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Geo: ELSS > Tropical Rainforest - Amazon > Flashcards

Tropical Rainforest - Amazon Flashcards

1
Q

Location of the Amazon

A

Brazil, Columbia, Venezuela, Peru and Bolivia are the main countries the Amazon rainforest covers.
They are all found in Northern and Central South America.

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2
Q

General facts about the amazon
HINT: area occupied, length of river, % of all tropical rainforest found in the Amazon, NPP, % lost to deforestation since 1970, amount of world’s carbon stored in Amazonia.

A

Area Amazon rainforest occupies: 6,000,000km2
Length of Amazon river: 6,700km
% of tropical rainforest in the world in the Amazon: 50%
Net Primary Productivity: 2200g/m2/yr (very high)
% of rainforest lost to deforestation since 1970: 20%
Amount of world carbon stored in Amazonia: 25% of biomass

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3
Q

Describe the climate of Amazonia

A

Roughly 26°c in winter and 27.5°c in summer. Extremely high all year round.
Annual rainfall is high specifically within winter.

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4
Q

Why are the highest levels of solar insolation on the equator? (2 reasons)

A

Curvature of the earth: As the sun is directly above the equator the rays are extremely concentrated on the equator. At the poles the suns rays are at an angle causing the radiation to be spread out and less concentrates.

Thickness of the atmosphere: As the sun is located above the equator the rays have to travel through less of the atmosphere, so less is reflected by the atmosphere

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5
Q

Why does the tropical rainforest have so much rainfall?

A

The tropical rainforests are found on the rising limb of the Hadley cell.

At the equator the air is rising due to intense levels of incoming solar radiation.

As the air rises it cools with altitude and condensation takes place to form clouds.

When enough condensation has occurred for the mass of liquid water in the cloud to overcome gravity it will fall as rain.

We call this type of rainfall convectional relief.

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6
Q

Describe the process of convectional rainfall

A
  1. As air cools at the DALR it is not able to hold as much water in gaseous (vapour) form and it approaches dew point.
  2. Water condenses as clouds, particles collide until rain droplets form.
  3. Rising air creates a zone of low pressure on the surface around the equator.
  4. Air rises, expands and cools.
  5. Convectional rainfall falls in large amounts at the equator, therefore making the growth of tropical rainforests possible.
  6. Equator receives high amounts of solar insolation and therefore heat.
  7. Heat from Earth’s surface causes air above to warm and rise.
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7
Q

Why is there still some variation in rainfall and temperature?

A
  • The earth is tilted relative to the sun – by 23.50
  • In June, the Northern Hemisphere is tilted towards from the sun
  • The most intense heating (sun directly overhead) from the sun moves to north of the equator toward the Tropic of Cancer
  • This causes the ITCZ (Inter-Tropical Convergence Zone) to also move north
  • The opposite occurs in December.
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8
Q

Describe the characteristics for the atmospheric, land and biomass stores of water in the tropical rainforest.

A

Atmosphere - amazon rainforest has a large sum of clouds and it stores more moisture in the air.

Land - precipitation and soil moisture soil. So much water percolates and leaches nutrients from the soil.

Biomass - extremely large

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9
Q

Describe the characteristics of flows for the atmosphere, land and biomass in the amazon rainforests water cycle.

A

Atmosphere - Large amount of precipitation and evaporation in the water cycle.

Land - Large amounts of water are evaporated off. Large amounts of interception and little surface runoff. Lots of infiltration as tree roots guide water into the soil.

Biomass - lots of transpiration and respiration due to tones of vegetation.

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10
Q

What percentage of precipitation in Amazonia is recycled by evapotranspiration?

A

50-60%

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11
Q

What are the inputs into the Amazon basin for the water cycle.

Why are they from the ocean they are from

A

Water evaporating from the Atlantic ocean and being carried by winds into the rainforest system , it then precipitates over the rainforest

  • Winds are westerly blowing warm, moist air from the Atlantic Ocean.
  • Most of the rain from the ocean is released near the coast though some continues inland.
  • The Pacific ocean has a cold ocean current running down South America so little evaporation takes place (so not an input of water to this system).
  • The Amazon river runs for 6,700km through the rainforest. Evaporation takes places from the water in the river as well making it another large input of water to the system.
  • The large number of trees means there is a lot of evapotranspiration as well.
  • The Andes on the west coast encourage precipitation on their eastern flank meaning that water will mainly run east wards into the rainforest river catchments and back into the Atlantic rather than the Pacific on the west.
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12
Q

What are the outputs from the amazon rainforest basin in the water cycle

A
  • Water is heated and evaporates into the atmosphere and it then gets carried into over regions by winds
  • Water is heated and evaporates over the amazon basin
  • Water is recycled within the amazon rainforest
  • Surface run off into the amazon river results in losing a huge amount of moisture which flows into Atlantic
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13
Q

Characteristics of precipitation in the amazon water cycle

A

High, average totals (>2000mm). Evenly distributed throughout the year though short drier season in some places. High-intensity, convectional rainfall.

