The Tundra Biome
Introduction: It is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian origin meaning "uplands", "treeless mountain tracts." It has extremely inhospitable conditions considering the lowest temperatures out of all the five biomes, ranging from -34 to 12 degrees Celsius. It has short summers and poor quality soil nutrients.
Precipitation: This biome observes a total of 150 to 250mm a year, including the melted snow. This is even less than most of the deserts of the world. However, the tundra is known as wet place because the low temperatures cause evaporation of water to be quite slow and gradual. Below is a graph of a tundra in Canada with its monthly precipitation and temperatures:
Soil: The tundra biome is quite adulated for its unique landscape. During the summer, water can accumulate underground, freeze and drive the soil into a small hill called Pingo. Tundra soils are usually formed at high latitudes which are frigid. Therefore, the soils are generally frozen and are classified as Gelisols ( specific types of soils of very cold climates). But, how are these Gelisols formed? The permafrost ( a frozen layer under the soil surface), needs to be within 100 cm of the soil surface. Then, the process of cryoturbation occurs where the soil has alternate freezing-thawing. This is also a major reason why trees are planted in unusual angles and creating infrastructure is inconvenient.
A very fascinating fact happens to be that the largest portion of soil organic matter in the world is located in the tundra biome. Hence, it plays a crucial role in the carbon cycle. More the organic soil matter, more the carbon stored that also backbones the growth of trees. However, there seems to be another contradiction arising- if we learnt that the soil found is frozen and Gelisols, how can it store so much of organic matter? This leads to a very surreal yet unique feature of this biome. Since the regions are too cold for the decomposition of organic matter, all the living matter is trapped in the soil. The tundra soil is also rich in nitrogen and phosphorus.
Types: There are three types of the tundra biome- arctic tundra, alpine tundra and antarctic tundra.
i) Arctic Tundra- This tundra occurs in the far Northern Hemisphere. It is usually frozen for most of the year and the soil is frozen from 25 to 90cm down, making it difficult for flora to flourish. However, the rocky land scaffolds specific kinds of Arctic vegetation such as moss, heath ( crowberry and black berry) and lichen. Its fauna includes reindeer (caribou), musk ox, Arctic hare, Arctic fox, snowy owl, lemmings and even polar bears near the ocean. While there are a few species of fishes, many species of birds migrate there for the marshes. There are two main seasons: winter and summers. During the winters, the soil is frozen so vegetation is close to negligent whereas during the summer, the permafrost thaws and plants grow and reproduce. The arctic tundra is rich in natural resources such as petroleum, natural gas and uranium. This kind of tundra is found in Alaska and parts of Russia.
ii) Antarctic Tundra- This majorly occurs in Antarctica. It is frigid and too arid to support vegetation and most of the region is covered by ice fields. However, some of the parts of the continent such as the Antarctic Peninsula have rocky soil that can support the flora and fauna. The flora consists of lichens, mosses, liverworts and some aquatic species. It even has two flowering types called the Antarctic Hair grass and Antarctic Pearlwort on the Antarctic Peninsula. The Antarctic Tundra is quite devoid of mammals. Sea mammals and sea birds include seals, penguins. Even polar bears are found near the seas.
iii) Alpine Tundra- This tundra occurs in mountains worldwide. It does not contain trees because the climate and soils at high altitudes block tree growth. The cold climate of the alpine tundra is by the mow temperatures, thereby having a polar climate. Its different from other types of tundra when spoken about its soil which doesn't particularly have permafrost. The flora is characterized by plants that grow close to the ground like perennial grasses, sedges, forbs, cushion plants, mosses and lichens. This is a special type of flora found as they are accustomed to the harsh living conditions where dryness and the ultraviolet radiation is common. The fauna includes marmot, ptarmigans, muskox, pikas, yellow-bellied marmot and collared lemmings.
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