Tundra (0)

Tundra
Tundra is the world's youngest biome . It was formed 10 000 years ago. Located at latitudes 55° to 70° North . Almost all tundras are located in the Northern Hemisphere, encircling arctic desert and extending south to the coniferous forests of the taiga . The ecotone (ecological boundary region) between the tundra and the forest is known as the tree line or timberline. Tundra comes from the Finnish word tunturi, meaning treeless plain . It is noted for its frost -moulded landscapes , extremely low temperatures , little precipitation, poor nutrients, and short growing seasons. Dead organic material functions as a nutrient pool. The two major nutrients are nitrogen and phosphorus . Nitrogen is created by biological fixation, and phosphorus is created by precipitation.
The most distinctive characteristic of tundra soil is its permafrost, a permanently frozen layer of ground . The average winter temperature is -28°C, but the average summer temperature is 3-16°C. During the brief summers, the top section of the soil may thaw out allowing plants and microorganisms to grow and reproduce. However, these plants and microorganisms become dormant during the cold winter months. Soil is formed slowly. The constant freezing and thawing in the tundra helps to break the rocks into smaller pieces. Permafrost consists mostly of gravel and finer material. The arctic tundra is also a windy place and winds can blow between 48 to 97 kilometres. The tundra is basically like a desert when it comes to precipitation. Only about 150-250 millimetres of precipitation (mostly snow ) fall each year . When water saturates the upper surface, bogs and ponds may form, providing moisture for plants, and breeding thousands of insects that attract many migrating birds .
Animals are adapted to handle cold winters and to breed and raise young quickly in the very short and cool summers. Some animals have grown thick fur that turns white in the winter. Others find a place to hibernate during the winter months. Many plants have dark red leaves that allow the plant to absorb more heat from the sun in the cold tundra climate. All of the plants are adapted to sweeping winds and disturbances of the soil. Many plants grow in a low, tight clump - this growth habit helps protect them from the cold and snow. They can carry out photosynthesis at low temperatures and low light intensities. The growing season is short and most plants reproduce by budding and division rather than sexually by flowering. There are no deep root systems in the vegetation of the tundra; however, there are a wide variety of plants that are able to resist the cold climate.
The fauna is also diverse . Animals such as mammals and birds also have additional insulation from fat. Many animals hibernate during the winter because food is not abundant. Another alternative is to migrate south in the winter, like birds do. Reptiles and amphibians are few or absent because of the extremely cold temperatures. Because of constant migration, the population continually oscillates.
Alpine tundra is located on mountains throughout the world at high altitude where trees cannot grow. The growing season is approximately 180 days . The nighttime temperature is usually below freezing. Unlike the arctic tundra, the soil in the alpine is well drained. The plants are very similar to those of the arctic ones. Animals living in the alpine tundra are also well adapted. There is barely any vegetation in the tundra, only about 1700 different species . These are mostly shrubs, sedges, mosses, lichens and grasses. There are about 400 varieties of flowers. The growing season in arctic tundra is only about 60 days long. While trees can't send their roots down, there are no trees, except for some birches in the lower latitudes. Willows do grow on some parts of the tundra but only as low carpets about 8 cm high. Most plants grow in a dense mat of roots that has developed over thousands of years. The soil is very low in nutrients and minerals, except where animal droppings fertilize the soil.
Although there isn't a lot of biodiversity, only 48 species of land mammals are found on the tundra, there are a lot of each species. These consist of slightly modified shrews, hares, rodents, wolves, foxes, bears and deer. There are huge herds of reindeer in North America that feed on lichens and plants. There are also smaller herds of musk oxen. Wolves, wolverines, arctic foxes, and polar bears are the predators of the tundra. Smaller mammals are snowshoe rabbits and lemmings. There aren 't many different species of insects in the tundra, but black flies, deer flies, mosquitoes and "no-see-ums" ( tiny biting midges) can make the tundra a miserable place to be in the summer. Mosquitoes can keep themselves from freezing by replacing the water in their bodies with a chemical called glycerol. It works like an antifreeze and allows them to survive under the snow during the winter. The marshy tundra is a great place for migratory birds like the harlequin duck, sandpipers and plovers.
The tundra is one of Earth's three major carbon dioxide sinks. A carbon dioxide sink is a biomass that takes in more carbon dioxide than it releases. Carbon dioxide is a greenhouse gas that contributes to global warming. During the short summer tundra's plants take in carbon dioxide, sunlight and water in the process of photosynthesis. Plants normally give off carbon dioxide after they die and decompose. But because of the short, cool summer and freezing winter temperatures, plants can't decompose. Remains of plants thousands of years old have been found in the tundra permafrost. In this way the tundra traps the carbon dioxide and removes it from the atmosphere. Today global warming is melting the permafrost of the tundra and every year several feet of tundra are lost . As the tundra melts, the plant mass decomposes and returns carbon dioxide to the atmosphere.
The tundra is a very fragile and difficult environment to survive in during the winter, and plants and animals have a hard time coping with any extra disturbances. The smallest stresses can bring about their destruction. More people moving to the tundra to work in the mines and oil rigs have created towns and more roads. These obstacles have disrupted some animal's movements to traditional feeding and denning grounds. When they try to pass through a town they are often scared away or shot. With their feeding patterns disrupted, many polar bears have starved. The Alaskan oil pipeline was built across a caribou migration route. In some places the pipeline has been raised above the ground so the caribou can pass under it. Pesticides have been used to control the hordes of insects. Thousands of migrating birds come to the tundra because of the abundant insects. Through the food chain the pesticides reach many of the animals that live on the tundra. Pollution from mining and drilling for oil has polluted the air, lakes and rivers . The land around some nickel mines in Russia has become so polluted that the plants in the surrounding area have died. Footprints and tire tracks can be visible for many years after they were made. When the sun hits the ruts it causes the permafrost to melt. This causes erosion and the ruts get bigger, and eventually the ruts turn into gullies. Tracks made during World War II have grown so large that some of them are now lakes.