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earths life support systems > Amazon rainforest > Flashcards

Amazon rainforest Flashcards

1
Q

Where is the amazon rainforest?

A

South America
70% in Brazil
Also in Peru, Ecuador, Venezuela, Bolivia and Guyana.

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2
Q

How many km2 does the amazon rainforest cover?

A

6 million km2

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3
Q

What are the flows and stores of the water cycle in the amazon?

A

Precipitation

Evapotranspiration

Run-off

Atmosphere

Soil/ground water

Temperature

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4
Q

Characteristics of precipitation in the amazon…

A

High av rainfall (>2000 mm)

Rainfall evenly distributed throughout the year though short drier seasons occur in some places.

High-intensity, conventional rainfall.

Intercepted rainfall accounts for 20-25% of all evaporation.

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5
Q

What are the characteristics of evapotranspiration in the amazon…

A

Elevated temperature, abundant moisture and dense vegetation= high rates of transpiration and evaporation.

Strong evapotranspiration precipitation feedback loops sustain high rainfall total.

1/2 rainfall returns to atmosphere by evapotranspiration

Most evaporation is intercepted moisture from leaf surfaces

Moisture lost in transpiration is derived for the soil via tree roots

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6
Q

Characteristics of run-off in the amazon…

A

Rapid run-off related to high rainfall, intensive rainfall events and well drained soils.

Depending on seasonal distribution of rainfall, river discharge may peak in one or two months of the year

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7
Q

Characteristics of the atmosphere as a store in the amazon rainforest…

A

Elevated temperature allows the atmosphere to store large amounts of moisture

Relatively humidity is also high

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8
Q

The characteristics of soil/groundwater as a store in the amazon…

A

Abundant rainfall and deep tropical soils leads to significant water storage in soils and aquifers

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9
Q

Vegetation characteristics in amazon as a store…

A

Rainforest trees play a crucial role in the water cycle, absorbing and storing water from the soil and releasing it through transpiration

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10
Q

Why do plants grow so effectively in the amazon (carbon)

A

Humid equatorial climate creates ideal conditions

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11
Q

What is net primary productivity (NPP) and what is the rate in the amazon?

A

NPP is the net amount of C02 taken in by vegetation in a particular area

In the amazon it is high, averaging 2,500 grams/m2/year

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12
Q

What is the biomass in the amazon?

A

Between 400 and 700 tonnes/ha

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13
Q

Large forest trees store a lot of carbon, how much do the store?

A

180 tonnes C/ha and 40 C/ha in their roots

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14
Q

How much carbon is stored in soil

A

Between 90 and 200 tonnes /ha

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15
Q

Amazon rainforest is a major reservoir of stored carbon, how much does it absorb per year?

A

2.4 billion tonnes a year

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16
Q

Are the exchanges/ recycling of carbon between atmosphere, biosphere and soil slow or rapid?

A

Rapid

17
Q

How do humid conditions affect the carbon cycle?

A

Quick decomposition of dead organic matter= quick release of CO2= fixation through photosynthesis

18
Q

What are the physical factors of the water cycle in the amazon

A

Geology

Relief

Temperature

19
Q

How does geology affect the water cycle in the amazon rainforest?

A

Impermeable surfaces cover most of the amazon basin and have minimum water storage capacity resulting in rapid run-off.

Permeable rocks such a limestone and and sandstone store precipitation and slow run-off

20
Q

How does relief affect the water cycle in the amazon?

A

Most of the amazon basin comprises of extensive lowlands.

On low lying land with gentle relief, water will move slowly across the surface as overland flow or through the soil as through flows to rivers and streams.

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

21
Q

How does temperature affect the water cycle in the amazon?

A

High temperatures result in high levels of evapotransportation

Convection is strong, leading to high atmospheric humidity, the development of thunderstorm clouds and intense precipitation.

Water is cycled constantly between land surface, trees and atmosphere by evaporation, transpiration and precipitation

22
Q

What is vegetation like in the amazon rainforest?

