The tundra biome represents the coldest of all the Earth’s major ecosystems, primarily defined by its perpetually low temperatures and treeless landscape. This unique environment circles the globe in the high northern latitudes, but also appears in isolated pockets on mountain ranges at any latitude. This geographically widespread biome spans multiple continents and political boundaries, supporting a mosaic of cold-adapted life.
Defining the Tundra Biome: Climate, Landscape, and Permafrost
The physical characteristics of the tundra are shaped by extremely low temperatures and a remarkably short growing season that lasts only about 50 to 60 days of the year. Mean winter temperatures often drop well below freezing, and even in summer, the average temperature rarely exceeds 12°C. Despite the presence of bogs and standing water in summer, the biome is considered a cold desert, receiving a very low annual precipitation of just 150 to 250 millimeters, including melted snow.
The defining feature of the tundra landscape is the presence of permafrost, which is ground that remains frozen for at least two consecutive years. This layer of permanently frozen soil can extend hundreds of meters deep in places like Siberia, acting as a barrier to deep root development. During the brief summer months, only the top layer, known as the active layer, thaws to a shallow depth of a few centimeters.
The inability of water to drain through the permafrost causes the landscape to become saturated and boggy during the summer thaw. This combination of a shallow, saturated active layer and high winds prevents large trees from growing. The constant freeze-thaw cycle also creates distinctive patterned ground, such as stone polygons, which shapes the surface of this biome.
The Major Nations of the Arctic Tundra
The most extensive and widely recognized form of this biome is the Arctic Tundra, which is defined by its high latitude, covering approximately 10% of the Earth’s surface. This vast, continuous belt of treeless land stretches across the Northern Hemisphere, situated north of the boreal forest, or taiga.
The nation containing the largest share of Arctic Tundra is the Russian Federation, where it covers significant portions of Siberia and its northern coast, including the Taymyr Peninsula. Russia’s immense size means it holds the most substantial and continuous stretch of this biome. Canada is the second-largest holder of Arctic Tundra, with the biome dominating its northern territories, including Nunavut, the Northwest Territories, and Yukon.
The United States also possesses a large segment of the Arctic Tundra, primarily in the state of Alaska. Further east, the Danish Realm includes Greenland, where the ice-free coastal areas support extensive tundra. The Scandinavian countries also host parts of the biome, with Norway, Sweden, and Finland containing Arctic Tundra in their northernmost regions.
Alpine Tundra and Southern Hemisphere Locations
While the Arctic Tundra is defined by latitude, the Alpine Tundra is determined by altitude, occurring on high-mountain summits and slopes above the natural tree line globally. This type shares many characteristics with its Arctic counterpart, including treelessness, strong winds, and a short growing season. However, Alpine Tundra generally lacks permafrost and often receives more precipitation.
Alpine Tundra exists in numerous countries worldwide, forming isolated pockets on major mountain chains. Examples include the high elevations of the Andes Mountains in South America, the Himalayas in Asia, and the Rocky Mountains in North America. Countries like Peru, Nepal, Switzerland, and the United States all contain patches of this high-altitude biome.
A third, much less extensive type is the Antarctic Tundra, which is found on the Antarctic Peninsula and several sub-Antarctic islands, such as South Georgia and the Kerguelen Islands. These small, isolated landmasses support minimal plant life, mainly mosses and lichens, due to the extremely cold and dry conditions of the region. This southern distribution is restricted because the Antarctic continent itself is largely covered by permanent ice sheets.
Life Strategies in the Tundra Environment
Life forms in the tundra exhibit specialized adaptations to cope with the extreme cold, high winds, and permanently frozen subsoil. Plants, which are mostly perennials, utilize a low-lying, cushion-like growth habit to stay out of the wind and benefit from the slightly warmer layer of air near the ground surface. Their shallow root systems are an accommodation to the permafrost, which limits the depth of soil available for anchorage and nutrient uptake.
Many tundra plants possess small leaves or hairy coatings to help retain moisture and warmth, while dark-colored flowers enable them to absorb solar radiation more efficiently. The short growing season means plants must complete their life cycle rapidly. They often reproduce asexually or rely on long life cycles to store energy between reproductive events.
Animals in the tundra similarly display adaptations focused on thermal regulation and energy conservation. Many mammals have a compact body shape with short limbs, ears, and tails to minimize surface area exposed to the cold, thereby reducing heat loss. Thick layers of fat, such as blubber, or dense, specialized fur and feathers provide insulation against the frigid temperatures. Behavioral strategies include seasonal migration, undertaken by animals like caribou, and hibernation, used by creatures such as the Arctic ground squirrel to survive the long, dark winter.