The Arctic and Alpine tundra biome Key Question

The Arctic and Alpine tundra biome

Key Question 1. 4 What are the characteristics of the arctic and alpine tundra environment that make it extreme? The climatic, biotic and soil characteristics of a tundra environment. The links between climate, biotic and soil characteristics. * * Key Question 1. 5 * How is human activity causing pressures on the alpine tundra environment? The threats that are posed by (i) mineral exploitation; (ii) airborne pollution; (iii) global warming; (iv) tourism. The positive and negative outcomes of human activity. * Key Question 1. 6 What are the strategies that can be used to manage human activity in alpine tundra environments? * Strategies that attempt to (i) conserve the tundra environment; (ii) alleviate the impacts of human activity; (iii) control the use of the tundra environment (iv) monitor the impacts of human activity. * The role of local, national and international groups in the management of the tundra environment.

Arctic tundra

Alpine tundra

Extent of periglacial environments today 14 -5 million km² of Arctic tundra are to be found in the far north of Eurasia and North America 9. 5 million km ² of Alpine tundra are to be found in the mountains of the Northern Hemisphere 1 million km ² of Alpine tundra are to be found in the Southern Hemisphere

Climate – Arctic tundra Climates are dominated by cold temperatures. Average temperatures in the warmest month are above 0°C but below 10°C. Temperatures remain above freezing for only 2 -6 months of the year. The snow covered surface raises the albedo (reflectivity) making it colder. Days are long in summer but north of the Arctic Circle no sun is to be seen in winter. Average precipitation is low, often 250 mm per annum or less, as the cold air can hold little moisture, making these areas cold deserts.

Polar high pressure Polar air masses – moving southwards from the Polar High Pressure area dominate weather patterns. Temperatures do show a maritime influence, reducing the range of temperature. Continental interiors exhibit some of the largest temperature ranges on Earth. Many locations show a summer maximum of precipitation. Up to 60% of precipitation falls as snow.

Climate - Alpine tundra Precipitation tends to increase with altitude. A higher % of precipitation falls as snow at high altitude. The mountains are above many clouds so the clear air means a high diurnal range of temperature. Most sites are much windier and therefore more exposed than lower altitudes.

Aspect North-facing slope (ubac in French – schattenseite in German) Exposure to wind aspect (the direction a slope faces) greatly affect temperature in Alpine valleys. South-facing slope (adret in French – sonnenseite in German)

Permafrost Much of the Northern Hemisphere is covered by permafrost, or permanently frozen ground. 7. 6 million km² of this cover is continuous, but further south as average annual temperatures approach 0°C cover is discontinuous. 14. 7 million km² is covered by discontinuous permafrost. Permafrost can be very deep, up to 700 m in Northern Canada and 1500 m in Siberia.

Permafrost Unfrozen ground is called talik. Transect through permafrost zone of Northern Canada The upper layer of ground is called the active layer, because it thaws in summer. Soils may be waterlogged, especially in depressions. Permafrost limits infiltration, so with snowmelt flooding is a severe problem. The refreezing of soil water is called cryoturbation or frost heave. This makes it difficult for soil horizons to form and causes damage to deep plant roots.

IPA Circumarctic Permafrost and Ground Ice Map The International Permafrost Association (IPA) undertook to compile and publish this circumpermafrost map, in response to a recognized need for a single, unified -arctic international map to depict the distribution and properties of permafrost in the Northern Hemisphere