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14
Q

Characteristics of interception in the amazon water cycle

A

This is high (around 10% of precipitation) and intercepted rainfall accounts for 20-25% of all evaporation.

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15
Q

Characteristics of evapotranspiration in the amazon water cycle

A

High rates of this due to high temperatures, abundant moisture and dense vegetation.
Strong evapotranspiration-precipitation feedback loops sustain high rainfall totals.
Around a half of incoming rainfall is returned to the atmosphere by evapotranspiration.
Moisture lost in transpiration is derived from the soil via tree roots.

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16
Q

Describe run-off in the amazon water cycle

A

Rapid related to the high rainfall, intensive rainfall events and well-drained soils.
Depending on seasonal distribution of rainfall, river discharge (stream flow) may peak in one or two months of the year.

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17
Q

PHYSICAL FACTORS: How does geology effect the water cycle?

A

Impermeable catchments (Guiana shield & Brazil shield surrounding the amazon basin) have minimal water storage capacity resulting in rapid run-off over the area of more permeable rock.

In periods of heavy rain, groundwater stored becomes saturated, increasing chances of flooding.

Due to different geology’s across the rainforest different places will have varying rainfall.

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18
Q

PHYSICAL FACTORS: how does relief affect the water cycle

A

Flat land surrounded by higher relief meaning land acts as a funnel across the width of South America.

In areas of gentle relief water moves horizontally through the soil to the rivers giving time for infiltration and percolation.

In the west, the Andes create steep catchments with rapid run-off.

This reduces infiltration and increases overland flow (the west is more likely to flood).

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19
Q

PHYSICAL FACTORS: how does temperature affect the water cycle

A

High temperatures and thermal energy throughout the year generate high rates of evapotranspiration (large atmospheric store).

Convection is strong leading to high humidity and intense precipitation.

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20
Q

Which physical factors is the largest specially?
Which physical factor is the largest temporally?

A
  • Temperature
  • Geology
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21
Q

MADEIRA RIVER ~ location

A

Madeira river basin within the eastern Bolivian lowlands, on the Brazilian shield.

22
Q

MADEIRA RIVER ~ when did the flood occur

A

22nd May - mid June 2014. One of the worst floods on record.

23
Q

MADERIA RIVER ~ what factors caused the flooding

A

Human :
Deforestation & Jrau and Santo Antonio hydroelectric dams. Converting forest into grassland makes the quantity of water that runs into rivers x26.7 and soil erosion by 10.8x.

Physical:
Large parts of flatlands are flood plains even in normal rainfall, extremely high rainfall, Brazilian shield.

24
Q

MADERIA RIVER ~ impacts of the flood

A

Social :
Affected more than 300,000 people
more than 60 people died in Bolivia
fast spread of bacterial infections
many lost their houses (wooden bungalows)
the population lived with polluted water for more than 40 days inside their homes.

Economic:
The flooding of the Rio Negro caused losses more than $200 million
water remained high adn inside homes in poor areas of Manaus for over 50 days
flooding usually occurs in 10-year cycles however here it takes 3 years.

25
Q

List the structure of the rainforest from lowest layer to highest.

A

Shrub layer, Lower tree canopy, middle/main canopy, emergents.

26
Q

What percentage of light reaches the forest floor?

A

Less than 3%

27
Q

What is GPP?
How is it created?
What is GPP like in the Amazon

A

Gross Primary Productivity ~ The amount of carbon removed from the atmosphere by plant photosynthesis.
Using satellite data.
There is always high carbon fixing and a high GPP all year round.
25T/ha/yr

28
Q

What percentage of the carbon is used up in respiration of the plants themselves?

A

40-60%

29
Q

What is NPP?
How is it measured?
What is the tropical rainforests NPP like?
What is the tropical rainforests NPP?

A

Net Primary Productivity ~ The amount of energy made available by plants to animals.
* NPP = GPP - respiration
It is measured in g/m2/yr
The rainforest overall gas a positive flux all year round greater than the transfer from atmosphere to biosphere.
2200 g/m2/yr

30
Q

Describe the Amazons nutrients cycle
Sizes of stores
Sizes of flows between which stores

A

STORES:
Large biomass
Small soil but larger than litter
Litter is very small

FLOWS:
Large uptake pathway between biomass and soil.
Large weathering and leaching from soil.
Large decay pathway between soil and litter
Medium precipitation and runoff from litter
Very small fall out pathway between litter and biomass.

31
Q

How does the Amazons carbon cycle differ to others around the world?

