arctic tundra carbon and water cycles Flashcards
what is meant by the term tundra
an ecosystem/ biome found at the north and south poles or at the top of a mountain
where is the arctic circle
66 degrees north of the equator
how much land does the arctic tundra occupy and in what regions
8 million km2 in northern canada, alaska and siberia
what is a negative heat balance
more outputs of heat than inputs. inputs are from solar radiation, outputs are from the release of gas and land
for how many months of the year does the arctic tundra have a negative heat balance and how will temperatures be during this time.
8-9 months. average monthly temperatures will be below freezing
what impact does the negative heat balance have on the ground
the ground is permanently frozen, only the top metre or so thaws during the arctic summer.
what underlies much of the tundra
permafrost, which is an important feature of the regions water cycle.
how low can temperatures drop during the winter
in winter for several weeks the sun remains below the horizon, temperatures can plunge below -40 degrees.
what feature of the summer months assists plants growing
long hours of daylight in the summer provide some compensation for the brevity of the growing season
what is precipitation like
mean annual precipitation is low (50-350mm)
what is biodiversity like
few plants and animals have adapted to this extreme environment, biodiversity is low and apart from a few dwarf species, the landscape is treeless.
how does variation vary based on latitude
conditions get harsher with latitude, in southern areas (the low arctic) conditions are less severe and vegetation provides a continuous ground cover. Further north in the high arctic, plant cover is discontinuous and there are extensive areas of bare ground.
what are stores of moisture in the atmosphere like at he tundra
small stores of moisture in the atmosphere owing to low temperatures
how does small amounts of vegetation impact the water cycle
limited transpiration because of sparseness of vegetation cover and the short growing season
what is evaporation like
low rates of evaporation. much of the suns energy is expended melting snow and ice so ground temperatures remain low and inhibit convection.
how does permafrost impact groundwater and soil water
limited groundwater and soil water because permafrost acts as a barrier to infiltration, percolation, recharge and groundwater flow
how is riverflow impacted during the summer months
melting snow, river and lake ice, and the uppermost active layer of the permafrost in spring and early summer results in a sharp increase in river flow
what occurs as a result of permafrost impeding drainage
extensive wetlands, ponds and lakes in the summer months. this temporary store of liquid is as a result of permafrost which impedes drainage.
why is permafrost significant to the carbon cycle
it has been a vast carbon sink, but now with climate change there are concerns of it becoming a carbon source
how much carbon is permafrost estimated to store globally
1600GT
why is there such an accumulation of carbon in tundra soils
accumulation of carbon is due to low temperatures which slow decomposition of dead plant material
what is the NPP is the arctic tundra
less than 200 grams/m2/year
describe the tundra biomass using figures
the tundra biomass is small- between 4-29 tonnes/ha depending on the density of the vegetation cover
how is the growing season in the tundra significant to its carbon cycle
during the growing season plants input carbon-rich litter to the soil and the activity of micro-organisms increases, releasing CO2 into the atmosphere by respiration
describe the tundra’s carbon cycle in winter
pockets of unfrozen soil and water act as sources of C02, meanwhile snow cover may insulate microbial organisms allowing some decomposition despite the low temperatures
how do increasing temperatures allow a decrease in the release of C02 into the atmosphere as well as an increase
melting permafrost results in greater amounts of carbon being released, however higher temperatures have stimulated plant growth and a greater uptake of C02 for photosynthesis, but also increasing the amount of plant litter entering the store
what are the the three main factors that influence flows and stores of water in the tundra
temperature, relief and rock permiability
what is the dominant rock type in the tundra and how does this influence permeability
crystalline rocks dominate the geology of the tundra in arctic and sub-arctic Canada, meaning adding to the lack of permeability as a result of permafrost
describe relief in the tundra
the ancient rock surface which underlies the tundra has been reduced to a gently undulating plain by hundreds of millions of years of erosion and weathering.
how does relief affect the water cycle in the tundra
minimal relief and chaotic glacial deposits impede drainage and contribute to waterlogging during the summer months
what is the main way that carbon is stored in the tundra
carbon is mainly stored as partly decomposed plant material frozen in the permafrost. most of the carbon has been locked away for at least the past 500,000 years.
