The tundra, derived from the Finnish word “tunturi” meaning treeless plain, represents one of Earth’s most extreme biomes. It is characterized by frost-molded landscapes, very low temperatures, and short growing seasons. Despite these challenging conditions, the tundra supports a diversity of life that has uniquely adapted to this environment.
Understanding the Tundra Environment
The tundra biome is defined by several environmental factors that make it a challenging habitat. A prominent feature is permafrost, a layer of permanently frozen subsoil that can extend hundreds of meters deep. This frozen ground prevents deep root systems and drainage, often leading to waterlogged conditions during the brief summer thaw.
Temperatures in the Arctic tundra average around -34°C (-30°F) in winter, while summer temperatures typically range from 3-12°C (37-54°F). Precipitation is low, comparable to some deserts, with annual totals often between 150 to 250 millimeters (6 to 10 inches), including melted snow. Strong winds further contribute to the harshness of the environment.
The growing season is short, lasting only 50 to 60 days in the Arctic tundra. This period of warmer temperatures allows the top layer of soil, known as the active layer, to thaw, creating bogs and ponds. Tundra regions are found globally as Arctic tundra encircling the North Pole and Alpine tundra located at high altitudes on mountains worldwide.
Plant Life’s Ingenious Survival
The vegetation is dominated by low-growing forms such as lichens, mosses, grasses, sedges, and dwarf shrubs like dwarf willow and arctic poppy. These plants adopt a low-lying growth habit, often forming “cushions” that protect them from strong winds and help them retain warmth close to the ground.
Shallow root systems are necessary because permafrost restricts root penetration to the active layer of soil that thaws in summer. Despite the cold, these plants are capable of photosynthesis at low light intensities and temperatures. The short growing season necessitates rapid reproduction, with many tundra plants utilizing budding and division rather than sexual reproduction to complete their life cycles swiftly.
Reindeer moss, a type of lichen, serves as a food source for herbivores. Cotton grass, a sedge, is common in boggy areas created by the summer thaw. These plant communities are specialized to thrive in a biome where trees cannot grow due to the frigid temperatures and short summers.
Mammals Adapted to Extreme Cold
Reindeer, also known as caribou, undertake extensive migrations to find food, though some herds remain year-round. Their thick fur provides insulation, trapping a layer of air close to their bodies to minimize heat loss.
The arctic fox changes its fur color seasonally, from brown in summer to white in winter, providing camouflage against the snowy backdrop. They have short ears and snouts, which reduce surface area exposed to the cold, and a bushy tail for warmth. Polar bears, found in coastal Arctic tundra, rely on a thick layer of blubber and dense fur for insulation, and they are adept hunters of seals.
Musk oxen possess a two-layered coat, including a dense undercoat called qiviut, which is warmer than wool and helps them endure frigid temperatures. Smaller mammals such as lemmings and arctic hares reside in the tundra. Arctic hares have large, well-furred feet for navigating snow, while lemmings burrow under the snow to create insulated tunnels.
Diverse Avian and Insect Inhabitants
Many bird species are migratory, using the tundra as a breeding ground during the summer. The snowy owl is well-camouflaged in its white plumage and preys on small mammals like lemmings. Ptarmigans, a type of grouse, change their plumage seasonally for camouflage, similar to the arctic fox. Arctic terns undertake one of the longest migrations of any bird, traveling from the Arctic to the Antarctic and back, utilizing the tundra’s abundant summer food resources for breeding.
Insects are abundant during the short warm season. Mosquitoes and black flies emerge in large numbers, particularly around the numerous bogs and ponds. Arctic bumblebees are present, and their ability to shiver allows them to generate heat, enabling flight in cooler temperatures than many other insects. These insects complete their life cycles rapidly, taking advantage of the window of warmer temperatures and continuous daylight. Some aquatic life, such as arctic char, can be found in tundra lakes and rivers, adapted to the cold freshwater conditions.