How much carbon does it store

A

Forest trees dominate the biomass of the amazon and are the principal carbon store

In total approximately 100 billion tonnes of carbon is locked up in the amazon rainforest

60% is stored above ground biomass the remainder is below ground mainly as roots and soil

23
Q

Photosynthesis

A

Connects the rain forest to the atmosphere carbon stores

24
Q

How does rainfall, temp and sunlight affect the carbon cycle in the amazon

A

High temp, high rainfall, intense sunlight stimulate primary production

NPP averages about 2500 grams/m2/year

25
Q

Organic matter+the carbon cycle in the amazon

A

Leaf litter and other dead organic matter accumulates temporary at the soil surface and with in rainforest soils.

High temp+humid conditions= rapid decomp of organic matter by bacteria

Decomp releases nutrients to soil which are immediately taken up by tree roots and CO2 which is emitted into atmosphere

26
Q

How does geology affect the carbon cycle in the amazon

A

Geology dominated by igneous rocks

Carbonates largely absent from the mineral comp of these rocks

However in western parts close to the Andes limestone occurs. They are significant carbon stores long term

27
Q

How severe is the deforestation in the amazon rainforest

A

Deforestation is very high

1970-present 70% of the forest has been destroyed or degraded

The forest is cleared for mining, logging, subsistence farming and cattle ranching.

28
Q

Deforestation causes floods- reduces stores so there’s greater run off…

What is an example of this in the amazon?

A

2014 Madeira river devastating floods

60 died 68,000 families evacuated

29
Q

Deforestation can lead to climate change at local and regional scales, how?

A

Converting rainforest into grassland increases run off by a factor of 27 and half of the rain falling on grass land goes directly into rivers

This reduces transpiration and atmosphere humidity which is responsible for cloud formation and convectional rainfall

Deforestation breaks this cycle and can lead to permanent climate change

30
Q

What affect does deforestation have on the carbon cycle?

A

Deforestation exhausts the carbon biomass store. Crop lands and pasture only contain a small amount of carbon compared to forest trees.

Drastically reduces inputs of organic material to soil.

Nutrients no longer taken up by the roots systems of trees are washed out of souls by rain water. Soil not protected by trees quickly eroded by run off

31
Q

What is the effect of less organic material in soil?

A

Soil depleted of carbon and exposed to strong sunlight support fewer decomposer organisms, thus reducing flow from soil to atmosphere.

32
Q

How has Brazil reacted to the deforestation and degradation of the rainforest?

A

It is an international and national concern because of the implications for global climate change

Brazil is committed to restoring 120,000 km2 of forest by 2030

33
Q

What are the 3 different types of management strategy?

A

Protection through legislation of large areas of primary forest so far unaffected by commercial developments

Projects to restore areas degraded or destroyed by subsistent farming, cattle ranching, logging or mining

Improvement in argricultural techniques to make permanent cultivation possible

34
Q

What have the Brazilian government done to reduce deforestation?

A

Since 1998

Forest conservation areas

Amazon Regional Protected Areas cover an area 20x bigger than Belgium

It has been affective 2015 44% of the rainforest was claimed national parks, wildlife reserves and indigenous reserves.

35
Q

What are the plans for reforesting projects sponsored by local authorities?

A

Sponsored by local authorities, NGOs and businesses- underway but slow progress.

Parica project western amazon- sustainable forestry scheme aims to develop 1,000km2 commercial timber plant on government-owned deforested land.

20mil fast growing tropical hard wood trees planted on 400 smallholdings, financial assistance given to smallholders

Although this is a monoculture it is sustainable + ensures carbon is sequestered and stored in trees and soil

Helps re-establish the water n carbon cycle

36
Q

Farming has been then main cause of deforestation in the Amazon.

Why has farming been unsustainable in the Amazon?

A

Low fertility soils meant that permanent cultivation proved unsustainable.

A few years later smallholders abandoned their plots which were then converted to low quality grassland

37
Q

How can we improve agriculture?

A

Diversification

Soil fertility can be maintained by rotational cropping and combining livestock and arable operations.

Integrating crops and livestock could allow a fivefold increase increase in ranching productivity and help slow rates of deforestation

38
Q

How can we improve and retain the fertility of soils?

A

Charcoal, waste and human manure

earths life support systems (5 decks)

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