2b. Its is possible to identify the physical and human factors that affect the water and carbon cycles in the arctic tundra Flashcards
How many km of land does the tundra occupy?
Some 8 million km2 in Northern Canada , Alaska and Siberia.
describe the climatic condition of the tundra
severe and become more extreme with latitude
What happens for 8 or 9 months of the year in the tundra?
It has a negative heat balance, average monthly temperatures are below freezing.
Describe precipitation in the tundra
mean annual precipitation is low.
What feature of the arctic tundra provides some brevity for the growing season?
Long daylight hours
How much precipitation falls annually in the tundra and what does most of it fall as?
50-350mm
Snow
Why is there limited transpiration in the tundra?
The spareness of vegetation and short goring season.
Why are rates of evaporation low in the tundra?
Much of the suns energy in summer is expended melting snow so that ground temperatures remain low to inhibit convection. Surface soil is also frozen for most of the year.
Why does the tundra have limited groundwater and soil moisture stores?
Permafrost acts as a barrier to infiltration. percolation, recharge and ground water flow
What sparks the sharp increase in river flow in the summer?
Melting of snow, river and lake ice and the uppermost accumulated in winter months active layer
Why are there extensive wetlands in the tundra?
Permafrost impedes drainage, creating a temporary water store.
Describe the tundra ecosystem
Treeless, very few species can survive low biodiversity, vegetation provides discontinuous ground cover in the southern areas.
How much carbon is the tundra permafrost estimated to contain?
1600 GT
Why does the tundra act as such an affective carbon sink
The low temperatures mean low rates of decomposition of dead animal and plants material.
How many times greater is the below ground carbon storage in the tundra than the above ground biomass?
5
When is the flux of carbon concentrated?
in the summer months when the active layer thaws.
Why do plants grow rapidly in the short summer in the tundra?
Long hours of daylight allow for a short but intensive growing season.
What is the NPP in the tundra?.
less than 200g/m2/year
What is the biomass in the tundra
Relatively small, ranging between 4 and 29 tonnes/ha depending on vegetation cover.
Describe the flux of carbon to the atmosphere in summer/growing season
During the growing season plants input carbon rich litter into the soil. the activity of micro organisms also increases , releasing co2 into the atmosphere through respiration.
Why are Co2 and methane emissions from the tundra not confined to the summer?
pockets of unfrozen soil act as sources of ch4 and co2
Snow cover can also insulate microbial organisms to aid decomposition.
Why is the tundra becoming a carbon source rather than sink?
Global warming.
why is the evidence for the tundra as a source of co2 unclear?
While levels of CO2 emission have increased, the warmer temperatures have also increased vegetation cover, increased the intake of co2 by photosynthesis. This has intern increased leaf litter entering soil. Therefore it is possible that the balance can be maintained.
How does temperature affect Drainage in the tundra?
Average temperatures are very low so most water stays frozen in the permafrost. During the short summer the active layer thaws and liquid water flows on the surface. Meltwater forms thousands of small pools and shallow lakes. drainage is poor because water cannot infiltrate the soil due to permafrost.
