The Arctic Tundra

Question 1

what are the climatic conditions?

Answer 1

for 8 or 9 months it has a negative heat balance with avg monthly temp below freezing, as a result the ground is permanently frozen with only the top metre thawing in summer
in winter temp can go below -40C
mean annual precipitation is low

Question 2

what is the biodiversity like?

Answer 2

low - few plants + animals have adapted to this environment
treeless
in low arctic conditions are less severe + vegetation provides continuous ground cover

Question 3

what are the main features of the water cycle?

Answer 3

• low precipitation (50-350mm) most = snow
• small stores of moisture due to low temp which reduce absolute humidity
• limited transpiration due to sparseness of the vegetation cover + short growing season
• low rates of evaporation ->. much of suns energy is melting snow so ground temp remains low
• limited groundwater + soil moisture stores, permafrost is a barrier to infiltration, percolation, recharge + groundwater flow

Question 4

what results in sharp increase in river flow?

Answer 4

melting of snow, river + lake ice + uppermost layer of the permafrost in spring + early summer

Question 5

what are the main features of the carbon cycle?

Answer 5

• permafrost is a vast carbon sink (global 1600 GT)
• accumulation of carbon is bc low temp + slow decomposition of dead plant materials
• flux of carbon concentrated in the summer when active layer thaws -> plants grow rapidly, long hours of daylight (but NPP is less than 200 grams/m2/yr)
• growing season; tundra plants carbon rich litter to the soil, activity of microorganisms increases, releasing Co2 to the atmosphere through respiration
• even in the winter pockets of unfrozen soil + water in permafrost act as sources of Co2

Question 6

permafrost used to function as a carbon sink what do people think it is now?

Answer 6

carbon source

Question 7

what evidence suggests that the arctic remans balanced in the carbon budget?

Answer 7

increase in outputs of carbon from permafrost but higher temp so growth of plants + greater uptake of Co2

Question 8

how does temperature affect flows + stores of water?

Answer 8

avg temp are well below freezing so water is stored as ground ice in the permafrost layer
during summer the shallow active layer thaws + liquid water flows on the surface -> meltwater forms million of pools + lakes.
draining = poor, water cannot infiltrate the soil bc of the permafrost.
in winter sub zero temp prevents evapotranspiration
humidity is low all year round + precipitation is sparse

Question 9

how does permeability affect flows + stores?

Answer 9

low owing to permafrost + the crystallin rocks which dominate the geology of the tundra in arctic

Question 10

how does relief affect flows + stores?

Answer 10

gentle undulating plain due to 100 mill yrs of erosion + weathering
minimal relief + chaotic glacial deposits impede drainage + contribute to water logging during summer months

Question 11

how long has the carbon been locked away for in the permafrost?

Answer 11

500,000 years

Question 12

why is total carbon store of the biomass relatively small?

Answer 12

low temp, unavailability of liquid water + parent rocks contains few nutrients = limits growth

Question 13

what slows decomposition + respiration?

Answer 13

low temp + water logging = limit flow of Co2 to atmosphere

Question 14

what has little influence on the water + carbon cycle?

Answer 14

impermeability of the permafrost, rock permability, porosity + mineral composition of rocks

Question 15

when were oil and gas discovered?

Answer 15

1968, prudhoe bay

Question 16

what challenges did the development of oil + gas experience?

Answer 16

• harsh climate -> extreme cold
• permafrost
• the melting of the active layer in summer
• poor accessibility

Question 17

by 1990s what % of USAs oil production was from north slope?

Answer 17

25%

Question 18

what is the % of usa’s production today from north slope?

Answer 18

6%

Question 19

why did the production decline?

Answer 19

high production costs

massive growth of the oil shale industry in usa

Question 20

how has oil + gas production affected carbon + water?

Answer 20

permafrost is highly sensitive to changes in thermal balance -> balance has been disrupted which have caused localised melting of the permafrost
melting is associated w:
- construction + operation of oil + gas installations
- dust deposition along roadsides creating darkened snow surfaces this increasing absorption of sunlight
- removal of vegetation cover which insulates permafrost

Question 21

what does melting of the permafrost do? CC

Answer 21

releases Co2 + methane, on north slope estimated co2 losses from permafrost very from 7 mill to 40 mill tonnes per yr
gas flaring + oil spillages also input co2 into atmosphere

Question 22

what does the destruction or grading of tundra vegetation do?

Answer 22

reduces photosynthesis + uptake of co2 from the atmosphere + the thawing of soil increases microbial activity, decomposition + emissions of co2

Question 23

how does the slow growing nature of tundra vegetation affect recovery?

Answer 23

regeneration from damage could take decades

Question 24

how does the melting of permafrost affect WC?

Answer 24

increases run off, river discharge making flooding more likely
in summer wetlands, pools etc have become more extensive, increasing evaporation

Question 25

how has drainage been disrupted?

Answer 25

strip mining of sand + gravel -> also exposes permafrost to further melting
also disrupted by road construction + seismic explosions u

Question 26

strategies to reduce the impact of development on the water + carbon cycle

Answer 26

insulated ice + gravel pads -> protecting permafrost from melting
buildings + pipelines elevated on piles -> allows cold air to circulate structures
drilling laterally beyond drilling platforms -> allows oil + gas to be accessed several km from drilling sit -> fewer sites needed -> impact on vegetation + permafrost is reduced
refrigerated supports -> used on trans-alaska pipeline to stabilise temp