Tundra Biome Learning Path

Definition and biome characteristics

In physical geography, a tundra is a biome where tree growth is hindered by frigid temperatures and short growing seasons. Tundra vegetation is typically made up of dwarf shrubs, sedges, grasses, mosses, and lichens, with scattered trees possible in some regions. The boundary between tundra and forest is called the tree line (timberline). Tundra soils are often rich in nutrients such as nitrogen and phosphorus, and when permafrost is present they can store large amounts of biomass and decomposed organic matter, including carbon and methane, effectively acting as a carbon sink. Tundra occurs in three main regions: Arctic, Alpine, and Antarctic. Arctic tundra lies in the far Northern Hemisphere north of the taiga belt and is commonly defined by areas with permanently frozen subsoil (permafrost). It has long, very cold winters and short, cool summers that thaw only the top layer of soil, leaving the ground soggy and supporting marshes, lakes, bogs, and streams. Antarctic tundra occurs on Antarctica and nearby islands where conditions are too cold and dry for most vegetation; plant life is concentrated in exposed rocky and soil areas, dominated largely by lichens, mosses, liverworts, algae, and a couple of flowering plants on parts of the Antarctic Peninsula. Alpine tundra occurs at high elevations worldwide where cold climate and soils prevent trees; it is generally better drained than Arctic tundra and transitions downslope to subalpine forests, with stunted forest forms in the forest–tundra ecotone (krummholz).

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Tree growth limits and growing season

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