A
  1. Relatively high NPP - a lot of carbon is stored in vegetation each year through growth. More is absorbed through photosynthesis than is respired. Rapid flux of photosynthesis, decomposition and respiration. Climatic conditions support high amounts of vegetation.
    1. Less carbon stored in soils than other ecosystems. Organic matter is quickly decomposed, mineralised and recycled so less carbon storage in soil than other ecosystems.
    2. Faster decomposition due to climatic conditions.
    3. High rates of photosynthesis.
    4. Rapid exchanges between biosphere and atmosphere.
32
Q

Facts about carbon stores in the amazon

A
  • Forest trees dominate the biomass and are the main carbon store
  • 100 billion tonnes of carbon is locked up in the amazon rainforest
  • 60% of rainforest carbon is stored in the above ground biomass of tree stems, branches and leaves (remainder is below ground, mainly as roots and soil organic matter)
  • Decomposition releases 1.7 billion tonnes of CO2 per year in the Amazon basin
  • Leaf litter and other dead organic matter accumulates temporarily at the soil surface and high temperatures and humidity promote rapid decomposition of organic litter by bacteria, fungi, and other soil organisms
33
Q

Facts about flows of carbon in the Amazon

A
  • 2.4 billion tonnes of CO2 is absorbed a year by amazon
  • 1.7 billion tonnes of CO2 is released a year by decomposition
  • Rainforest is a very important global sink
  • Photosynthesis connects the rainforest to the atmosphere carbon stores
  • High temperatures, high rainfall and intense sunlight stimulate primary production - photosynthesis (NPP averages about 2200grams/m2/year
  • Amazonia alone accounts for 15-25% of all NPP in terrestrial ecosystems
  • Decomposition releases nutrients to the soil for immediate take-up by tree root systems, and emits CO2 which is returned to the atmosphere
34
Q

Human factors in the amazon affecting the water cycle - facts

A

50% of the amazon could become degraded savannah if the climate changes.

In the last 50 years deforestation has made its way to about 20% of the amazons vegetation.

4/5 of deforested land has been converted into pasture for cattle farming.

35
Q

List the human factors leading to deforestation and changes in the amazons carbon and water cycle

A

Fires, mining, oil and gas exploitation, hydroelectric dams, crop and cattle farming, agriculture, deforestation.

36
Q

Impacts of deforestation on stores and flows of water cycle in the amazon - changes and impacts.

A

Height of trees have halves and the canopy has been removed.
- increase in the washing away of the organic layer, decrease in interception by drip tip and increase in surface run off.

Trees that have been cut down will have maintained air moisture by evapotranspiration
- warm and damp conditions will be lost slowing down decomposition rates and precipitation which is crucial for trees to survive.

Trees cut down being removed or cut down
- would have aided infiltration to maintain soil moisture. The soil moisture store is reduced and the biomass store is reduced.

37
Q

Impacts of deforestation on stores and flows of water cycle in the amazon - further notes

A

Ø Outputs through evapotranspiration: There are less trees in the rainforest meaning that evapotranspiration cannot take place at the same rate due to limited surfaces, this results in increased run off which can result in the soil becoming saturated and can cause flooding

Ø Recycling of rainfall: As evapotranspiration slows, the rate at which water is being inputted into the system, is faster than the rate that it is leaving resulting in increased run off and saturated soil

Ø Infiltration: Increased absorption of solar energy at surface and higher temperatures

Ø Surface runoff (and as an output):

Ø Interception: As the canopy layer is removed, less interception occurs which can result in the rate rainfall is input into the soil increasing

Ø Cloud formation: Clouds will form less as the rate of evaporation/evapotranspiration reduces which can lead to less precipitation and therefore drought

Ø Soil moisture storage (remember there is less organic material on the surface to hold moisture): The soil moisture storage is reduced and there is less organic matter which means increasingly creating conditions more likely to flood and environment drier

38
Q

How much of the amazon rainforest has been lost so far?

A

20% - averaged 17,500km2/year between 1970 and 2013

39
Q

Effects on the carbon cycle of switching from forest to grassland - human activity

A
  • increases run off by 27 times

* Half of all rainfall goes directly into rivers

40
Q

Effects on the water cycle through the removal of trees - human activity

A

Less water taken out of soil and transferred to the atmosphere through transpiration.

Less interception so more falls directly on the soil.

Trees stabilise albedo and ground temperatures.

Stops contributions to atmospheric humidity and affects cloud formation and condensation - impacts on climate change.

Increased run off which contributes to soil erosion especially as tree roots are not present to hold matter together (links to carbon cycle).

41
Q

Further changes and effects on the carbon cycle within the Amazon - human

A

Switch from forest to soya cultivation ~ Carbon stored drops to 2.7 tonnes/ha.

Burning of trees to clear land for farming ~ Carbon returned to atmosphere store - long term impacts on NPP.

