The Arctic Tundra Flashcards
General Info
8 million km2 across Canada, Alaska and Siberia
9 months of the year is below 0 degrees c
Temp goes below -40oC for a few weeks in winter when sun doesn’t come above the horizon
Little plants, low biodiversity
Water cycle in the tundra (7)
Low annual precip - 50 - 350mm, mostly snow
Little moisture in atmosphere = low temp
Limited transpiration - little vegetation and short growing season
Low rates of evap - suns energy goes towards melting the ice and snow, and is frozen most of year
Permafrost acts as a barrier to percolation, throughflow, infiltration, recharge etc. = little groundwater storage
Melting of the uppermost active layer in spring and summer - sharp increase in river flow
Lots of wetlands and ponds in summer, due to saturated floors
Carbon cycle in tundra
permafrost is a vast carbon sink, containing 1600GT of carbon
The accumulation of carbon is due to low temperatures, slowing decomp of dead plants
amount of carbon in tundra soils is 5x that of above ground biomass.
In the past, the tundra was a carbon sink but is concerns is now turning into a carbon source. - whilst permafrost is melting, increased temp means more plant growth and uptake of CO2 , so could remain in balance.
1/75th NPP Tropical rainforest
Growing season in tundra (CC)
in and outflows of carbon is most in summer when plants grow in short summer - long daylight hours allows them to flower in few weeks
However, NPP is less than 200g/m2/year
During growing season, tundra plants input rich litter into soil
Activity of micro organisms increases releasing CO2 through respiration.
However, CO2 and CH4 is also released in winter, when pockets of unfrozen soil and water release Carbon
Snow cover can insulate micro organisms and allow some decomp
High winds = most plants under 15cm
Physical factors and seasonal changes to WC
temp below freezing most of year so water is stored as ground ice in the permafrost layer.
During short summer, the active layer thaws and water flows on surface, forming millions of pools and shallow lakes.
Poor drainage. No Evap trans in winter, some from the pools in summer.
Low humidity all year
Low permeability due to permafrost and crystalline rocks
The underlying rock surface is flat due to millions of years of erosion and weathering.
Minimal relief contributes to waterlogging
Physical factors and seasonal changes to WC
Most of the carbon formed from decomposed plant remains has been locked away for 500k years
low temps, little available water and little nutrients in rocks = little carbon in biomass
Due to the little permeability of the permafrost, rock permeability, porosity and minerals give little impact on the cycles
How does Oil and Gas production impact melt the ice
Permafrost is highly sensitive to changes in temp, melting of it has been caused by:
Construction of oil and gas installations, settlements and infrastructure, diffusing heat to the environment
Dust deposited on road sides is dark, absorbing more sunlight
Removal of vegetation, insulating permafrost.
Impact of OIL and Gas on the WC and CC
melting releases CO2 and methane causing CO2 losses of 7-40m/tonnes/year and CH4 losses of 24,000-115,000 losses per year.
Gas flaring and oil spillages also release CO2
Loss of vegetation melts ice and decrease photosy..
due to the temp, regen of this takes decades.
Melting also causes runoff and river discharge
More pools and hence evap
strip mining causes artificial lakes leading to disrupted drainage
drainage also disrupted by roads
Arctic amplification and neg feed back loop
Increase in temp - perma melts - increase co2 and methane - increase temp.
Increase temp, more plant growth, more co2 removed from cycle, fall in temp
