Tundra
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What is a tundra ecosystem?
A tundra is a treeless biome in cold regions, typically north of the Arctic Circle (Arctic tundra) or above the timberline of high mountains (alpine tundra). It features large expanses of bare ground and low vegetation like mosses, lichens, herbs, and small shrubs, supporting unique animal life.
Tundra ecosystems have simple food chains that are vulnerable if a species declines. Though they have fewer species overall, many are unique to these areas, making tundra important for global biodiversity. Bacteria and fungi are also plentiful, playing a vital role in the ecosystem through nutrient regeneration and the carbon cycle.
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Where are tundra ecosystems found in the world?
Tundra ecosystems are located in the northern hemisphere between 60° and 75° latitude, mainly along the Arctic coast of North America and Eurasia, and on the coastal margins of Greenland. The southern limit of Arctic tundra is along the northern edge of the coniferous forest belt, above latitude 60° N in North America and mostly north of 70° N in Eurasia.
Alpine tundra, covering about 3% of Earth’s land, exists in mountainous regions globally at high elevations where trees cannot grow due to low temperatures and strong winds. Because nearly all of Antarctica is covered with ice, it lacks a well-developed tundra, though lichens, mosses, and a few flowering plants can be found in favorable habitats there.
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What is the climate like in the tundra?
The tundra climate is characterized by sub-freezing mean annual temperatures and moderately low precipitation. It is located between 60° and 75° latitude, mainly along the Arctic coast of North America and Eurasia, and on Greenland's coastal margins.
Winters are long and cold, with temperatures potentially below 0 °C (32 °F) for 6–10 months. Winter precipitation is mainly dry snow. Summers are generally mild, with daily maximum temperatures from 15 to 18 °C (59 to 64 °F). Annual precipitation typically totals less than 35 cm (about 14 inches), but can range from 25 to 100 cm (10 to 39 inches). Though snow cover melts in the warmer season, frost and snow are possible in any month.
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Which plants and animals live in the tundra ecosystem?
The tundra is home to a limited number of plant and animal species, but the number of individuals per species is often high. Many tundra species are unique to this biome, making it an important contributor to global biodiversity.
Typical animals of the Arctic tundra include the polar bear ( Ursus maritimus), Arctic fox (Alopex lagopus), Arctic wolf (Canis lupus), Arctic hare (Lepus arcticus), lemmings and ptarmigan (Lagopus). The characteristic large herbivores of the Arctic tundra are the reindeer (Rangifer tarandus) and the musk ox (Ovibos moschatus). Most tundra birds are migratory, but the ptarmigan is an exception.
Tundra vegetation includes lichens, mosses, sedges, cotton grass, low willows, grasses, and rushes.
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How do plants and animals survive in harsh tundra conditions?
In the harsh tundra, plants and animals have unique adaptations for survival. Plants stay low to the ground to avoid strong winds and conserve heat, and many are perennials, maximizing the short growing season. They flower quickly and some can even continue to develop seeds after freezing.
Animals like musk oxen have thick coats to retain heat, while others such as arctic hares and ptarmigans, change color with the seasons for camouflage. Small mammals, such as lemmings, reproduce quickly, and some remain active under the snow during winter. Migratory birds and mammals leave during the winter, while those that stay have developed strategies to conserve energy and find food in the challenging environment.
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How are human activities and climate change affecting tundra ecosystems?
Human activities and climate change significantly impact tundra ecosystems. Construction, mining, and resource extraction disrupt landscapes and pollute the environment, threatening wildlife habitats. Climate change, amplified in the Arctic, causes earlier spring thaws and later autumn freezes, diminishing habitats for native animals.
The melting of permafrost, containing vast amounts of organic matter, leads to the release of greenhouse gases like CO2 and methane, further exacerbating global warming. These changes affect the integrity and sustainability of tundra ecosystems, demanding urgent attention from scientists and policymakers.
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Tundra, a major zone of treeless level or rolling ground found in cold regions, mostly north of the Arctic Circle (Arctic tundra) or above the timberline on high mountains (alpine tundra). Tundra is known for large stretches of bare ground and rock and for patchy mantles of low vegetation such as mosses, lichens, herbs, and small shrubs. This surface supports a meagre but unique variety of animals. The Finns called their treeless northern reaches the tunturi, but the concept of a vast frozen plain as a special ecological realm called tundra was developed by the Russians.
One constant factor shaping the tundra is alternate freezing and thawing of the ground. Along with the factors mentioned above, this freeze-thaw cycle sets the tundra apart from two ecosystems frequently found adjacent to it—the icy polar barrens on the one hand and the evergreen taiga on the other. Permafrost—perennially frozen ground—is a significant feature of the Arctic tundra; however, it does not typically occur in alpine regions.
Distribution
The global extent of the tundra biome is considerable, accounting for roughly 10 percent of Earth’s surface. The southern limit of Arctic tundra follows the northern edge of the coniferous forest belt. In North America this line lies above latitude 60° N, while in Eurasia most of it occurs north of 70° N—except in eastern Siberia, where it extends southward to 60° N in Kamchatka. The northward bulge of forest in Eurasia is a result of the warmer summers that occur over that large contiguous landmass.
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Alpine tundra covers approximately 3 percent of Earth’s land surface, and it is mostly found in the Northern Hemisphere. This habitat can be found in mountainous areas worldwide, occurring at high elevations where temperatures are too low and winds are too strong for the growth of trees. The average elevation where alpine tundra occurs is generally higher near the Equator than at the poles.
Because nearly all of Antarctica is covered with ice, it lacks a well-developed tundra, though lichens, mosses, and at least three species of flowering plants occur in more favourable habitats there.
