Case Studies

Question 1

Amazon rainforest water cycle - precipitation

Answer 1

High average annual rainfall - >2000 mm

High intensity conventional rainfall

Interception by forest trees is high - 10% of precipitation account for 20-25% of all evaporation

Question 2

Amazon rainforest - water cycle - evapotranspiration

Answer 2

High rates of evaporation and transpiration due to high temperatures, abundant moisture and dense vegetation

Around half of incoming rainfall is returned to the atmosphere by evaptranspiration

Most evaporation is from intercepted moisture from leaf surfaces

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

Question 3

Amazon rainforest - water cycle - run-off

Answer 3

Rapid runoff due to high rainfall, intensive rainfall events and well-drained soils.

Question 4

Amazon rainforest - water cycle - atmosphere

Answer 4

High temperatures allow the atmosphere to store large amounts of moisture

Absolute humidity and relative humidity is high

Question 5

Amazon - water cycle - soil/groundwater

Answer 5

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

Question 6

Amazon - water - vegetation

Answer 6

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

Question 7

Rainforest - carbon - climate

Answer 7

Humid equatorial climate creates ideal conditions for plant growth.

Net primary productivity is high, averaging 2500 grams/m squared/year.

Large forest trees typically store 180 tonnes c/ha above ground and a further 40 tonnes C/ha on their roots

Question 8

Rainforest - carbon - exchanges

Answer 8

Exchanges between atmosphere, biosphere and soil is rapid

Warm humid conditions allow for decomposition of dead organic matter leading to the quick release of co2.

Rates of carbon fixation through photosynthesis are high

Question 9

Rainforest - carbon - soil

Answer 9

Amazonia’s leached and acidic souls contain only limited carbon and nutrient stores.

The fact that such poor soils support a biome with the highest NPP and biomass of all terrestrial ecosystems, emphasising the speed with which organic matter is broken down, mineralised and recycled

Question 10

Physical factors - amazon water cycle - geology

Answer 10

Impermeable catchments (eg large parts of the amazon basin are an ancient shield area comprising impermeable, crystalline rocks) have minimal water storage capacity resulting in rapid runoff.

Permeable rocks such as limestone and sandstone store rainwater and slow runoff

Question 11

Physical factors - water - rainforest - relief

Answer 11

Most of the amazon basin comprises extensive lowlands

In areas of gentle relief water moves across the surface (overland flow) or horizontally through the soil (throughflow) to streams and rivers.

In the west the Andes create steep catchments with rapid runoff.

Question 12

Physical factors - water - amazon - temperature

Answer 12

High temperature throughout the year generate high rates of evaporranspiration

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

Water is cycled continually between the land surface, forest trees and the atmosphere by evaporation, transpiration and precipitation

Question 13

Physical factors - carbon - amazon - trees

Answer 13

100 billion tonnes of carbon is stored in the rainforest

60% of rainforest carbon is stored in above ground biomass of tree stems, branches and leaves.

Photosynthesis connects the rainforest to the atmosphere carbon stores

Question 14

Physical factors - amazon - carbon - temperatures

Answer 14

Leaf litter and dead organic matter accumulates temporarily at the soil surface and within rainforest soils

High temperatures and humid conditions promote rapid decomposition or organic litter, releasing nutrients to the soil for immediate take up by tree root systems and emits co2 which is returned to the atmosphere

Question 15

Physical factors - rainforest - carbon - geology

Answer 15

Dominated by ancient igneous and metamorphic rocks. Caribonates are largely absent from the mineral composition.

In west part of basin near Andes , outcrops of limestone occur

Question 16

Human factors - amazon - water - floods

Answer 16

2014 - floods occurred in Madeira river due to deforestation

60 people died, 68,000 evacuated and outbreaks of cholera

Question 17

Human factors - amazon - stores and flows of water cycle

Answer 17

Deforestation has reduced water storage in forest trees, permeable rocks (due to more rapid runoff)

Less evapotranspiration and therefore less precipitation.

Meanwhile total runoff and runoff speeds have increased, raising flood risks throughout basin

Question 18

Floods of 2014

Answer 18

Between 2000 and 2012 30,000km of rainforest cleared for subsistence farming and cattle ranching. Much of this deforestation occurred on the steep slopes of the Andes.

Resulted in massive runoff and massive reduction in water storage

Question 19

Future deforestation - amazon

Answer 19

20% decline in regional rainfall as the rainforest dries out and forest trees are replaced by grasslands.

Question 20

Deforestation affect on carbon

Answer 20

Exhausts main store - grasslands only store 16.2 tonnes/ha

Reduces input of organic matter to the soil - reduces flow of carbon to the atmosphere

Question 21

Protection through legislation- amazon

Answer 21

1998 Brazilian government has established many forest conservation areas.

By2015 44% of the Brazilian amazon comprised national parks, wildlife reserves and indigenous reserves where farming is banned

Question 22

Projects to reforest areas - amazon

Answer 22

Parica project - aims to develop an1000km commercial timber plantation on government owned, deforested land.