Switch from forest for grassland (usually for cattle ranching) ~ Carbon stored drops to 16.2 tonnes/ha. This is a very small amount of carbon compared to trees. It exhausts the carbon biomass store of 180 tonnes/ha.

Removal of biomass store of nutrients through logging ~ Fewer nutrients available overall in ecosystem. Soil exhausted of nutrients through leaching (from rainwater hitting the soil directly rather than being intercepted) and vulnerable to erosion by run-off. Soils without protective cover of trees are quickly eroded by run-off. Main nutrients ~ Potassium, magnesium and calcium.

Removal of trees that photosynthesise. ~ Long term changes to NPP - carbon usually returned to atmosphere if biomass is burnt (combustion) or left to decompose.

Removal of input of organic matter to soils ~ Soil is depleted of carbon and cannot return as much carbon to atmosphere as it also doesn’t support decomposers as strong sunlight. Depleted of carbon, exposed to strong insulation, support fewer decomposers organisms, thus reduce flux of carbon to atmosphere.

42
Q

Management strategies to protect the rainforest - Afforestation

Overall impact on forest, water cycle and carbon cycle

A

OVERALL IMPACT ON FOREST
Biodiversity is constantly being reduced and monoculture is encouraged however it is economically and socially sustainable as locals can continue to benefit through resources the rainforest supplies.

IMPACT ON WATER CYCLE
Increases evapotranspiration, infiltration and interception. Reduces surface runoff and therefore maintains the nutrients left in the soil.

IMPACT ON CARBON CYCLE
Sequesters carbon in trees and vegetation. New plants can take in the carbon that was once emitted due to deforestation.

FACTS

  • EG: Patricia Project (1000km^2 of sustainable forestry on government land) - not on large enough scale
  • Landowners are paid to preserve and restore the forest
43
Q

Management strategies to protect the rainforest - Improving agricultural techniques

Overall impact on forest, water cycle and carbon cycle

A

OVERALL IMPACT ON FOREST
Successful for soil regeneration as more nutrients can infiltrate the soil. Doesn’t stop that eventually soil will be depleted anyway. Contour row crop systems - has some effect but doesn’t eliminate the fact that soil will eventually be depleted.

IMPACT ON WATER CYCLE
Increase in biomass reduced overland flows. Planting crops perpendicular to a hill side reduces soil erosion and water performing surface runoff which reduces nutrients. An increase in storage capacity for the soil reduces the amount of saturated overland flow.

IMPACT ON CARBON CYCLE
Increase in the biomass store reduces the atmospheric store which is needed as a result of previous deforestation.

FACTS

  • Farming is the reason for 4/5ths of deforestation
  • Plantations reduce the NPP from 180T/ha to 3T/ha
44
Q

Management strategies to protect the rainforest - Protection of remaining rainforest.

Overall impact on forest, water cycle and carbon cycle

A

OVERALL IMPACT ON FOREST
Maintains the rainforests biodiversity and natural habitats for animals. Protects interlinking relationships between plants and animals.
However this causes the economy to suffer as the locals can’t benefit off the rainforests resources.

IMPACTS ON THE WATER CYCLE
Maintains the rate of evapotranspiration.
Maintains surface runoff or overflow as roots allow water to penetrate the soil and maintains interference.

IMPACTS ON THE CARBON CYCLE
Maintains the amount of CO2 trapped in vegetation and trees - as they aren’t cut down large masses of CO2 aren’t released into the atmosphere.

FACTS

  • Brazil spends $50m a year protecting its protected areas
  • Over 44% of the Amazon is not protected
45
Q

The role of tropical peatland in the water and carbon cycle - What have studies shown about how much carbon is held in peat bogs?

A

Could be up to 90% in the amazon

46
Q

Benefits of biodiversity on the stores of the carbon cycle

A
  • Stores more carbon than any other terrestrial ecosystem

* As trees grow larger, they develop more biomass which contains carbon

47
Q

Benefits of biodiversity on the flows of carbon

A

• High flux of carbon from stores in soil due to high decomposition and uptake from trees

48
Q

Key facts and figures about biodiversity in the amazon

A
  • 1% of tree species store 50% of the Amazon’s carbon
  • The Amazon is home to an estimated 16,000 tree species - 182 are hyperdominant
  • The Amazon covers an estimated 5.3m km2 and holds 17% of global terrestrial vegetation carbon stock
49
Q

Facts about flows of water in the amazon

A
  • River has a discharge of 750,000km^3 a year
  • 2000mm of rain a year
  • 50% or precipitation recycled
  • 10% of rain is intercepted, which contributes to 25% of evaporation
  • A single tree can release 1000L of water a day, and there are 3 billion trees
50
Q

Facts about water stores in Amazon

A
  • 20% of worlds flowing fresh water
  • 50% of tree is made up of water, and there are 3am trees

Geo: ELSS (4 decks)

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