in places that have been deliberately burned to clear for agriculture

A

The burning produces airborne aerosols around which water vapour condense. As a result, smaller droplets occur in clouds, which are too small to precipitate, resulting in less rain

38
Q

Why do tropical rainforests account for between 30-50% or global photosynthesis

A

Because the warm, humid tropical climate is ideal for plant growth

39
Q

Why are tropical forests sometimes called the ‘Lungs of the Earth’

A

Becsuse the forest absorbs huge amounts of carbon from the atmosphere and emit a great deal of oxygen

40
Q

What percentage of wood is carbon

A

50%

41
Q

Rainforests are carbon sinks, why is this good

A

They help mitigate the effects of climate change

42
Q

In a typical year, how much carbon dioxide does the Amazon rainforest absorb

A

2.2 billion tonnes

43
Q

In a typical year, how much carbon dioxide does the Amazon rainforest emit through decomposition and organism respiration

A

1.9 billion tonnes

44
Q

What can be the outputs of carbon in a rainforest

A

Decomposition
Organism respiration
Soil removed by streams

45
Q

What do rainforests store more of than any other type of ecosystem

A

Carbon (as sugar and starches)

46
Q

What percentage of the terrestrial biomass is though to be stored in rainforests

A

40-50% , which has been estimated as more than 17 kilograms of carbon per square metre

47
Q

How much carbon does the Amazon rainforest contain per square meter

A

Between 14 and 40 kilograms , the soil lying under rainforests also contain substantial amounts of carbon

48
Q

Where does soil contains its carbon

A

In roots, microorganisms, soil fungus and plants

49
Q

What percentage of global soil carbon is stored in the Amazon

A

27%

50
Q

What percentage of all carbon in tropical rainforests is found in below ground root systems and soil organic matter

A

40%

51
Q

How much carbon in the upper 50 centimetres of the soil level does Amazonian soil confirm

A

Four to nine kilograms

52
Q

How much carbon in the upper 50 centimetres of the soil level does pastureland soil confirm

A

One kilogram

53
Q

Why are tropical rainforests capacity to recycle the worlds increasing carbon dioxide emissions beginning to appear in doubt

A

As human activity alters their extent and dominant processes

54
Q

What is the second largest anthropogenic source of carbon dioxide to the atmosphere

A

Deforestation

55
Q

Of global carbon emissions, what percentage does deforestation in tropical rainforests create

A

6%-17%

56
Q

When forests are cleared and burned, whether for farming, mining, rocks or settlements, what percentage of carbon is lost to the atmosphere

A

30-60%

57
Q

What happens to unburned vegetation

A

It decays and is lost within 10 years

58
Q

At what rate has the size of the Amazon been decreasing per year since 2000

A

0.3%

59
Q

What are the pros and cons of burning

A

It is cheap and effective but can burn out of control for weeks

60
Q

Why does deforestation mean that photosynthesis rates drop

A

Because there is less vegetation, especially if it is brunt as it will only start again once new plants start to colonise the area

61
Q

Due to deforestation, what does plant and animal respiration drop to

A

Almost zero

62
Q

Due to deforestation, what happens to de composers

A

They become largely absent from the environment

63
Q

Due to the slash and burn technique, what increases the carbon content in the soil

A

Becsuse the rain will wash the ash into the ground so that, in the short term, the carbon content increases

64
Q

In the past (1990) how much carbon dioxide did the Amazon absorb

A

2.2 billion tons

65
Q

In the Amazon, what is declining

A

Its capacity to operate as a major carbon sink

66
Q

In 2015, how much carbon dioxide did the Amazon absorb

A

1 billion

67
Q

Why does the Amazon basin no longer represent a continental carbon sink

A

Because the recent absorption of carbon is less than the total co2 emitted by Latin America counties each year

68
Q

What is the reason for the decline of carbon capture in the Amazon thought to relate to

A

Substantial tree death within the Amazon basin - it has been assumed that increased atmospheric carbon dioxide levels would stimulate biomass growth (carbon fertilisation) and regulate the emission rise. However it appears that while rainforest plants do grow faster, they die sooner. This has increased metabolic stress that has been compounded but recurrent drought, unusually high temperatures, continued illegal logging and conversion to agriculture.

69
Q

What does it appear the rainforest is under threat from

A

Both direct human activity and climate change arising from indirect action in releasing stored hydrocarbons in such massive quantities

Statistics Of Case Studies (12 decks)

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