The Arctic Tundra Flashcards
How big is the Arctic tundra?
8 million km2
What countries/regions is the Arctic tundra in?
Canada, Alaska, Siberia
Where does the Arctic tundra extend to/from?
from the northern edge of the boreal coniferous forest to the Arctic Ocean
What is the southern limit of the Arctic tundra?
the 10 degrees July isotherm
For how many months does the tundra have a negative heat balance (average temperatures below freezing)?
8 or 9 months
For how long is the ground frozen?
permanently
How much permafrost thaws in the summer?
top metre
What happens in winter?
the sun remains permanently below the horizon and temperatures reach -40
Why is there low biodiversity?
few plants and animals have adapted to the extreme environment
What plant is not present?
trees
What is the annual preciptiation?
low - 50-350mm
what form is most of the precipitation?
snow
why is there low humidity
the cold
why is there little transpiration
sparse vegetation and short growing season
why is there low evaporation
the Sun’s energy is used to melt snow and most surface water is frozen
what is permafrost a barrier to?
infiltration and percolation = limited groundwater stores
what accumulates in winter
snow and ice
why does river flow increase in summer
snow/ice and active layer melt
why are there wetlands in summer
permafrost limits drainage of melted ice
how much carbon does the tundra contain
1600 Gt
what slows decomposition
low temperatures
how much more carbon is there in the soil than the above ground biomass
5X
what do long daylight hours in summer allow for
rapid plant growth
what is the NPP
200 g/m2/year
what is the biomass
4-29 tonnes/ha
what do plants input to the soil during the growing season
carbon-rich litter
the activity of what increases in summer, and what does this release
microorganisms - CO2 via respiration
What are a source of CO2 and CH4 in winter
pockets of unfrozen soil
what is the effect of insulating snow
microbes can carry out some decomposition
what may global warming do to the tundra
make it a carbon source. But increases in plant growth may take in more CO2
what is the effect of temperature on water storage
average temperatures below freezing so water is stored as ice
what forms when the active layer thaws
pools and lakes
why is drainage poor
the permafrost
what carbon cycle process does the cold prevent
evapotranspiration
from what does evapotranspiration occur in summer
pools and vegetation
what are low all year
humidity and precipitation
what lies under the tundra
ancient rock
what has reduced the ancient rock to a gentle plain
weathering and erosion
what does the gentle plain of the tundra cause
impedes drainage and causes waterlogging in the summer
what is carbon mainly stored as
partly decomposed plants in the permafrost
what factors limit plant growth
low temperatures, no liquid water, little nutrients
what are low due to limited plant growth
NPP and photosynthesis
what compensates for the short growing season
long daylight hours
what are the results of low temperatures and water logging on the carbon cycle
slow decomposition and respiration
what size is the flow of CO2 to the atmosphere in the tundra
small
why do rock porosity and mineral composition have little influence on the carbon and water cycles
the impermeability of the tundra
when and where was oil and gas discovered in the tundra
Prudhoe Bay - 1968
why is it difficult for oil and gas industries to function in the tundra
extreme cold
long periods of darkness
poor accessibility
what was oil and gas production in the tundra driven by
high global energy prices and the US government’s policy to reduce dependence on oil imports
by the early 1990s the North Slope of Alaska accounted for how much of the USA’s domestic oil production
1/4
how much USA oil does the North Slope of Alaska contribute to today
6%
why has oil and gas production in Alaska declined
high production costs and growth of the US oil shale industry
why does the melting of the permafrost make flooding more likely
increases run off and river discharge
what process increases because summer wetlands are becoming more extensive
evaporation
what is the effect of mining sand and gravel
artificial lakes that disrupt drainage and cause furhter melting
what human activity disrupts drainage
road construction
seismic explosions to prospect for oil and gas
what human activity reduces run off
abstracting water from creeks and rivers
why is the permafrost melting
construction and infrastructure diffusing heat
dust reducing albedo so more sunlight absorbed
removal of insulating vegetation cover
what gasses does melting release
CO2 and CH4
how much CO2 is estimated to be lost due to melting
7-40 million tonnes a year
what human activities in the tundra input CO2 to the atmosphere
gas flaring and oil spills
what is the result of loss of vegetation on the carbon cycle
reduces photosynthesis so less CO2 fixed by plants
what process in the carbon cycle increases due to melting
decomposition
why does tundra vegetation take decades to recover
slow growing
what management strategy goes under roads to prevent melting
insulated ice and gravel pads
what management strategy allows cold air to circulate beneath structures
elevate buildings and pipelines on piles
what management strategy allows oil and gas to be accessed several km from the drilling site, and why is this good
drilling laterally - less construction sites are needed
what management strategy means that fewer exploration wells are needed
more powerful computers detect oil and gas remotely
what management strategy is used on the Trans-Alaska pipeline
refrigerated supports
why are the management strategies also pragmatic
melting permafrost causes widespread damage to buildings and roads