Financial assistance is given to smallholders for land preparation, planting and the maintenance of plots.

Tree nurseries provide them with seedlings

Is sustainable and sequesters carbon in the trees, reducing the co2 emissions from deforestation and reduces runoff.

Question 23

Indigenous surui peope

Answer 23

2009 - first indigenous people to join the UNs reducing emissions from deforestation and degradation scheme

Provides payment to the tribe for protecting the rainforest and abandoning logging - granting them carbon credit.

2013 - natura (tnc) purchased 120,000 tonnes of carbon credit from the surui

Question 24

Improved agriculutural techniques

Answer 24

Diversification - soil fertility can be maintained by rotational cropping and integrating crops and livestock can help slow rates of deforestation

Question 25

Tundra - water cycle - precipitation

Answer 25

Low annual precipitation with most of it falling as snow

Question 26

Tundra - water cycle - atmosphere

Answer 26

Small stores of moisture in atmosphere lead to low temperatures which reduce absolute humidity

Question 27

Water cycle - tundra - evapotranspiration

Answer 27

Limited transpiration - due to spare ness of vegetation cover Low rates of evaporation - much of suns energy used melting snow in summer

Question 28

Water cycle - tundra - river flows

Answer 28

Melting of active layer in spring results in sharp increase in river flows

Question 29

Water cycle - tundra - groundwater

Answer 29

Limited ground water and soil moisture stores-permafrost is a barrier to infiltration, percolation, recharge and groundwater flow

Question 30

Carbon cycle - tundra - storage

Answer 30

1600 GT of carbon - due to low temperatures which slow decomposition of dead plants

Question 31

Carbon cycle - tundra - temperatures

Answer 31

Flux of carbon concentrated in summer months when active layer thaws Plants grow rapidly in summer due to long hours of daylight During growing season tundra plants input carbon-rich litter into soil. The activity of microorganisms increases, releasing co2 to atmosphere through respiration In winter pockets of unfrozen soil in permafrost act as a source of co2 and ch4. Snow cover may insulate microbial organisms and allow some decomposition

Question 32

Carbon cycle tundra - today

Answer 32

Now becoming a carbon source rather than a sink More heat due to global warming leads to more plants - more decomposition

Question 33

Physical factors - water - tundra - temperature

Answer 33

Below freezing temps means for most of the year water is stored as ground ice in permafrost layer Summer - active layer melts and liquid water flows on surface forming pools and shallow lakes This meltwater forms pools but there is poor drainage as water cannot infiltrate soil

Question 34

Physical factors - water - tundra - evapotranspiration

Answer 34

Winter - no evapotranspiration due to sub zero temperatures Summer - some evapotranspiration from standing water, soils and vegetation

Question 35

Physical factors - water - tundra - geology

Answer 35

Permeability is low owing to the permafrost and the crystalline rocks which dominate the geology of the tundra in the arctic Minimal relief and glacial deposits impede drainage and contribute to water logging during summer months

Question 36

Physical factors - carbon - tundra - storage

Answer 36

Carbon is mainly stored as partly decomposed plant remains frozen in the permafrost

Question 37

Physical factors - carbon - tundra - plant growth

Answer 37

Low temps, unavailability of liquid water and limited nutrients limits plant growth Low temperatures slow decomposition and respiration and the flow of co2 to the atmosphere

Question 38

Physical factors - carbon - tundra - geology

Answer 38

Owing to the impermeabilty of the permafrost, porosity and the mineral composition of rocks exert little influence over the carbon cycle

Question 39

Oil and gas production

Answer 39

North slope of Alaska | 1990s - north slope accounted for nearly a quarter of usas domestic oil production

Question 40

Oil and gas production - melting

Answer 40

Construction and operation of oil and gas installations, settlements and infrastructure diffuses heat directly to the environment Dust deposition along roadsides creates darkened snow surfaces, increasing absorption of sunlight Removal of vegetation cover which stops the insulation of permafrost

Question 41

Oil and gas production - permafrost melting releases co2 and methane

Answer 41

North slope - losses of co2 from permafrost vary from 7-40 million tonnes per year Gas flaring and oil spillages emit co2 Destruction of tundra vegetation reduces photosynthesis and uptake of co2 from atmosphere Thawing of soil increases microbial activity, decomposition and emissions of co2

Question 42

Oil and gas production- affect on water

Answer 42

Increased runoff and river discharge - increased evaporation in summer Strip mining of sand and gravel for construction creates artificial lakes which disrupt drainage and expose permafrost to further melting Drainage networks disrupted by road construction Water abstracted from creeks and rivers for industrial use and for building or ice roads in winter reduce runoff

Question 43

Oil and gas production - management strategies

Answer 43

Insulated ice and gravel pads - roads and other infrastructural features can be constructed on insulating pads - prevents permafrost from melting Buildings and pipelines elevated in piles - allows cola air to circulate beneath these structures Building laterally beyond drilling platforms - new techniques allow oil and gas to be accessed kms from drilling sites Refrigerated supports - trans Alaska pipeline - stabilise the temperature of permafrost