2.b. ARTIC TUNDRA CASE STUDY Flashcards
(19 cards)
Ao1 how big is artic tundra where is it?
8 million km2 in northern canada, alaska, siberia –> extends from the northern limit of the boreal forest to the artic ocean.
southern limit = approx the 10*C july isotherm..tree line
what is the precipitation in the artic? W CYCLE
low annual precipitation (50-35mm). most falls as snow –> small store of moisture in the atmosphere as low temp reduce ABSOLUTE HUMIDITY
what is transportation like in the artic? W CYCLE
limited transportation as sparse vegetation and short growing season.
what is evaporation like in the artic? W CYCLE
low evaporation as much of sun’s energy in summer is used melting snow..so grow temps remain low.. therefore little CONVECTION
what is the groundwater and soil moisture stores like in the artic? W CYCLE
surface + soil water is frozen. limited groundwater and soil moisture stores. permafrost is barrier to infiltration, percolation, recharge and groundwater flow.
what are the seasonal changes in the artic? W CYCLE
accumulation of snow and river/lake ice in winter. melting snow and ice and top 1m of permafrost in spring/summer = big increase in river flow creating extensive wetlands, ponds, lakes. storage on the surface in the summer = a temporary store.
what does permafrost prevent in the artic? W CYCLE
permafrost prevents water infiltrating. minimal relief impedes drainage and leads to water logging.
how is carbon stored in tundra soils? C CYCLE
permafrost is a vast carbon sink. the accumulation and slow decomposition of dead plant matter (due to frozen temps) means overall, carbon stored in the tundra soils is 5x greater than that in the above ground biomass (vegetation)
what are the seasonal changes in the artic? C CYCLE
the flux of carbon is concentrated in the summer when active top layer of permafrost melts and plants grow rapdily in the long hours of daylight - these plants then input carbon rich litter to the soil. decomposition via microbial activity increases and releases carbon dioxide through respiration.
what are the seasonal changes in the winter in the artic C CYCLE?
in the winter, pockets of unfrozen water and soil act as carbon sources. in places the snow insulates microbial organisms and allows some slow decomposition.
what is happening to the permafrost as a carbon sink/source? in the artic C CYCLE
in past permafrost acted as carbon sink - today concered it has become a carbon source. outputs of carbon from thawing permafrost have increased in recent decades - but there has also been increase in plant growth, taking in increased co2 and increasing amount of litter entering the store - it is therefore possible that carbon budget could once again reach and equilibrium.
how does temperature affect flows and stores in water cycle?
temperature: 8/9 months of the yr there is negative heat balance. avg. monthly temps are below freezing so ground is permanently frozen. only top metre thaws in the short summer –> this makes ground impermeable for most of the year
- in summer when top layer thaws, water sits on surface as it can’t infiltrate due to impermeable ground
how does relief affect flows and stores in water cycle?
minimal relief due to years of erosion + weathering means water does not flow downhill but sits on surface –> leading to waterlogging
how does temperature affect flows and stores in carbon cycle?
temperature: little vegetation grows therefore little carbon stored in biomass and slow decomposition. frozen permafrost is a store of carbon - when it thaws carbon is released
how does organic matter in soil affect flows and stores in carbon cycle?
organic matter in soil: largest proportion of organic matter found in soil in the world. slow decomposition so the soil stores 5x more vegetation.
- snow insulates the microbes so there is small amount of decomposition taking place in the winter - living things remain trapped in the soil
how does mineral composition of rocks affect flows and stores in carbon cycle?
mineral composition of rocks: soils are generally frozen. lots of freeze thaw occurs leading to cryoturbation (mixing) - so mixed rock fragments and sediment left behind by glaciers forms the soil.
where was oil and gas discovered?
north slope of alaska vast wilderness of tundra = great ecological value. oil and gas discovered at Prudhoe Bay in 1968.
- extracting this is challenge due to remote + harsh location
what is the impact of developing oil and gas industry on the carbon cycle?
significant impact on permafrost - changes the thermal balance and it melts
- installing operations, settlements, infrastructure diffuses heat
- dust is created on the roads which makes the snow dark - so it absorbs rather than reflects the sun ray’s = no albedo affect
- vegetation is removed –> which would have insulated the permafrost
- melting permafrost releases co2 and ch4
- gas flaring and oil spills also input co2 into the atmosphere
- thawing soil increases microbial activity, decomposition increases and as a result co2 emissions increase
- vegetation grows really slowly.. so slow recovery from any damage caused
what is the impact of developing oil and gas industry on the water cycle?
- melting permafrost + snow increases runoff and river discharge = therefore increases flood risk
- in summer ponds/lakes form due to melting..increasing evaporation
- mining for gravel + sand creates artificial lakes which disrupt drainage and exposes the permafrost = leads to further melting
- drainage networks disrupted by road contrusction and explosions used to prospect for oil / gas
- water is extracted from creeks and rivers for industrial use and for building the ice roads needed for transportation - leading to a decrease in localised water storage.
