THE TUNDRA ECOSYSTEM

1
THE TUNDRA ECOSYSTEM
The Finnish term for a cold treeless region.
2
Location
Mainly polewards of 60N.
Also found at high altitudes such as Rockies and
Himalayas.
Includes areas of Alaska, Canada, Greenland,
Scandinavia and Russia.
Only found on some islands on the edge of
Antarctica as there is very little land south of
60 except for the frozen continent.
Is found between the polar ice cap and coniferous
forest biome.
3
CLIMATE
Low annual precipitation which coincides with
peak temperatures convectional rain.
Short growing season. Only 5 months where
temperature is above freezing and only 3 months
where temperature is above 6C
Max. temperature is 15C but is rarely above 10C
Large temperature range of 64C
7 months where average temperature is below
freezing
Precipitation levels are comparable to deserts.
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Reasons for climate

• High pressure areas
• Global circulation patterns leave air sinking
  over the poles in the polar cell. This leads to
  high pressure and very little rain.
• Cold air temperatures can hold little moisture.

• Insolation
• Low levels of insolation.
• At least two months with now sunlight at all.
• Lands of the midnight sun

Albedo Snow surfaces have a high albedo (0.8) so
they reflect incoming solar energy.

• Latitude
• Sun at a low angle so rays hit obliquely and
  cover a larger area.
• More rays reflected, absorbed or scattered by
  dust and pollution in atmosphere

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A tundra biome has a NNP of 250g/m²/year. Why?
Poor drainage soils are waterlogged in summer
which means a lack of oxygen.
Very short growing season
Recycling of nutrients is slow plants lie
dormant, animals migrate or hibernate.
Very low temperatures
Why a low NPP?
Low rainfall
Low energy environment long periods of
continuous night.
Moisture held in snow and ice and not available
to plants.
Instability of soils by solifluction and heaving
disrupt plants.
Thin soils because of lack of weathering due to
permafrost
Low insolation reduces photosynthesis.
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Tundra soils Gley soil

• Gley waterlogged
• Soils waterlogged due to permafrost acting as an
  impermeable layer.
• Grey colour due to the reduction of ferric iron
  to ferrous iron.
• Organic matter is small and decomposes slowly so
  few nutrients.
• Very few bacteria can survive the conditions to
  decompose and mix the soil.
• Thin layer of acidic peat on the surface
• More favourable conditions lead to podsols.

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Land-based food web
Migratory birds in summer in feed on the large
number of insects. In Canada over 100 species of
bird including Arctic Tern.
Small number of species because the ecosystem is
so specialised.
Number of individuals is high.
Vegetation low lying due to strong winds and
abrasion by snow.
Due to low number of species the chain is very
vulnerable.
Vegetation has a high sugar content and so allow
animals to survive the winter.
Few species of bird remain all year only Rock
Ptarmigan and Snowy Owl.
Large mammals such as caribou and musk ox are
herbivores.
No tertiary consumers chain too limited for
omnivores.
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Plant and animal adaptations to the tundra biome
Sketch a typical plant and animal and use the
information sheet to annotate it with
adaptations.
9
Use the information sheet to add detail to these
threats. Then write up two case studies on human
impacts on the tundra biome from Siberia and
Alaska.
Government settlement policy
Ozone thinning
Wilderness tourism
Climate change
Threats to the tundra biome
Military installations
Pollution
Mineral and energy development