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Far north in the land of northern lights and the midnight sun, soils form that are partially frozen year round. These soils are also found on mountaintops. Most of these soils have permafrost, which is soil that is frozen year round. At the surface, freezing and thawing creates very special landforms and patterns in these soils. They are not used for agricultural productivity, but they help form a special habitat for lots of different types of wildlife. These soils are unique, and important, as they store a lot of carbon in the soil.
This lesson is appropriate for grades 4+.
1) What does the word Tundra mean?
Tundra means barren or treeless land.
Tundra comes from the Finnish word tunturia. Although usually thought of as treeless, some low-growing trees (e.g. birch or willow) do grow in tundra soils. These ‘trees’ are often only tens of centimeters tall.
2) Tundra soils occur in what type of environments?
Tundra soils form in cold environments.
Tundra soils form in cold environments with short growing seasons and harsh winters. These soils may be at high elevation (mountains) or high latitude (arctic or Antarctic).
3) Often tundra soils have permafrost, which is what?
As the name indicates, these soils are permanently frozen.
Permafrost is a condition where the mean annual temperature of the soil in below 0oC and the surface is not insulated. It may be dry permafrost (without ice) or wet permafrost (with ice). Even though the soil is permanently frozen, the surface layer or active zone thaws during the summer (often less than a meter deep) to allow plant growth.
Glossary of terms:
In current glossary:
Other glossary words:
Gelisol- a classification of soil that contain permafrost, a layer of soil near the surface that is frozen year-round.
Ice lens- a lens or pocket of ice in soil where water has frozen.
Patterned ground-a characteristic of tundra soils where the water repeatedly fills cracks and freezes resulting in a shaped or polygon pattern.
Pingo-a raised mound of soil that has been pushed upward as an underground pond of water freezes.
Activities or information:
1) Oil Pipeline in the Tundra
Building a pipeline across permafrost in Alaska (grades K-8) Contains information on the types of permafrost along the trans-Alaskan pipeline and the design solution for pipeline construction on these soils.
Permafrost and Frozen Soils - National Snow and Ice Center (grades 5-8) Discusses characteristics of permafrost and effects of climate change and global warming on permafrost degradation.
All About Frozen Ground - National Snow and Ice Center (grades 5-8) Contains information and educational activities on permafrost (be sure to check the links in the left-hand column including classroom activities).
3) Activity for the classroom
Alaksa's Cold Desert - Bureau of Land Management (grades K-8) Contains hands-on activities that show a) the effect of temperature on decay and b) the effect of freezing on expansion of wet soil.
Tundra Biomes - Blue Planet Biomes (grades 5-8) This site talks about the arctic tundra being the world’s youngest biome and discusses the interactions among soils, plants, and weather.
Different Types of Tundra - UC Berkeley (grades 5-8) This site compares and contrasts arctic and alpine tundra.
Arctic Biomes- The Wild Classroom (grades 5-8) This site briefly discusses the climate, flora, and fauna of the tundra, and briefly give background on global warming versus carbon sequestered in permafrost soils.
1) Why might an Alaskan home owner build her house above the soil?
An air space under the house will circulate cold air to stabilize the foundation and help reduce the melting of permafrost.
2) What is a Gelisol?
These are soils that contain a permafrost layer.
3) Does the surface of permafrost soils ever melt?
Yes, it melts during the brief summer when plants actively growth in the soil.
4) What causes patterned ground to form in tundra soils?
Water repeatedly flows into cracks and freezes. Year after year this pushes soil away and up from the cracks forming polygons.
5) Is the tundra landscape always flat?
Most arctic tundra soils are flat to rolling but alpine tundra can be on gentle to moderate slopes.
6) Why are there so many mosquitoes associated with arctic soils?
During the summer months when the surface soils melt, the ground is soggy and becomes a perfect breeding place for mosquitoes to reproduce.
7) On the arctic tundra landscape, one can occasionally find low lying hills in the middle of a flat area. What are these called and how do they form?
These are pingos that form when an underground pond of water freezes, expands, and pushes the soil upward.