Tundra ecosystem and global warming
The tundra ecosystem is characterized by its treeless landscapes found primarily in the Arctic and at high elevations on mountains, with harsh climatic conditions that include extremely cold winters and brief, cool summers. The Arctic tundra is defined by permafrost, a permanently frozen layer of ground that shapes its unique landscape and supports a limited variety of plant and animal species, such as hardy shrubs, grasses, and migratory birds. However, this delicate ecosystem is significantly affected by global warming, which leads to the thawing of permafrost and an advance of tree lines into tundra regions, reducing the overall tundra area and altering the habitat.
As temperatures rise, the thawing permafrost not only disrupts the landscape but also releases stored greenhouse gases, such as carbon dioxide, into the atmosphere, exacerbating climate change. This transition from tundra to boreal forest also increases the risk of wildfires, further contributing to greenhouse gas emissions. Additionally, the changing vegetation affects local fauna, with vulnerable Arctic species facing competition from species typically found in warmer climates. Overall, the tundra's sensitivity to climate changes highlights its critical role in the global ecosystem and the potential cascading effects of warming on biodiversity and climate regulation.
Tundra ecosystem and global warming
Definition
Tundraecosystems are treeless regions found in the Arctic and on mountaintops. The word “tundra” is derived from the Finnish word tunturi, which refers to treeless areas of hills and mountains. There are two types of tundra: those in the north, called Arctic tundra, and those in high mountains, called alpine tundra. Antarctica has some tundra as well. Tundra climate is very harsh, involving extremely cold and snowy winters and short, cool summers with very little precipitation. In the Arctic tundra, the average temperature is between -12° and -7° Celsius. Most Arctic tundra regions have permafrost, a layer of ground below the surface soil that remains permanently frozen. The tundra landscape is shaped by periodic freezing and thawing of soil, which forms cracks and alters drainage.
On the tundra, tree growth is hindered by low temperatures and short growing seasons. The boundary between tundra and forest is known as the tree line, or timberline. The plant species on the tundra are few, and most are low-growing. Tundra vegetation consists mainly of sedges, grasses, dwarf shrubs, wildflowers, mosses, and lichens. During summer months, scattered wildflowers, such as purple mountain saxifrage and Arctic poppies, are also present. The summer growing season is short, only fifty to sixty days, during which the Sun shines twenty-four hours a day. Hardy plants, such as cushion plants, survive by growing in rock depressions, where it is warmer and sheltered from the wind. Plant communities in the tundra have adapted to gusty winds and soil disturbances and are able to photosynthesize at low temperatures and with fluctuating light intensities.
Animal life on the tundra is somewhat limited by the challenging environment. Most Arctic wildlife consists of species that are the same or similar to those found worldwide. Tundra ecosystems also support a variety of animal species that do not live in other areas, such as the Arctic hare, musk oxen, lemming, Arctic ground squirrel, and a grouselike bird called a ptarmigan. Other animals, such as caribou and many species of bird, migrate annually to the Arctic. Arctic foxes, polar bears, some brown bears, gray wolves, and snow geese are also seen on the tundra. Large grazing animals such as caribou and reindeer feed on tundra vegetation. Mountain goats, big-horned sheep, rabbits, and birds inhabit alpine tundra. During summer months, many birds nest in shrubs on the tundra, migrating to warmer climates as winter approaches. Insects such as black flies, mosquitoes, butterflies, and grasshoppers are abundant. Tundra predators include the wolf, arctic fox, and snowy owl.
Significance for Climate Change
Although it remains one of the least exploited regions on Earth, the Arctic tundra is changing dramatically as a result of warmer temperatures. The tundra ecosystem is extremely sensitive to disturbance, and global warming is consequently likely to have some of its greatest effects in the tundra. Some major impacts associated with rising temperatures in the tundra are thawing of and advancing tree lines, both of which decrease tundra area and contribute further to global warming.
Permafrost is the foundation for most of the Arctic’s unique ecosystem. Thawing permafrost disrupts the tundra landscape by forming bogs and shallow lakes. Shrubs and spruce that previously were not able to grow in the tundra because of permafrost are able to thrive in thawed tundra soil. Permafrost is also believed to contain large amounts of carbon sequestered in frozen soil. As it thaws, greenhouse gases (GHGs), such as carbon dioxide (CO2), are released into the atmosphere.
As the Earth warms, tundra in northern Canada and Siberia is rapidly being replaced by northern, or boreal, forests. Over the last century, the tree line has advanced into the area, with trees currently living where no tree had previously grown during the last one thousand years. With continued warming, treelines may continue to advance, and tundra landscapes may be transformed into woodland areas. In addition to being a consequence of global warming, the encroaching tree line also contributes to global warming by absorbing larger amounts of sunlight.
Tundra, particularly when it is snow- or ice-covered, has a high albedo, or reflectivity, that helps maintain the region’s cooler temperatures by reflecting sunlight rather than absorbing it. Compared to tundra, trees have low reflectivity; consequently, more heat is retained in areas with greater tree growth. The shift in tundra vegetation from grasses to shrubs and trees also increases the risk of wildfire in the tundra by creating more available to burn. Fires in the tundra may potentially release more carbon into the atmosphere, adding to GHGs already contributing to global warming.
As the tundra shrinks, the few plant and animal species that thrive in the harsh environment will be affected. These species are highly vulnerable to environmental stresses such as reduced snow cover and warmer temperatures brought on by global warming. Animal species are affected by changes in the vegetation and in their habitats. Animals that generally live in warmer climates, such as the red fox, have moved onto the tundra and begun competing with Arctic species for territory and food.
Bibliography
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