Alaskan Tundra

Question 1

what are the mean temperatures?

Answer 1

below -15°C

Question 2

how many months is the tundra in a negative heat balance?

Answer 2

8 to 9

Question 3

mean annual precipitation is

Answer 3

low

Question 4

describe the biodiversity and ecosystem

Answer 4

biodiversity is low and apart from a few dwarf species, the ecosystem is treeless

Question 5

Are the conditions in the lower arctic similar to the northern arctic

Answer 5

Conditions are less severe In the lower arctic

Question 6

describe annual precipitation pattern

Answer 6

low annual precipitation, with less than 100mm in some locations, mostly falling as snow

Question 7

Describe and explain the atmospheric moisture store.

Answer 7

small moisture owing to lower temperatures which reduce absolute humidity

Question 8

Give 2 reasons why the transpiration rates are low

Answer 8

limited due to sparsness of vegetation and short growing season of only 3 months

Question 9

why are there low rates of evaporation?

Answer 9

This is because the solar energy is concentrated on melting ice so ground temperatures remain low and inhibit convention.

Question 10

why are there limited groundwater and soil moisture stores?

Answer 10

Permafrost is a barrier to infiltration, percolation and groundwater flow

Question 11

Why does river flow increase In the tundra? Give an example of this

Answer 11

Accumulations river and lake ice and melting during spring and summer increases river flow. The Yukon river has a minimum discharge of 340 cumecs in the winter and maximum of 24,600 in the summer

Question 12

How many lake and wetlands are found in Alaska? Give a reasoning behind this figure.

Answer 12

over 3 million, there are so many owing to impermeability of permafrost

Question 13

How much carbon is held in the permafrost?

Answer 13

over 1600GT, it’s a global carbon sink.

Question 14

overall carbon held in tundra soils is … greater than the above ground biomass

Answer 14

5x

Question 15

What time is flux of carbon concentrated? what is the NPP?

Answer 15

During the summer, when the long daylight hours allow plants such as crowberry to flower within just a few weeks. But average NPP is still low, at less than 200 grams/m^2/year

Question 16

Describe the flux of carbon to the atmosphere during summer and winter months.

Answer 16

Activity of micro organisms release carbon dioxide and methane to the atmosphere. Whilst, pockets of unfrozen soil and water in the winter release the 2, also snow cover insulates microbial organisms and can allow some decomposition to take place.

Question 17

Explain why the permafrost may become a carbon source rather than sink and why some believe it will remain at balance.

Answer 17

Thawing of permafrost may lead to increased carbon dioxide in the atmosphere. It will also stimulate plant growth and greater uptake of Carbon dioxide. This will increase plant litter.It is therefore possible that the tundra today remains at balance

Question 18

Name 3 factors influencing flows and stores of water in the tundra

Answer 18

1. Temperature
2. Relief
3. Rock permeability

Question 19

Explain the impact of temperature on flows and stores of water

Answer 19

1. Average temperatures are well below freezing so most water is stored as ground ice in the permafrost
2. shallow active layer thaws in the summer, forming millions of pools, with poor drainage
3. Sub zero temperatures in the winter prevent evapotranspiration
4. In the summer some evapotranspiration can occur

Question 20

Explain the effects of permeability on flows and stores in the Tundra

Answer 20

Low permeability owing to the permafrost and precambrian igneous and metamorphic rocks which dominate the geology

Question 21

Explain the geological structure impacts water flows and stores

Answer 21

The underlying rock structure has been reduced to gently undulating plain, the minimal relief impedes drainage and has led to waterlogged conditions

Question 22

What is most carbon stored as In the tundra?

Answer 22

partly decomposed plants remains

Question 23

Explain the effect of low temperatures on the flows of carbon in the tundra.

Answer 23

low temperatures, lack of liquid water and few nutrients within the rock structure limit plant growth. Total carbon stored in biomass Is low as well as NPP. However there is compensation for the short growing season of 3 months with long daylight hours.

Question 24

What 2 factors reduce flow of carbon dioxide to the atmosphere?

Answer 24

owning to waterlogged conditions and low temperatures which slow decomposition

Question 25

Impact of geology on water and carbon cycle?

Answer 25

It’s very limited owing to impermeable permafrost with the mineral composition exerting little pressure

Question 26

where was oil and gas discovered in Alaska at 1968?

Answer 26

Prudhoe bay

Question 27

What were the challenges of oil and gas drilling in the Alaska?

Answer 27

1. Fragile wilderness of great ecological value
2. Poor accessibility
3. Remoteness
4. Extreme weather conditions with long daylight hours

Question 28

Give 2 reasons why drilling of oil went ahead despite the immense challenges.

Answer 28

High global energy prices and the US’s desire to reduce dependence on oil imports

Question 29

By early 1990, how much of the USs oil production was from Alaska and how much has this changed by?

Answer 29

Was previously 1/4 but now less than 4%

Question 30

Give 2 reasons why oil production has declined in Alaska.

Answer 30

1. High production costs
2. Massive growth of USs oil shale industry

Question 31

Give 3 reasons for localised melting on the Alaskan tundra, caused by oil and gas companies

Answer 31

1. construction of infrastructure and settlements has led to heat diffusion
2. Dust deposition along roadsides has created darkened surfaces, which absorb more light
3. removal of vegetation which insulates the permafrost

Question 32

what are the estimated carbon dioxide on the North slope?

Answer 32

7 - 40 million tonnes/year

Question 33

give 3 ways atmospheric carbon dioxide store is increasing?

Answer 33

1. destruction and degrading of tundra vegetation means less uptake of carbon dioxide
2. thawing of permafrost increases microbial activity and therefore decomposition
3. oil spillages and gas flarings

Question 34

carbon dioxide emissions on the tundra have increased by … since 1975 as an estimate

Answer 34

75%

Question 35

why has flood risk increased due to oil and gas production

Answer 35

increased melting of permafrost and snow cover leads to more run off and river discharge, making flooding more likely

Question 36

Explain the effect of strip mining for aggregates. Give an example.

Answer 36

Create artificial lakes which disrupt drainage and expose land to further melting. Artificial lake at goldstream has led to around 15m thawing in the last 60 years

Question 37

What is the effect of water abstraction?

Answer 37

reduce localised run-off

Question 38

give 5 management strategies and briefly explain there role in reducing impact on the W and C cycles

Answer 38

1. Insulated gravel ice and gravel pads- roads an infrastructure can be built upon these to reduce melting, Spine Road at Prudhoe bay lies on a 2m gravel pad
2. building and pipelines elevated on piles- construction on piles allows air to cooler air to circulate underneath and limit the impact of ice melt from heat generating buildings
3. Lateral drilling- impact on vegetation is significantly reduced, as you can access areas from a single site, e.g. Shells snake drill
4. Powerful computers- fewer exploration wells are needed, 10% of super computers are delivered to oil industry on average, 2 main tasks are seismic data processing and reservoir modelling
5. Refrigerated supports- used on trans-Alaska pipeline to stabilise temperatures